[llvm-commits] [parallel] CVS: llvm/runtime/libpng/ANNOUNCE CHANGES INSTALL KNOWNBUG LICENSE LICENSE.TXT Makefile README TODO Y2KINFO configure example.c libpng.3 libpng.txt libpngpf.3 png.5 png.c png.h pngasmrd.h pngbar.jpg pngbar.png pngconf.h pngerror.c pnggccrd.c pngget.c pngmem.c pngnow.png pngpread.c pngread.c pngrio.c pngrtran.c pngrutil.c pngset.c pngtest.c pngtest.png pngtrans.c pngvcrd.c pngwio.c pngwrite.c pngwtran.c pngwutil.c

Misha Brukman brukman at cs.uiuc.edu
Mon Mar 1 18:19:58 PST 2004


Changes in directory llvm/runtime/libpng:

ANNOUNCE added (r1.1.2.1)
CHANGES added (r1.1.2.1)
INSTALL added (r1.1.2.1)
KNOWNBUG added (r1.1.2.1)
LICENSE added (r1.1.2.1)
LICENSE.TXT added (r1.1.2.1)
Makefile added (r1.2.2.1)
README added (r1.1.2.1)
TODO added (r1.1.2.1)
Y2KINFO added (r1.1.2.1)
configure added (r1.1.2.1)
example.c added (r1.1.2.1)
libpng.3 added (r1.1.2.1)
libpng.txt added (r1.1.2.1)
libpngpf.3 added (r1.1.2.1)
png.5 added (r1.1.2.1)
png.c added (r1.1.2.1)
png.h added (r1.1.2.1)
pngasmrd.h added (r1.1.2.1)
pngbar.jpg added (r1.1.2.1)
pngbar.png added (r1.1.2.1)
pngconf.h added (r1.1.2.1)
pngerror.c added (r1.1.2.1)
pnggccrd.c added (r1.1.2.1)
pngget.c added (r1.1.2.1)
pngmem.c added (r1.1.2.1)
pngnow.png added (r1.1.2.1)
pngpread.c added (r1.1.2.1)
pngread.c added (r1.1.2.1)
pngrio.c added (r1.1.2.1)
pngrtran.c added (r1.1.2.1)
pngrutil.c added (r1.1.2.1)
pngset.c added (r1.1.2.1)
pngtest.c added (r1.1.2.1)
pngtest.png added (r1.1.2.1)
pngtrans.c added (r1.1.2.1)
pngvcrd.c added (r1.1.2.1)
pngwio.c added (r1.1.2.1)
pngwrite.c added (r1.1.2.1)
pngwtran.c added (r1.1.2.1)
pngwutil.c added (r1.1.2.1)

---
Log message:

Merge from trunk

---
Diffs of the changes:  (+45272 -0)

Index: llvm/runtime/libpng/ANNOUNCE
diff -c /dev/null llvm/runtime/libpng/ANNOUNCE:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/ANNOUNCE	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,29 ----
+ 
+ Libpng 1.2.5 - October 3, 2002
+ 
+ This is a public release of libpng, intended for use in production codes.
+ 
+ Changes since the last public release (1.2.4):
+ 
+   Revised makefile.cygwin to use DLL number 12 instead of 13.
+   Added code to contrib/gregbook/readpng2.c to ignore unused chunks.
+   Replaced toucan.png in contrib/gregbook (it has been corrupt since 1.0.11)
+   Removed some stray *.o files from contrib/gregbook.
+   Changed png_error() to png_warning() about "Too much data" in pngpread.c
+     and about "Extra compressed data" in pngrutil.c.
+   Prevent png_ptr->pass from exceeding 7 in png_push_finish_row().
+   Updated makefile.hggcc
+   Updated png.c and pnggccrd.c handling of return from png_mmx_support()
+   Only issue png_warning() about "Too much data" in pngpread.c when avail_in
+     is nonzero.
+   Updated makefiles to install a separate libpng.so.3 with its own rpath.
+   Revised makefiles to not remove previous minor versions of shared libraries.
+   Revised 13 makefiles to remove "-lz" and "-L$(ZLIBLIB)", etc., from shared
+     library loader directive.
+   Revised libpng-config script.
+   Relocated two misplaced PNGAPI lines in pngtest.c
+ 
+ Send comments/corrections/commendations to
+ png-implement at ccrc.wustl.edu or to randeg at alum.rpi.edu
+ 
+ Glenn R-P


Index: llvm/runtime/libpng/CHANGES
diff -c /dev/null llvm/runtime/libpng/CHANGES:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/CHANGES	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,1184 ----
+ 
+ CHANGES - changes for libpng
+ 
+ version 0.2
+   added reader into png.h
+   fixed small problems in stub file
+ version 0.3
+   added pull reader
+   split up pngwrite.c to several files
+   added pnglib.txt
+   added example.c
+   cleaned up writer, adding a few new tranformations
+   fixed some bugs in writer
+   interfaced with zlib 0.5
+   added K&R support
+   added check for 64 KB blocks for 16 bit machines
+ version 0.4
+   cleaned up code and commented code
+   simplified time handling into png_time
+   created png_color_16 and png_color_8 to handle color needs
+   cleaned up color type defines
+   fixed various bugs
+   made various names more consistant
+   interfaced with zlib 0.71
+   cleaned up zTXt reader and writer (using zlib's Reset functions)
+   split transformations into pngrtran.c and pngwtran.c
+ version 0.5
+   interfaced with zlib 0.8
+   fixed many reading and writing bugs
+   saved using 3 spaces instead of tabs
+ version 0.6
+   added png_large_malloc() and png_large_free()
+   added png_size_t
+   cleaned up some compiler warnings
+   added png_start_read_image()
+ version 0.7
+   cleaned up lots of bugs
+   finished dithering and other stuff
+   added test program
+   changed name from pnglib to libpng
+ version 0.71 [June, 1995]
+   changed pngtest.png for zlib 0.93
+   fixed error in libpng.txt and example.c
+ version 0.8
+   cleaned up some bugs
+   added png_set_filler()
+   split up pngstub.c into pngmem.c, pngio.c, and pngerror.c
+   added #define's to remove unwanted code
+   moved png_info_init() to png.c
+   added old_size into png_realloc()
+   added functions to manually set filtering and compression info
+   changed compression parameters based on image type
+   optimized filter selection code
+   added version info
+   changed external functions passing floats to doubles (k&r problems?)
+   put all the configurable stuff in pngconf.h
+   enabled png_set_shift to work with paletted images on read
+   added png_read_update_info() - updates info structure with
+      transformations
+ version 0.81 [August, 1995]
+   incorporated Tim Wegner's medium model code (thanks, Tim)
+ version 0.82 [September, 1995]
+   [unspecified changes]
+ version 0.85 [December, 1995]
+   added more medium model code (almost everything's a far)
+   added i/o, error, and memory callback functions
+   fixed some bugs (16 bit, 4 bit interlaced, etc.)
+   added first run progressive reader (barely tested)
+ version 0.86 [January, 1996]
+   fixed bugs
+   improved documentation
+ version 0.87 [January, 1996]
+   fixed medium model bugs
+   fixed other bugs introduced in 0.85 and 0.86
+   added some minor documentation
+ version 0.88 [January, 1996]
+   fixed progressive bugs
+   replaced tabs with spaces
+   cleaned up documentation
+   added callbacks for read/write and warning/error functions
+ version 0.89 [July, 1996]
+   added new initialization API to make libpng work better with shared libs
+      we now have png_create_read_struct(), png_create_write_struct(),
+      png_create_info_struct(), png_destroy_read_struct(), and
+      png_destroy_write_struct() instead of the separate calls to
+      malloc and png_read_init(), png_info_init(), and png_write_init()
+   changed warning/error callback functions to fix bug - this means you
+      should use the new initialization API if you were using the old
+      png_set_message_fn() calls, and that the old API no longer exists
+      so that people are aware that they need to change their code
+   changed filter selection API to allow selection of multiple filters
+      since it didn't work in previous versions of libpng anyways
+   optimized filter selection code
+   fixed png_set_background() to allow using an arbitrary RGB color for
+      paletted images
+   fixed gamma and background correction for paletted images, so
+      png_correct_palette is not needed unless you are correcting an
+      external palette (you will need to #define PNG_CORRECT_PALETTE_SUPPORTED
+      in pngconf.h) - if nobody uses this, it may disappear in the future.
+   fixed bug with Borland 64K memory allocation (Alexander Lehmann)
+   fixed bug in interlace handling (Smarasderagd, I think)
+   added more error checking for writing and image to reduce invalid files
+   separated read and write functions so that they won't both be linked
+      into a binary when only reading or writing functionality is used
+   new pngtest image also has interlacing and zTXt
+   updated documentation to reflect new API
+ version 0.90 [January, 1997]
+   made CRC errors/warnings on critical and ancillary chunks configurable
+   libpng will use the zlib CRC routines by (compile-time) default
+   changed DOS small/medium model memory support - needs zlib 1.04 (Tim Wegner)
+   added external C++ wrapper statements to png.h (Gilles Dauphin)
+   allow PNG file to be read when some or all of file signature has already
+      been read from the beginning of the stream.  ****This affects the size
+      of info_struct and invalidates all programs that use a shared libpng****
+   fixed png_filler() declarations
+   fixed? background color conversions
+   fixed order of error function pointers to match documentation
+   current chunk name is now available in png_struct to reduce the number
+      of nearly identical error messages (will simplify multi-lingual
+      support when available)
+   try to get ready for unknown-chunk callback functions:
+      - previously read critical chunks are flagged, so the chunk handling
+        routines can determine if the chunk is in the right place
+      - all chunk handling routines have the same prototypes, so we will
+        be able to handle all chunks via a callback mechanism
+   try to fix Linux "setjmp" buffer size problems
+   removed png_large_malloc, png_large_free, and png_realloc functions.
+ version 0.95 [March, 1997]
+   fixed bug in pngwutil.c allocating "up_row" twice and "avg_row" never
+   fixed bug in PNG file signature compares when start != 0
+   changed parameter type of png_set_filler(...filler...) from png_byte
+      to png_uint_32
+   added test for MACOS to ensure that both math.h and fp.h are not #included
+   added macros for libpng to be compiled as a Windows DLL (Andreas Kupries)
+   added "packswap" transformation, which changes the endianness of
+      packed-pixel bytes (Kevin Bracey)
+   added "strip_alpha" transformation, which removes the alpha channel of
+      input images without using it (not neccesarily a good idea)
+   added "swap_alpha" transformation, which puts the alpha channel in front
+      of the color bytes instead of after
+   removed all implicit variable tests which assume NULL == 0 (I think)
+   changed several variables to "png_size_t" to show 16/32-bit limitations
+   added new pCAL chunk read/write support
+   added experimental filter selection weighting (Greg Roelofs)
+   removed old png_set_rgbx() and png_set_xrgb() functions that have been
+      obsolete for about 2 years now (use png_set_filler() instead)
+   added macros to read 16- and 32-bit ints directly from buffer, to be
+      used only on those systems that support it (namely PowerPC and 680x0)
+      With some testing, this may become the default for MACOS/PPC systems.
+   only calculate CRC on data if we are going to use it
+   added macros for zTXt compression type PNG_zTXt_COMPRESSION_???
+   added macros for simple libpng debugging output selectable at compile time
+   removed PNG_READ_END_MODE in progressive reader (Smarasderagd)
+   more description of info_struct in libpng.txt and png.h
+   more instructions in example.c
+   more chunk types tested in pngtest.c
+   renamed pngrcb.c to pngset.c, and all png_read_<chunk> functions to be
+      png_set_<chunk>.  We now have corresponding png_get_<chunk>
+      functions in pngget.c to get infomation in info_ptr.  This isolates
+      the application from the internal organization of png_info_struct
+      (good for shared library implementations).
+ version 0.96 [May, 1997]
+   fixed serious bug with < 8bpp images introduced in 0.95
+   fixed 256-color transparency bug (Greg Roelofs)
+   fixed up documentation (Greg Roelofs, Laszlo Nyul)
+   fixed "error" in pngconf.h for Linux setjmp() behaviour
+   fixed DOS medium model support (Tim Wegner)
+   fixed png_check_keyword() for case with error in static string text
+   added read of CRC after IEND chunk for embedded PNGs (Laszlo Nyul)
+   added typecasts to quiet compiler errors
+   added more debugging info
+ version 0.97 [January, 1998]
+   removed PNG_USE_OWN_CRC capability
+   relocated png_set_crc_action from pngrutil.c to pngrtran.c
+   fixed typecasts of "new_key", etc. (Andreas Dilger)
+   added RFC 1152 [sic] date support
+   fixed bug in gamma handling of 4-bit grayscale
+   added 2-bit grayscale gamma handling (Glenn R-P)
+   added more typecasts. 65536L becomes (png_uint_32)65536L, etc. (Glenn R-P)
+   minor corrections in libpng.txt
+   added simple sRGB support (Glenn R-P)
+   easier conditional compiling, e.g. define PNG_READ/WRITE_NOT_FULLY_SUPPORTED;
+      all configurable options can be selected from command-line instead
+      of having to edit pngconf.h (Glenn R-P)
+   fixed memory leak in pngwrite.c (free info_ptr->text) (Glenn R-P)
+   added more conditions for png_do_background, to avoid changing
+      black pixels to background when a background is supplied and
+      no pixels are transparent
+   repaired PNG_NO_STDIO behaviour
+   tested NODIV support and made it default behaviour (Greg Roelofs)
+   added "-m" option and PNGTEST_DEBUG_MEMORY to pngtest (John Bowler)
+   regularized version numbering scheme and bumped shared-library major
+      version number to 2 to avoid problems with libpng 0.89 apps (Greg Roelofs)
+ version 0.98 [January, 1998]
+   cleaned up some typos in libpng.txt and in code documentation
+   fixed memory leaks in pCAL chunk processing (Glenn R-P and John Bowler)
+   cosmetic change "display_gamma" to "screen_gamma" in pngrtran.c
+   changed recommendation about file_gamma for PC images to .51 from .45,
+      in example.c and libpng.txt, added comments to distinguish between
+      screen_gamma, viewing_gamma, and display_gamma.
+   changed all references to RFC1152 to read RFC1123 and changed the
+      PNG_TIME_RFC1152_SUPPORTED macro to PNG_TIME_RFC1123_SUPPORTED
+   added png_invert_alpha capability (Glenn R-P -- suggestion by Jon Vincent)
+   changed srgb_intent from png_byte to int to avoid compiler bugs
+ version 0.99 [January 30, 1998]
+   free info_ptr->text instead of end_info_ptr->text in pngread.c (John Bowler)
+   fixed a longstanding "packswap" bug in pngtrans.c
+   fixed some inconsistencies in pngconf.h that prevented compiling with
+      PNG_READ_GAMMA_SUPPORTED and PNG_READ_hIST_SUPPORTED undefined
+   fixed some typos and made other minor rearrangement of libpng.txt (Andreas)
+   changed recommendation about file_gamma for PC images to .50 from .51 in
+      example.c and libpng.txt, and changed file_gamma for sRGB images to .45
+   added a number of functions to access information from the png structure
+      png_get_image_height(), etc. (Glenn R-P, suggestion by Brad Pettit)
+   added TARGET_MACOS similar to zlib-1.0.8
+   define PNG_ALWAYS_EXTERN when __MWERKS__ && WIN32 are defined
+   added type casting to all png_malloc() function calls
+ version 0.99a [January 31, 1998]
+   Added type casts and parentheses to all returns that return a value.(Tim W.)
+ version 0.99b [February 4, 1998]
+   Added type cast png_uint_32 on malloc function calls where needed.
+   Changed type of num_hist from png_uint_32 to int (same as num_palette).
+   Added checks for rowbytes overflow, in case png_size_t is less than 32 bits.
+   Renamed makefile.elf to makefile.lnx.
+ version 0.99c [February 7, 1998]
+   More type casting.  Removed erroneous overflow test in pngmem.c.
+   Added png_buffered_memcpy() and png_buffered_memset(), apply them to rowbytes.
+   Added UNIX manual pages libpng.3 (incorporating libpng.txt) and  png.5.
+ version 0.99d [February 11, 1998]
+   Renamed "far_to_near()" "png_far_to_near()"
+   Revised libpng.3
+   Version 99c "buffered" operations didn't work as intended.  Replaced them
+     with png_memcpy_check() and png_memset_check().
+   Added many "if (png_ptr == NULL) return" to quell compiler warnings about
+     unused png_ptr, mostly in pngget.c and pngset.c.
+   Check for overlength tRNS chunk present when indexed-color PLTE is read.
+   Cleaned up spelling errors in libpng.3/libpng.txt
+   Corrected a problem with png_get_tRNS() which returned undefined trans array
+ version 0.99e [February 28, 1998]
+   Corrected png_get_tRNS() again.
+   Add parentheses for easier reading of pngget.c, fixed "||" should be "&&".
+   Touched up example.c to make more of it compileable, although the entire
+     file still can't be compiled (Willem van Schaik)
+   Fixed a bug in png_do_shift() (Bryan Tsai)
+   Added a space in png.h prototype for png_write_chunk_start()
+   Replaced pngtest.png with one created with zlib 1.1.1
+   Changed pngtest to report PASS even when file size is different (Jean-loup G.)
+   Corrected some logic errors in png_do_invert_alpha() (Chris Patterson)
+ version 0.99f [March 5, 1998]
+   Corrected a bug in pngpread() introduced in version 99c (Kevin Bracey)
+   Moved makefiles into a "scripts" directory, and added INSTALL instruction file
+   Added makefile.os2 and pngos2.def (A. Zabolotny) and makefile.s2x (W. Sebok)
+   Added pointers to "note on libpng versions" in makefile.lnx and README
+   Added row callback feature when reading and writing nonprogressive rows
+      and added a test of this feature in pngtest.c
+   Added user transform callbacks, with test of the feature in pngtest.c
+ version 0.99g [March 6, 1998, morning]
+   Minor changes to pngtest.c to suppress compiler warnings.
+   Removed "beta" language from documentation.
+ version 0.99h [March 6, 1998, evening]
+   Minor changes to previous minor changes to pngtest.c
+   Changed PNG_READ_NOT_FULLY_SUPPORTED to PNG_READ_TRANSFORMS_NOT_SUPPORTED
+   and added PNG_PROGRESSIVE_READ_NOT_SUPPORTED macro
+   Added user transform capability
+ version 1.00 [March 7, 1998]
+   Changed several typedefs in pngrutil.c
+   Added makefile.wat (Pawel Mrochen), updated makefile.tc3 (Willem van Schaik)
+   replaced "while(1)" with "for(;;)"
+   added PNGARG() to prototypes in pngtest.c and removed some prototypes
+   updated some of the makefiles (Tom Lane)
+   changed some typedefs (s_start, etc.) in pngrutil.c
+   fixed dimensions of "short_months" array in pngwrite.c
+   Replaced ansi2knr.c with the one from jpeg-v6
+ version 1.0.0 [March 8, 1998]
+   Changed name from 1.00 to 1.0.0 (Adam Costello)
+   Added smakefile.ppc (with SCOPTIONS.ppc) for Amiga PPC (Andreas Kleinert)
+ version 1.0.0a [March 9, 1998]
+   Fixed three bugs in pngrtran.c to make gamma+background handling consistent
+   (Greg Roelofs)
+   Changed format of the PNG_LIBPNG_VER integer to xyyzz instead of xyz
+   for major, minor, and bugfix releases.  This is 10001. (Adam Costello,
+   Tom Lane)
+   Make months range from 1-12 in png_convert_to_rfc1123
+ version 1.0.0b [March 13, 1998]
+   Quieted compiler complaints about two empty "for" loops in pngrutil.c
+   Minor changes to makefile.s2x
+   Removed #ifdef/#endif around a png_free() in pngread.c
+ version 1.0.1 [March 14, 1998]
+   Changed makefile.s2x to reduce security risk of using a relative pathname
+   Fixed some typos in the documentation (Greg).
+   Fixed a problem with value of "channels" returned by png_read_update_info()
+ version 1.0.1a [April 21, 1998]
+   Optimized Paeth calculations by replacing abs() function calls with intrinsics
+   plus other loop optimizations. Improves avg decoding speed by about 20%.
+   Commented out i386istic "align" compiler flags in makefile.lnx.
+   Reduced the default warning level in some makefiles, to make them consistent.
+   Removed references to IJG and JPEG in the ansi2knr.c copyright statement.
+   Fixed a bug in png_do_strip_filler with XXRRGGBB => RRGGBB transformation.
+   Added grayscale and 16-bit capability to png_do_read_filler().
+   Fixed a bug in pngset.c, introduced in version 0.99c, that sets rowbytes
+     too large when writing an image with bit_depth < 8 (Bob Dellaca).
+   Corrected some bugs in the experimental weighted filtering heuristics.
+   Moved a misplaced pngrutil code block that truncates tRNS if it has more
+     than num_palette entries -- test was done before num_palette was defined.
+   Fixed a png_convert_to_rfc1123() bug that converts day 31 to 0 (Steve Eddins).
+   Changed compiler flags in makefile.wat for better optimization (Pawel Mrochen).
+ version 1.0.1b [May 2, 1998]
+   Relocated png_do_gray_to_rgb() within png_do_read_transformations() (Greg).
+   Relocated the png_composite macros from pngrtran.c to png.h (Greg).
+   Added makefile.sco (contributed by Mike Hopkirk).
+   Fixed two bugs (missing definitions of "istop") introduced in libpng-1.0.1a.
+   Fixed a bug in pngrtran.c that would set channels=5 under some circumstances.
+   More work on the Paeth-filtering, achieving imperceptible speedup (A Kleinert).
+   More work on loop optimization which may help when compiled with C++ compilers.
+   Added warnings when people try to use transforms they've defined out.
+   Collapsed 4 "i" and "c" loops into single "i" loops in pngrtran and pngwtran.
+   Revised paragraph about png_set_expand() in libpng.txt and libpng.3 (Greg)
+ version 1.0.1c [May 11, 1998]
+   Fixed a bug in pngrtran.c (introduced in libpng-1.0.1a) where the masks for
+     filler bytes should have been 0xff instead of 0xf.
+   Added max_pixel_depth=32 in pngrutil.c when using FILLER with palette images.
+   Moved PNG_WRITE_WEIGHTED_FILTER_SUPPORTED and PNG_WRITE_FLUSH_SUPPORTED
+     out of the PNG_WRITE_TRANSFORMS_NOT_SUPPORTED block of pngconf.h
+   Added "PNG_NO_WRITE_TRANSFORMS" etc., as alternatives for *_NOT_SUPPORTED,
+     for consistency, in pngconf.h
+   Added individual "ifndef PNG_NO_[CAPABILITY]" in pngconf.h to make it easier
+     to remove unwanted capabilities via the compile line
+   Made some corrections to grammar (which, it's) in documentation (Greg).
+   Corrected example.c, use of row_pointers in png_write_image().
+ version 1.0.1d [May 24, 1998]
+   Corrected several statements that used side effects illegally in pngrutil.c
+     and pngtrans.c, that were introduced in version 1.0.1b
+   Revised png_read_rows() to avoid repeated if-testing for NULL (A Kleinert)
+   More corrections to example.c, use of row_pointers in png_write_image()
+     and png_read_rows().
+   Added pngdll.mak and pngdef.pas to scripts directory, contributed by
+     Bob Dellaca, to make a png32bd.dll with Borland C++ 4.5
+   Fixed error in example.c with png_set_text: num_text is 3, not 2 (Guido V.)
+   Changed several loops from count-down to count-up, for consistency.
+ version 1.0.1e [June 6, 1998]
+   Revised libpng.txt and libpng.3 description of png_set_read|write_fn(), and
+     added warnings when people try to set png_read_fn and png_write_fn in
+     the same structure.
+   Added a test such that png_do_gamma will be done when num_trans==0
+     for truecolor images that have defined a background.  This corrects an
+     error that was introduced in libpng-0.90 that can cause gamma processing
+     to be skipped.
+   Added tests in png.h to include "trans" and "trans_values" in structures
+     when PNG_READ_BACKGROUND_SUPPORTED or PNG_READ_EXPAND_SUPPORTED is defined.
+   Add png_free(png_ptr->time_buffer) in png_destroy_read_struct()
+   Moved png_convert_to_rfc_1123() from pngwrite.c to png.c
+   Added capability for user-provided malloc_fn() and free_fn() functions,
+     and revised pngtest.c to demonstrate their use, replacing the
+     PNGTEST_DEBUG_MEM feature.
+   Added makefile.w32, for Microsoft C++ 4.0 and later (Tim Wegner).
+ version 1.0.2 [June 14, 1998]
+   Fixed two bugs in makefile.bor .
+ version 1.0.2a [December 30, 1998]
+   Replaced and extended code that was removed from png_set_filler() in 1.0.1a.
+   Fixed a bug in png_do_filler() that made it fail to write filler bytes in
+     the left-most pixel of each row (Kevin Bracey).
+   Changed "static pngcharp tIME_string" to "static char tIME_string[30]"
+     in pngtest.c (Duncan Simpson).
+   Fixed a bug in pngtest.c that caused pngtest to try to write a tIME chunk
+     even when no tIME chunk was present in the source file.
+   Fixed a problem in pngrutil.c: gray_to_rgb didn't always work with 16-bit.
+   Fixed a problem in png_read_push_finish_row(), which would not skip some
+     passes that it should skip, for images that are less than 3 pixels high.
+   Interchanged the order of calls to png_do_swap() and png_do_shift()
+     in pngwtran.c (John Cromer).
+   Added #ifdef PNG_DEBUG/#endif surrounding use of PNG_DEBUG in png.h .
+   Changed "bad adaptive filter type" from error to warning in pngrutil.c .
+   Fixed a documentation error about default filtering with 8-bit indexed-color.
+   Separated the PNG_NO_STDIO macro into PNG_NO_STDIO and PNG_NO_CONSOLE_IO
+     (L. Peter Deutsch).
+   Added png_set_rgb_to_gray() and png_get_rgb_to_gray_status() functions.
+   Added png_get_copyright() and png_get_header_version() functions.
+   Revised comments on png_set_progressive_read_fn() in libpng.txt and example.c
+   Added information about debugging in libpng.txt and libpng.3 .
+   Changed "ln -sf" to "ln -s -f" in makefile.s2x, makefile.lnx, and makefile.sco.
+   Removed lines after Dynamic Dependencies" in makefile.aco .
+   Revised makefile.dec to make a shared library (Jeremie Petit).
+   Removed trailing blanks from all files.
+ version 1.0.2a [January 6, 1999]
+   Removed misplaced #endif and #ifdef PNG_NO_EXTERN near the end of png.h
+   Added "if" tests to silence complaints about unused png_ptr in png.h and png.c
+   Changed "check_if_png" function in example.c to return true (nonzero) if PNG.
+   Changed libpng.txt to demonstrate png_sig_cmp() instead of png_check_sig()
+     which is obsolete.
+ version 1.0.3 [January 14, 1999]
+   Added makefile.hux, for Hewlett Packard HPUX 10.20 and 11.00 (Jim Rice)
+   Added a statement of Y2K compliance in png.h, libpng.3, and Y2KINFO.
+ version 1.0.3a [August 12, 1999]
+   Added check for PNG_READ_INTERLACE_SUPPORTED in pngread.c; issue a warning
+      if an attempt is made to read an interlaced image when it's not supported.
+   Added check if png_ptr->trans is defined before freeing it in pngread.c
+   Modified the Y2K statement to include versions back to version 0.71
+   Fixed a bug in the check for valid IHDR bit_depth/color_types in pngrutil.c
+   Modified makefile.wat (added -zp8 flag, ".symbolic", changed some comments)
+   Replaced leading blanks with tab characters in makefile.hux
+   Changed "dworkin.wustl.edu" to "ccrc.wustl.edu" in various documents.
+   Changed (float)red and (float)green to (double)red, (double)green
+      in png_set_rgb_to_gray() to avoid "promotion" problems in AIX.
+   Fixed a bug in pngconf.h that omitted <stdio.h> when PNG_DEBUG==0 (K Bracey).
+   Reformatted libpng.3 and libpngpf.3 with proper fonts (script by J. vanZandt).
+   Updated documentation to refer to the PNG-1.2 specification.
+   Removed ansi2knr.c and left pointers to the latest source for ansi2knr.c
+     in makefile.knr, INSTALL, and README (L. Peter Deutsch)
+   Fixed bugs in calculation of the length of rowbytes when adding alpha
+     channels to 16-bit images, in pngrtran.c (Chris Nokleberg)
+   Added function png_set_user_transform_info() to store user_transform_ptr,
+     user_depth, and user_channels into the png_struct, and a function
+     png_get_user_transform_ptr() to retrieve the pointer (Chris Nokleberg)
+   Added function png_set_empty_plte_permitted() to make libpng useable
+     in MNG applications.
+   Corrected the typedef for png_free_ptr in png.h (Jesse Jones).
+   Correct gamma with srgb is 45455 instead of 45000 in pngrutil.c, to be
+     consistent with PNG-1.2, and allow variance of 500 before complaining.
+   Added assembler code contributed by Intel in file pngvcrd.c and modified
+     makefile.w32 to use it (Nirav Chhatrapati, INTEL Corporation, Gilles Vollant)
+   Changed "ln -s -f" to "ln -f -s" in the makefiles to make Solaris happy.
+   Added some aliases for png_set_expand() in pngrtran.c, namely
+     png_set_expand_PLTE(), png_set_expand_depth(), and png_set_expand_tRNS()
+     (Greg Roelofs, in "PNG: The Definitive Guide").
+   Added makefile.beo for BEOS on X86, contributed by Sander Stok.
+ version 1.0.3b [August 26, 1999]
+   Replaced 2147483647L several places with PNG_MAX_UINT macro, defined in png.h
+   Changed leading blanks to tabs in all makefiles.
+   Define PNG_USE_PNGVCRD in makefile.w32, to get MMX assembler code.
+   Made alternate versions of  png_set_expand() in pngrtran.c, namely
+     png_set_gray_1_2_4_to_8, png_set_palette_to_rgb, and png_set_tRNS_to_alpha
+     (Greg Roelofs, in "PNG: The Definitive Guide").  Deleted the 1.0.3a aliases.
+   Relocated start of 'extern "C"' block in png.h so it doesn't include pngconf.h
+   Revised calculation of num_blocks in pngmem.c to avoid a potentially
+     negative shift distance, whose results are undefined in the C language.
+   Added a check in pngset.c to prevent writing multiple tIME chunks.
+   Added a check in pngwrite.c to detect invalid small window_bits sizes.
+ version 1.0.3d [September 4, 1999]
+   Fixed type casting of igamma in pngrutil.c
+   Added new png_expand functions to scripts/pngdef.pas and pngos2.def
+   Added a demo read_user_transform_fn that examines the row filters in pngtest.c
+ version 1.0.4 [September 24, 1999]
+   Define PNG_ALWAYS_EXTERN in pngconf.h if __STDC__ is defined
+   Delete #define PNG_INTERNAL and include "png.h" from pngasmrd.h
+   Made several minor corrections to pngtest.c
+   Renamed the makefiles with longer but more user friendly extensions.
+   Copied the PNG copyright and license to a separate LICENSE file.
+   Revised documentation, png.h, and example.c to remove reference to
+     "viewing_gamma" which no longer appears in the PNG specification.
+   Revised pngvcrd.c to use MMX code for interlacing only on the final pass.
+   Updated pngvcrd.c to use the faster C filter algorithms from libpng-1.0.1a
+   Split makefile.win32vc into two versions, makefile.vcawin32 (uses MMX
+     assembler code) and makefile.vcwin32 (doesn't).
+   Added a CPU timing report to pngtest.c (enabled by defining PNGTEST_TIMING)
+   Added a copy of pngnow.png to the distribution.
+ version 1.0.4a [September 25, 1999]
+   Increase max_pixel_depth in pngrutil.c if a user transform needs it.
+   Changed several division operations to right-shifts in pngvcrd.c
+ version 1.0.4b [September 30, 1999]
+   Added parentheses in line 3732 of pngvcrd.c
+   Added a comment in makefile.linux warning about buggy -O3 in pgcc 2.95.1
+ version 1.0.4c [October 1, 1999]
+   Added a "png_check_version" function in png.c and pngtest.c that will generate
+     a helpful compiler error if an old png.h is found in the search path.
+   Changed type of png_user_transform_depth|channels from int to png_byte.
+ version 1.0.4d [October 6, 1999]
+   Changed 0.45 to 0.45455 in png_set_sRGB()
+   Removed unused PLTE entries from pngnow.png
+   Re-enabled some parts of pngvcrd.c (png_combine_row) that work properly.
+ version 1.0.4e [October 10, 1999]
+   Fixed sign error in pngvcrd.c (Greg Roelofs)
+   Replaced some instances of memcpy with simple assignments in pngvcrd (GR-P)
+ version 1.0.4f [October 15, 1999]
+   Surrounded example.c code with #if 0 .. #endif to prevent people from
+     inadvertently trying to compile it.
+   Changed png_get_header_version() from a function to a macro in png.h
+   Added type casting mostly in pngrtran.c and pngwtran.c
+   Removed some pointless "ptr = NULL" in pngmem.c
+   Added a "contrib" directory containing the source code from Greg's book.
+ version 1.0.5 [October 15, 1999]
+   Minor editing of the INSTALL and README files.
+ version 1.0.5a [October 23, 1999]
+   Added contrib/pngsuite and contrib/pngminus (Willem van Schaik)
+   Fixed a typo in the png_set_sRGB() function call in example.c (Jan Nijtmans)
+   Further optimization and bugfix of pngvcrd.c
+   Revised pngset.c so that it does not allocate or free memory in the user's
+     text_ptr structure.  Instead, it makes its own copy.
+   Created separate write_end_info_struct in pngtest.c for a more severe test.
+   Added code in pngwrite.c to free info_ptr->text[i].key to stop a memory leak.
+ version 1.0.5b [November 23, 1999]
+   Moved PNG_FLAG_HAVE_CHUNK_HEADER, PNG_FLAG_BACKGROUND_IS_GRAY and
+     PNG_FLAG_WROTE_tIME from flags to mode.
+   Added png_write_info_before_PLTE() function.
+   Fixed some typecasting in contrib/gregbook/*.c
+   Updated scripts/makevms.com and added makevms.com to contrib/gregbook
+     and contrib/pngminus (Martin Zinser)
+ version 1.0.5c [November 26, 1999]
+   Moved png_get_header_version from png.h to png.c, to accomodate ansi2knr.
+   Removed all global arrays (according to PNG_NO_GLOBAL_ARRAYS macro), to
+     accomodate making DLL's: Moved usr_png_ver from global variable to function
+     png_get_header_ver() in png.c.  Moved png_sig to png_sig_bytes in png.c and
+     eliminated use of png_sig in pngwutil.c.  Moved the various png_CHNK arrays
+     into pngtypes.h.  Eliminated use of global png_pass arrays.  Declared the
+     png_CHNK and png_pass arrays to be "const".  Made the global arrays
+     available to applications (although none are used in libpng itself) when
+     PNG_NO_GLOBAL_ARRAYS is not defined or when PNG_GLOBAL_ARRAYS is defined.
+   Removed some extraneous "-I" from contrib/pngminus/makefile.std
+   Changed the PNG_sRGB_INTENT macros in png.h to be consistent with PNG-1.2.
+   Change PNG_SRGB_INTENT to PNG_sRGB_INTENT in libpng.txt and libpng.3
+ version 1.0.5d [November 29, 1999]
+   Add type cast (png_const_charp) two places in png.c
+   Eliminated pngtypes.h; use macros instead to declare PNG_CHNK arrays.
+   Renamed "PNG_GLOBAL_ARRAYS" to "PNG_USE_GLOBAL_ARRAYS" and made available
+     to applications a macro "PNG_USE_LOCAL_ARRAYS".
+   #ifdef out all the new declarations when PNG_USE_GLOBAL_ARRAYS is defined.
+   Added PNG_EXPORT_VAR macro to accommodate making DLL's.
+ version 1.0.5e [November 30, 1999]
+   Added iCCP, iTXt, and sPLT support; added "lang" member to the png_text
+     structure; refactored the inflate/deflate support to make adding new chunks
+     with trailing compressed parts easier in the future, and added new functions
+     png_free_iCCP, png_free_pCAL, png_free_sPLT, png_free_text, png_get_iCCP,
+     png_get_spalettes, png_set_iCCP, png_set_spalettes (Eric S. Raymond).
+   NOTE: Applications that write text chunks MUST define png_text->lang
+     before calling png_set_text(). It must be set to NULL if you want to
+     write tEXt or zTXt chunks.  If you want your application to be able to
+     run with older versions of libpng, use
+ 
+       #ifdef PNG_iTXt_SUPPORTED
+          png_text[i].lang = NULL;
+       #endif
+ 
+   Changed png_get_oFFs() and png_set_oFFs() to use signed rather than unsigned
+     offsets (Eric S. Raymond).
+   Combined PNG_READ_cHNK_SUPPORTED and PNG_WRITE_cHNK_SUPPORTED macros into
+     PNG_cHNK_SUPPORTED and combined the three types of PNG_text_SUPPORTED
+     macros, leaving the separate macros also available.
+   Removed comments on #endifs at the end of many short, non-nested #if-blocks.
+ version 1.0.5f [December 6, 1999]
+   Changed makefile.solaris to issue a warning about potential problems when
+     the ucb "ld" is in the path ahead of the ccs "ld".
+   Removed "- [date]" from the "synopsis" line in libpng.3 and libpngpf.3.
+   Added sCAL chunk support (Eric S. Raymond).
+ version 1.0.5g [December 7, 1999]
+   Fixed "png_free_spallettes" typo in png.h
+   Added code to handle new chunks in pngpread.c
+   Moved PNG_CHNK string macro definitions outside of PNG_NO_EXTERN block
+   Added "translated_key" to png_text structure and png_write_iTXt().
+   Added code in pngwrite.c to work around a newly discovered zlib bug.
+ version 1.0.5h [December 10, 1999]
+   NOTE: regarding the note for version 1.0.5e, the following must also
+     be included in your code:
+         png_text[i].translated_key = NULL;
+   Unknown chunk handling is now supported.
+   Option to eliminate all floating point support was added.  Some new
+     fixed-point functions such as png_set_gAMA_fixed() were added.
+   Expanded tabs and removed trailing blanks in source files.
+ version 1.0.5i [December 13, 1999]
+   Added some type casts to silence compiler warnings.
+   Renamed "png_free_spalette" to "png_free_spalettes" for consistency.
+   Removed leading blanks from a #define in pngvcrd.c
+   Added some parameters to the new png_set_keep_unknown_chunks() function.
+   Added a test for up->location != 0 in the first instance of writing
+     unknown chunks in pngwrite.c
+   Changed "num" to "i" in png_free_spalettes() and png_free_unknowns() to
+     prevent recursion.
+   Added png_free_hIST() function.
+   Various patches to fix bugs in the sCAL and integer cHRM processing,
+     and to add some convenience macros for use with sCAL.
+ version 1.0.5j [December 21, 1999]
+   Changed "unit" parameter of png_write_sCAL from png_byte to int, to work
+     around buggy compilers.
+   Added new type "png_fixed_point" for integers that hold float*100000 values
+   Restored backward compatibility of tEXt/zTXt chunk processing:
+     Restored the first four members of png_text to the same order as v.1.0.5d.
+     Added members "lang_key" and "itxt_length" to png_text struct.  Set
+     text_length=0 when "text" contains iTXt data.  Use the "compression"
+     member to distinguish among tEXt/zTXt/iTXt types.  Added
+     PNG_ITXT_COMPRESSION_NONE (1) and PNG_ITXT_COMPRESSION_zTXt(2) macros.
+     The "Note" above, about backward incompatibility of libpng-1.0.5e, no
+     longer applies.
+   Fixed png_read|write_iTXt() to read|write parameters in the right order,
+     and to write the iTXt chunk after IDAT if it appears in the end_ptr.
+   Added pnggccrd.c, version of pngvcrd.c Intel assembler for gcc (Greg Roelofs)
+   Reversed the order of trying to write floating-point and fixed-point gAMA.
+ version 1.0.5k [December 27, 1999]
+   Added many parentheses, e.g., "if (a && b & c)" becomes "if (a && (b & c))"
+   Added png_handle_as_unknown() function (Glenn)
+   Added png_free_chunk_list() function and chunk_list and num_chunk_list members
+     of png_ptr.
+   Eliminated erroneous warnings about multiple sPLT chunks and sPLT-after-PLTE.
+   Fixed a libpng-1.0.5h bug in pngrutil.c that was issuing erroneous warnings
+     about ignoring incorrect gAMA with sRGB (gAMA was in fact not ignored)
+   Added png_free_tRNS(); png_set_tRNS() now malloc's its own trans array (ESR).
+   Define png_get_int_32 when oFFs chunk is supported as well as when pCAL is.
+   Changed type of proflen from png_int_32 to png_uint_32 in png_get_iCCP().
+ version 1.0.5l [January 1, 2000]
+   Added functions png_set_read_user_chunk_fn() and png_get_user_chunk_ptr()
+     for setting a callback function to handle unknown chunks and for
+     retrieving the associated user pointer (Glenn).
+ version 1.0.5m [January 7, 2000]
+   Added high-level functions png_read_png(), png_write_png(), png_free_pixels().
+ version 1.0.5n [January 9, 2000]
+   Added png_free_PLTE() function, and modified png_set_PLTE() to malloc its
+     own memory for info_ptr->palette.  This makes it safe for the calling
+     application to free its copy of the palette any time after it calls
+     png_set_PLTE().
+ version 1.0.5o [January 20, 2000]
+   Cosmetic changes only (removed some trailing blanks and TABs)
+ version 1.0.5p [January 31, 2000]
+   Renamed pngdll.mak to makefile.bd32
+   Cosmetic changes in pngtest.c
+ version 1.0.5q [February 5, 2000]
+   Relocated the makefile.solaris warning about PATH problems.
+   Fixed pngvcrd.c bug by pushing/popping registers in mmxsupport (Bruce Oberg)
+   Revised makefile.gcmmx
+   Added PNG_SETJMP_SUPPORTED, PNG_SETJMP_NOT_SUPPORTED, and PNG_ABORT() macros
+ version 1.0.5r [February 7, 2000]
+   Removed superfluous prototype for png_get_itxt from png.h
+   Fixed a bug in pngrtran.c that improperly expanded the background color.
+   Return *num_text=0 from png_get_text() when appropriate, and fix documentation
+     of png_get_text() in libpng.txt/libpng.3.
+ version 1.0.5s [February 18, 2000]
+   Added "png_jmp_env()" macro to pngconf.h, to help people migrate to the
+     new error handler that's planned for the next libpng release, and changed
+     example.c, pngtest.c, and contrib programs to use this macro.
+   Revised some of the DLL-export macros in pngconf.h (Greg Roelofs)
+   Fixed a bug in png_read_png() that caused it to fail to expand some images
+     that it should have expanded.
+   Fixed some mistakes in the unused and undocumented INCH_CONVERSIONS functions
+     in pngget.c
+   Changed the allocation of palette, history, and trans arrays back to
+     the version 1.0.5 method (linking instead of copying) which restores
+     backward compatibility with version 1.0.5.  Added some remarks about
+     that in example.c.  Added "free_me" member to info_ptr and png_ptr
+     and added png_free_data() function.
+   Updated makefile.linux and makefile.gccmmx to make directories conditionally.
+   Made cosmetic changes to pngasmrd.h
+   Added png_set_rows() and png_get_rows(), for use with png_read|write_png().
+   Modified png_read_png() to allocate info_ptr->row_pointers only if it
+     hasn't already been allocated.
+ version 1.0.5t [March 4, 2000]
+   Changed png_jmp_env() migration aiding macro to png_jmpbuf().
+   Fixed "interlace" typo (should be "interlaced") in contrib/gregbook/read2-x.c
+   Fixed bug with use of PNG_BEFORE_IHDR bit in png_ptr->mode, introduced when
+     PNG_FLAG_HAVE_CHUNK_HEADER was moved into png_ptr->mode in version 1.0.5b
+   Files in contrib/gregbook were revised to use png_jmpbuf() and to select
+     a 24-bit visual if one is available, and to allow abbreviated options.
+   Files in contrib/pngminus were revised to use the png_jmpbuf() macro.
+   Removed spaces in makefile.linux and makefile.gcmmx, introduced in 1.0.5s
+ version 1.0.5u [March 5, 2000]
+   Simplified the code that detects old png.h in png.c and pngtest.c
+   Renamed png_spalette (_p, _pp) to png_sPLT_t (_tp, _tpp)
+   Increased precision of rgb_to_gray calculations from 8 to 15 bits and
+     added png_set_rgb_to_gray_fixed() function.
+   Added makefile.bc32 (32-bit Borland C++, C mode)
+ version 1.0.5v [March 11, 2000]
+   Added some parentheses to the png_jmpbuf macro definition.
+   Updated references to the zlib home page, which has moved to freesoftware.com.
+   Corrected bugs in documentation regarding png_read_row() and png_write_row().
+   Updated documentation of png_rgb_to_gray calculations in libpng.3/libpng.txt.
+   Renamed makefile.borland,turboc3 back to makefile.bor,tc3 as in version 1.0.3,
+     revised borland makefiles; added makefile.ibmvac3 and makefile.gcc (Cosmin)
+ version 1.0.6 [March 20, 2000]
+   Minor revisions of makefile.bor, libpng.txt, and gregbook/rpng2-win.c
+   Added makefile.sggcc (SGI IRIX with gcc)
+ version 1.0.6d [April 7, 2000]
+   Changed sprintf() to strcpy() in png_write_sCAL_s() to work without STDIO
+   Added data_length parameter to png_decompress_chunk() function
+   Revised documentation to remove reference to abandoned png_free_chnk functions
+   Fixed an error in png_rgb_to_gray_fixed()
+   Revised example.c, usage of png_destroy_write_struct().
+   Renamed makefile.ibmvac3 to makefile.ibmc, added libpng.icc IBM project file
+   Added a check for info_ptr->free_me&PNG_FREE_TEXT when freeing text in png.c
+   Simplify png_sig_bytes() function to remove use of non-ISO-C strdup().
+ version 1.0.6e [April 9, 2000]
+   Added png_data_freer() function.
+   In the code that checks for over-length tRNS chunks, added check of
+     info_ptr->num_trans as well as png_ptr->num_trans (Matthias Benckmann)
+   Minor revisions of libpng.txt/libpng.3.
+   Check for existing data and free it if the free_me flag is set, in png_set_*()
+     and png_handle_*().
+   Only define PNG_WEIGHTED_FILTERS_SUPPORTED when PNG_FLOATING_POINT_SUPPORTED
+     is defined.
+   Changed several instances of PNG_NO_CONSOLE_ID to PNG_NO_STDIO in pngrutil.c
+     and mentioned the purposes of the two macros in libpng.txt/libpng.3.
+ version 1.0.6f [April 14, 2000]
+   Revised png_set_iCCP() and png_set_rows() to avoid prematurely freeing data.
+   Add checks in png_set_text() for NULL members of the input text structure.
+   Revised libpng.txt/libpng.3.
+   Removed superfluous prototype for png_set_itxt from png.h
+   Removed "else" from pngread.c, after png_error(), and changed "0" to "length".
+   Changed several png_errors about malformed ancillary chunks to png_warnings.
+ version 1.0.6g [April 24, 2000]
+   Added png_pass-* arrays to pnggccrd.c when PNG_USE_LOCAL_ARRAYS is defined.
+   Relocated paragraph about png_set_background() in libpng.3/libpng.txt
+     and other revisions (Matthias Benckmann)
+   Relocated info_ptr->free_me, png_ptr->free_me, and other info_ptr and
+     png_ptr members to restore binary compatibility with libpng-1.0.5
+     (breaks compatibility with libpng-1.0.6).
+ version 1.0.6h [April 24, 2000]
+   Changed shared library so-number pattern from 2.x.y.z to xy.z (this builds
+     libpng.so.10 & libpng.so.10.6h instead of libpng.so.2 & libpng.so.2.1.0.6h)
+     This is a temporary change for test purposes.
+ version 1.0.6i [May 2, 2000]
+   Rearranged some members at the end of png_info and png_struct, to put
+     unknown_chunks_num and free_me within the original size of the png_structs
+     and free_me, png_read_user_fn, and png_free_fn within the original png_info,
+     because some old applications allocate the structs directly instead of
+     using png_create_*().
+   Added documentation of user memory functions in libpng.txt/libpng.3
+   Modified png_read_png so that it will use user_allocated row_pointers
+     if present, unless free_me directs that it be freed, and added description
+     of the use of png_set_rows() and png_get_rows() in libpng.txt/libpng.3.
+   Added PNG_LEGACY_SUPPORTED macro, and #ifdef out all new (since version
+     1.00) members of png_struct and png_info, to regain binary compatibility
+     when you define this macro.  Capabilities lost in this event
+     are user transforms (new in version 1.0.0),the user transform pointer
+     (new in version 1.0.2), rgb_to_gray (new in 1.0.5), iCCP, sCAL, sPLT,
+     the high-level interface, and unknown chunks support (all new in 1.0.6).
+     This was necessary because of old applications that allocate the structs
+     directly as authors were instructed to do in libpng-0.88 and earlier,
+     instead of using png_create_*().
+   Added modes PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT which
+     can be used to detect codes that directly allocate the structs, and
+     code to check these modes in png_read_init() and png_write_init() and
+     generate a libpng error if the modes aren't set and PNG_LEGACY_SUPPORTED
+     was not defined.
+   Added makefile.intel and updated makefile.watcom (Pawel Mrochen)
+ version 1.0.6j [May 3, 2000]
+   Overloaded png_read_init() and png_write_init() with macros that convert
+     calls to png_read_init_2() or png_write_init_2() that check the version
+     and structure sizes.
+ version 1.0.7beta11 [May 7, 2000]
+   Removed the new PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT modes
+     which are no longer used.
+   Eliminated the three new members of png_text when PNG_LEGACY_SUPPORTED is
+     defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXT_SUPPORTED
+     is defined.
+   Made PNG_NO_READ|WRITE_iTXt the default setting, to avoid memory
+     overrun when old applications fill the info_ptr->text structure directly.
+   Added PNGAPI macro, and added it to the definitions of all exported functions.
+   Relocated version macro definitions ahead of the includes of zlib.h and
+     pngconf.h in png.h.
+ version 1.0.7beta12 [May 12, 2000]
+   Revised pngset.c to avoid a problem with expanding the png_debug macro.
+   Deleted some extraneous defines from pngconf.h
+   Made PNG_NO_CONSOLE_IO the default condition when PNG_BUILD_DLL is defined.
+   Use MSC _RPTn debugging instead of fprintf if _MSC_VER is defined.
+   Added png_access_version_number() function.
+   Check for mask&PNG_FREE_CHNK (for TEXT, SCAL, PCAL) in png_free_data().
+   Expanded libpng.3/libpng.txt information about png_data_freer().
+ version 1.0.7beta14 [May 17, 2000] (beta13 was not published)
+   Changed pnggccrd.c and pngvcrd.c to handle bad adaptive filter types as
+     warnings instead of errors, as pngrutil.c does.
+   Set the PNG_INFO_IDAT valid flag in png_set_rows() so png_write_png()
+     will actually write IDATs.
+   Made the default PNG_USE_LOCAL_ARRAYS depend on PNG_DLL instead of WIN32.
+   Make png_free_data() ignore its final parameter except when freeing data
+     that can have multiple instances (text, sPLT, unknowns).
+   Fixed a new bug in png_set_rows().
+   Removed info_ptr->valid tests from png_free_data(), as in version 1.0.5.
+   Added png_set_invalid() function.
+   Fixed incorrect illustrations of png_destroy_write_struct() in example.c.
+ version 1.0.7beta15 [May 30, 2000]
+   Revised the deliberately erroneous Linux setjmp code in pngconf.h to produce
+     fewer error messages.
+   Rearranged checks for Z_OK to check the most likely path first in pngpread.c
+     and pngwutil.c.
+   Added checks in pngtest.c for png_create_*() returning NULL, and mentioned
+     in libpng.txt/libpng.3 the need for applications to check this.
+   Changed names of png_default_*() functions in pngtest to pngtest_*().
+   Changed return type of png_get_x|y_offset_*() from png_uint_32 to png_int_32.
+   Fixed some bugs in the unused PNG_INCH_CONVERSIONS functions in pngget.c
+   Set each pointer to NULL after freeing it in png_free_data().
+   Worked around a problem in pngconf.h; AIX's strings.h defines an "index"
+     macro that conflicts with libpng's png_color_16.index. (Dimitri Papadapoulos)
+   Added "msvc" directory with MSVC++ project files (Simon-Pierre Cadieux).
+ version 1.0.7beta16 [June 4, 2000]
+   Revised the workaround of AIX string.h "index" bug.
+   Added a check for overlength PLTE chunk in pngrutil.c.
+   Added PNG_NO_POINTER_INDEXING macro to use array-indexing instead of pointer
+     indexing in pngrutil.c and pngwutil.c to accommodate a buggy compiler.
+   Added a warning in png_decompress_chunk() when it runs out of data, e.g.
+     when it tries to read an erroneous PhotoShop iCCP chunk.
+   Added PNG_USE_DLL macro.
+   Revised the copyright/disclaimer/license notice.
+   Added contrib/msvctest directory
+ version 1.0.7rc1 [June 9, 2000]
+   Corrected the definition of PNG_TRANSFORM_INVERT_ALPHA  (0x0400 not 0x0200)
+   Added contrib/visupng directory (Willem van Schaik)
+ version 1.0.7beta18 [June 23, 2000]
+   Revised PNGAPI definition, and pngvcrd.c to work with __GCC__
+     and do not redefine PNGAPI if it is passed in via a compiler directive.
+   Revised visupng/PngFile.c to remove returns from within the Try block.
+   Removed leading underscores from "_PNG_H" and "_PNG_SAVE_BSD_SOURCE" macros.
+   Updated contrib/visupng/cexcept.h to version 1.0.0.
+   Fixed bugs in pngwrite.c and pngwutil.c that prevented writing iCCP chunks.
+ version 1.0.7rc2 [June 28, 2000]
+   Updated license to include disclaimers required by UCITA.
+   Fixed "DJBPP" typo in pnggccrd.c introduced in beta18.
+ version 1.0.7 [July 1, 2000]
+   Revised the definition of "trans_values" in libpng.3/libpng.txt
+ version 1.0.8beta1 [July 8, 2000]
+   Added png_free(png_ptr, key) two places in pngpread.c to stop memory leaks.
+   Changed PNG_NO_STDIO to PNG_NO_CONSOLE_IO, several places in pngrutil.c and
+      pngwutil.c.
+   Changed PNG_EXPORT_VAR to use PNG_IMPEXP, in pngconf.h.
+   Removed unused "#include <assert.h>" from png.c
+   Added WindowsCE support.
+   Revised pnggccrd.c to work with gcc-2.95.2 and in the Cygwin environment.
+ version 1.0.8beta2 [July 10, 2000]
+   Added project files to the wince directory and made further revisions
+      of pngtest.c, pngrio.c, and pngwio.c in support of WindowsCE.
+ version 1.0.8beta3 [July 11, 2000]
+   Only set the PNG_FLAG_FREE_TRNS or PNG_FREE_TRNS flag in png_handle_tRNS()
+      for indexed-color input files to avoid potential double-freeing trans array
+      under some unusual conditions; problem was introduced in version 1.0.6f.
+   Further revisions to pngtest.c and files in the wince subdirectory.
+ version 1.0.8beta4 [July 14, 2000]
+   Added the files pngbar.png and pngbar.jpg to the distribution.
+   Added makefile.cygwin, and cygwin support in pngconf.h
+   Added PNG_NO_ZALLOC_ZERO macro (makes png_zalloc skip zeroing memory)
+ version 1.0.8rc1 [July 16, 2000]
+   Revised png_debug() macros and statements to eliminate compiler warnings.
+ version 1.0.8 [July 24, 2000]
+   Added png_flush() in pngwrite.c, after png_write_IEND().
+   Updated makefile.hpux to build a shared library.
+ version 1.0.9beta1 [November 10, 2000]
+   Fixed typo in scripts/makefile.hpux
+   Updated makevms.com in scripts and contrib/* and contrib/* (Martin Zinser)
+   Fixed seqence-point bug in contrib/pngminus/png2pnm (Martin Zinser)
+   Changed "cdrom.com" in documentation to "libpng.org"
+   Revised pnggccrd.c to get it all working, and updated makefile.gcmmx (Greg).
+   Changed type of "params" from voidp to png_voidp in png_read|write_png().
+   Make sure PNGAPI and PNG_IMPEXP are defined in pngconf.h.
+   Revised the 3 instances of WRITEFILE in pngtest.c.
+   Relocated "msvc" and "wince" project subdirectories into "dll" subdirectory.
+   Updated png.rc in dll/msvc project
+   Revised makefile.dec to define and use LIBPATH and INCPATH
+   Increased size of global png_libpng_ver[] array from 12 to 18 chars.
+   Made global png_libpng_ver[], png_sig[] and png_pass_*[] arrays const.
+   Removed duplicate png_crc_finish() from png_handle_bKGD() function.
+   Added a warning when application calls png_read_update_info() multiple times.
+   Revised makefile.cygwin
+   Fixed bugs in iCCP support in pngrutil.c and pngwutil.c.
+   Replaced png_set_empty_plte_permitted() with png_permit_mng_features().
+ version 1.0.9beta2 [November 19, 2000]
+   Renamed the "dll" subdirectory "projects".
+   Added borland project files to "projects" subdirectory.
+   Set VS_FF_PRERELEASE and VS_FF_PATCHED flags in msvc/png.rc when appropriate.
+   Add error message in png_set_compression_buffer_size() when malloc fails.
+ version 1.0.9beta3 [November 23, 2000]
+   Revised PNG_LIBPNG_BUILD_TYPE macro in png.h, used in the msvc project.
+   Removed the png_flush() in pngwrite.c that crashes some applications
+     that don't set png_output_flush_fn.
+   Added makefile.macosx and makefile.aix to scripts directory.
+ version 1.0.9beta4 [December 1, 2000]
+   Change png_chunk_warning to png_warning in png_check_keyword().
+   Increased the first part of msg buffer from 16 to 18 in png_chunk_error().
+ version 1.0.9beta5 [December 15, 2000]
+   Added support for filter method 64 (for PNG datastreams embedded in MNG).
+ version 1.0.9beta6 [December 18, 2000]
+   Revised png_set_filter() to accept filter method 64 when appropriate.
+   Added new PNG_HAVE_PNG_SIGNATURE bit to png_ptr->mode and use it to
+     help prevent applications from using MNG features in PNG datastreams.
+   Added png_permit_mng_features() function.
+   Revised libpng.3/libpng.txt.  Changed "filter type" to "filter method".
+ version 1.0.9rc1 [December 23, 2000]
+   Revised test for PNG_HAVE_PNG_SIGNATURE in pngrutil.c
+   Fixed error handling of unknown compression type in png_decompress_chunk().
+   In pngconf.h, define __cdecl when _MSC_VER is defined.
+ version 1.0.9beta7 [December 28, 2000]
+   Changed PNG_TEXT_COMPRESSION_zTXt to PNG_COMPRESSION_TYPE_BASE several places.
+   Revised memory management in png_set_hIST and png_handle_hIST in a backward
+     compatible manner.  PLTE and tRNS were revised similarly.
+   Revised the iCCP chunk reader to ignore trailing garbage.
+ version 1.0.9beta8 [January 12, 2001]
+   Moved pngasmrd.h into pngconf.h.
+   Improved handling of out-of-spec garbage iCCP chunks generated by PhotoShop.
+ version 1.0.9beta9 [January 15, 2001]
+   Added png_set_invalid, png_permit_mng_features, and png_mmx_supported to
+     wince and msvc project module definition files.
+   Minor revision of makefile.cygwin.
+   Fixed bug with progressive reading of narrow interlaced images in pngpread.c
+ version 1.0.9beta10 [January 16, 2001]
+   Do not typedef png_FILE_p in pngconf.h when PNG_NO_STDIO is defined.
+   Fixed "png_mmx_supported" typo in project definition files.
+ version 1.0.9beta11 [January 19, 2001]
+   Updated makefile.sgi to make shared library.
+   Removed png_mmx_support() function and disabled PNG_MNG_FEATURES_SUPPORTED
+     by default, for the benefit of DLL forward compatibility.  These will
+     be re-enabled in version 1.2.0.
+ version 1.0.9rc2 [January 22, 2001]
+   Revised cygwin support.
+ version 1.0.9 [January 31, 2001]
+   Added check of cygwin's ALL_STATIC in pngconf.h
+   Added "-nommx" parameter to contrib/gregbook/rpng2-win and rpng2-x demos.
+ version 1.0.10beta1 [March 14, 2001]
+   Revised makefile.dec, makefile.sgi, and makefile.sggcc; added makefile.hpgcc.
+   Reformatted libpng.3 to eliminate bad line breaks.
+   Added checks for _mmx_supported in the read_filter_row function of pnggccrd.c
+   Added prototype for png_mmx_support() near the top of pnggccrd.c
+   Moved some error checking from png_handle_IHDR to png_set_IHDR.
+   Added PNG_NO_READ_SUPPORTED and PNG_NO_WRITE_SUPPORTED macros.
+   Revised png_mmx_support() function in pnggccrd.c
+   Restored version 1.0.8 PNG_WRITE_EMPTY_PLTE_SUPPORTED behavior in pngwutil.c
+   Fixed memory leak in contrib/visupng/PngFile.c
+   Fixed bugs in png_combine_row() in pnggccrd.c and pngvcrd.c (C version)
+   Added warnings when retrieving or setting gamma=0.
+   Increased the first part of msg buffer from 16 to 18 in png_chunk_warning().
+ version 1.0.10rc1 [March 23, 2001]
+   Changed all instances of memcpy, strcpy, and strlen to png_memcpy, png_strcpy,
+     and png_strlen.
+   Revised png_mmx_supported() function in pnggccrd.c to return proper value.
+   Fixed bug in progressive reading (pngpread.c) with small images (height < 8).
+ version 1.0.10 [March 30, 2001]
+   Deleted extraneous space (introduced in 1.0.9) from line 42 of makefile.cygwin
+   Added beos project files (Chris Herborth)
+ version 1.0.11beta1 [April 3, 2001]
+   Added type casts on several png_malloc() calls (Dimitri Papadapoulos).
+   Removed a no-longer needed AIX work-around from pngconf.h
+   Changed several "//" single-line comments to C-style in pnggccrd.c
+ version 1.0.11beta2 [April 11, 2001]
+   Removed PNGAPI from several functions whose prototypes did not have PNGAPI.
+   Updated scripts/pngos2.def
+ version 1.0.11beta3 [April 14, 2001]
+   Added checking the results of many instances of png_malloc() for NULL
+ version 1.0.11beta4 [April 20, 2001]
+   Undid the changes from version 1.0.11beta3.  Added a check for NULL return
+     from user's malloc_fn().
+   Removed some useless type casts of the NULL pointer.
+   Added makefile.netbsd
+ version 1.0.11 [April 27, 2001]
+   Revised makefile.netbsd
+ version 1.0.12beta1 [May 14, 2001]
+   Test for Windows platform in pngconf.h when including malloc.h (Emmanuel Blot)
+   Updated makefile.cygwin and handling of Cygwin's ALL_STATIC in pngconf.h
+   Added some never-to-be-executed code in pnggccrd.c to quiet compiler warnings.
+   Eliminated the png_error about apps using png_read|write_init().  Instead,
+     libpng will reallocate the png_struct and info_struct if they are too small.
+     This retains future binary compatibility for old applications written for
+     libpng-0.88 and earlier.
+ version 1.2.0beta1 [May 6, 2001]
+   Bumped DLLNUM to 2.
+   Re-enabled PNG_MNG_FEATURES_SUPPORTED and enabled PNG_ASSEMBLER_CODE_SUPPORTED
+     by default.
+   Added runtime selection of MMX features.
+   Added png_set_strip_error_numbers function and related macros.
+ version 1.2.0beta2 [May 7, 2001]
+   Finished merging 1.2.0beta1 with version 1.0.11
+   Added a check for attempts to read or write PLTE in grayscale PNG datastreams.
+ version 1.2.0beta3 [May 17, 2001]
+   Enabled user memory function by default.
+   Modified png_create_struct so it passes user mem_ptr to user memory allocator.
+   Increased png_mng_features flag from png_byte to png_uint_32.
+   Bumped shared-library (so-number) and dll-number to 3.
+ version 1.2.0beta4 [June 23, 2001]
+   Check for missing profile length field in iCCP chunk and free chunk_data
+      in case of truncated iCCP chunk.
+   Bumped shared-library number to 3 in makefile.sgi and makefile.sggcc
+   Bumped dll-number from 2 to 3 in makefile.cygwin
+   Revised contrib/gregbook/rpng*-x.c to avoid a memory leak and to exit cleanly
+      if user attempts to run it on an 8-bit display.
+   Updated contrib/gregbook
+   Use png_malloc instead of png_zalloc to allocate palette in pngset.c
+   Updated makefile.ibmc
+   Added some typecasts to eliminate gcc 3.0 warnings.  Changed prototypes
+      of png_write_oFFS width and height from png_uint_32 to png_int_32.
+   Updated example.c
+   Revised prototypes for png_debug_malloc and png_debug_free in pngtest.c
+ version 1.2.0beta5 [August 8, 2001]
+   Revised contrib/gregbook
+   Revised makefile.gcmmx
+   Revised pnggccrd.c to conditionally compile some thread-unsafe code only
+      when PNG_THREAD_UNSAFE_OK is defined.
+   Added tests to prevent pngwutil.c from writing a bKGD or tRNS chunk with
+      value exceeding 2^bit_depth-1
+   Revised makefile.sgi and makefile.sggcc
+   Replaced calls to fprintf(stderr,...) with png_warning() in pnggccrd.c
+   Removed restriction that do_invert_mono only operate on 1-bit opaque files
+ version 1.2.0 [September 1, 2001]
+   Changed a png_warning() to png_debug() in pnggccrd.c
+   Fixed contrib/gregbook/rpng-x.c, rpng2-x.c to avoid crash with XFreeGC().
+ version 1.2.1beta1 [October 19, 2001]
+   Revised makefile.std in contrib/pngminus
+   Include background_1 in png_struct regardless of gamma support.
+   Revised makefile.netbsd and makefile.macosx, added makefile.darwin.
+   Revised example.c to provide more details about using row_callback().
+ version 1.2.1beta2 [October 25, 2001]
+   Added type cast to each NULL appearing in a function call, except for
+     WINCE functions.
+   Added makefile.so9.
+ version 1.2.1beta3 [October 27, 2001]
+   Removed type casts from all NULLs.
+   Simplified png_create_struct_2().
+ version 1.2.1beta4 [November 7, 2001]
+   Revised png_create_info_struct() and png_creat_struct_2().
+   Added error message if png_write_info() was omitted.
+   Type cast NULLs appearing in function calls when _NO_PROTO or
+     PNG_TYPECAST_NULL is defined.
+ version 1.2.1rc1 [November 24, 2001]
+   Type cast NULLs appearing in function calls except when PNG_NO_TYPECAST_NULL
+     is defined.
+   Changed typecast of "size" argument to png_size_t in pngmem.c calls to
+     the user malloc_fn, to agree with the prototype in png.h
+   Added a pop/push operation to pnggccrd.c, to preserve Eflag (Maxim Sobolev)
+   Updated makefile.sgi to recognize LIBPATH and INCPATH.
+   Updated various makefiles so "make clean" does not remove previous major
+     version of the shared library.
+ version 1.2.1rc2 [December 4, 2001]
+   Always allocate 256-entry internal palette, hist, and trans arrays, to
+     avoid out-of-bounds memory reference caused by invalid PNG datastreams.
+   Added a check for prefix_length > data_length in iCCP chunk handler.
+ version 1.2.1 [December 7, 2001]
+   None.
+ version 1.2.2beta1 [February 22, 2002]
+   Fixed a bug with reading the length of iCCP profiles (Larry Reeves).
+   Revised makefile.linux, makefile.gcmmx, and makefile.sgi to generate
+     libpng.a, libpng12.so (not libpng.so.3), and libpng12/png.h
+   Revised makefile.darwin to remove "-undefined suppress" option.
+   Added checks for gamma and chromaticity values over 21474.83, which exceed
+     the limit for PNG unsigned 32-bit integers when encoded.
+   Revised calls to png_create_read_struct() and png_create_write_struct()
+     for simpler debugging.
+   Revised png_zalloc() so zlib handles errors (uses PNG_FLAG_MALLOC_NULL_MEM_OK)
+ version 1.2.2beta2 [February 23, 2002]
+   Check chunk_length and idat_size for invalid (over PNG_MAX_UINT) lengths.
+   Check for invalid image dimensions in png_get_IHDR.
+   Added missing "fi;" in the install target of the SGI makefiles.
+   Added install-static to all makefiles that make shared libraries.
+   Always do gamma compensation when image is partially transparent.
+ version 1.2.2beta3 [March 7, 2002]
+   Compute background.gray and background_1.gray even when color_type is RGB
+     in case image gets reduced to gray later.
+   Modified shared-library makefiles to install pkgconfig/libpngNN.pc.
+   Export (with PNGAPI) png_zalloc, png_zfree, and png_handle_as_unknown
+   Removed unused png_write_destroy_info prototype from png.h
+   Eliminated incorrect use of width_mmx from pnggccrd.c in pixel_bytes == 8 case
+   Added install-shared target to all makefiles that make shared libraries.
+   Stopped a double free of palette, hist, and trans when not using free_me.
+   Added makefile.32sunu for Sun Ultra 32 and makefile.64sunu for Sun Ultra 64.
+ version 1.2.2beta4 [March 8, 2002]
+   Compute background.gray and background_1.gray even when color_type is RGB
+     in case image gets reduced to gray later (Jason Summers).
+   Relocated a misplaced /bin/rm in the "install-shared" makefile targets
+   Added PNG_1_0_X macro which can be used to build a 1.0.x-compatible library.
+ version 1.2.2beta5 [March 26, 2002]
+   Added missing PNGAPI to several function definitions.
+   Check for invalid bit_depth or color_type in png_get_IHDR(), and
+     check for missing PLTE or IHDR in png_push_read_chunk() (Matthias Clasen).
+   Revised iTXt support to accept NULL for lang and lang_key.
+   Compute gamma for color components of background even when color_type is gray.
+   Changed "()" to "{}" in scripts/libpng.pc.in.
+   Revised makefiles to put png.h and pngconf.h only in $prefix/include/libpngNN
+   Revised makefiles to make symlink to libpng.so.NN in addition to libpngNN.so
+ version 1.2.2beta6 [March 31, 2002]
+ version 1.0.13beta1 [March 31, 2002]
+   Prevent png_zalloc() from trying to memset memory that it failed to acquire.
+   Add typecasts of PNG_MAX_UINT in pngset_cHRM_fixed() (Matt Holgate).
+   Ensure that the right function (user or default) is used to free the
+     png_struct after an error in png_create_read_struct_2().
+ version 1.2.2rc1 [April 7, 2002]
+ version 1.0.13rc1 [April 7, 2002]
+   Save the ebx register in pnggccrd.c (Sami Farin)
+   Add "mem_ptr = png_ptr->mem_ptr" in png_destroy_write_struct() (Paul Gardner).
+   Updated makefiles to put headers in include/libpng and remove old include/*.h.
+ version 1.2.2 [April 15, 2002]
+ version 1.0.13 [April 15, 2002]
+   Revised description of png_set_filter() in libpng.3/libpng.txt.
+   Revised makefile.netbsd and added makefile.neNNbsd and makefile.freebsd
+ version 1.0.13patch01 [April 17, 2002]
+ version 1.2.2patch01 [April 17, 2002]
+   Changed ${PNGMAJ}.${PNGVER} bug to ${PNGVER} in makefile.sgi and makefile.sggcc
+   Fixed VER -> PNGVER typo in makefile.macosx and added install-static to install
+   Added install: target to makefile.32sunu and makefile.64sunu
+ version 1.0.13patch03 [April 18, 2002]
+ version 1.2.2patch03 [April 18, 2002]
+   Revised 15 makefiles to link libpng.a to libpngNN.a and the include libpng
+   subdirectory to libpngNN subdirectory without the full pathname.
+   Moved generation of libpng.pc from "install" to "all" in 15 makefiles.
+ version 1.2.3rc1 [April 28, 2002]
+   Added install-man target to 15 makefiles (Dimitri Papadopolous-Orfanos).
+   Added $(DESTDIR) feature to 24 makefiles (Tim Mooney)
+   Fixed bug with $prefix, should be $(prefix) in makefile.hpux.
+   Updated cygwin-specific portion of pngconf.h and revised makefile.cygwin
+   Added a link from libpngNN.pc to libpng.pc in 15 makefiles.
+   Added links from include/libpngNN/*.h to include/*.h in 24 makefiles.
+   Revised makefile.darwin to make relative links without full pathname.
+   Added setjmp() at the end of png_create_*_struct_2() in case user forgets
+     to put one in their application.
+   Restored png_zalloc() and png_zfree() prototypes to version 1.2.1 and
+     removed them from module definition files.
+ version 1.2.3rc2 [May 1, 2002]
+   Fixed bug in reporting number of channels in pngget.c and pngset.c,
+     that was introduced in version 1.2.2beta5.
+   Exported png_zalloc(), png_zfree(), png_default_read(), png_default_write(),
+     png_default_flush(), and png_push_fill_buffer() and included them in
+     module definition files.
+   Added "libpng.pc" dependency to the "install-shared" target in 15 makefiles.
+ version 1.2.3rc3 [May 1, 2002]
+   Revised prototype for png_default_flush()
+   Remove old libpng.pc and libpngNN.pc before installing new ones.
+ version 1.2.3rc4 [May 2, 2002]
+   Typos in *.def files (png_default_read|write -> png_default_read|write_data)
+   In makefiles, changed rm libpng.NN.pc to rm libpngNN.pc
+   Added libpng-config and libpngNN-config and modified makefiles to install them.
+   Changed $(MANPATH) to $(DESTDIR)$(MANPATH) in makefiles
+   Added "Win32 DLL VB" configuration to projects/msvc/libpng.dsp
+ version 1.2.3rc5 [May 11, 2002]
+   Changed "error" and "message" in prototypes to "error_message" and
+     "warning_message" to avoid namespace conflict.
+   Revised 15 makefiles to build libpng-config from libpng-config-*.in
+   Once more restored png_zalloc and png_zfree to regular nonexported form.
+   Restored png_default_read|write_data, png_default_flush, png_read_fill_buffer
+     to nonexported form, but with PNGAPI, and removed them from module def files.
+ version 1.2.3rc6 [May 14, 2002]
+   Removed "PNGAPI" from png_zalloc() and png_zfree() in png.c
+   Changed "Gz" to "Gd" in projects/msvc/libpng.dsp and zlib.dsp.
+   Removed leftover libpng-config "sed" script from four makefiles.
+   Revised libpng-config creating script in 16 makefiles.
+ version 1.2.3 [May 22, 2002]
+   Revised libpng-config target in makefile.cygwin.
+   Removed description of png_set_mem_fn() from documentation.
+   Revised makefile.freebsd.
+   Minor cosmetic changes to 15 makefiles, e.g., $(DI) = $(DESTDIR)/$(INCDIR).
+   Revised projects/msvc/README.txt
+   Changed -lpng to -lpngNN in LDFLAGS in several makefiles.
+ version 1.2.4beta1 [May 24, 2002]
+   Added libpng.pc and libpng-config to "all:" target in 16 makefiles.
+   Fixed bug in 16 makefiles: $(DESTDIR)/$(LIBPATH) to $(DESTDIR)$(LIBPATH)
+   Added missing "\" before closing double quote in makefile.gcmmx.
+   Plugged various memory leaks; added png_malloc_warn() and png_set_text_2()
+     functions.
+ version 1.2.4beta2 [June 25, 2002]
+   Plugged memory leak of png_ptr->current_text (Matt Holgate).
+   Check for buffer overflow before reading CRC in pngpread.c (Warwick Allison)
+   Added -soname to the loader flags in makefile.dec, makefile.sgi, and
+     makefile.sggcc.
+   Added "test-installed" target to makefile.linux, makefile.gcmmx,
+     makefile.sgi, and makefile.sggcc.
+ version 1.2.4beta3 [June 28, 2002]
+   Plugged memory leak of row_buf in pngtest.c when there is a png_error().
+   Detect buffer overflow in pngpread.c when IDAT is corrupted with extra data.
+   Added "test-installed" target to makefile.32sunu, makefile.64sunu,
+     makefile.beos, makefile.darwin, makefile.dec, makefile.macosx, 
+     makefile.solaris, makefile.hpux, makefile.hpgcc, and makefile.so9.
+ version 1.2.4rc1 and 1.0.14rc1 [July 2, 2002]
+   Added "test-installed" target to makefile.cygwin and makefile.sco.
+   Revised pnggccrd.c to be able to back out version 1.0.x via PNG_1_0_X macro.
+ version 1.2.4 and 1.0.14 [July 8, 2002]
+   Changed png_warning() to png_error() when width is too large to process.
+ version 1.2.4patch01 [July 20, 2002]
+   Revised makefile.cygwin to use DLL number 12 instead of 13.
+ version 1.2.5beta1 [August 6, 2002]
+   Added code to contrib/gregbook/readpng2.c to ignore unused chunks.
+   Replaced toucan.png in contrib/gregbook (it has been corrupt since 1.0.11)
+   Removed some stray *.o files from contrib/gregbook.
+   Changed png_error() to png_warning() about "Too much data" in pngpread.c
+     and about "Extra compressed data" in pngrutil.c.
+   Prevent png_ptr->pass from exceeding 7 in png_push_finish_row().
+   Updated makefile.hpgcc
+   Updated png.c and pnggccrd.c handling of return from png_mmx_support()
+ version 1.2.5beta2 [August 15, 2002]
+   Only issue png_warning() about "Too much data" in pngpread.c when avail_in
+     is nonzero.
+   Updated makefiles to install a separate libpng.so.3 with its own rpath.
+ version 1.2.5rc1 and 1.0.15rc1 [August 24, 2002]
+   Revised makefiles to not remove previous minor versions of shared libraries.
+ version 1.2.5rc2 and 1.0.15rc2 [September 16, 2002]
+   Revised 13 makefiles to remove "-lz" and "-L$(ZLIBLIB)", etc., from shared
+     library loader directive.
+   Added missing "$OBJSDLL" line to makefile.gcmmx.
+   Added missing "; fi" to makefile.32sunu.
+ version 1.2.5rc3 and 1.0.15rc3 [September 18, 2002]
+   Revised libpng-config script.
+ version 1.2.5 and 1.0.15 [October 3, 2002]
+   Revised makefile.macosx, makefile.darwin, makefile.hpgcc, and makefile.hpux,
+     and makefile.aix.
+   Relocated two misplaced PNGAPI lines in pngtest.c
+ 
+ Send comments/corrections/commendations to
+ png-implement at ccrc.wustl.edu or to randeg at alum.rpi.edu
+ 
+ Glenn R-P


Index: llvm/runtime/libpng/INSTALL
diff -c /dev/null llvm/runtime/libpng/INSTALL:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/INSTALL	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,151 ----
+ 
+ Installing libpng version 1.2.5 - October 3, 2002
+ 
+ Before installing libpng, you must first install zlib.  zlib
+ can usually be found wherever you got libpng.  zlib can be
+ placed in another directory, at the same level as libpng.
+ Note that your system might already have a preinstalled
+ zlib, but you will still need to have access to the
+ zlib.h and zconf.h include files that correspond to the
+ version of zlib that's installed.
+ 
+ You can rename the directories that you downloaded (they
+ might be called "libpng-1.2.5" or "lpng109" and "zlib-1.1.4"
+ or "zlib114") so that you have directories called "zlib" and "libpng".
+ 
+ Your directory structure should look like this:
+ 
+    ..       (the parent directory)
+       libpng  (this directory)
+           INSTALL (this file)
+           README
+           *.h
+           *.c
+           contrib
+              gregbook
+              msvctest
+              pngminus
+              pngsuite
+              visupng
+           projects
+              beos
+              borland
+              msvc
+              netware.txt
+              wince.txt
+           scripts
+              makefile.*
+              libpng*.in
+           pngtest.png
+           etc.
+       zlib
+           README
+           *.h
+           *.c
+           contrib
+           etc.
+ 
+ If the line endings in the files look funny, you may wish to get the other
+ distribution of libpng.  It is available in both tar.gz (UNIX style line
+ endings) and zip (DOS style line endings) formats.
+ 
+ If you are building libpng with MSVC, you can enter the libpng\msvc directory
+ and follow the instructions in msvc\README.txt.
+ 
+ You can build libpng for WindowsCE by entering the downloading and installing
+ the libpng\wince directory as instructed in the projects\wince.txt file, and
+ then following the instructions in the README* files.  Similarly, you can
+ build libpng for Netware as instructed in projects\netware.txt.
+ 
+ Else enter the zlib directory and follow the instructions in zlib/README,
+ then come back here and choose the appropriate makefile.sys in the scripts
+ directory.
+ 
+ The files that are presently available in the scripts directory
+ include
+ 
+  makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
+  makefile.linux    =>  Linux/ELF makefile (gcc, creates libpng12.so.0.1.2.5)
+  makefile.gcmmx    =>  Linux/ELF makefile (gcc, creates libpng12.so.0.1.2.5,
+                        uses assembler code tuned for Intel MMX platform)
+  makefile.gcc      =>  Generic makefile (gcc, creates static libpng.a)
+  makefile.knr      =>  Archaic UNIX Makefile that converts files with
+                        ansi2knr (Requires ansi2knr.c from
+                        ftp://ftp.cs.wisc.edu/ghost)
+  makefile.aix      =>  AIX/gcc makefile
+  makefile.cygwin   =>  Cygwin/gcc makefile
+  makefile.darwin   =>  Darwin makefile
+  makefile.dec      =>  DEC Alpha UNIX makefile
+  makefile.hpgcc    =>  FreeBSD makefile
+  makefile.hpgcc    =>  HPUX makefile using gcc
+  makefile.hpux     =>  HPUX (10.20 and 11.00) makefile
+  makefile.ibmc     =>  IBM C/C++ version 3.x for Win32 and OS/2 (static)
+  makefile.intel    =>  Intel C/C++ version 4.0 and later
+  libpng.icc        =>  Project file for IBM VisualAge/C++ version 4.0 or later
+  makefile.macosx   =>  MACOS X Makefile
+  makefile.netbsd   =>  NetBSD/cc makefile, uses PNGGCCRD, makes libpng.so.
+  makefile.ne0bsd  =>  NetBSD/cc makefile, uses PNGGCCRD, makes libpng0.so
+  makefile.openbsd  =>  OpenBSD makefile
+  makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
+  makefile.sggcc    =>  Silicon Graphics (gcc, creates libpng12.so.0.1.2.5)
+  makefile.sunos    =>  Sun makefile
+  makefile.solaris  =>  Solaris 2.X makefile (gcc, creates libpng12.so.0.1.2.5)
+  makefile.so9      =>  Solaris 9 makefile (gcc, creates libpng12.so.0.1.2.5)
+  makefile.32sunu   =>  Sun Ultra 32-bit makefile
+  makefile.64sunu   =>  Sun Ultra 64-bit makefile
+  makefile.sco      =>  For SCO OSr5  ELF and Unixware 7 with Native cc
+  makefile.mips     =>  MIPS makefile
+  makefile.acorn    =>  Acorn makefile
+  makefile.amiga    =>  Amiga makefile
+  smakefile.ppc     =>  AMIGA smakefile for SAS C V6.58/7.00 PPC compiler
+                        (Requires SCOPTIONS, copied from scripts/SCOPTIONS.ppc)
+  makefile.atari    =>  Atari makefile
+  makefile.beos     =>  BEOS makefile for X86
+  makefile.bor      =>  Borland makefile (uses bcc)
+  makefile.bc32     =>  32-bit Borland C++ (all modules compiled in C mode)
+  makefile.bd32     =>  To make a png32bd.dll with Borland C++ 4.5
+  makefile.tc3      =>  Turbo C 3.0 makefile
+  makefile.dj2      =>  DJGPP 2 makefile
+  makefile.msc      =>  Microsoft C makefile
+  makefile.vcawin32 =>  makefile for Microsoft Visual C++ 5.0 and later (uses
+                        assembler code tuned for Intel MMX platform)
+  makefile.vcwin32  =>  makefile for Microsoft Visual C++ 4.0 and later (does
+                        not use assembler code)
+  makefile.os2      =>  OS/2 Makefile (gcc and emx, requires pngos2.def)
+  pngos2.def        =>  OS/2 module definition file used by makefile.os2
+  makefile.watcom   =>  Watcom 10a+ Makefile, 32-bit flat memory model
+  makevms.com       =>  VMS build script
+  descrip.mms       =>  VMS makefile for MMS or MMK
+  pngdef.pas        =>  Defines for a png32bd.dll with Borland C++ 4.5
+  SCOPTIONS.ppc     =>  Used with smakefile.ppc
+ 
+ Copy the file (or files) that you need from the
+ scripts directory into this directory, for example
+ 
+    MSDOS example: copy scripts\makefile.msc makefile
+    UNIX example:    cp scripts/makefile.std makefile
+ 
+ Read the makefile to see if you need to change any source or
+ target directories to match your preferences.
+ 
+ Then read pngconf.h to see if you want to make any configuration
+ changes.
+ 
+ Then just run "make test" which will create the libpng library in
+ this directory and run a quick test that reads the "pngtest.png"
+ file and writes a "pngout.png" file that should be identical to it.
+ Look for "9782 zero samples" in the output of the test.  For more
+ confidence, you can run another test by typing "pngtest pngnow.png"
+ and looking for "289 zero samples" in the output.  Also, you can
+ run "pngtest -m *.png" in the "contrib/pngsuite" directory and compare
+ your output with the result shown in contrib/pngsuite/README.
+ 
+ Most of the makefiles will allow you to run "make install" to
+ put the library in its final resting place (if you want to
+ do that, run "make install" in the zlib directory first if necessary).
+ Some also allow you to run "make test-installed" after you have
+ run "make install".
+ 
+ Further information can be found in the README and libpng.txt
+ files, in the individual makefiles, in png.h, in the README files in
+ subdirectories of the LIB directory, and the manual pages libpng.3 and png.5.


Index: llvm/runtime/libpng/KNOWNBUG
diff -c /dev/null llvm/runtime/libpng/KNOWNBUG:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/KNOWNBUG	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,11 ----
+ 
+ Known bugs in libpng version 1.2.5
+ 
+ 1. April 22, 2001: pnggccrd.c has been reported to crash on NetBSD when
+    reading interlaced PNG files, when assembler code is enabled but running
+    on a non-MMX i386 platform.
+ 
+    STATUS: Under investigation.  The change to pnggccrd.c in libpng-1.2.1
+    fixed a problem under FreeBSD but not the problem with NetBSD, which
+    still fails as of libpng-1.2.2rc1.
+ 


Index: llvm/runtime/libpng/LICENSE
diff -c /dev/null llvm/runtime/libpng/LICENSE:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/LICENSE	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,102 ----
+ 
+ This copy of the libpng notices is provided for your convenience.  In case of
+ any discrepancy between this copy and the notices in the file png.h that is
+ included in the libpng distribution, the latter shall prevail.
+ 
+ COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+ 
+ If you modify libpng you may insert additional notices immediately following
+ this sentence.
+ 
+ libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
+ Copyright (c) 2000-2002 Glenn Randers-Pehrson
+ and are distributed according to the same disclaimer and license as libpng-1.0.6
+ with the following individuals added to the list of Contributing Authors
+ 
+    Simon-Pierre Cadieux
+    Eric S. Raymond
+    Gilles Vollant
+ 
+ and with the following additions to the disclaimer:
+ 
+    There is no warranty against interference with your enjoyment of the
+    library or against infringement.  There is no warranty that our
+    efforts or the library will fulfill any of your particular purposes
+    or needs.  This library is provided with all faults, and the entire
+    risk of satisfactory quality, performance, accuracy, and effort is with
+    the user.
+ 
+ libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
+ Copyright (c) 1998, 1999 Glenn Randers-Pehrson, and are
+ distributed according to the same disclaimer and license as libpng-0.96,
+ with the following individuals added to the list of Contributing Authors:
+ 
+    Tom Lane
+    Glenn Randers-Pehrson
+    Willem van Schaik
+ 
+ libpng versions 0.89, June 1996, through 0.96, May 1997, are
+ Copyright (c) 1996, 1997 Andreas Dilger
+ Distributed according to the same disclaimer and license as libpng-0.88,
+ with the following individuals added to the list of Contributing Authors:
+ 
+    John Bowler
+    Kevin Bracey
+    Sam Bushell
+    Magnus Holmgren
+    Greg Roelofs
+    Tom Tanner
+ 
+ libpng versions 0.5, May 1995, through 0.88, January 1996, are
+ Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ 
+ For the purposes of this copyright and license, "Contributing Authors"
+ is defined as the following set of individuals:
+ 
+    Andreas Dilger
+    Dave Martindale
+    Guy Eric Schalnat
+    Paul Schmidt
+    Tim Wegner
+ 
+ The PNG Reference Library is supplied "AS IS".  The Contributing Authors
+ and Group 42, Inc. disclaim all warranties, expressed or implied,
+ including, without limitation, the warranties of merchantability and of
+ fitness for any purpose.  The Contributing Authors and Group 42, Inc.
+ assume no liability for direct, indirect, incidental, special, exemplary,
+ or consequential damages, which may result from the use of the PNG
+ Reference Library, even if advised of the possibility of such damage.
+ 
+ Permission is hereby granted to use, copy, modify, and distribute this
+ source code, or portions hereof, for any purpose, without fee, subject
+ to the following restrictions:
+ 
+ 1. The origin of this source code must not be misrepresented.
+ 
+ 2. Altered versions must be plainly marked as such and must not
+    be misrepresented as being the original source.
+ 
+ 3. This Copyright notice may not be removed or altered from any
+    source or altered source distribution.
+ 
+ The Contributing Authors and Group 42, Inc. specifically permit, without
+ fee, and encourage the use of this source code as a component to
+ supporting the PNG file format in commercial products.  If you use this
+ source code in a product, acknowledgment is not required but would be
+ appreciated.
+ 
+ 
+ A "png_get_copyright" function is available, for convenient use in "about"
+ boxes and the like:
+ 
+    printf("%s",png_get_copyright(NULL));
+ 
+ Also, the PNG logo (in PNG format, of course) is supplied in the
+ files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
+ 
+ Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is a
+ certification mark of the Open Source Initiative.
+ 
+ Glenn Randers-Pehrson
+ randeg at alum.rpi.edu
+ October 3, 2002


Index: llvm/runtime/libpng/LICENSE.TXT
diff -c /dev/null llvm/runtime/libpng/LICENSE.TXT:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/LICENSE.TXT	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,9 ----
+ This is the libpng library.  It is licensed to you under the Illinois Open
+ Source License.
+ 
+ In addition, you must follow any additional licensing restrictions in the
+ LICENSE file.
+ 
+ The LICENSE file from the original libpng distribution contains additional
+ copyrights.
+ 


Index: llvm/runtime/libpng/Makefile
diff -c /dev/null llvm/runtime/libpng/Makefile:1.2.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/Makefile	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,19 ----
+ ##===- runtime/libdummy/Makefile ------------------------------*- Makefile -*-===##
+ # 
+ #                     The LLVM Compiler Infrastructure
+ #
+ # This file was developed by the LLVM research group and is distributed under
+ # the University of Illinois Open Source License. See LICENSE.TXT for details.
+ # 
+ ##===----------------------------------------------------------------------===##
+ LEVEL = ../..
+ BYTECODE_LIBRARY=1
+ BUILD_ARCHIVE=1
+ DONT_BUILD_RELINKED=1
+ LIBRARYNAME=png
+ 
+ Source = png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
+ 	       pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
+ 	       pngwtran.c pngmem.c pngerror.c pngpread.c
+ 
+ include $(LEVEL)/Makefile.common


Index: llvm/runtime/libpng/README
diff -c /dev/null llvm/runtime/libpng/README:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/README	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,269 ----
+ README for libpng 1.2.5 - October 3, 2002 (shared library 12.0)
+ See the note about version numbers near the top of png.h
+ 
+ See INSTALL for instructions on how to install libpng.
+ 
+ Libpng comes in two distribution formats.  Get libpng-*.tar.gz if you
+ want UNIX-style line endings in the text files, or lpng*.zip if you want
+ DOS-style line endings.
+ 
+ Version 0.89 was the first official release of libpng.  Don't let the
+ fact that it's the first release fool you.  The libpng library has been in
+ extensive use and testing since mid-1995.  By late 1997 it had
+ finally gotten to the stage where there hadn't been significant
+ changes to the API in some time, and people have a bad feeling about
+ libraries with versions < 1.0.  Version 1.0.0 was released in
+ March 1998.
+ 
+ ****
+ Note that some of the changes to the png_info structure render this
+ version of the library binary incompatible with libpng-0.89 or
+ earlier versions if you are using a shared library.  The type of the
+ "filler" parameter for png_set_filler() has changed from png_byte to
+ png_uint_32, which will affect shared-library applications that use
+ this function.
+ 
+ To avoid problems with changes to the internals of png_info_struct,
+ new APIs have been made available in 0.95 to avoid direct application
+ access to info_ptr.  These functions are the png_set_<chunk> and
+ png_get_<chunk> functions.  These functions should be used when
+ accessing/storing the info_struct data, rather than manipulating it
+ directly, to avoid such problems in the future.
+ 
+ It is important to note that the APIs do not make current programs
+ that access the info struct directly incompatible with the new
+ library.  However, it is strongly suggested that new programs use
+ the new APIs (as shown in example.c and pngtest.c), and older programs
+ be converted to the new format, to facilitate upgrades in the future.
+ ****
+ 
+ Additions since 0.90 include the ability to compile libpng as a
+ Windows DLL, and new APIs for accessing data in the info struct.
+ Experimental functions include the ability to set weighting and cost
+ factors for row filter selection, direct reads of integers from buffers
+ on big-endian processors that support misaligned data access, faster
+ methods of doing alpha composition, and more accurate 16->8 bit color
+ conversion.
+ 
+ The additions since 0.89 include the ability to read from a PNG stream
+ which has had some (or all) of the signature bytes read by the calling
+ application.  This also allows the reading of embedded PNG streams that
+ do not have the PNG file signature.  As well, it is now possible to set
+ the library action on the detection of chunk CRC errors.  It is possible
+ to set different actions based on whether the CRC error occurred in a
+ critical or an ancillary chunk.
+ 
+ The changes made to the library, and bugs fixed are based on discussions
+ on the PNG implementation mailing list <png-implement at ccrc.wustl.edu>
+ and not on material submitted privately to Guy, Andreas, or Glenn.  They will
+ forward any good suggestions to the list.
+ 
+ For a detailed description on using libpng, read libpng.txt.  For
+ examples of libpng in a program, see example.c and pngtest.c.  For usage
+ information and restrictions (what little they are) on libpng, see
+ png.h.  For a description on using zlib (the compression library used by
+ libpng) and zlib's restrictions, see zlib.h
+ 
+ I have included a general makefile, as well as several machine and
+ compiler specific ones, but you may have to modify one for your own needs.
+ 
+ You should use zlib 1.0.4 or later to run this, but it MAY work with
+ versions as old as zlib 0.95.  Even so, there are bugs in older zlib
+ versions which can cause the output of invalid compression streams for
+ some images.  You will definitely need zlib 1.0.4 or later if you are
+ taking advantage of the MS-DOS "far" structure allocation for the small
+ and medium memory models.  You should also note that zlib is a
+ compression library that is useful for more things than just PNG files.
+ You can use zlib as a drop-in replacement for fread() and fwrite() if
+ you are so inclined.
+ 
+ zlib should be available at the same place that libpng is.
+ If not, it should be at ftp.uu.net in /graphics/png
+ Eventually, it will be at ftp.uu.net in /pub/archiving/zip/zlib
+ 
+ You may also want a copy of the PNG specification.  It is available
+ as an RFC and a W3C Recommendation.  Failing
+ these resources you can try ftp.uu.net in the /graphics/png directory.
+ 
+ This code is currently being archived at ftp.uu.net in the
+ /graphics/png directory, and on CompuServe, Lib 20 (PNG SUPPORT)
+ at GO GRAPHSUP.  If you can't find it in any of those places,
+ e-mail me, and I'll help you find it.
+ 
+ If you have any code changes, requests, problems, etc., please e-mail
+ them to me.  Also, I'd appreciate any make files or project files,
+ and any modifications you needed to make to get libpng to compile,
+ along with a #define variable to tell what compiler/system you are on.
+ If you needed to add transformations to libpng, or wish libpng would
+ provide the image in a different way, drop me a note (and code, if
+ possible), so I can consider supporting the transformation.
+ Finally, if you get any warning messages when compiling libpng
+ (note: not zlib), and they are easy to fix, I'd appreciate the
+ fix.  Please mention "libpng" somewhere in the subject line.  Thanks.
+ 
+ This release was created and will be supported by myself (of course
+ based in a large way on Guy's and Andreas' earlier work), and the PNG group.
+ 
+ randeg at alum.rpi.edu
+ png-implement at ccrc.wustl.edu
+ 
+ You can't reach Guy, the original libpng author, at the addresses
+ given in previous versions of this document.  He and Andreas will read mail
+ addressed to the png-implement list, however.
+ 
+ Please do not send general questions about PNG.  Send them to
+ the address in the specification (png-group at w3.org).  At the same
+ time, please do not send libpng questions to that address, send them to me
+ or to png-implement at ccrc.wustl.edu.  I'll
+ get them in the end anyway.  If you have a question about something
+ in the PNG specification that is related to using libpng, send it
+ to me.  Send me any questions that start with "I was using libpng,
+ and ...".  If in doubt, send questions to me.  I'll bounce them
+ to others, if necessary.
+ 
+ Please do not send suggestions on how to change PNG.  We have
+ been discussing PNG for three years now, and it is official and
+ finished.  If you have suggestions for libpng, however, I'll
+ gladly listen.  Even if your suggestion is not used for version
+ 1.0, it may be used later.
+ 
+ Files in this distribution:
+ 
+       ANNOUNCE      =>  Announcement of this version, with recent changes
+       CHANGES       =>  Description of changes between libpng versions
+       KNOWNBUG      =>  List of known bugs and deficiencies
+       LICENSE       =>  License to use and redistribute libpng
+       README        =>  This file
+       TODO          =>  Things not implemented in the current library
+       Y2KINFO       =>  Statement of Y2K compliance
+       example.c     =>  Example code for using libpng functions
+       libpng.3      =>  manual page for libpng (includes libpng.txt)
+       libpng.txt    =>  Description of libpng and its functions
+       libpngpf.3    =>  manual page for libpng's private functions
+       png.5         =>  manual page for the PNG format
+       png.c         =>  Basic interface functions common to library
+       png.h         =>  Library function and interface declarations
+       pngconf.h     =>  System specific library configuration
+       pngasmrd.h    =>  Header file for assembler-coded functions
+       pngerror.c    =>  Error/warning message I/O functions
+       pngget.c      =>  Functions for retrieving info from struct
+       pngmem.c      =>  Memory handling functions
+       pngbar.png    =>  PNG logo, 88x31
+       pngnow.png    =>  PNG logo, 98x31
+       pngpread.c    =>  Progressive reading functions
+       pngread.c     =>  Read data/helper high-level functions
+       pngrio.c      =>  Lowest-level data read I/O functions
+       pngrtran.c    =>  Read data transformation functions
+       pngrutil.c    =>  Read data utility functions
+       pngset.c      =>  Functions for storing data into the info_struct
+       pngtest.c     =>  Library test program
+       pngtest.png   =>  Library test sample image
+       pngtrans.c    =>  Common data transformation functions
+       pngwio.c      =>  Lowest-level write I/O functions
+       pngwrite.c    =>  High-level write functions
+       pngwtran.c    =>  Write data transformations
+       pngwutil.c    =>  Write utility functions
+       contrib       =>  Contributions
+        gregbook         =>  source code for PNG reading and writing, from
+                             Greg Roelofs' "PNG: The Definitive Guide",
+                             O'Reilly, 1999
+        msvctest     =>  Builds and runs pngtest using a MSVC workspace
+        pngminus     =>  Simple pnm2png and png2pnm programs
+        pngsuite     =>  Test images
+        visupng      =>  Contains a MSVC workspace for VisualPng
+       projects      =>  Contains project files and workspaces for building DLL
+        beos             =>  Contains a Beos workspace for building libpng
+        borland          =>  Contains a Borland workspace for building libpng
+                             and zlib
+        msvc             =>  Contains a Microsoft Visual C++ (MSVC) workspace
+                             for building libpng and zlib
+        netware.txt      =>  Contains instructions for downloading a set of
+                             project files for building libpng and zlib on
+                             Netware.
+        wince.txt        =>  Contains instructions for downloading a Microsoft
+                             Visual C++ (Windows CD Toolkit) workspace for
+                             building libpng and zlib on WindowsCE
+       scripts       =>  Directory containing scripts for building libpng:
+        descrip.mms      =>  VMS makefile for MMS or MMK
+        makefile.std     =>  Generic UNIX makefile (cc, creates static libpng.a)
+        makefile.linux   =>  Linux/ELF makefile
+                             (gcc, creates libpng12.so.0.1.2.5)
+        makefile.gcmmx   =>  Linux/ELF makefile (gcc, creates
+                             libpng12.so.0.1.2.5, uses assembler code
+                             tuned for Intel MMX platform)
+        makefile.gcc     =>  Generic makefile (gcc, creates static libpng.a)
+        makefile.knr     =>  Archaic UNIX Makefile that converts files with
+                             ansi2knr (Requires ansi2knr.c from
+                             ftp://ftp.cs.wisc.edu/ghost)
+        makefile.aix     =>  AIX makefile
+        makefile.cygwin  =>  Cygwin/gcc makefile
+        makefile.darwin  =>  Darwin makefile
+        makefile.dec     =>  DEC Alpha UNIX makefile
+        makefile.freebsd =>  FreeBSD makefile
+        makefile.hpgcc   =>  HPUX makefile using gcc
+        makefile.hpux    =>  HPUX (10.20 and 11.00) makefile
+        makefile.ibmc    =>  IBM C/C++ version 3.x for Win32 and OS/2 (static)
+        makefile.intel   =>  Intel C/C++ version 4.0 and later
+        libpng.icc       =>  Project file, IBM VisualAge/C++ 4.0 or later
+        makefile.macosx  =>  MACOS X Makefile
+        makefile.netbsd  =>  NetBSD/cc makefile, PNGGCCRD, makes libpng.so.
+        makefile.ne0bsd =>  NetBSD/cc makefile, PNGGCCRD, makes libpng0.so
+        makefile.openbsd =>  OpenBSD makefile
+        makefile.sgi     =>  Silicon Graphics IRIX (cc, creates static lib)
+        makefile.sggcc   =>  Silicon Graphics (gcc, creates libpng12.so.0.1.2.5)
+        makefile.sunos   =>  Sun makefile
+        makefile.solaris =>  Solaris 2.X makefile
+                             (gcc, creates libpng12.so.0.1.2.5)
+        makefile.so9     =>  Solaris 9 makefile
+                             (gcc, creates libpng12.so.0.1.2.5)
+        makefile.32sunu  =>  Sun Ultra 32-bit makefile
+        makefile.64sunu  =>  Sun Ultra 64-bit makefile
+        makefile.sco     =>  For SCO OSr5  ELF and Unixware 7 with Native cc
+        makefile.mips    =>  MIPS makefile
+        makefile.acorn   =>  Acorn makefile
+        makefile.amiga   =>  Amiga makefile
+        smakefile.ppc    =>  AMIGA smakefile for SAS C V6.58/7.00 PPC
+                             compiler (Requires SCOPTIONS, copied from
+                             scripts/SCOPTIONS.ppc)
+        makefile.atari   =>  Atari makefile
+        makefile.beos    =>  BEOS makefile for X86
+        makefile.bor     =>  Borland makefile (uses bcc)
+        makefile.bc32    =>  32-bit Borland C++ (all modules compiled in C mode)
+        makefile.bd32    =>  To make a png32bd.dll with Borland C++ 4.5
+        makefile.tc3     =>  Turbo C 3.0 makefile
+        makefile.dj2     =>  DJGPP 2 makefile
+        makefile.msc     =>  Microsoft C makefile
+        makefile.vcawin32 => makefile for Microsoft Visual C++ 5.0 and
+                             later (uses assembler code tuned for Intel MMX
+                             platform)
+        makefile.vcwin32 =>  makefile for Microsoft Visual C++ 4.0 and
+                             later (does not use assembler code)
+        makefile.os2     =>  OS/2 Makefile (gcc and emx, requires pngos2.def)
+        pngos2.def       =>  OS/2 module definition file used by makefile.os2
+        makefile.watcom  =>  Watcom 10a+ Makefile, 32-bit flat memory model
+        makevms.com      =>  VMS build script
+        pngdef.pas       =>  Defines for a png32bd.dll with Borland C++ 4.5
+        SCOPTIONS.ppc    =>  Used with smakefile.ppc
+       mangle        =>  Directory containing scripts to build libpng12m.so:
+        mangle.in        =>  Function-decoration macros added to png.h by the
+                             makefiles.
+        makefile.linux   =>  Linux/ELF makefile
+                             (gcc, creates libpng12m.so.0.1.2.5)
+        makefile.gcmmx   =>  Linux/ELF makefile (gcc, creates
+                             libpng12.so.0m.1.2.5, uses assembler code
+                             tuned for Intel MMX platform)
+        makefile.sgi     =>  Silicon Graphics (cc, creates libpng12m.so)
+        makefile.sggcc   =>  Silicon Graphics (gcc, creates libpng12m.so)
+ 
+ Good luck, and happy coding.
+ 
+ -Glenn Randers-Pehrson
+  Internet: randeg at alum.rpi.edu
+ 
+ -Andreas Eric Dilger
+  Internet: adilger at enel.ucalgary.ca
+  Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
+ 
+ -Guy Eric Schalnat
+  (formerly of Group 42, Inc)
+  Internet: gschal at infinet.com


Index: llvm/runtime/libpng/TODO
diff -c /dev/null llvm/runtime/libpng/TODO:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/TODO	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,24 ----
+ TODO - list of things to do for libpng:
+ 
+ Final bug fixes.
+ Improve API by hiding the png_struct and png_info structs.
+ Finish work on the no-floating-point version (including gamma compensation)
+ Better C++ wrapper/full C++ implementation?
+ Fix problem with C++ and EXTERN "C".
+ cHRM transformation.
+ Improve setjmp/longjmp usage or remove it in favor of returning error codes.
+ Add "grayscale->palette" transformation and "palette->grayscale" detection.
+ Improved dithering.
+ Multi-lingual error and warning message support.
+ Complete sRGB transformation (presently it simply uses gamma=0.45455).
+ Man pages for function calls.
+ Better documentation.
+ Better filter selection
+    (counting huffman bits/precompression?  filter inertia?  filter costs?).
+ Histogram creation.
+ Text conversion between different code pages (Latin-1 -> Mac and DOS).
+ Should we always malloc 2^bit_depth PLTE/tRNS/hIST entries for safety?
+ Build gamma tables using fixed point (and do away with floating point entirely).
+ Use greater precision when changing to linear gamma for compositing against
+   background and doing rgb-to-gray transformation.
+ Investigate pre-incremented loop counters and other loop constructions.


Index: llvm/runtime/libpng/Y2KINFO
diff -c /dev/null llvm/runtime/libpng/Y2KINFO:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/Y2KINFO	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,55 ----
+    Y2K compliance in libpng:
+    =========================
+ 
+       October 3, 2002
+ 
+       Since the PNG Development group is an ad-hoc body, we can't make
+       an official declaration.
+ 
+       This is your unofficial assurance that libpng from version 0.71 and
+       upward through 1.2.5 are Y2K compliant.  It is my belief that earlier
+       versions were also Y2K compliant.
+ 
+       Libpng only has three year fields.  One is a 2-byte unsigned integer
+       that will hold years up to 65535.  The other two hold the date in text
+       format, and will hold years up to 9999.
+ 
+       The integer is
+           "png_uint_16 year" in png_time_struct.
+ 
+       The strings are
+           "png_charp time_buffer" in png_struct and
+           "near_time_buffer", which is a local character string in png.c.
+ 
+       There are seven time-related functions:
+ 
+           png_convert_to_rfc_1123() in png.c
+             (formerly png_convert_to_rfc_1152() in error)
+           png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
+           png_convert_from_time_t() in pngwrite.c
+           png_get_tIME() in pngget.c
+           png_handle_tIME() in pngrutil.c, called in pngread.c
+           png_set_tIME() in pngset.c
+           png_write_tIME() in pngwutil.c, called in pngwrite.c
+ 
+       All appear to handle dates properly in a Y2K environment.  The
+       png_convert_from_time_t() function calls gmtime() to convert from system
+       clock time, which returns (year - 1900), which we properly convert to
+       the full 4-digit year.  There is a possibility that applications using
+       libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
+       function, or that they are incorrectly passing only a 2-digit year
+       instead of "year - 1900" into the png_convert_from_struct_tm() function,
+       but this is not under our control.  The libpng documentation has always
+       stated that it works with 4-digit years, and the APIs have been
+       documented as such.
+ 
+       The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
+       integer to hold the year, and can hold years as large as 65535.
+ 
+       zlib, upon which libpng depends, is also Y2K compliant.  It contains
+       no date-related code.
+ 
+ 
+          Glenn Randers-Pehrson
+          libpng maintainer
+          PNG Development Group


Index: llvm/runtime/libpng/configure
diff -c /dev/null llvm/runtime/libpng/configure:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/configure	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,6 ----
+ echo "
+   There is no \"configure\" script for Libpng-1.2.5.  Instead, please
+   copy the appropriate makefile for your system from the \"scripts\"
+   directory.  Read the INSTALL file for more details.
+ "
+ 


Index: llvm/runtime/libpng/example.c
diff -c /dev/null llvm/runtime/libpng/example.c:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/example.c	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,804 ----
+ 
+ #if 0 /* in case someone actually tries to compile this */
+ 
+ /* example.c - an example of using libpng */
+ 
+ /* This is an example of how to use libpng to read and write PNG files.
+  * The file libpng.txt is much more verbose then this.  If you have not
+  * read it, do so first.  This was designed to be a starting point of an
+  * implementation.  This is not officially part of libpng, is hereby placed
+  * in the public domain, and therefore does not require a copyright notice.
+  *
+  * This file does not currently compile, because it is missing certain
+  * parts, like allocating memory to hold an image.  You will have to
+  * supply these parts to get it to compile.  For an example of a minimal
+  * working PNG reader/writer, see pngtest.c, included in this distribution;
+  * see also the programs in the contrib directory.
+  */
+ 
+ #include "png.h"
+ 
+  /* The png_jmpbuf() macro, used in error handling, became available in
+   * libpng version 1.0.6.  If you want to be able to run your code with older
+   * versions of libpng, you must define the macro yourself (but only if it
+   * is not already defined by libpng!).
+   */
+ 
+ #ifndef png_jmpbuf
+ #  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+ #endif
+ 
+ /* Check to see if a file is a PNG file using png_sig_cmp().  png_sig_cmp()
+  * returns zero if the image is a PNG and nonzero if it isn't a PNG.
+  *
+  * The function check_if_png() shown here, but not used, returns nonzero (true)
+  * if the file can be opened and is a PNG, 0 (false) otherwise.
+  *
+  * If this call is successful, and you are going to keep the file open,
+  * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
+  * you have created the png_ptr, so that libpng knows your application
+  * has read that many bytes from the start of the file.  Make sure you
+  * don't call png_set_sig_bytes() with more than 8 bytes read or give it
+  * an incorrect number of bytes read, or you will either have read too
+  * many bytes (your fault), or you are telling libpng to read the wrong
+  * number of magic bytes (also your fault).
+  *
+  * Many applications already read the first 2 or 4 bytes from the start
+  * of the image to determine the file type, so it would be easiest just
+  * to pass the bytes to png_sig_cmp() or even skip that if you know
+  * you have a PNG file, and call png_set_sig_bytes().
+  */
+ #define PNG_BYTES_TO_CHECK 4
+ int check_if_png(char *file_name, FILE **fp)
+ {
+    char buf[PNG_BYTES_TO_CHECK];
+ 
+    /* Open the prospective PNG file. */
+    if ((*fp = fopen(file_name, "rb")) == NULL)
+       return 0;
+ 
+    /* Read in some of the signature bytes */
+    if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK)
+       return 0;
+ 
+    /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
+       Return nonzero (true) if they match */
+ 
+    return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
+ }
+ 
+ /* Read a PNG file.  You may want to return an error code if the read
+  * fails (depending upon the failure).  There are two "prototypes" given
+  * here - one where we are given the filename, and we need to open the
+  * file, and the other where we are given an open file (possibly with
+  * some or all of the magic bytes read - see comments above).
+  */
+ #ifdef open_file /* prototype 1 */
+ void read_png(char *file_name)  /* We need to open the file */
+ {
+    png_structp png_ptr;
+    png_infop info_ptr;
+    unsigned int sig_read = 0;
+    png_uint_32 width, height;
+    int bit_depth, color_type, interlace_type;
+    FILE *fp;
+ 
+    if ((fp = fopen(file_name, "rb")) == NULL)
+       return (ERROR);
+ #else no_open_file /* prototype 2 */
+ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
+ {
+    png_structp png_ptr;
+    png_infop info_ptr;
+    png_uint_32 width, height;
+    int bit_depth, color_type, interlace_type;
+ #endif no_open_file /* only use one prototype! */
+ 
+    /* Create and initialize the png_struct with the desired error handler
+     * functions.  If you want to use the default stderr and longjump method,
+     * you can supply NULL for the last three parameters.  We also supply the
+     * the compiler header file version, so that we know if the application
+     * was compiled with a compatible version of the library.  REQUIRED
+     */
+    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
+       png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+ 
+    if (png_ptr == NULL)
+    {
+       fclose(fp);
+       return (ERROR);
+    }
+ 
+    /* Allocate/initialize the memory for image information.  REQUIRED. */
+    info_ptr = png_create_info_struct(png_ptr);
+    if (info_ptr == NULL)
+    {
+       fclose(fp);
+       png_destroy_read_struct(&png_ptr, png_infopp_NULL, png_infopp_NULL);
+       return (ERROR);
+    }
+ 
+    /* Set error handling if you are using the setjmp/longjmp method (this is
+     * the normal method of doing things with libpng).  REQUIRED unless you
+     * set up your own error handlers in the png_create_read_struct() earlier.
+     */
+ 
+    if (setjmp(png_jmpbuf(png_ptr)))
+    {
+       /* Free all of the memory associated with the png_ptr and info_ptr */
+       png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
+       fclose(fp);
+       /* If we get here, we had a problem reading the file */
+       return (ERROR);
+    }
+ 
+    /* One of the following I/O initialization methods is REQUIRED */
+ #ifdef streams /* PNG file I/O method 1 */
+    /* Set up the input control if you are using standard C streams */
+    png_init_io(png_ptr, fp);
+ 
+ #else no_streams /* PNG file I/O method 2 */
+    /* If you are using replacement read functions, instead of calling
+     * png_init_io() here you would call:
+     */
+    png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
+    /* where user_io_ptr is a structure you want available to the callbacks */
+ #endif no_streams /* Use only one I/O method! */
+ 
+    /* If we have already read some of the signature */
+    png_set_sig_bytes(png_ptr, sig_read);
+ 
+ #ifdef hilevel
+    /*
+     * If you have enough memory to read in the entire image at once,
+     * and you need to specify only transforms that can be controlled
+     * with one of the PNG_TRANSFORM_* bits (this presently excludes
+     * dithering, filling, setting background, and doing gamma
+     * adjustment), then you can read the entire image (including
+     * pixels) into the info structure with this call:
+     */
+    png_read_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL);
+ #else
+    /* OK, you're doing it the hard way, with the lower-level functions */
+ 
+    /* The call to png_read_info() gives us all of the information from the
+     * PNG file before the first IDAT (image data chunk).  REQUIRED
+     */
+    png_read_info(png_ptr, info_ptr);
+ 
+    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
+        &interlace_type, int_p_NULL, int_p_NULL);
+ 
+ /* Set up the data transformations you want.  Note that these are all
+  * optional.  Only call them if you want/need them.  Many of the
+  * transformations only work on specific types of images, and many
+  * are mutually exclusive.
+  */
+ 
+    /* tell libpng to strip 16 bit/color files down to 8 bits/color */
+    png_set_strip_16(png_ptr);
+ 
+    /* Strip alpha bytes from the input data without combining with the
+     * background (not recommended).
+     */
+    png_set_strip_alpha(png_ptr);
+ 
+    /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
+     * byte into separate bytes (useful for paletted and grayscale images).
+     */
+    png_set_packing(png_ptr);
+ 
+    /* Change the order of packed pixels to least significant bit first
+     * (not useful if you are using png_set_packing). */
+    png_set_packswap(png_ptr);
+ 
+    /* Expand paletted colors into true RGB triplets */
+    if (color_type == PNG_COLOR_TYPE_PALETTE)
+       png_set_palette_rgb(png_ptr);
+ 
+    /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
+    if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
+       png_set_gray_1_2_4_to_8(png_ptr);
+ 
+    /* Expand paletted or RGB images with transparency to full alpha channels
+     * so the data will be available as RGBA quartets.
+     */
+    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
+       png_set_tRNS_to_alpha(png_ptr);
+ 
+    /* Set the background color to draw transparent and alpha images over.
+     * It is possible to set the red, green, and blue components directly
+     * for paletted images instead of supplying a palette index.  Note that
+     * even if the PNG file supplies a background, you are not required to
+     * use it - you should use the (solid) application background if it has one.
+     */
+ 
+    png_color_16 my_background, *image_background;
+ 
+    if (png_get_bKGD(png_ptr, info_ptr, &image_background))
+       png_set_background(png_ptr, image_background,
+                          PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
+    else
+       png_set_background(png_ptr, &my_background,
+                          PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
+ 
+    /* Some suggestions as to how to get a screen gamma value */
+ 
+    /* Note that screen gamma is the display_exponent, which includes
+     * the CRT_exponent and any correction for viewing conditions */
+    if (/* We have a user-defined screen gamma value */)
+    {
+       screen_gamma = user-defined screen_gamma;
+    }
+    /* This is one way that applications share the same screen gamma value */
+    else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)
+    {
+       screen_gamma = atof(gamma_str);
+    }
+    /* If we don't have another value */
+    else
+    {
+       screen_gamma = 2.2;  /* A good guess for a PC monitors in a dimly
+                               lit room */
+       screen_gamma = 1.7 or 1.0;  /* A good guess for Mac systems */
+    }
+ 
+    /* Tell libpng to handle the gamma conversion for you.  The final call
+     * is a good guess for PC generated images, but it should be configurable
+     * by the user at run time by the user.  It is strongly suggested that
+     * your application support gamma correction.
+     */
+ 
+    int intent;
+ 
+    if (png_get_sRGB(png_ptr, info_ptr, &intent))
+       png_set_gamma(png_ptr, screen_gamma, 0.45455);
+    else
+    {
+       double image_gamma;
+       if (png_get_gAMA(png_ptr, info_ptr, &image_gamma))
+          png_set_gamma(png_ptr, screen_gamma, image_gamma);
+       else
+          png_set_gamma(png_ptr, screen_gamma, 0.45455);
+    }
+ 
+    /* Dither RGB files down to 8 bit palette or reduce palettes
+     * to the number of colors available on your screen.
+     */
+    if (color_type & PNG_COLOR_MASK_COLOR)
+    {
+       int num_palette;
+       png_colorp palette;
+ 
+       /* This reduces the image to the application supplied palette */
+       if (/* we have our own palette */)
+       {
+          /* An array of colors to which the image should be dithered */
+          png_color std_color_cube[MAX_SCREEN_COLORS];
+ 
+          png_set_dither(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
+             MAX_SCREEN_COLORS, png_uint_16p_NULL, 0);
+       }
+       /* This reduces the image to the palette supplied in the file */
+       else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette))
+       {
+          png_uint_16p histogram = NULL;
+ 
+          png_get_hIST(png_ptr, info_ptr, &histogram);
+ 
+          png_set_dither(png_ptr, palette, num_palette,
+                         max_screen_colors, histogram, 0);
+       }
+    }
+ 
+    /* invert monochrome files to have 0 as white and 1 as black */
+    png_set_invert_mono(png_ptr);
+ 
+    /* If you want to shift the pixel values from the range [0,255] or
+     * [0,65535] to the original [0,7] or [0,31], or whatever range the
+     * colors were originally in:
+     */
+    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
+    {
+       png_color_8p sig_bit;
+ 
+       png_get_sBIT(png_ptr, info_ptr, &sig_bit);
+       png_set_shift(png_ptr, sig_bit);
+    }
+ 
+    /* flip the RGB pixels to BGR (or RGBA to BGRA) */
+    if (color_type & PNG_COLOR_MASK_COLOR)
+       png_set_bgr(png_ptr);
+ 
+    /* swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
+    png_set_swap_alpha(png_ptr);
+ 
+    /* swap bytes of 16 bit files to least significant byte first */
+    png_set_swap(png_ptr);
+ 
+    /* Add filler (or alpha) byte (before/after each RGB triplet) */
+    png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
+ 
+    /* Turn on interlace handling.  REQUIRED if you are not using
+     * png_read_image().  To see how to handle interlacing passes,
+     * see the png_read_row() method below:
+     */
+    number_passes = png_set_interlace_handling(png_ptr);
+ 
+    /* Optional call to gamma correct and add the background to the palette
+     * and update info structure.  REQUIRED if you are expecting libpng to
+     * update the palette for you (ie you selected such a transform above).
+     */
+    png_read_update_info(png_ptr, info_ptr);
+ 
+    /* Allocate the memory to hold the image using the fields of info_ptr. */
+ 
+    /* The easiest way to read the image: */
+    png_bytep row_pointers[height];
+ 
+    for (row = 0; row < height; row++)
+    {
+       row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
+          info_ptr));
+    }
+ 
+    /* Now it's time to read the image.  One of these methods is REQUIRED */
+ #ifdef entire /* Read the entire image in one go */
+    png_read_image(png_ptr, row_pointers);
+ 
+ #else no_entire /* Read the image one or more scanlines at a time */
+    /* The other way to read images - deal with interlacing: */
+ 
+    for (pass = 0; pass < number_passes; pass++)
+    {
+ #ifdef single /* Read the image a single row at a time */
+       for (y = 0; y < height; y++)
+       {
+          png_read_rows(png_ptr, &row_pointers[y], png_bytepp_NULL, 1);
+       }
+ 
+ #else no_single /* Read the image several rows at a time */
+       for (y = 0; y < height; y += number_of_rows)
+       {
+ #ifdef sparkle /* Read the image using the "sparkle" effect. */
+          png_read_rows(png_ptr, &row_pointers[y], png_bytepp_NULL,
+             number_of_rows);
+ #else no_sparkle /* Read the image using the "rectangle" effect */
+          png_read_rows(png_ptr, png_bytepp_NULL, &row_pointers[y],
+             number_of_rows);
+ #endif no_sparkle /* use only one of these two methods */
+       }
+ 
+       /* if you want to display the image after every pass, do
+          so here */
+ #endif no_single /* use only one of these two methods */
+    }
+ #endif no_entire /* use only one of these two methods */
+ 
+    /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
+    png_read_end(png_ptr, info_ptr);
+ #endif hilevel
+ 
+    /* At this point you have read the entire image */
+ 
+    /* clean up after the read, and free any memory allocated - REQUIRED */
+    png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
+ 
+    /* close the file */
+    fclose(fp);
+ 
+    /* that's it */
+    return (OK);
+ }
+ 
+ /* progressively read a file */
+ 
+ int
+ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
+ {
+    /* Create and initialize the png_struct with the desired error handler
+     * functions.  If you want to use the default stderr and longjump method,
+     * you can supply NULL for the last three parameters.  We also check that
+     * the library version is compatible in case we are using dynamically
+     * linked libraries.
+     */
+    *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
+        png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+ 
+    if (*png_ptr == NULL)
+    {
+       *info_ptr = NULL;
+       return (ERROR);
+    }
+ 
+    *info_ptr = png_create_info_struct(png_ptr);
+ 
+    if (*info_ptr == NULL)
+    {
+       png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL);
+       return (ERROR);
+    }
+ 
+    if (setjmp(png_jmpbuf((*png_ptr))))
+    {
+       png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL);
+       return (ERROR);
+    }
+ 
+    /* This one's new.  You will need to provide all three
+     * function callbacks, even if you aren't using them all.
+     * If you aren't using all functions, you can specify NULL
+     * parameters.  Even when all three functions are NULL,
+     * you need to call png_set_progressive_read_fn().
+     * These functions shouldn't be dependent on global or
+     * static variables if you are decoding several images
+     * simultaneously.  You should store stream specific data
+     * in a separate struct, given as the second parameter,
+     * and retrieve the pointer from inside the callbacks using
+     * the function png_get_progressive_ptr(png_ptr).
+     */
+    png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
+       info_callback, row_callback, end_callback);
+ 
+    return (OK);
+ }
+ 
+ int
+ process_data(png_structp *png_ptr, png_infop *info_ptr,
+    png_bytep buffer, png_uint_32 length)
+ {
+    if (setjmp(png_jmpbuf((*png_ptr))))
+    {
+       /* Free the png_ptr and info_ptr memory on error */
+       png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL);
+       return (ERROR);
+    }
+ 
+    /* This one's new also.  Simply give it chunks of data as
+     * they arrive from the data stream (in order, of course).
+     * On Segmented machines, don't give it any more than 64K.
+     * The library seems to run fine with sizes of 4K, although
+     * you can give it much less if necessary (I assume you can
+     * give it chunks of 1 byte, but I haven't tried with less
+     * than 256 bytes yet).  When this function returns, you may
+     * want to display any rows that were generated in the row
+     * callback, if you aren't already displaying them there.
+     */
+    png_process_data(*png_ptr, *info_ptr, buffer, length);
+    return (OK);
+ }
+ 
+ info_callback(png_structp png_ptr, png_infop info)
+ {
+ /* do any setup here, including setting any of the transformations
+  * mentioned in the Reading PNG files section.  For now, you _must_
+  * call either png_start_read_image() or png_read_update_info()
+  * after all the transformations are set (even if you don't set
+  * any).  You may start getting rows before png_process_data()
+  * returns, so this is your last chance to prepare for that.
+  */
+ }
+ 
+ row_callback(png_structp png_ptr, png_bytep new_row,
+    png_uint_32 row_num, int pass)
+ {
+ /*
+  * This function is called for every row in the image.  If the
+  * image is interlaced, and you turned on the interlace handler,
+  * this function will be called for every row in every pass.
+  *
+  * In this function you will receive a pointer to new row data from
+  * libpng called new_row that is to replace a corresponding row (of
+  * the same data format) in a buffer allocated by your application.
+  * 
+  * The new row data pointer new_row may be NULL, indicating there is
+  * no new data to be replaced (in cases of interlace loading).
+  * 
+  * If new_row is not NULL then you need to call
+  * png_progressive_combine_row() to replace the corresponding row as
+  * shown below:
+  */
+    /* Check if row_num is in bounds. */
+    if((row_num >= 0) && (row_num < height))
+    {
+      /* Get pointer to corresponding row in our
+       * PNG read buffer.
+       */
+      png_bytep old_row = ((png_bytep *)our_data)[row_num];
+ 
+      /* If both rows are allocated then copy the new row
+       * data to the corresponding row data.
+       */
+      if((old_row != NULL) && (new_row != NULL))
+      png_progressive_combine_row(png_ptr, old_row, new_row);
+    }
+ /*
+  * The rows and passes are called in order, so you don't really
+  * need the row_num and pass, but I'm supplying them because it
+  * may make your life easier.
+  *
+  * For the non-NULL rows of interlaced images, you must call
+  * png_progressive_combine_row() passing in the new row and the
+  * old row, as demonstrated above.  You can call this function for
+  * NULL rows (it will just return) and for non-interlaced images
+  * (it just does the png_memcpy for you) if it will make the code
+  * easier.  Thus, you can just do this for all cases:
+  */
+ 
+    png_progressive_combine_row(png_ptr, old_row, new_row);
+ 
+ /* where old_row is what was displayed for previous rows.  Note
+  * that the first pass (pass == 0 really) will completely cover
+  * the old row, so the rows do not have to be initialized.  After
+  * the first pass (and only for interlaced images), you will have
+  * to pass the current row as new_row, and the function will combine
+  * the old row and the new row.
+  */
+ }
+ 
+ end_callback(png_structp png_ptr, png_infop info)
+ {
+ /* this function is called when the whole image has been read,
+  * including any chunks after the image (up to and including
+  * the IEND).  You will usually have the same info chunk as you
+  * had in the header, although some data may have been added
+  * to the comments and time fields.
+  *
+  * Most people won't do much here, perhaps setting a flag that
+  * marks the image as finished.
+  */
+ }
+ 
+ /* write a png file */
+ void write_png(char *file_name /* , ... other image information ... */)
+ {
+    FILE *fp;
+    png_structp png_ptr;
+    png_infop info_ptr;
+    png_colorp palette;
+ 
+    /* open the file */
+    fp = fopen(file_name, "wb");
+    if (fp == NULL)
+       return (ERROR);
+ 
+    /* Create and initialize the png_struct with the desired error handler
+     * functions.  If you want to use the default stderr and longjump method,
+     * you can supply NULL for the last three parameters.  We also check that
+     * the library version is compatible with the one used at compile time,
+     * in case we are using dynamically linked libraries.  REQUIRED.
+     */
+    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
+       png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+ 
+    if (png_ptr == NULL)
+    {
+       fclose(fp);
+       return (ERROR);
+    }
+ 
+    /* Allocate/initialize the image information data.  REQUIRED */
+    info_ptr = png_create_info_struct(png_ptr);
+    if (info_ptr == NULL)
+    {
+       fclose(fp);
+       png_destroy_write_struct(&png_ptr,  png_infopp_NULL);
+       return (ERROR);
+    }
+ 
+    /* Set error handling.  REQUIRED if you aren't supplying your own
+     * error handling functions in the png_create_write_struct() call.
+     */
+    if (setjmp(png_jmpbuf(png_ptr)))
+    {
+       /* If we get here, we had a problem reading the file */
+       fclose(fp);
+       png_destroy_write_struct(&png_ptr, &info_ptr);
+       return (ERROR);
+    }
+ 
+    /* One of the following I/O initialization functions is REQUIRED */
+ #ifdef streams /* I/O initialization method 1 */
+    /* set up the output control if you are using standard C streams */
+    png_init_io(png_ptr, fp);
+ #else no_streams /* I/O initialization method 2 */
+    /* If you are using replacement read functions, instead of calling
+     * png_init_io() here you would call */
+    png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
+       user_IO_flush_function);
+    /* where user_io_ptr is a structure you want available to the callbacks */
+ #endif no_streams /* only use one initialization method */
+ 
+ #ifdef hilevel
+    /* This is the easy way.  Use it if you already have all the
+     * image info living info in the structure.  You could "|" many
+     * PNG_TRANSFORM flags into the png_transforms integer here.
+     */
+    png_write_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL);
+ #else
+    /* This is the hard way */
+ 
+    /* Set the image information here.  Width and height are up to 2^31,
+     * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
+     * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
+     * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
+     * or PNG_COLOR_TYPE_RGB_ALPHA.  interlace is either PNG_INTERLACE_NONE or
+     * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
+     * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
+     */
+    png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
+       PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+ 
+    /* set the palette if there is one.  REQUIRED for indexed-color images */
+    palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
+              * sizeof (png_color));
+    /* ... set palette colors ... */
+    png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH);
+    /* You must not free palette here, because png_set_PLTE only makes a link to
+       the palette that you malloced.  Wait until you are about to destroy
+       the png structure. */
+ 
+    /* optional significant bit chunk */
+    /* if we are dealing with a grayscale image then */
+    sig_bit.gray = true_bit_depth;
+    /* otherwise, if we are dealing with a color image then */
+    sig_bit.red = true_red_bit_depth;
+    sig_bit.green = true_green_bit_depth;
+    sig_bit.blue = true_blue_bit_depth;
+    /* if the image has an alpha channel then */
+    sig_bit.alpha = true_alpha_bit_depth;
+    png_set_sBIT(png_ptr, info_ptr, sig_bit);
+ 
+ 
+    /* Optional gamma chunk is strongly suggested if you have any guess
+     * as to the correct gamma of the image.
+     */
+    png_set_gAMA(png_ptr, info_ptr, gamma);
+ 
+    /* Optionally write comments into the image */
+    text_ptr[0].key = "Title";
+    text_ptr[0].text = "Mona Lisa";
+    text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
+    text_ptr[1].key = "Author";
+    text_ptr[1].text = "Leonardo DaVinci";
+    text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE;
+    text_ptr[2].key = "Description";
+    text_ptr[2].text = "<long text>";
+    text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;
+ #ifdef PNG_iTXt_SUPPORTED
+    text_ptr[0].lang = NULL;
+    text_ptr[1].lang = NULL;
+    text_ptr[2].lang = NULL;
+ #endif
+    png_set_text(png_ptr, info_ptr, text_ptr, 3);
+ 
+    /* other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs, */
+    /* note that if sRGB is present the gAMA and cHRM chunks must be ignored
+     * on read and must be written in accordance with the sRGB profile */
+ 
+    /* Write the file header information.  REQUIRED */
+    png_write_info(png_ptr, info_ptr);
+ 
+    /* If you want, you can write the info in two steps, in case you need to
+     * write your private chunk ahead of PLTE:
+     *
+     *   png_write_info_before_PLTE(write_ptr, write_info_ptr);
+     *   write_my_chunk();
+     *   png_write_info(png_ptr, info_ptr);
+     *
+     * However, given the level of known- and unknown-chunk support in 1.1.0
+     * and up, this should no longer be necessary.
+     */
+ 
+    /* Once we write out the header, the compression type on the text
+     * chunks gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
+     * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again
+     * at the end.
+     */
+ 
+    /* set up the transformations you want.  Note that these are
+     * all optional.  Only call them if you want them.
+     */
+ 
+    /* invert monochrome pixels */
+    png_set_invert_mono(png_ptr);
+ 
+    /* Shift the pixels up to a legal bit depth and fill in
+     * as appropriate to correctly scale the image.
+     */
+    png_set_shift(png_ptr, &sig_bit);
+ 
+    /* pack pixels into bytes */
+    png_set_packing(png_ptr);
+ 
+    /* swap location of alpha bytes from ARGB to RGBA */
+    png_set_swap_alpha(png_ptr);
+ 
+    /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
+     * RGB (4 channels -> 3 channels). The second parameter is not used.
+     */
+    png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+ 
+    /* flip BGR pixels to RGB */
+    png_set_bgr(png_ptr);
+ 
+    /* swap bytes of 16-bit files to most significant byte first */
+    png_set_swap(png_ptr);
+ 
+    /* swap bits of 1, 2, 4 bit packed pixel formats */
+    png_set_packswap(png_ptr);
+ 
+    /* turn on interlace handling if you are not using png_write_image() */
+    if (interlacing)
+       number_passes = png_set_interlace_handling(png_ptr);
+    else
+       number_passes = 1;
+ 
+    /* The easiest way to write the image (you may have a different memory
+     * layout, however, so choose what fits your needs best).  You need to
+     * use the first method if you aren't handling interlacing yourself.
+     */
+    png_uint_32 k, height, width;
+    png_byte image[height][width*bytes_per_pixel];
+    png_bytep row_pointers[height];
+    for (k = 0; k < height; k++)
+      row_pointers[k] = image + k*width*bytes_per_pixel;
+ 
+    /* One of the following output methods is REQUIRED */
+ #ifdef entire /* write out the entire image data in one call */
+    png_write_image(png_ptr, row_pointers);
+ 
+    /* the other way to write the image - deal with interlacing */
+ 
+ #else no_entire /* write out the image data by one or more scanlines */
+    /* The number of passes is either 1 for non-interlaced images,
+     * or 7 for interlaced images.
+     */
+    for (pass = 0; pass < number_passes; pass++)
+    {
+       /* Write a few rows at a time. */
+       png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows);
+ 
+       /* If you are only writing one row at a time, this works */
+       for (y = 0; y < height; y++)
+       {
+          png_write_rows(png_ptr, &row_pointers[y], 1);
+       }
+    }
+ #endif no_entire /* use only one output method */
+ 
+    /* You can write optional chunks like tEXt, zTXt, and tIME at the end
+     * as well.  Shouldn't be necessary in 1.1.0 and up as all the public
+     * chunks are supported and you can use png_set_unknown_chunks() to
+     * register unknown chunks into the info structure to be written out.
+     */
+ 
+    /* It is REQUIRED to call this to finish writing the rest of the file */
+    png_write_end(png_ptr, info_ptr);
+ #endif hilevel
+ 
+    /* If you png_malloced a palette, free it here (don't free info_ptr->palette,
+       as recommended in versions 1.0.5m and earlier of this example; if
+       libpng mallocs info_ptr->palette, libpng will free it).  If you
+       allocated it with malloc() instead of png_malloc(), use free() instead
+       of png_free(). */
+    png_free(png_ptr, palette);
+    palette=NULL;
+ 
+    /* Similarly, if you png_malloced any data that you passed in with
+       png_set_something(), such as a hist or trans array, free it here,
+       when you can be sure that libpng is through with it. */
+    png_free(png_ptr, trans);
+    trans=NULL;
+ 
+    /* clean up after the write, and free any memory allocated */
+    png_destroy_write_struct(&png_ptr, &info_ptr);
+ 
+    /* close the file */
+    fclose(fp);
+ 
+    /* that's it */
+    return (OK);
+ }
+ 
+ #endif /* if 0 */


Index: llvm/runtime/libpng/libpng.3
diff -c /dev/null llvm/runtime/libpng/libpng.3:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/libpng.3	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,3958 ----
+ .TH LIBPNG 3 "October 3, 2002"
+ .SH NAME
+ libpng \- Portable Network Graphics (PNG) Reference Library 1.2.5
+ .SH SYNOPSIS
+ \fI\fB
+ 
+ \fB#include <png.h>\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_check_sig (png_bytep \fP\fIsig\fP\fB, int \fInum\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_structp png_create_read_struct_2(png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_structp png_create_write_struct_2(png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_debug(int \fP\fIlevel\fP\fB, png_const_charp \fImessage\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_debug1(int \fP\fIlevel\fP\fB, png_const_charp \fP\fImessage\fP\fB, \fIp1\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_debug2(int \fP\fIlevel\fP\fB, png_const_charp \fP\fImessage\fP\fB, \fP\fIp1\fP\fB, \fIp2\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_free_default(png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_asm_flags (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_bit_depth (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_channels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, double \fP\fI*green_y\fP\fB, double \fP\fI*blue_x\fP\fB, double \fI*blue_y\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_uint_32 \fP\fI*green_x\fP\fB, png_uint_32 \fP\fI*green_y\fP\fB, png_uint_32 \fP\fI*blue_x\fP\fB, png_uint_32 \fI*blue_y\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_color_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_compression_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_copyright (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_get_error_ptr (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_filter_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_header_ver (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_header_version (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_charpp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, int \fP\fI*compression_type\fP\fB, int \fI*filter_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_image_height (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_image_width (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_interlace_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_libpng_ver (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_get_mem_ptr(png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_mmx_bitdepth_threshold (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_mmx_flagmask (int \fP\fIflag_select\fP\fB, int \fI*compilerID\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_mmx_rowbytes_threshold (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_charp \fP\fI*units\fP\fB, png_charpp \fI*params\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBfloat png_get_pixel_aspect_ratio (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_get_progressive_ptr (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_byte png_get_rgb_to_gray_status (png_structp \fIpng_ptr)
+ 
+ \fBpng_uint_32 png_get_rowbytes (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_bytepp png_get_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_bytep png_get_signature (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fI*intent\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_values\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_get_user_chunk_ptr (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_get_user_transform_ptr (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_valid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_int_32 png_get_x_offset_microns (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_int_32 png_get_x_offset_pixels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_x_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_int_32 png_get_y_offset_microns (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_int_32 png_get_y_offset_pixels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_y_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_compression_buffer_size (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBDEPRECATED: void png_info_init (png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBDEPRECATED: void png_info_init_2 (png_infopp \fP\fIptr_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_malloc_default(png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_malloc_warn (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoidp png_memcpy (png_voidp \fP\fIs1\fP\fB, png_voidp \fP\fIs2\fP\fB, png_size_t \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_memcpy_check (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIs1\fP\fB, png_voidp \fP\fIs2\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoidp png_memset (png_voidp \fP\fIs1\fP\fB, int \fP\fIvalue\fP\fB, png_size_t \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_memset_check (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIs1\fP\fB, int \fP\fIvalue\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_mmx_support \fI(void\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBDEPRECATED: void png_permit_empty_plte (png_structp \fP\fIpng_ptr\fP\fB, int \fIempty_plte_permitted\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_destroy (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_infop \fIend_info_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBDEPRECATED: void png_read_init (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBDEPRECATED: void png_read_init_2 (png_structpp \fP\fIptr_ptr\fP\fB, png_const_charp \fP\fIuser_png_ver\fP\fB, png_size_t \fP\fIpng_struct_size\fP\fB, png_size_t \fIpng_info_size\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_set_asm_flags (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIasm_flags\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_dither (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_dither\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_gray_1_2_4_to_8(png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_charp \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fIfilter_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_mem_fn(png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_set_mmx_thresholds (png_structp \fP\fIpng_ptr\fP\fB, png_byte \fP\fImmx_bitdepth_threshold\fP\fB, png_uint_32 \fImmx_rowbytes_threshold\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_palette_to_rgb(png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_fixed_point \fP\fIred\fP\fB, png_fixed_point \fIgreen\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIintent\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIintent\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_strip_error_numbers (png_structp \fIpng_ptr,
+ 
+ \fBpng_uint_32 \fIstrip_mode\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_values\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_tRNS_to_alpha(png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_unknown_chunk_location(png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_set_compression_buffer_size(png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_destroy (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBDEPRECATED: void png_write_init (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBDEPRECATED: void png_write_init_2 (png_structpp \fP\fIptr_ptr\fP\fB, png_const_charp \fP\fIuser_png_ver\fP\fB, png_size_t \fP\fIpng_struct_size\fP\fB, png_size_t \fIpng_info_size\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ .SH DESCRIPTION
+ The
+ .I libpng
+ library supports encoding, decoding, and various manipulations of
+ the Portable Network Graphics (PNG) format image files.  It uses the
+ .IR zlib(3)
+ compression library.
+ Following is a copy of the libpng.txt file that accompanies libpng.
+ .SH LIBPNG.TXT
+ libpng.txt - A description on how to use and modify libpng
+ 
+  libpng version 1.2.5 - October 3, 2002
+  Updated and distributed by Glenn Randers-Pehrson
+  <randeg at alum.rpi.edu>
+  Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  For conditions of distribution and use, see copyright
+  notice in png.h.
+ 
+  based on:
+ 
+  libpng 1.0 beta 6  version 0.96 May 28, 1997
+  Updated and distributed by Andreas Dilger
+  Copyright (c) 1996, 1997 Andreas Dilger
+ 
+  libpng 1.0 beta 2 - version 0.88  January 26, 1996
+  For conditions of distribution and use, see copyright
+  notice in png.h. Copyright (c) 1995, 1996 Guy Eric
+  Schalnat, Group 42, Inc.
+ 
+  Updated/rewritten per request in the libpng FAQ
+  Copyright (c) 1995, 1996 Frank J. T. Wojcik
+  December 18, 1995 & January 20, 1996
+ 
+ .SH I. Introduction
+ 
+ This file describes how to use and modify the PNG reference library
+ (known as libpng) for your own use.  There are five sections to this
+ file: introduction, structures, reading, writing, and modification and
+ configuration notes for various special platforms.  In addition to this
+ file, example.c is a good starting point for using the library, as
+ it is heavily commented and should include everything most people
+ will need.  We assume that libpng is already installed; see the
+ INSTALL file for instructions on how to install libpng.
+ 
+ Libpng was written as a companion to the PNG specification, as a way
+ of reducing the amount of time and effort it takes to support the PNG
+ file format in application programs.
+ 
+ The PNG-1.2 specification is available at <http://www.libpng.org/pub/png>
+ and at <ftp://ftp.uu.net/graphics/png/documents/>.
+ 
+ The PNG-1.0 specification is available
+ as RFC 2083 <ftp://ftp.uu.net/graphics/png/documents/> and as a
+ W3C Recommendation <http://www.w3.org/TR/REC.png.html>. Some
+ additional chunks are described in the special-purpose public chunks
+ documents at <ftp://ftp.uu.net/graphics/png/documents/>.
+ 
+ Other information
+ about PNG, and the latest version of libpng, can be found at the PNG home
+ page, <http://www.libpng.org/pub/png/>
+ and at <ftp://ftp.uu.net/graphics/png/>.
+ 
+ Most users will not have to modify the library significantly; advanced
+ users may want to modify it more.  All attempts were made to make it as
+ complete as possible, while keeping the code easy to understand.
+ Currently, this library only supports C.  Support for other languages
+ is being considered.
+ 
+ Libpng has been designed to handle multiple sessions at one time,
+ to be easily modifiable, to be portable to the vast majority of
+ machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
+ to use.  The ultimate goal of libpng is to promote the acceptance of
+ the PNG file format in whatever way possible.  While there is still
+ work to be done (see the TODO file), libpng should cover the
+ majority of the needs of its users.
+ 
+ Libpng uses zlib for its compression and decompression of PNG files.
+ Further information about zlib, and the latest version of zlib, can
+ be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
+ The zlib compression utility is a general purpose utility that is
+ useful for more than PNG files, and can be used without libpng.
+ See the documentation delivered with zlib for more details.
+ You can usually find the source files for the zlib utility wherever you
+ find the libpng source files.
+ 
+ Libpng is thread safe, provided the threads are using different
+ instances of the structures.  Each thread should have its own
+ png_struct and png_info instances, and thus its own image.
+ Libpng does not protect itself against two threads using the
+ same instance of a structure.  Note: thread safety may be defeated
+ by use of some of the MMX assembler code in pnggccrd.c, which is only
+ compiled when the user defines PNG_THREAD_UNSAFE_OK.
+ 
+ 
+ .SH II. Structures
+ 
+ There are two main structures that are important to libpng, png_struct
+ and png_info.  The first, png_struct, is an internal structure that
+ will not, for the most part, be used by a user except as the first
+ variable passed to every libpng function call.
+ 
+ The png_info structure is designed to provide information about the
+ PNG file.  At one time, the fields of png_info were intended to be
+ directly accessible to the user.  However, this tended to cause problems
+ with applications using dynamically loaded libraries, and as a result
+ a set of interface functions for png_info (the png_get_*() and png_set_*()
+ functions) was developed.  The fields of png_info are still available for
+ older applications, but it is suggested that applications use the new
+ interfaces if at all possible.
+ 
+ Applications that do make direct access to the members of png_struct (except
+ for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
+ and applications that make direct access to the members of png_info must
+ be recompiled if they were compiled or loaded with libpng version 1.0.6,
+ in which the members were in a different order.  In version 1.0.7, the
+ members of the png_info structure reverted to the old order, as they were
+ in versions 0.97c through 1.0.5.  Starting with version 2.0.0, both
+ structures are going to be hidden, and the contents of the structures will
+ only be accessible through the png_get/png_set functions.
+ 
+ The png.h header file is an invaluable reference for programming with libpng.
+ And while I'm on the topic, make sure you include the libpng header file:
+ 
+ #include <png.h>
+ 
+ .SH III. Reading
+ 
+ We'll now walk you through the possible functions to call when reading
+ in a PNG file sequentially, briefly explaining the syntax and purpose
+ of each one.  See example.c and png.h for more detail.  While
+ progressive reading is covered in the next section, you will still
+ need some of the functions discussed in this section to read a PNG
+ file.
+ 
+ .SS Setup
+ 
+ You will want to do the I/O initialization(*) before you get into libpng,
+ so if it doesn't work, you don't have much to undo.  Of course, you
+ will also want to insure that you are, in fact, dealing with a PNG
+ file.  Libpng provides a simple check to see if a file is a PNG file.
+ To use it, pass in the first 1 to 8 bytes of the file to the function
+ png_sig_cmp(), and it will return 0 if the bytes match the corresponding
+ bytes of the PNG signature, or nonzero otherwise.  Of course, the more bytes
+ you pass in, the greater the accuracy of the prediction.
+ 
+ If you are intending to keep the file pointer open for use in libpng,
+ you must ensure you don't read more than 8 bytes from the beginning
+ of the file, and you also have to make a call to png_set_sig_bytes_read()
+ with the number of bytes you read from the beginning.  Libpng will
+ then only check the bytes (if any) that your program didn't read.
+ 
+ (*): If you are not using the standard I/O functions, you will need
+ to replace them with custom functions.  See the discussion under
+ Customizing libpng.
+ 
+ 
+     FILE *fp = fopen(file_name, "rb");
+     if (!fp)
+     {
+         return (ERROR);
+     }
+     fread(header, 1, number, fp);
+     is_png = !png_sig_cmp(header, 0, number);
+     if (!is_png)
+     {
+         return (NOT_PNG);
+     }
+ 
+ 
+ Next, png_struct and png_info need to be allocated and initialized.  In
+ order to ensure that the size of these structures is correct even with a
+ dynamically linked libpng, there are functions to initialize and
+ allocate the structures.  We also pass the library version, optional
+ pointers to error handling functions, and a pointer to a data struct for
+ use by the error functions, if necessary (the pointer and functions can
+ be NULL if the default error handlers are to be used).  See the section
+ on Changes to Libpng below regarding the old initialization functions.
+ The structure allocation functions quietly return NULL if they fail to
+ create the structure, so your application should check for that.
+ 
+     png_structp png_ptr = png_create_read_struct
+        (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+         user_error_fn, user_warning_fn);
+     if (!png_ptr)
+         return (ERROR);
+ 
+     png_infop info_ptr = png_create_info_struct(png_ptr);
+     if (!info_ptr)
+     {
+         png_destroy_read_struct(&png_ptr,
+            (png_infopp)NULL, (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+     png_infop end_info = png_create_info_struct(png_ptr);
+     if (!end_info)
+     {
+         png_destroy_read_struct(&png_ptr, &info_ptr,
+           (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+ If you want to use your own memory allocation routines,
+ define PNG_USER_MEM_SUPPORTED and use
+ png_create_read_struct_2() instead of png_create_read_struct():
+ 
+     png_structp png_ptr = png_create_read_struct_2
+        (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+         user_error_fn, user_warning_fn, (png_voidp)
+         user_mem_ptr, user_malloc_fn, user_free_fn);
+ 
+ The error handling routines passed to png_create_read_struct()
+ and the memory alloc/free routines passed to png_create_struct_2()
+ are only necessary if you are not using the libpng supplied error
+ handling and memory alloc/free functions.
+ 
+ When libpng encounters an error, it expects to longjmp back
+ to your routine.  Therefore, you will need to call setjmp and pass
+ your png_jmpbuf(png_ptr).  If you read the file from different
+ routines, you will need to update the jmpbuf field every time you enter
+ a new routine that will call a png_*() function.
+ 
+ See your documentation of setjmp/longjmp for your compiler for more
+ information on setjmp/longjmp.  See the discussion on libpng error
+ handling in the Customizing Libpng section below for more information
+ on the libpng error handling.  If an error occurs, and libpng longjmp's
+ back to your setjmp, you will want to call png_destroy_read_struct() to
+ free any memory.
+ 
+     if (setjmp(png_jmpbuf(png_ptr)))
+     {
+         png_destroy_read_struct(&png_ptr, &info_ptr,
+            &end_info);
+         fclose(fp);
+         return (ERROR);
+     }
+ 
+ If you would rather avoid the complexity of setjmp/longjmp issues,
+ you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
+ errors will result in a call to PNG_ABORT() which defaults to abort().
+ 
+ Now you need to set up the input code.  The default for libpng is to
+ use the C function fread().  If you use this, you will need to pass a
+ valid FILE * in the function png_init_io().  Be sure that the file is
+ opened in binary mode.  If you wish to handle reading data in another
+ way, you need not call the png_init_io() function, but you must then
+ implement the libpng I/O methods discussed in the Customizing Libpng
+ section below.
+ 
+     png_init_io(png_ptr, fp);
+ 
+ If you had previously opened the file and read any of the signature from
+ the beginning in order to see if this was a PNG file, you need to let
+ libpng know that there are some bytes missing from the start of the file.
+ 
+     png_set_sig_bytes(png_ptr, number);
+ 
+ .SS Setting up callback code
+ 
+ You can set up a callback function to handle any unknown chunks in the
+ input stream. You must supply the function
+ 
+     read_chunk_callback(png_ptr ptr,
+          png_unknown_chunkp chunk);
+     {
+        /* The unknown chunk structure contains your
+           chunk data: */
+            png_byte name[5];
+            png_byte *data;
+            png_size_t size;
+        /* Note that libpng has already taken care of
+           the CRC handling */
+ 
+        /* put your code here.  Return one of the
+           following: */
+ 
+        return (-n); /* chunk had an error */
+        return (0); /* did not recognize */
+        return (n); /* success */
+     }
+ 
+ (You can give your function another name that you like instead of
+ "read_chunk_callback")
+ 
+ To inform libpng about your function, use
+ 
+     png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
+         read_chunk_callback);
+ 
+ This names not only the callback function, but also a user pointer that
+ you can retrieve with
+ 
+     png_get_user_chunk_ptr(png_ptr);
+ 
+ At this point, you can set up a callback function that will be
+ called after each row has been read, which you can use to control
+ a progress meter or the like.  It's demonstrated in pngtest.c.
+ You must supply a function
+ 
+     void read_row_callback(png_ptr ptr, png_uint_32 row,
+        int pass);
+     {
+       /* put your code here */
+     }
+ 
+ (You can give it another name that you like instead of "read_row_callback")
+ 
+ To inform libpng about your function, use
+ 
+     png_set_read_status_fn(png_ptr, read_row_callback);
+ 
+ .SS Unknown-chunk handling
+ 
+ Now you get to set the way the library processes unknown chunks in the
+ input PNG stream. Both known and unknown chunks will be read.  Normal
+ behavior is that known chunks will be parsed into information in
+ various info_ptr members; unknown chunks will be discarded. To change
+ this, you can call:
+ 
+     png_set_keep_unknown_chunks(png_ptr, info_ptr, keep,
+         chunk_list, num_chunks);
+     keep       - 0: do not keep
+                  1: keep only if safe-to-copy
+                  2: keep even if unsafe-to-copy
+     chunk_list - list of chunks affected (a byte string,
+                  five bytes per chunk, NULL or '\0' if
+                  num_chunks is 0)
+     num_chunks - number of chunks affected; if 0, all
+                  unknown chunks are affected
+ 
+ Unknown chunks declared in this way will be saved as raw data onto a
+ list of png_unknown_chunk structures.  If a chunk that is normally
+ known to libpng is named in the list, it will be handled as unknown,
+ according to the "keep" directive.  If a chunk is named in successive
+ instances of png_set_keep_unknown_chunks(), the final instance will
+ take precedence.
+ 
+ .SS The high-level read interface
+ 
+ At this point there are two ways to proceed; through the high-level
+ read interface, or through a sequence of low-level read operations.
+ You can use the high-level interface if (a) you are willing to read
+ the entire image into memory, and (b) the input transformations
+ you want to do are limited to the following set:
+ 
+     PNG_TRANSFORM_IDENTITY      No transformation
+     PNG_TRANSFORM_STRIP_16      Strip 16-bit samples to
+                                 8 bits
+     PNG_TRANSFORM_STRIP_ALPHA   Discard the alpha channel
+     PNG_TRANSFORM_PACKING       Expand 1, 2 and 4-bit
+                                 samples to bytes
+     PNG_TRANSFORM_PACKSWAP      Change order of packed
+                                 pixels to LSB first
+     PNG_TRANSFORM_EXPAND        Perform set_expand()
+     PNG_TRANSFORM_INVERT_MONO   Invert monochrome images
+     PNG_TRANSFORM_SHIFT         Normalize pixels to the
+                                 sBIT depth
+     PNG_TRANSFORM_BGR           Flip RGB to BGR, RGBA
+                                 to BGRA
+     PNG_TRANSFORM_SWAP_ALPHA    Flip RGBA to ARGB or GA
+                                 to AG
+     PNG_TRANSFORM_INVERT_ALPHA  Change alpha from opacity
+                                 to transparency
+     PNG_TRANSFORM_SWAP_ENDIAN   Byte-swap 16-bit samples
+ 
+ (This excludes setting a background color, doing gamma transformation,
+ dithering, and setting filler.)  If this is the case, simply do this:
+ 
+     png_read_png(png_ptr, info_ptr, png_transforms, NULL)
+ 
+ where png_transforms is an integer containing the logical OR of
+ some set of transformation flags.  This call is equivalent to png_read_info(),
+ followed the set of transformations indicated by the transform mask,
+ then png_read_image(), and finally png_read_end().
+ 
+ (The final parameter of this call is not yet used.  Someday it might point
+ to transformation parameters required by some future input transform.)
+ 
+ After you have called png_read_png(), you can retrieve the image data
+ with
+ 
+    row_pointers = png_get_rows(png_ptr, info_ptr);
+ 
+ where row_pointers is an array of pointers to the pixel data for each row:
+ 
+    png_bytep row_pointers[height];
+ 
+ If you know your image size and pixel size ahead of time, you can allocate
+ row_pointers prior to calling png_read_png() with
+ 
+    row_pointers = png_malloc(png_ptr,
+       height*sizeof(png_bytep));
+    for (int i=0; i<height, i++)
+       row_pointers[i]=png_malloc(png_ptr,
+          width*pixel_size);
+    png_set_rows(png_ptr, info_ptr, &row_pointers);
+ 
+ Alternatively you could allocate your image in one big block and define
+ row_pointers[i] to point into the proper places in your block.
+ 
+ If you use png_set_rows(), the application is responsible for freeing
+ row_pointers (and row_pointers[i], if they were separately allocated).
+ 
+ If you don't allocate row_pointers ahead of time, png_read_png() will
+ do it, and it'll be free'ed when you call png_destroy_*().
+ 
+ .SS The low-level read interface
+ 
+ If you are going the low-level route, you are now ready to read all
+ the file information up to the actual image data.  You do this with a
+ call to png_read_info().
+ 
+     png_read_info(png_ptr, info_ptr);
+ 
+ This will process all chunks up to but not including the image data.
+ 
+ .SS Querying the info structure
+ 
+ Functions are used to get the information from the info_ptr once it
+ has been read.  Note that these fields may not be completely filled
+ in until png_read_end() has read the chunk data following the image.
+ 
+     png_get_IHDR(png_ptr, info_ptr, &width, &height,
+        &bit_depth, &color_type, &interlace_type,
+        &compression_type, &filter_method);
+ 
+     width          - holds the width of the image
+                      in pixels (up to 2^31).
+     height         - holds the height of the image
+                      in pixels (up to 2^31).
+     bit_depth      - holds the bit depth of one of the
+                      image channels.  (valid values are
+                      1, 2, 4, 8, 16 and depend also on
+                      the color_type.  See also
+                      significant bits (sBIT) below).
+     color_type     - describes which color/alpha channels
+                          are present.
+                      PNG_COLOR_TYPE_GRAY
+                         (bit depths 1, 2, 4, 8, 16)
+                      PNG_COLOR_TYPE_GRAY_ALPHA
+                         (bit depths 8, 16)
+                      PNG_COLOR_TYPE_PALETTE
+                         (bit depths 1, 2, 4, 8)
+                      PNG_COLOR_TYPE_RGB
+                         (bit_depths 8, 16)
+                      PNG_COLOR_TYPE_RGB_ALPHA
+                         (bit_depths 8, 16)
+ 
+                      PNG_COLOR_MASK_PALETTE
+                      PNG_COLOR_MASK_COLOR
+                      PNG_COLOR_MASK_ALPHA
+ 
+     filter_method  - (must be PNG_FILTER_TYPE_BASE
+                      for PNG 1.0, and can also be
+                      PNG_INTRAPIXEL_DIFFERENCING if
+                      the PNG datastream is embedded in
+                      a MNG-1.0 datastream)
+     compression_type - (must be PNG_COMPRESSION_TYPE_BASE
+                      for PNG 1.0)
+     interlace_type - (PNG_INTERLACE_NONE or
+                      PNG_INTERLACE_ADAM7)
+     Any or all of interlace_type, compression_type, of
+     filter_method can be NULL if you are
+     not interested in their values.
+ 
+     channels = png_get_channels(png_ptr, info_ptr);
+     channels       - number of channels of info for the
+                      color type (valid values are 1 (GRAY,
+                      PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
+                      4 (RGB_ALPHA or RGB + filler byte))
+     rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+     rowbytes       - number of bytes needed to hold a row
+ 
+     signature = png_get_signature(png_ptr, info_ptr);
+     signature      - holds the signature read from the
+                      file (if any).  The data is kept in
+                      the same offset it would be if the
+                      whole signature were read (i.e. if an
+                      application had already read in 4
+                      bytes of signature before starting
+                      libpng, the remaining 4 bytes would
+                      be in signature[4] through signature[7]
+                      (see png_set_sig_bytes())).
+ 
+ 
+     width            = png_get_image_width(png_ptr,
+                          info_ptr);
+     height           = png_get_image_height(png_ptr,
+                          info_ptr);
+     bit_depth        = png_get_bit_depth(png_ptr,
+                          info_ptr);
+     color_type       = png_get_color_type(png_ptr,
+                          info_ptr);
+     filter_method    = png_get_filter_type(png_ptr,
+                          info_ptr);
+     compression_type = png_get_compression_type(png_ptr,
+                          info_ptr);
+     interlace_type   = png_get_interlace_type(png_ptr,
+                          info_ptr);
+ 
+ 
+ These are also important, but their validity depends on whether the chunk
+ has been read.  The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
+ png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
+ data has been read, or zero if it is missing.  The parameters to the
+ png_get_<chunk> are set directly if they are simple data types, or a pointer
+ into the info_ptr is returned for any complex types.
+ 
+     png_get_PLTE(png_ptr, info_ptr, &palette,
+                      &num_palette);
+     palette        - the palette for the file
+                      (array of png_color)
+     num_palette    - number of entries in the palette
+ 
+     png_get_gAMA(png_ptr, info_ptr, &gamma);
+     gamma          - the gamma the file is written
+                      at (PNG_INFO_gAMA)
+ 
+     png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
+     srgb_intent    - the rendering intent (PNG_INFO_sRGB)
+                      The presence of the sRGB chunk
+                      means that the pixel data is in the
+                      sRGB color space.  This chunk also
+                      implies specific values of gAMA and
+                      cHRM.
+ 
+     png_get_iCCP(png_ptr, info_ptr, &name,
+        &compression_type, &profile, &proflen);
+     name            - The profile name.
+     compression     - The compression type; always
+                       PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
+                       You may give NULL to this argument to
+                       ignore it.
+     profile         - International Color Consortium color
+                       profile data. May contain NULs.
+     proflen         - length of profile data in bytes.
+ 
+     png_get_sBIT(png_ptr, info_ptr, &sig_bit);
+     sig_bit        - the number of significant bits for
+                      (PNG_INFO_sBIT) each of the gray,
+                      red, green, and blue channels,
+                      whichever are appropriate for the
+                      given color type (png_color_16)
+ 
+     png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans,
+                      &trans_values);
+     trans          - array of transparent entries for
+                      palette (PNG_INFO_tRNS)
+     trans_values   - graylevel or color sample values of
+                      the single transparent color for
+                      non-paletted images (PNG_INFO_tRNS)
+     num_trans      - number of transparent entries
+                      (PNG_INFO_tRNS)
+ 
+     png_get_hIST(png_ptr, info_ptr, &hist);
+                      (PNG_INFO_hIST)
+     hist           - histogram of palette (array of
+                      png_uint_16)
+ 
+     png_get_tIME(png_ptr, info_ptr, &mod_time);
+     mod_time       - time image was last modified
+                     (PNG_VALID_tIME)
+ 
+     png_get_bKGD(png_ptr, info_ptr, &background);
+     background     - background color (PNG_VALID_bKGD)
+                      valid 16-bit red, green and blue
+                      values, regardless of color_type
+ 
+     num_comments   = png_get_text(png_ptr, info_ptr,
+                      &text_ptr, &num_text);
+     num_comments   - number of comments
+     text_ptr       - array of png_text holding image
+                      comments
+     text_ptr[i].compression - type of compression used
+                  on "text" PNG_TEXT_COMPRESSION_NONE
+                            PNG_TEXT_COMPRESSION_zTXt
+                            PNG_ITXT_COMPRESSION_NONE
+                            PNG_ITXT_COMPRESSION_zTXt
+     text_ptr[i].key   - keyword for comment.  Must contain
+                          1-79 characters.
+     text_ptr[i].text  - text comments for current
+                          keyword.  Can be empty.
+     text_ptr[i].text_length - length of text string,
+                  after decompression, 0 for iTXt
+     text_ptr[i].itxt_length - length of itxt string,
+                  after decompression, 0 for tEXt/zTXt
+     text_ptr[i].lang  - language of comment (empty
+                          string for unknown).
+     text_ptr[i].lang_key  - keyword in UTF-8
+                          (empty string for unknown).
+     num_text       - number of comments (same as
+                      num_comments; you can put NULL here
+                      to avoid the duplication)
+     Note while png_set_text() will accept text, language,
+     and translated keywords that can be NULL pointers, the
+     structure returned by png_get_text will always contain
+     regular zero-terminated C strings.  They might be
+     empty strings but they will never be NULL pointers.
+ 
+     num_spalettes = png_get_sPLT(png_ptr, info_ptr,
+        &palette_ptr);
+     palette_ptr    - array of palette structures holding
+                      contents of one or more sPLT chunks
+                      read.
+     num_spalettes  - number of sPLT chunks read.
+ 
+     png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
+        &unit_type);
+     offset_x       - positive offset from the left edge
+                      of the screen
+     offset_y       - positive offset from the top edge
+                      of the screen
+     unit_type      - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
+ 
+     png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
+        &unit_type);
+     res_x          - pixels/unit physical resolution in
+                      x direction
+     res_y          - pixels/unit physical resolution in
+                      x direction
+     unit_type      - PNG_RESOLUTION_UNKNOWN,
+                      PNG_RESOLUTION_METER
+ 
+     png_get_sCAL(png_ptr, info_ptr, &unit, &width,
+        &height)
+     unit        - physical scale units (an integer)
+     width       - width of a pixel in physical scale units
+     height      - height of a pixel in physical scale units
+                  (width and height are doubles)
+ 
+     png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
+        &height)
+     unit        - physical scale units (an integer)
+     width       - width of a pixel in physical scale units
+     height      - height of a pixel in physical scale units
+                  (width and height are strings like "2.54")
+ 
+     num_unknown_chunks = png_get_unknown_chunks(png_ptr,
+        info_ptr, &unknowns)
+     unknowns          - array of png_unknown_chunk
+                         structures holding unknown chunks
+     unknowns[i].name  - name of unknown chunk
+     unknowns[i].data  - data of unknown chunk
+     unknowns[i].size  - size of unknown chunk's data
+     unknowns[i].location - position of chunk in file
+ 
+     The value of "i" corresponds to the order in which the
+     chunks were read from the PNG file or inserted with the
+     png_set_unknown_chunks() function.
+ 
+ The data from the pHYs chunk can be retrieved in several convenient
+ forms:
+ 
+     res_x = png_get_x_pixels_per_meter(png_ptr,
+        info_ptr)
+     res_y = png_get_y_pixels_per_meter(png_ptr,
+        info_ptr)
+     res_x_and_y = png_get_pixels_per_meter(png_ptr,
+        info_ptr)
+     res_x = png_get_x_pixels_per_inch(png_ptr,
+        info_ptr)
+     res_y = png_get_y_pixels_per_inch(png_ptr,
+        info_ptr)
+     res_x_and_y = png_get_pixels_per_inch(png_ptr,
+        info_ptr)
+     aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
+        info_ptr)
+ 
+    (Each of these returns 0 [signifying "unknown"] if
+        the data is not present or if res_x is 0;
+        res_x_and_y is 0 if res_x != res_y)
+ 
+ The data from the oFFs chunk can be retrieved in several convenient
+ forms:
+ 
+     x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
+     y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
+     x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
+     y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
+ 
+    (Each of these returns 0 [signifying "unknown" if both
+        x and y are 0] if the data is not present or if the
+        chunk is present but the unit is the pixel)
+ 
+ For more information, see the png_info definition in png.h and the
+ PNG specification for chunk contents.  Be careful with trusting
+ rowbytes, as some of the transformations could increase the space
+ needed to hold a row (expand, filler, gray_to_rgb, etc.).
+ See png_read_update_info(), below.
+ 
+ A quick word about text_ptr and num_text.  PNG stores comments in
+ keyword/text pairs, one pair per chunk, with no limit on the number
+ of text chunks, and a 2^31 byte limit on their size.  While there are
+ suggested keywords, there is no requirement to restrict the use to these
+ strings.  It is strongly suggested that keywords and text be sensible
+ to humans (that's the point), so don't use abbreviations.  Non-printing
+ symbols are not allowed.  See the PNG specification for more details.
+ There is also no requirement to have text after the keyword.
+ 
+ Keywords should be limited to 79 Latin-1 characters without leading or
+ trailing spaces, but non-consecutive spaces are allowed within the
+ keyword.  It is possible to have the same keyword any number of times.
+ The text_ptr is an array of png_text structures, each holding a
+ pointer to a language string, a pointer to a keyword and a pointer to
+ a text string.  The text string, language code, and translated
+ keyword may be empty or NULL pointers.  The keyword/text
+ pairs are put into the array in the order that they are received.
+ However, some or all of the text chunks may be after the image, so, to
+ make sure you have read all the text chunks, don't mess with these
+ until after you read the stuff after the image.  This will be
+ mentioned again below in the discussion that goes with png_read_end().
+ 
+ .SS Input transformations
+ 
+ After you've read the header information, you can set up the library
+ to handle any special transformations of the image data.  The various
+ ways to transform the data will be described in the order that they
+ should occur.  This is important, as some of these change the color
+ type and/or bit depth of the data, and some others only work on
+ certain color types and bit depths.  Even though each transformation
+ checks to see if it has data that it can do something with, you should
+ make sure to only enable a transformation if it will be valid for the
+ data.  For example, don't swap red and blue on grayscale data.
+ 
+ The colors used for the background and transparency values should be
+ supplied in the same format/depth as the current image data.  They
+ are stored in the same format/depth as the image data in a bKGD or tRNS
+ chunk, so this is what libpng expects for this data.  The colors are
+ transformed to keep in sync with the image data when an application
+ calls the png_read_update_info() routine (see below).
+ 
+ Data will be decoded into the supplied row buffers packed into bytes
+ unless the library has been told to transform it into another format.
+ For example, 4 bit/pixel paletted or grayscale data will be returned
+ 2 pixels/byte with the leftmost pixel in the high-order bits of the
+ byte, unless png_set_packing() is called.  8-bit RGB data will be stored
+ in RGB RGB RGB format unless png_set_filler() is called to insert filler
+ bytes, either before or after each RGB triplet.  16-bit RGB data will
+ be returned RRGGBB RRGGBB, with the most significant byte of the color
+ value first, unless png_set_strip_16() is called to transform it to
+ regular RGB RGB triplets, or png_set_filler() is called to insert
+ filler bytes, either before or after each RRGGBB triplet.  Similarly,
+ 8-bit or 16-bit grayscale data can be modified with png_set_filler()
+ or png_set_strip_16().
+ 
+ The following code transforms grayscale images of less than 8 to 8 bits,
+ changes paletted images to RGB, and adds a full alpha channel if there is
+ transparency information in a tRNS chunk.  This is most useful on
+ grayscale images with bit depths of 2 or 4 or if there is a multiple-image
+ viewing application that wishes to treat all images in the same way.
+ 
+     if (color_type == PNG_COLOR_TYPE_PALETTE)
+         png_set_palette_to_rgb(png_ptr);
+ 
+     if (color_type == PNG_COLOR_TYPE_GRAY &&
+         bit_depth < 8) png_set_gray_1_2_4_to_8(png_ptr);
+ 
+     if (png_get_valid(png_ptr, info_ptr,
+         PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
+ 
+ These three functions are actually aliases for png_set_expand(), added
+ in libpng version 1.0.4, with the function names expanded to improve code
+ readability.  In some future version they may actually do different
+ things.
+ 
+ PNG can have files with 16 bits per channel.  If you only can handle
+ 8 bits per channel, this will strip the pixels down to 8 bit.
+ 
+     if (bit_depth == 16)
+         png_set_strip_16(png_ptr);
+ 
+ If, for some reason, you don't need the alpha channel on an image,
+ and you want to remove it rather than combining it with the background
+ (but the image author certainly had in mind that you *would* combine
+ it with the background, so that's what you should probably do):
+ 
+     if (color_type & PNG_COLOR_MASK_ALPHA)
+         png_set_strip_alpha(png_ptr);
+ 
+ In PNG files, the alpha channel in an image
+ is the level of opacity.  If you need the alpha channel in an image to
+ be the level of transparency instead of opacity, you can invert the
+ alpha channel (or the tRNS chunk data) after it's read, so that 0 is
+ fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
+ images) is fully transparent, with
+ 
+     png_set_invert_alpha(png_ptr);
+ 
+ PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
+ they can, resulting in, for example, 8 pixels per byte for 1 bit
+ files.  This code expands to 1 pixel per byte without changing the
+ values of the pixels:
+ 
+     if (bit_depth < 8)
+         png_set_packing(png_ptr);
+ 
+ PNG files have possible bit depths of 1, 2, 4, 8, and 16.  All pixels
+ stored in a PNG image have been "scaled" or "shifted" up to the next
+ higher possible bit depth (e.g. from 5 bits/sample in the range [0,31] to
+ 8 bits/sample in the range [0, 255]).  However, it is also possible to
+ convert the PNG pixel data back to the original bit depth of the image.
+ This call reduces the pixels back down to the original bit depth:
+ 
+     png_color_8p sig_bit;
+ 
+     if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
+         png_set_shift(png_ptr, sig_bit);
+ 
+ PNG files store 3-color pixels in red, green, blue order.  This code
+ changes the storage of the pixels to blue, green, red:
+ 
+     if (color_type == PNG_COLOR_TYPE_RGB ||
+         color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+         png_set_bgr(png_ptr);
+ 
+ PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
+ into 4 or 8 bytes for windowing systems that need them in this format:
+ 
+     if (color_type == PNG_COLOR_TYPE_RGB)
+         png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
+ 
+ where "filler" is the 8 or 16-bit number to fill with, and the location is
+ either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
+ you want the filler before the RGB or after.  This transformation
+ does not affect images that already have full alpha channels.  To add an
+ opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
+ will generate RGBA pixels.
+ 
+ If you are reading an image with an alpha channel, and you need the
+ data as ARGB instead of the normal PNG format RGBA:
+ 
+     if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+         png_set_swap_alpha(png_ptr);
+ 
+ For some uses, you may want a grayscale image to be represented as
+ RGB.  This code will do that conversion:
+ 
+     if (color_type == PNG_COLOR_TYPE_GRAY ||
+         color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+           png_set_gray_to_rgb(png_ptr);
+ 
+ Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
+ with alpha.
+ 
+     if (color_type == PNG_COLOR_TYPE_RGB ||
+         color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+           png_set_rgb_to_gray_fixed(png_ptr, error_action,
+              int red_weight, int green_weight);
+ 
+     error_action = 1: silently do the conversion
+     error_action = 2: issue a warning if the original
+                       image has any pixel where
+                       red != green or red != blue
+     error_action = 3: issue an error and abort the
+                       conversion if the original
+                       image has any pixel where
+                       red != green or red != blue
+ 
+     red_weight:       weight of red component times 100000
+     green_weight:     weight of green component times 100000
+                       If either weight is negative, default
+                       weights (21268, 71514) are used.
+ 
+ If you have set error_action = 1 or 2, you can
+ later check whether the image really was gray, after processing
+ the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
+ It will return a png_byte that is zero if the image was gray or
+ 1 if there were any non-gray pixels.  bKGD and sBIT data
+ will be silently converted to grayscale, using the green channel
+ data, regardless of the error_action setting.
+ 
+ With red_weight+green_weight<=100000,
+ the normalized graylevel is computed:
+ 
+     int rw = red_weight * 65536;
+     int gw = green_weight * 65536;
+     int bw = 65536 - (rw + gw);
+     gray = (rw*red + gw*green + bw*blue)/65536;
+ 
+ The default values approximate those recommended in the Charles
+ Poynton's Color FAQ, <http://www.inforamp.net/~poynton/>
+ Copyright (c) 1998-01-04 Charles Poynton poynton at inforamp.net
+ 
+     Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
+ 
+ Libpng approximates this with
+ 
+     Y = 0.21268 * R    + 0.7151 * G    + 0.07217 * B
+ 
+ which can be expressed with integers as
+ 
+     Y = (6969 * R + 23434 * G + 2365 * B)/32768
+ 
+ The calculation is done in a linear colorspace, if the image gamma
+ is known.
+ 
+ If you have a grayscale and you are using png_set_expand_depth(),
+ png_set_expand(), or png_set_gray_to_rgb to change to truecolor or to
+ a higher bit-depth, you must either supply the background color as a gray
+ value at the original file bit-depth (need_expand = 1) or else supply the
+ background color as an RGB triplet at the final, expanded bit depth
+ (need_expand = 0).  Similarly, if you are reading a paletted image, you
+ must either supply the background color as a palette index (need_expand = 1)
+ or as an RGB triplet that may or may not be in the palette (need_expand = 0).
+ 
+     png_color_16 my_background;
+     png_color_16p image_background;
+ 
+     if (png_get_bKGD(png_ptr, info_ptr, &image_background))
+         png_set_background(png_ptr, image_background,
+           PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
+     else
+         png_set_background(png_ptr, &my_background,
+           PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
+ 
+ The png_set_background() function tells libpng to composite images
+ with alpha or simple transparency against the supplied background
+ color.  If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
+ you may use this color, or supply another color more suitable for
+ the current display (e.g., the background color from a web page).  You
+ need to tell libpng whether the color is in the gamma space of the
+ display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
+ (PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
+ that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
+ know why anyone would use this, but it's here).
+ 
+ To properly display PNG images on any kind of system, the application needs
+ to know what the display gamma is.  Ideally, the user will know this, and
+ the application will allow them to set it.  One method of allowing the user
+ to set the display gamma separately for each system is to check for a
+ SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be
+ correctly set.
+ 
+ Note that display_gamma is the overall gamma correction required to produce
+ pleasing results, which depends on the lighting conditions in the surrounding
+ environment.  In a dim or brightly lit room, no compensation other than
+ the physical gamma exponent of the monitor is needed, while in a dark room
+ a slightly smaller exponent is better.
+ 
+    double gamma, screen_gamma;
+ 
+    if (/* We have a user-defined screen
+        gamma value */)
+    {
+       screen_gamma = user_defined_screen_gamma;
+    }
+    /* One way that applications can share the same
+       screen gamma value */
+    else if ((gamma_str = getenv("SCREEN_GAMMA"))
+       != NULL)
+    {
+       screen_gamma = (double)atof(gamma_str);
+    }
+    /* If we don't have another value */
+    else
+    {
+       screen_gamma = 2.2; /* A good guess for a
+            PC monitor in a bright office or a dim room */
+       screen_gamma = 2.0; /* A good guess for a
+            PC monitor in a dark room */
+       screen_gamma = 1.7 or 1.0;  /* A good
+            guess for Mac systems */
+    }
+ 
+ The png_set_gamma() function handles gamma transformations of the data.
+ Pass both the file gamma and the current screen_gamma.  If the file does
+ not have a gamma value, you can pass one anyway if you have an idea what
+ it is (usually 0.45455 is a good guess for GIF images on PCs).  Note
+ that file gammas are inverted from screen gammas.  See the discussions
+ on gamma in the PNG specification for an excellent description of what
+ gamma is, and why all applications should support it.  It is strongly
+ recommended that PNG viewers support gamma correction.
+ 
+    if (png_get_gAMA(png_ptr, info_ptr, &gamma))
+       png_set_gamma(png_ptr, screen_gamma, gamma);
+    else
+       png_set_gamma(png_ptr, screen_gamma, 0.45455);
+ 
+ If you need to reduce an RGB file to a paletted file, or if a paletted
+ file has more entries then will fit on your screen, png_set_dither()
+ will do that.  Note that this is a simple match dither that merely
+ finds the closest color available.  This should work fairly well with
+ optimized palettes, and fairly badly with linear color cubes.  If you
+ pass a palette that is larger then maximum_colors, the file will
+ reduce the number of colors in the palette so it will fit into
+ maximum_colors.  If there is a histogram, it will use it to make
+ more intelligent choices when reducing the palette.  If there is no
+ histogram, it may not do as good a job.
+ 
+    if (color_type & PNG_COLOR_MASK_COLOR)
+    {
+       if (png_get_valid(png_ptr, info_ptr,
+          PNG_INFO_PLTE))
+       {
+          png_uint_16p histogram = NULL;
+ 
+          png_get_hIST(png_ptr, info_ptr,
+             &histogram);
+          png_set_dither(png_ptr, palette, num_palette,
+             max_screen_colors, histogram, 1);
+       }
+       else
+       {
+          png_color std_color_cube[MAX_SCREEN_COLORS] =
+             { ... colors ... };
+ 
+          png_set_dither(png_ptr, std_color_cube,
+             MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
+             NULL,0);
+       }
+    }
+ 
+ PNG files describe monochrome as black being zero and white being one.
+ The following code will reverse this (make black be one and white be
+ zero):
+ 
+    if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
+       png_set_invert_mono(png_ptr);
+ 
+ This function can also be used to invert grayscale and gray-alpha images:
+ 
+    if (color_type == PNG_COLOR_TYPE_GRAY ||
+         color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+       png_set_invert_mono(png_ptr);
+ 
+ PNG files store 16 bit pixels in network byte order (big-endian,
+ ie. most significant bits first).  This code changes the storage to the
+ other way (little-endian, i.e. least significant bits first, the
+ way PCs store them):
+ 
+     if (bit_depth == 16)
+         png_set_swap(png_ptr);
+ 
+ If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
+ need to change the order the pixels are packed into bytes, you can use:
+ 
+     if (bit_depth < 8)
+        png_set_packswap(png_ptr);
+ 
+ Finally, you can write your own transformation function if none of
+ the existing ones meets your needs.  This is done by setting a callback
+ with
+ 
+     png_set_read_user_transform_fn(png_ptr,
+        read_transform_fn);
+ 
+ You must supply the function
+ 
+     void read_transform_fn(png_ptr ptr, row_info_ptr
+        row_info, png_bytep data)
+ 
+ See pngtest.c for a working example.  Your function will be called
+ after all of the other transformations have been processed.
+ 
+ You can also set up a pointer to a user structure for use by your
+ callback function, and you can inform libpng that your transform
+ function will change the number of channels or bit depth with the
+ function
+ 
+     png_set_user_transform_info(png_ptr, user_ptr,
+        user_depth, user_channels);
+ 
+ The user's application, not libpng, is responsible for allocating and
+ freeing any memory required for the user structure.
+ 
+ You can retrieve the pointer via the function
+ png_get_user_transform_ptr().  For example:
+ 
+     voidp read_user_transform_ptr =
+        png_get_user_transform_ptr(png_ptr);
+ 
+ The last thing to handle is interlacing; this is covered in detail below,
+ but you must call the function here if you want libpng to handle expansion
+ of the interlaced image.
+ 
+     number_of_passes = png_set_interlace_handling(png_ptr);
+ 
+ After setting the transformations, libpng can update your png_info
+ structure to reflect any transformations you've requested with this
+ call.  This is most useful to update the info structure's rowbytes
+ field so you can use it to allocate your image memory.  This function
+ will also update your palette with the correct screen_gamma and
+ background if these have been given with the calls above.
+ 
+     png_read_update_info(png_ptr, info_ptr);
+ 
+ After you call png_read_update_info(), you can allocate any
+ memory you need to hold the image.  The row data is simply
+ raw byte data for all forms of images.  As the actual allocation
+ varies among applications, no example will be given.  If you
+ are allocating one large chunk, you will need to build an
+ array of pointers to each row, as it will be needed for some
+ of the functions below.
+ 
+ .SS Reading image data
+ 
+ After you've allocated memory, you can read the image data.
+ The simplest way to do this is in one function call.  If you are
+ allocating enough memory to hold the whole image, you can just
+ call png_read_image() and libpng will read in all the image data
+ and put it in the memory area supplied.  You will need to pass in
+ an array of pointers to each row.
+ 
+ This function automatically handles interlacing, so you don't need
+ to call png_set_interlace_handling() or call this function multiple
+ times, or any of that other stuff necessary with png_read_rows().
+ 
+    png_read_image(png_ptr, row_pointers);
+ 
+ where row_pointers is:
+ 
+    png_bytep row_pointers[height];
+ 
+ You can point to void or char or whatever you use for pixels.
+ 
+ If you don't want to read in the whole image at once, you can
+ use png_read_rows() instead.  If there is no interlacing (check
+ interlace_type == PNG_INTERLACE_NONE), this is simple:
+ 
+     png_read_rows(png_ptr, row_pointers, NULL,
+        number_of_rows);
+ 
+ where row_pointers is the same as in the png_read_image() call.
+ 
+ If you are doing this just one row at a time, you can do this with
+ a single row_pointer instead of an array of row_pointers:
+ 
+     png_bytep row_pointer = row;
+     png_read_row(png_ptr, row_pointer, NULL);
+ 
+ If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
+ get somewhat harder.  The only current (PNG Specification version 1.2)
+ interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7)
+ is a somewhat complicated 2D interlace scheme, known as Adam7, that
+ breaks down an image into seven smaller images of varying size, based
+ on an 8x8 grid.
+ 
+ libpng can fill out those images or it can give them to you "as is".
+ If you want them filled out, there are two ways to do that.  The one
+ mentioned in the PNG specification is to expand each pixel to cover
+ those pixels that have not been read yet (the "rectangle" method).
+ This results in a blocky image for the first pass, which gradually
+ smooths out as more pixels are read.  The other method is the "sparkle"
+ method, where pixels are drawn only in their final locations, with the
+ rest of the image remaining whatever colors they were initialized to
+ before the start of the read.  The first method usually looks better,
+ but tends to be slower, as there are more pixels to put in the rows.
+ 
+ If you don't want libpng to handle the interlacing details, just call
+ png_read_rows() seven times to read in all seven images.  Each of the
+ images is a valid image by itself, or they can all be combined on an
+ 8x8 grid to form a single image (although if you intend to combine them
+ you would be far better off using the libpng interlace handling).
+ 
+ The first pass will return an image 1/8 as wide as the entire image
+ (every 8th column starting in column 0) and 1/8 as high as the original
+ (every 8th row starting in row 0), the second will be 1/8 as wide
+ (starting in column 4) and 1/8 as high (also starting in row 0).  The
+ third pass will be 1/4 as wide (every 4th pixel starting in column 0) and
+ 1/8 as high (every 8th row starting in row 4), and the fourth pass will
+ be 1/4 as wide and 1/4 as high (every 4th column starting in column 2,
+ and every 4th row starting in row 0).  The fifth pass will return an
+ image 1/2 as wide, and 1/4 as high (starting at column 0 and row 2),
+ while the sixth pass will be 1/2 as wide and 1/2 as high as the original
+ (starting in column 1 and row 0).  The seventh and final pass will be as
+ wide as the original, and 1/2 as high, containing all of the odd
+ numbered scanlines.  Phew!
+ 
+ If you want libpng to expand the images, call this before calling
+ png_start_read_image() or png_read_update_info():
+ 
+     if (interlace_type == PNG_INTERLACE_ADAM7)
+         number_of_passes
+            = png_set_interlace_handling(png_ptr);
+ 
+ This will return the number of passes needed.  Currently, this
+ is seven, but may change if another interlace type is added.
+ This function can be called even if the file is not interlaced,
+ where it will return one pass.
+ 
+ If you are not going to display the image after each pass, but are
+ going to wait until the entire image is read in, use the sparkle
+ effect.  This effect is faster and the end result of either method
+ is exactly the same.  If you are planning on displaying the image
+ after each pass, the "rectangle" effect is generally considered the
+ better looking one.
+ 
+ If you only want the "sparkle" effect, just call png_read_rows() as
+ normal, with the third parameter NULL.  Make sure you make pass over
+ the image number_of_passes times, and you don't change the data in the
+ rows between calls.  You can change the locations of the data, just
+ not the data.  Each pass only writes the pixels appropriate for that
+ pass, and assumes the data from previous passes is still valid.
+ 
+     png_read_rows(png_ptr, row_pointers, NULL,
+        number_of_rows);
+ 
+ If you only want the first effect (the rectangles), do the same as
+ before except pass the row buffer in the third parameter, and leave
+ the second parameter NULL.
+ 
+     png_read_rows(png_ptr, NULL, row_pointers,
+        number_of_rows);
+ 
+ .SS Finishing a sequential read
+ 
+ After you are finished reading the image through either the high- or
+ low-level interfaces, you can finish reading the file.  If you are
+ interested in comments or time, which may be stored either before or
+ after the image data, you should pass the separate png_info struct if
+ you want to keep the comments from before and after the image
+ separate.  If you are not interested, you can pass NULL.
+ 
+    png_read_end(png_ptr, end_info);
+ 
+ When you are done, you can free all memory allocated by libpng like this:
+ 
+    png_destroy_read_struct(&png_ptr, &info_ptr,
+        &end_info);
+ 
+ It is also possible to individually free the info_ptr members that
+ point to libpng-allocated storage with the following function:
+ 
+     png_free_data(png_ptr, info_ptr, mask, seq)
+     mask - identifies data to be freed, a mask
+            containing the logical OR of one or
+            more of
+              PNG_FREE_PLTE, PNG_FREE_TRNS,
+              PNG_FREE_HIST, PNG_FREE_ICCP,
+              PNG_FREE_PCAL, PNG_FREE_ROWS,
+              PNG_FREE_SCAL, PNG_FREE_SPLT,
+              PNG_FREE_TEXT, PNG_FREE_UNKN,
+            or simply PNG_FREE_ALL
+     seq  - sequence number of item to be freed
+            (-1 for all items)
+ 
+ This function may be safely called when the relevant storage has
+ already been freed, or has not yet been allocated, or was allocated
+ by the user and not by libpng,  and will in those
+ cases do nothing.  The "seq" parameter is ignored if only one item
+ of the selected data type, such as PLTE, is allowed.  If "seq" is not
+ -1, and multiple items are allowed for the data type identified in
+ the mask, such as text or sPLT, only the n'th item in the structure
+ is freed, where n is "seq".
+ 
+ The default behavior is only to free data that was allocated internally
+ by libpng.  This can be changed, so that libpng will not free the data,
+ or so that it will free data that was allocated by the user with png_malloc()
+ or png_zalloc() and passed in via a png_set_*() function, with
+ 
+     png_data_freer(png_ptr, info_ptr, freer, mask)
+     mask   - which data elements are affected
+              same choices as in png_free_data()
+     freer  - one of
+                PNG_DESTROY_WILL_FREE_DATA
+                PNG_SET_WILL_FREE_DATA
+                PNG_USER_WILL_FREE_DATA
+ 
+ This function only affects data that has already been allocated.
+ You can call this function after reading the PNG data but before calling
+ any png_set_*() functions, to control whether the user or the png_set_*()
+ function is responsible for freeing any existing data that might be present,
+ and again after the png_set_*() functions to control whether the user
+ or png_destroy_*() is supposed to free the data.  When the user assumes
+ responsibility for libpng-allocated data, the application must use
+ png_free() to free it, and when the user transfers responsibility to libpng
+ for data that the user has allocated, the user must have used png_malloc()
+ or png_zalloc() to allocate it.
+ 
+ If you allocated your row_pointers in a single block, as suggested above in
+ the description of the high level read interface, you must not transfer
+ responsibility for freeing it to the png_set_rows or png_read_destroy function,
+ because they would also try to free the individual row_pointers[i].
+ 
+ If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
+ separately, do not transfer responsibility for freeing text_ptr to libpng,
+ because when libpng fills a png_text structure it combines these members with
+ the key member, and png_free_data() will free only text_ptr.key.  Similarly,
+ if you transfer responsibility for free'ing text_ptr from libpng to your
+ application, your application must not separately free those members.
+ 
+ The png_free_data() function will turn off the "valid" flag for anything
+ it frees.  If you need to turn the flag off for a chunk that was freed by your
+ application instead of by libpng, you can use
+ 
+     png_set_invalid(png_ptr, info_ptr, mask);
+     mask - identifies the chunks to be made invalid,
+            containing the logical OR of one or
+            more of
+              PNG_INFO_gAMA, PNG_INFO_sBIT,
+              PNG_INFO_cHRM, PNG_INFO_PLTE,
+              PNG_INFO_tRNS, PNG_INFO_bKGD,
+              PNG_INFO_hIST, PNG_INFO_pHYs,
+              PNG_INFO_oFFs, PNG_INFO_tIME,
+              PNG_INFO_pCAL, PNG_INFO_sRGB,
+              PNG_INFO_iCCP, PNG_INFO_sPLT,
+              PNG_INFO_sCAL, PNG_INFO_IDAT
+ 
+ For a more compact example of reading a PNG image, see the file example.c.
+ 
+ .SS Reading PNG files progressively
+ 
+ The progressive reader is slightly different then the non-progressive
+ reader.  Instead of calling png_read_info(), png_read_rows(), and
+ png_read_end(), you make one call to png_process_data(), which calls
+ callbacks when it has the info, a row, or the end of the image.  You
+ set up these callbacks with png_set_progressive_read_fn().  You don't
+ have to worry about the input/output functions of libpng, as you are
+ giving the library the data directly in png_process_data().  I will
+ assume that you have read the section on reading PNG files above,
+ so I will only highlight the differences (although I will show
+ all of the code).
+ 
+ png_structp png_ptr;
+ png_infop info_ptr;
+ 
+  /*  An example code fragment of how you would
+      initialize the progressive reader in your
+      application. */
+  int
+  initialize_png_reader()
+  {
+     png_ptr = png_create_read_struct
+         (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+          user_error_fn, user_warning_fn);
+     if (!png_ptr)
+         return (ERROR);
+     info_ptr = png_create_info_struct(png_ptr);
+     if (!info_ptr)
+     {
+         png_destroy_read_struct(&png_ptr, (png_infopp)NULL,
+            (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+     if (setjmp(png_jmpbuf(png_ptr)))
+     {
+         png_destroy_read_struct(&png_ptr, &info_ptr,
+            (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+     /* This one's new.  You can provide functions
+        to be called when the header info is valid,
+        when each row is completed, and when the image
+        is finished.  If you aren't using all functions,
+        you can specify NULL parameters.  Even when all
+        three functions are NULL, you need to call
+        png_set_progressive_read_fn().  You can use
+        any struct as the user_ptr (cast to a void pointer
+        for the function call), and retrieve the pointer
+        from inside the callbacks using the function
+ 
+           png_get_progressive_ptr(png_ptr);
+ 
+        which will return a void pointer, which you have
+        to cast appropriately.
+      */
+     png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
+         info_callback, row_callback, end_callback);
+ 
+     return 0;
+  }
+ 
+  /* A code fragment that you call as you receive blocks
+    of data */
+  int
+  process_data(png_bytep buffer, png_uint_32 length)
+  {
+     if (setjmp(png_jmpbuf(png_ptr)))
+     {
+         png_destroy_read_struct(&png_ptr, &info_ptr,
+            (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+     /* This one's new also.  Simply give it a chunk
+        of data from the file stream (in order, of
+        course).  On machines with segmented memory
+        models machines, don't give it any more than
+        64K.  The library seems to run fine with sizes
+        of 4K. Although you can give it much less if
+        necessary (I assume you can give it chunks of
+        1 byte, I haven't tried less then 256 bytes
+        yet).  When this function returns, you may
+        want to display any rows that were generated
+        in the row callback if you don't already do
+        so there.
+      */
+     png_process_data(png_ptr, info_ptr, buffer, length);
+     return 0;
+  }
+ 
+  /* This function is called (as set by
+     png_set_progressive_read_fn() above) when enough data
+     has been supplied so all of the header has been
+     read.
+  */
+  void
+  info_callback(png_structp png_ptr, png_infop info)
+  {
+     /* Do any setup here, including setting any of
+        the transformations mentioned in the Reading
+        PNG files section.  For now, you _must_ call
+        either png_start_read_image() or
+        png_read_update_info() after all the
+        transformations are set (even if you don't set
+        any).  You may start getting rows before
+        png_process_data() returns, so this is your
+        last chance to prepare for that.
+      */
+  }
+ 
+  /* This function is called when each row of image
+     data is complete */
+  void
+  row_callback(png_structp png_ptr, png_bytep new_row,
+     png_uint_32 row_num, int pass)
+  {
+     /* If the image is interlaced, and you turned
+        on the interlace handler, this function will
+        be called for every row in every pass.  Some
+        of these rows will not be changed from the
+        previous pass.  When the row is not changed,
+        the new_row variable will be NULL.  The rows
+        and passes are called in order, so you don't
+        really need the row_num and pass, but I'm
+        supplying them because it may make your life
+        easier.
+ 
+        For the non-NULL rows of interlaced images,
+        you must call png_progressive_combine_row()
+        passing in the row and the old row.  You can
+        call this function for NULL rows (it will just
+        return) and for non-interlaced images (it just
+        does the memcpy for you) if it will make the
+        code easier.  Thus, you can just do this for
+        all cases:
+      */
+ 
+         png_progressive_combine_row(png_ptr, old_row,
+           new_row);
+ 
+     /* where old_row is what was displayed for
+        previously for the row.  Note that the first
+        pass (pass == 0, really) will completely cover
+        the old row, so the rows do not have to be
+        initialized.  After the first pass (and only
+        for interlaced images), you will have to pass
+        the current row, and the function will combine
+        the old row and the new row.
+     */
+  }
+ 
+  void
+  end_callback(png_structp png_ptr, png_infop info)
+  {
+     /* This function is called after the whole image
+        has been read, including any chunks after the
+        image (up to and including the IEND).  You
+        will usually have the same info chunk as you
+        had in the header, although some data may have
+        been added to the comments and time fields.
+ 
+        Most people won't do much here, perhaps setting
+        a flag that marks the image as finished.
+      */
+  }
+ 
+ 
+ 
+ .SH IV. Writing
+ 
+ Much of this is very similar to reading.  However, everything of
+ importance is repeated here, so you won't have to constantly look
+ back up in the reading section to understand writing.
+ 
+ .SS Setup
+ 
+ You will want to do the I/O initialization before you get into libpng,
+ so if it doesn't work, you don't have anything to undo. If you are not
+ using the standard I/O functions, you will need to replace them with
+ custom writing functions.  See the discussion under Customizing libpng.
+ 
+     FILE *fp = fopen(file_name, "wb");
+     if (!fp)
+     {
+        return (ERROR);
+     }
+ 
+ Next, png_struct and png_info need to be allocated and initialized.
+ As these can be both relatively large, you may not want to store these
+ on the stack, unless you have stack space to spare.  Of course, you
+ will want to check if they return NULL.  If you are also reading,
+ you won't want to name your read structure and your write structure
+ both "png_ptr"; you can call them anything you like, such as
+ "read_ptr" and "write_ptr".  Look at pngtest.c, for example.
+ 
+     png_structp png_ptr = png_create_write_struct
+        (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+         user_error_fn, user_warning_fn);
+     if (!png_ptr)
+        return (ERROR);
+ 
+     png_infop info_ptr = png_create_info_struct(png_ptr);
+     if (!info_ptr)
+     {
+        png_destroy_write_struct(&png_ptr,
+          (png_infopp)NULL);
+        return (ERROR);
+     }
+ 
+ If you want to use your own memory allocation routines,
+ define PNG_USER_MEM_SUPPORTED and use
+ png_create_write_struct_2() instead of png_create_write_struct():
+ 
+     png_structp png_ptr = png_create_write_struct_2
+        (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+         user_error_fn, user_warning_fn, (png_voidp)
+         user_mem_ptr, user_malloc_fn, user_free_fn);
+ 
+ After you have these structures, you will need to set up the
+ error handling.  When libpng encounters an error, it expects to
+ longjmp() back to your routine.  Therefore, you will need to call
+ setjmp() and pass the png_jmpbuf(png_ptr).  If you
+ write the file from different routines, you will need to update
+ the png_jmpbuf(png_ptr) every time you enter a new routine that will
+ call a png_*() function.  See your documentation of setjmp/longjmp
+ for your compiler for more information on setjmp/longjmp.  See
+ the discussion on libpng error handling in the Customizing Libpng
+ section below for more information on the libpng error handling.
+ 
+     if (setjmp(png_jmpbuf(png_ptr)))
+     {
+        png_destroy_write_struct(&png_ptr, &info_ptr);
+        fclose(fp);
+        return (ERROR);
+     }
+     ...
+     return;
+ 
+ If you would rather avoid the complexity of setjmp/longjmp issues,
+ you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
+ errors will result in a call to PNG_ABORT() which defaults to abort().
+ 
+ Now you need to set up the output code.  The default for libpng is to
+ use the C function fwrite().  If you use this, you will need to pass a
+ valid FILE * in the function png_init_io().  Be sure that the file is
+ opened in binary mode.  Again, if you wish to handle writing data in
+ another way, see the discussion on libpng I/O handling in the Customizing
+ Libpng section below.
+ 
+     png_init_io(png_ptr, fp);
+ 
+ .SS Write callbacks
+ 
+ At this point, you can set up a callback function that will be
+ called after each row has been written, which you can use to control
+ a progress meter or the like.  It's demonstrated in pngtest.c.
+ You must supply a function
+ 
+     void write_row_callback(png_ptr, png_uint_32 row,
+        int pass);
+     {
+       /* put your code here */
+     }
+ 
+ (You can give it another name that you like instead of "write_row_callback")
+ 
+ To inform libpng about your function, use
+ 
+     png_set_write_status_fn(png_ptr, write_row_callback);
+ 
+ You now have the option of modifying how the compression library will
+ run.  The following functions are mainly for testing, but may be useful
+ in some cases, like if you need to write PNG files extremely fast and
+ are willing to give up some compression, or if you want to get the
+ maximum possible compression at the expense of slower writing.  If you
+ have no special needs in this area, let the library do what it wants by
+ not calling this function at all, as it has been tuned to deliver a good
+ speed/compression ratio. The second parameter to png_set_filter() is
+ the filter method, for which the only valid values are 0 (as of the
+ July 1999 PNG specification, version 1.2) or 64 (if you are writing
+ a PNG datastream that is to be embedded in a MNG datastream).  The third
+ parameter is a flag that indicates which filter type(s) are to be tested
+ for each scanline.  See the PNG specification for details on the specific filter
+ types.
+ 
+ 
+     /* turn on or off filtering, and/or choose
+        specific filters.  You can use either a single
+        PNG_FILTER_VALUE_NAME or the logical OR of one
+        or more PNG_FILTER_NAME masks. */
+     png_set_filter(png_ptr, 0,
+        PNG_FILTER_NONE  | PNG_FILTER_VALUE_NONE |
+        PNG_FILTER_SUB   | PNG_FILTER_VALUE_SUB  |
+        PNG_FILTER_UP    | PNG_FILTER_VALUE_UP   |
+        PNG_FILTER_AVE   | PNG_FILTER_VALUE_AVE  |
+        PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
+        PNG_ALL_FILTERS);
+ 
+ If an application
+ wants to start and stop using particular filters during compression,
+ it should start out with all of the filters (to ensure that the previous
+ row of pixels will be stored in case it's needed later), and then add
+ and remove them after the start of compression.
+ 
+ If you are writing a PNG datastream that is to be embedded in a MNG
+ datastream, the second parameter can be either 0 or 64.
+ 
+ The png_set_compression_*() functions interface to the zlib compression
+ library, and should mostly be ignored unless you really know what you are
+ doing.  The only generally useful call is png_set_compression_level()
+ which changes how much time zlib spends on trying to compress the image
+ data.  See the Compression Library (zlib.h and algorithm.txt, distributed
+ with zlib) for details on the compression levels.
+ 
+     /* set the zlib compression level */
+     png_set_compression_level(png_ptr,
+         Z_BEST_COMPRESSION);
+ 
+     /* set other zlib parameters */
+     png_set_compression_mem_level(png_ptr, 8);
+     png_set_compression_strategy(png_ptr,
+         Z_DEFAULT_STRATEGY);
+     png_set_compression_window_bits(png_ptr, 15);
+     png_set_compression_method(png_ptr, 8);
+     png_set_compression_buffer_size(png_ptr, 8192)
+ 
+ extern PNG_EXPORT(void,png_set_zbuf_size)
+ 
+ .SS Setting the contents of info for output
+ 
+ You now need to fill in the png_info structure with all the data you
+ wish to write before the actual image.  Note that the only thing you
+ are allowed to write after the image is the text chunks and the time
+ chunk (as of PNG Specification 1.2, anyway).  See png_write_end() and
+ the latest PNG specification for more information on that.  If you
+ wish to write them before the image, fill them in now, and flag that
+ data as being valid.  If you want to wait until after the data, don't
+ fill them until png_write_end().  For all the fields in png_info and
+ their data types, see png.h.  For explanations of what the fields
+ contain, see the PNG specification.
+ 
+ Some of the more important parts of the png_info are:
+ 
+     png_set_IHDR(png_ptr, info_ptr, width, height,
+        bit_depth, color_type, interlace_type,
+        compression_type, filter_method)
+     width          - holds the width of the image
+                      in pixels (up to 2^31).
+     height         - holds the height of the image
+                      in pixels (up to 2^31).
+     bit_depth      - holds the bit depth of one of the
+                      image channels.
+                      (valid values are 1, 2, 4, 8, 16
+                      and depend also on the
+                      color_type.  See also significant
+                      bits (sBIT) below).
+     color_type     - describes which color/alpha
+                      channels are present.
+                      PNG_COLOR_TYPE_GRAY
+                         (bit depths 1, 2, 4, 8, 16)
+                      PNG_COLOR_TYPE_GRAY_ALPHA
+                         (bit depths 8, 16)
+                      PNG_COLOR_TYPE_PALETTE
+                         (bit depths 1, 2, 4, 8)
+                      PNG_COLOR_TYPE_RGB
+                         (bit_depths 8, 16)
+                      PNG_COLOR_TYPE_RGB_ALPHA
+                         (bit_depths 8, 16)
+ 
+                      PNG_COLOR_MASK_PALETTE
+                      PNG_COLOR_MASK_COLOR
+                      PNG_COLOR_MASK_ALPHA
+ 
+     interlace_type - PNG_INTERLACE_NONE or
+                      PNG_INTERLACE_ADAM7
+     compression_type - (must be
+                      PNG_COMPRESSION_TYPE_DEFAULT)
+     filter_method  - (must be PNG_FILTER_TYPE_DEFAULT
+                      or, if you are writing a PNG to
+                      be embedded in a MNG datastream,
+                      can also be
+                      PNG_INTRAPIXEL_DIFFERENCING)
+ 
+     png_set_PLTE(png_ptr, info_ptr, palette,
+        num_palette);
+     palette        - the palette for the file
+                      (array of png_color)
+     num_palette    - number of entries in the palette
+ 
+     png_set_gAMA(png_ptr, info_ptr, gamma);
+     gamma          - the gamma the image was created
+                      at (PNG_INFO_gAMA)
+ 
+     png_set_sRGB(png_ptr, info_ptr, srgb_intent);
+     srgb_intent    - the rendering intent
+                      (PNG_INFO_sRGB) The presence of
+                      the sRGB chunk means that the pixel
+                      data is in the sRGB color space.
+                      This chunk also implies specific
+                      values of gAMA and cHRM.  Rendering
+                      intent is the CSS-1 property that
+                      has been defined by the International
+                      Color Consortium
+                      (http://www.color.org).
+                      It can be one of
+                      PNG_sRGB_INTENT_SATURATION,
+                      PNG_sRGB_INTENT_PERCEPTUAL,
+                      PNG_sRGB_INTENT_ABSOLUTE, or
+                      PNG_sRGB_INTENT_RELATIVE.
+ 
+ 
+     png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
+        srgb_intent);
+     srgb_intent    - the rendering intent
+                      (PNG_INFO_sRGB) The presence of the
+                      sRGB chunk means that the pixel
+                      data is in the sRGB color space.
+                      This function also causes gAMA and
+                      cHRM chunks with the specific values
+                      that are consistent with sRGB to be
+                      written.
+ 
+     png_set_iCCP(png_ptr, info_ptr, name, compression_type,
+                       profile, proflen);
+     name            - The profile name.
+     compression     - The compression type; always
+                       PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
+                       You may give NULL to this argument to
+                       ignore it.
+     profile         - International Color Consortium color
+                       profile data. May contain NULs.
+     proflen         - length of profile data in bytes.
+ 
+     png_set_sBIT(png_ptr, info_ptr, sig_bit);
+     sig_bit        - the number of significant bits for
+                      (PNG_INFO_sBIT) each of the gray, red,
+                      green, and blue channels, whichever are
+                      appropriate for the given color type
+                      (png_color_16)
+ 
+     png_set_tRNS(png_ptr, info_ptr, trans, num_trans,
+        trans_values);
+     trans          - array of transparent entries for
+                      palette (PNG_INFO_tRNS)
+     trans_values   - graylevel or color sample values of
+                      the single transparent color for
+                      non-paletted images (PNG_INFO_tRNS)
+     num_trans      - number of transparent entries
+                      (PNG_INFO_tRNS)
+ 
+     png_set_hIST(png_ptr, info_ptr, hist);
+                     (PNG_INFO_hIST)
+     hist           - histogram of palette (array of
+                      png_uint_16)
+ 
+     png_set_tIME(png_ptr, info_ptr, mod_time);
+     mod_time       - time image was last modified
+                      (PNG_VALID_tIME)
+ 
+     png_set_bKGD(png_ptr, info_ptr, background);
+     background     - background color (PNG_VALID_bKGD)
+ 
+     png_set_text(png_ptr, info_ptr, text_ptr, num_text);
+     text_ptr       - array of png_text holding image
+                      comments
+     text_ptr[i].compression - type of compression used
+                  on "text" PNG_TEXT_COMPRESSION_NONE
+                            PNG_TEXT_COMPRESSION_zTXt
+                            PNG_ITXT_COMPRESSION_NONE
+                            PNG_ITXT_COMPRESSION_zTXt
+     text_ptr[i].key   - keyword for comment.  Must contain
+                  1-79 characters.
+     text_ptr[i].text  - text comments for current
+                          keyword.  Can be NULL or empty.
+     text_ptr[i].text_length - length of text string,
+                  after decompression, 0 for iTXt
+     text_ptr[i].itxt_length - length of itxt string,
+                  after decompression, 0 for tEXt/zTXt
+     text_ptr[i].lang  - language of comment (NULL or
+                          empty for unknown).
+     text_ptr[i].translated_keyword  - keyword in UTF-8 (NULL
+                          or empty for unknown).
+     num_text       - number of comments
+ 
+     png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
+        num_spalettes);
+     palette_ptr    - array of png_sPLT_struct structures
+                      to be added to the list of palettes
+                      in the info structure.
+     num_spalettes  - number of palette structures to be
+                      added.
+ 
+     png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
+         unit_type);
+     offset_x  - positive offset from the left
+                      edge of the screen
+     offset_y  - positive offset from the top
+                      edge of the screen
+     unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
+ 
+     png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
+         unit_type);
+     res_x       - pixels/unit physical resolution
+                   in x direction
+     res_y       - pixels/unit physical resolution
+                   in y direction
+     unit_type   - PNG_RESOLUTION_UNKNOWN,
+                   PNG_RESOLUTION_METER
+ 
+     png_set_sCAL(png_ptr, info_ptr, unit, width, height)
+     unit        - physical scale units (an integer)
+     width       - width of a pixel in physical scale units
+     height      - height of a pixel in physical scale units
+                   (width and height are doubles)
+ 
+     png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
+     unit        - physical scale units (an integer)
+     width       - width of a pixel in physical scale units
+     height      - height of a pixel in physical scale units
+                  (width and height are strings like "2.54")
+ 
+     png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
+        num_unknowns)
+     unknowns          - array of png_unknown_chunk
+                         structures holding unknown chunks
+     unknowns[i].name  - name of unknown chunk
+     unknowns[i].data  - data of unknown chunk
+     unknowns[i].size  - size of unknown chunk's data
+     unknowns[i].location - position to write chunk in file
+                            0: do not write chunk
+                            PNG_HAVE_IHDR: before PLTE
+                            PNG_HAVE_PLTE: before IDAT
+                            PNG_AFTER_IDAT: after IDAT
+ 
+ The "location" member is set automatically according to
+ what part of the output file has already been written.
+ You can change its value after calling png_set_unknown_chunks()
+ as demonstrated in pngtest.c.  Within each of the "locations",
+ the chunks are sequenced according to their position in the
+ structure (that is, the value of "i", which is the order in which
+ the chunk was either read from the input file or defined with
+ png_set_unknown_chunks).
+ 
+ A quick word about text and num_text.  text is an array of png_text
+ structures.  num_text is the number of valid structures in the array.
+ Each png_text structure holds a language code, a keyword, a text value,
+ and a compression type.
+ 
+ The compression types have the same valid numbers as the compression
+ types of the image data.  Currently, the only valid number is zero.
+ However, you can store text either compressed or uncompressed, unlike
+ images, which always have to be compressed.  So if you don't want the
+ text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
+ Because tEXt and zTXt chunks don't have a language field, if you
+ specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
+ any language code or translated keyword will not be written out.
+ 
+ Until text gets around 1000 bytes, it is not worth compressing it.
+ After the text has been written out to the file, the compression type
+ is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
+ so that it isn't written out again at the end (in case you are calling
+ png_write_end() with the same struct.
+ 
+ The keywords that are given in the PNG Specification are:
+ 
+     Title            Short (one line) title or
+                      caption for image
+     Author           Name of image's creator
+     Description      Description of image (possibly long)
+     Copyright        Copyright notice
+     Creation Time    Time of original image creation
+                      (usually RFC 1123 format, see below)
+     Software         Software used to create the image
+     Disclaimer       Legal disclaimer
+     Warning          Warning of nature of content
+     Source           Device used to create the image
+     Comment          Miscellaneous comment; conversion
+                      from other image format
+ 
+ The keyword-text pairs work like this.  Keywords should be short
+ simple descriptions of what the comment is about.  Some typical
+ keywords are found in the PNG specification, as is some recommendations
+ on keywords.  You can repeat keywords in a file.  You can even write
+ some text before the image and some after.  For example, you may want
+ to put a description of the image before the image, but leave the
+ disclaimer until after, so viewers working over modem connections
+ don't have to wait for the disclaimer to go over the modem before
+ they start seeing the image.  Finally, keywords should be full
+ words, not abbreviations.  Keywords and text are in the ISO 8859-1
+ (Latin-1) character set (a superset of regular ASCII) and can not
+ contain NUL characters, and should not contain control or other
+ unprintable characters.  To make the comments widely readable, stick
+ with basic ASCII, and avoid machine specific character set extensions
+ like the IBM-PC character set.  The keyword must be present, but
+ you can leave off the text string on non-compressed pairs.
+ Compressed pairs must have a text string, as only the text string
+ is compressed anyway, so the compression would be meaningless.
+ 
+ PNG supports modification time via the png_time structure.  Two
+ conversion routines are provided, png_convert_from_time_t() for
+ time_t and png_convert_from_struct_tm() for struct tm.  The
+ time_t routine uses gmtime().  You don't have to use either of
+ these, but if you wish to fill in the png_time structure directly,
+ you should provide the time in universal time (GMT) if possible
+ instead of your local time.  Note that the year number is the full
+ year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
+ that months start with 1.
+ 
+ If you want to store the time of the original image creation, you should
+ use a plain tEXt chunk with the "Creation Time" keyword.  This is
+ necessary because the "creation time" of a PNG image is somewhat vague,
+ depending on whether you mean the PNG file, the time the image was
+ created in a non-PNG format, a still photo from which the image was
+ scanned, or possibly the subject matter itself.  In order to facilitate
+ machine-readable dates, it is recommended that the "Creation Time"
+ tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
+ although this isn't a requirement.  Unlike the tIME chunk, the
+ "Creation Time" tEXt chunk is not expected to be automatically changed
+ by the software.  To facilitate the use of RFC 1123 dates, a function
+ png_convert_to_rfc1123(png_timep) is provided to convert from PNG
+ time to an RFC 1123 format string.
+ 
+ .SS Writing unknown chunks
+ 
+ You can use the png_set_unknown_chunks function to queue up chunks
+ for writing.  You give it a chunk name, raw data, and a size; that's
+ all there is to it.  The chunks will be written by the next following
+ png_write_info_before_PLTE, png_write_info, or png_write_end function.
+ Any chunks previously read into the info structure's unknown-chunk
+ list will also be written out in a sequence that satisfies the PNG
+ specification's ordering rules.
+ 
+ .SS The high-level write interface
+ 
+ At this point there are two ways to proceed; through the high-level
+ write interface, or through a sequence of low-level write operations.
+ You can use the high-level interface if your image data is present
+ in the info structure.  All defined output
+ transformations are permitted, enabled by the following masks.
+ 
+     PNG_TRANSFORM_IDENTITY      No transformation
+     PNG_TRANSFORM_PACKING       Pack 1, 2 and 4-bit samples
+     PNG_TRANSFORM_PACKSWAP      Change order of packed
+                                 pixels to LSB first
+     PNG_TRANSFORM_INVERT_MONO   Invert monochrome images
+     PNG_TRANSFORM_SHIFT         Normalize pixels to the
+                                 sBIT depth
+     PNG_TRANSFORM_BGR           Flip RGB to BGR, RGBA
+                                 to BGRA
+     PNG_TRANSFORM_SWAP_ALPHA    Flip RGBA to ARGB or GA
+                                 to AG
+     PNG_TRANSFORM_INVERT_ALPHA  Change alpha from opacity
+                                 to transparency
+     PNG_TRANSFORM_SWAP_ENDIAN   Byte-swap 16-bit samples
+     PNG_TRANSFORM_STRIP_FILLER  Strip out filler bytes.
+ 
+ If you have valid image data in the info structure (you can use
+ png_set_rows() to put image data in the info structure), simply do this:
+ 
+     png_write_png(png_ptr, info_ptr, png_transforms, NULL)
+ 
+ where png_transforms is an integer containing the logical OR of some set of
+ transformation flags.  This call is equivalent to png_write_info(),
+ followed the set of transformations indicated by the transform mask,
+ then png_write_image(), and finally png_write_end().
+ 
+ (The final parameter of this call is not yet used.  Someday it might point
+ to transformation parameters required by some future output transform.)
+ 
+ .SS The low-level write interface
+ 
+ If you are going the low-level route instead, you are now ready to
+ write all the file information up to the actual image data.  You do
+ this with a call to png_write_info().
+ 
+     png_write_info(png_ptr, info_ptr);
+ 
+ Note that there is one transformation you may need to do before
+ png_write_info().  In PNG files, the alpha channel in an image is the
+ level of opacity.  If your data is supplied as a level of
+ transparency, you can invert the alpha channel before you write it, so
+ that 0 is fully transparent and 255 (in 8-bit or paletted images) or
+ 65535 (in 16-bit images) is fully opaque, with
+ 
+     png_set_invert_alpha(png_ptr);
+ 
+ This must appear before png_write_info() instead of later with the
+ other transformations because in the case of paletted images the tRNS
+ chunk data has to be inverted before the tRNS chunk is written.  If
+ your image is not a paletted image, the tRNS data (which in such cases
+ represents a single color to be rendered as transparent) won't need to
+ be changed, and you can safely do this transformation after your
+ png_write_info() call.
+ 
+ If you need to write a private chunk that you want to appear before
+ the PLTE chunk when PLTE is present, you can write the PNG info in
+ two steps, and insert code to write your own chunk between them:
+ 
+     png_write_info_before_PLTE(png_ptr, info_ptr);
+     png_set_unknown_chunks(png_ptr, info_ptr, ...);
+     png_write_info(png_ptr, info_ptr);
+ 
+ After you've written the file information, you can set up the library
+ to handle any special transformations of the image data.  The various
+ ways to transform the data will be described in the order that they
+ should occur.  This is important, as some of these change the color
+ type and/or bit depth of the data, and some others only work on
+ certain color types and bit depths.  Even though each transformation
+ checks to see if it has data that it can do something with, you should
+ make sure to only enable a transformation if it will be valid for the
+ data.  For example, don't swap red and blue on grayscale data.
+ 
+ PNG files store RGB pixels packed into 3 or 6 bytes.  This code tells
+ the library to strip input data that has 4 or 8 bytes per pixel down
+ to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
+ bytes per pixel).
+ 
+     png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+ 
+ where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
+ PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
+ is stored XRGB or RGBX.
+ 
+ PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
+ they can, resulting in, for example, 8 pixels per byte for 1 bit files.
+ If the data is supplied at 1 pixel per byte, use this code, which will
+ correctly pack the pixels into a single byte:
+ 
+     png_set_packing(png_ptr);
+ 
+ PNG files reduce possible bit depths to 1, 2, 4, 8, and 16.  If your
+ data is of another bit depth, you can write an sBIT chunk into the
+ file so that decoders can recover the original data if desired.
+ 
+     /* Set the true bit depth of the image data */
+     if (color_type & PNG_COLOR_MASK_COLOR)
+     {
+         sig_bit.red = true_bit_depth;
+         sig_bit.green = true_bit_depth;
+         sig_bit.blue = true_bit_depth;
+     }
+     else
+     {
+         sig_bit.gray = true_bit_depth;
+     }
+     if (color_type & PNG_COLOR_MASK_ALPHA)
+     {
+         sig_bit.alpha = true_bit_depth;
+     }
+ 
+     png_set_sBIT(png_ptr, info_ptr, &sig_bit);
+ 
+ If the data is stored in the row buffer in a bit depth other than
+ one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
+ this will scale the values to appear to be the correct bit depth as
+ is required by PNG.
+ 
+     png_set_shift(png_ptr, &sig_bit);
+ 
+ PNG files store 16 bit pixels in network byte order (big-endian,
+ ie. most significant bits first).  This code would be used if they are
+ supplied the other way (little-endian, i.e. least significant bits
+ first, the way PCs store them):
+ 
+     if (bit_depth > 8)
+        png_set_swap(png_ptr);
+ 
+ If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
+ need to change the order the pixels are packed into bytes, you can use:
+ 
+     if (bit_depth < 8)
+        png_set_packswap(png_ptr);
+ 
+ PNG files store 3 color pixels in red, green, blue order.  This code
+ would be used if they are supplied as blue, green, red:
+ 
+     png_set_bgr(png_ptr);
+ 
+ PNG files describe monochrome as black being zero and white being
+ one. This code would be used if the pixels are supplied with this reversed
+ (black being one and white being zero):
+ 
+     png_set_invert_mono(png_ptr);
+ 
+ Finally, you can write your own transformation function if none of
+ the existing ones meets your needs.  This is done by setting a callback
+ with
+ 
+     png_set_write_user_transform_fn(png_ptr,
+        write_transform_fn);
+ 
+ You must supply the function
+ 
+     void write_transform_fn(png_ptr ptr, row_info_ptr
+        row_info, png_bytep data)
+ 
+ See pngtest.c for a working example.  Your function will be called
+ before any of the other transformations are processed.
+ 
+ You can also set up a pointer to a user structure for use by your
+ callback function.
+ 
+     png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
+ 
+ The user_channels and user_depth parameters of this function are ignored
+ when writing; you can set them to zero as shown.
+ 
+ You can retrieve the pointer via the function png_get_user_transform_ptr().
+ For example:
+ 
+     voidp write_user_transform_ptr =
+        png_get_user_transform_ptr(png_ptr);
+ 
+ It is possible to have libpng flush any pending output, either manually,
+ or automatically after a certain number of lines have been written.  To
+ flush the output stream a single time call:
+ 
+     png_write_flush(png_ptr);
+ 
+ and to have libpng flush the output stream periodically after a certain
+ number of scanlines have been written, call:
+ 
+     png_set_flush(png_ptr, nrows);
+ 
+ Note that the distance between rows is from the last time png_write_flush()
+ was called, or the first row of the image if it has never been called.
+ So if you write 50 lines, and then png_set_flush 25, it will flush the
+ output on the next scanline, and every 25 lines thereafter, unless
+ png_write_flush() is called before 25 more lines have been written.
+ If nrows is too small (less than about 10 lines for a 640 pixel wide
+ RGB image) the image compression may decrease noticeably (although this
+ may be acceptable for real-time applications).  Infrequent flushing will
+ only degrade the compression performance by a few percent over images
+ that do not use flushing.
+ 
+ .SS Writing the image data
+ 
+ That's it for the transformations.  Now you can write the image data.
+ The simplest way to do this is in one function call.  If you have the
+ whole image in memory, you can just call png_write_image() and libpng
+ will write the image.  You will need to pass in an array of pointers to
+ each row.  This function automatically handles interlacing, so you don't
+ need to call png_set_interlace_handling() or call this function multiple
+ times, or any of that other stuff necessary with png_write_rows().
+ 
+     png_write_image(png_ptr, row_pointers);
+ 
+ where row_pointers is:
+ 
+     png_byte *row_pointers[height];
+ 
+ You can point to void or char or whatever you use for pixels.
+ 
+ If you don't want to write the whole image at once, you can
+ use png_write_rows() instead.  If the file is not interlaced,
+ this is simple:
+ 
+     png_write_rows(png_ptr, row_pointers,
+        number_of_rows);
+ 
+ row_pointers is the same as in the png_write_image() call.
+ 
+ If you are just writing one row at a time, you can do this with
+ a single row_pointer instead of an array of row_pointers:
+ 
+     png_bytep row_pointer = row;
+ 
+     png_write_row(png_ptr, row_pointer);
+ 
+ When the file is interlaced, things can get a good deal more
+ complicated.  The only currently (as of the PNG Specification
+ version 1.2, dated July 1999) defined interlacing scheme for PNG files
+ is the "Adam7" interlace scheme, that breaks down an
+ image into seven smaller images of varying size.  libpng will build
+ these images for you, or you can do them yourself.  If you want to
+ build them yourself, see the PNG specification for details of which
+ pixels to write when.
+ 
+ If you don't want libpng to handle the interlacing details, just
+ use png_set_interlace_handling() and call png_write_rows() the
+ correct number of times to write all seven sub-images.
+ 
+ If you want libpng to build the sub-images, call this before you start
+ writing any rows:
+ 
+     number_of_passes =
+        png_set_interlace_handling(png_ptr);
+ 
+ This will return the number of passes needed.  Currently, this
+ is seven, but may change if another interlace type is added.
+ 
+ Then write the complete image number_of_passes times.
+ 
+     png_write_rows(png_ptr, row_pointers,
+        number_of_rows);
+ 
+ As some of these rows are not used, and thus return immediately,
+ you may want to read about interlacing in the PNG specification,
+ and only update the rows that are actually used.
+ 
+ .SS Finishing a sequential write
+ 
+ After you are finished writing the image, you should finish writing
+ the file.  If you are interested in writing comments or time, you should
+ pass an appropriately filled png_info pointer.  If you are not interested,
+ you can pass NULL.
+ 
+     png_write_end(png_ptr, info_ptr);
+ 
+ When you are done, you can free all memory used by libpng like this:
+ 
+     png_destroy_write_struct(&png_ptr, &info_ptr);
+ 
+ It is also possible to individually free the info_ptr members that
+ point to libpng-allocated storage with the following function:
+ 
+     png_free_data(png_ptr, info_ptr, mask, seq)
+     mask  - identifies data to be freed, a mask
+             containing the logical OR of one or
+             more of
+               PNG_FREE_PLTE, PNG_FREE_TRNS,
+               PNG_FREE_HIST, PNG_FREE_ICCP,
+               PNG_FREE_PCAL, PNG_FREE_ROWS,
+               PNG_FREE_SCAL, PNG_FREE_SPLT,
+               PNG_FREE_TEXT, PNG_FREE_UNKN,
+             or simply PNG_FREE_ALL
+     seq   - sequence number of item to be freed
+             (-1 for all items)
+ 
+ This function may be safely called when the relevant storage has
+ already been freed, or has not yet been allocated, or was allocated
+ by the user  and not by libpng,  and will in those
+ cases do nothing.  The "seq" parameter is ignored if only one item
+ of the selected data type, such as PLTE, is allowed.  If "seq" is not
+ -1, and multiple items are allowed for the data type identified in
+ the mask, such as text or sPLT, only the n'th item in the structure
+ is freed, where n is "seq".
+ 
+ If you allocated data such as a palette that you passed
+ in to libpng with png_set_*, you must not free it until just before the call to
+ png_destroy_write_struct().
+ 
+ The default behavior is only to free data that was allocated internally
+ by libpng.  This can be changed, so that libpng will not free the data,
+ or so that it will free data that was allocated by the user with png_malloc()
+ or png_zalloc() and passed in via a png_set_*() function, with
+ 
+     png_data_freer(png_ptr, info_ptr, freer, mask)
+     mask   - which data elements are affected
+              same choices as in png_free_data()
+     freer  - one of
+                PNG_DESTROY_WILL_FREE_DATA
+                PNG_SET_WILL_FREE_DATA
+                PNG_USER_WILL_FREE_DATA
+ 
+ For example, to transfer responsibility for some data from a read structure
+ to a write structure, you could use
+ 
+     png_data_freer(read_ptr, read_info_ptr,
+        PNG_USER_WILL_FREE_DATA,
+        PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
+     png_data_freer(write_ptr, write_info_ptr,
+        PNG_DESTROY_WILL_FREE_DATA,
+        PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
+ 
+ thereby briefly reassigning responsibility for freeing to the user but
+ immediately afterwards reassigning it once more to the write_destroy
+ function.  Having done this, it would then be safe to destroy the read
+ structure and continue to use the PLTE, tRNS, and hIST data in the write
+ structure.
+ 
+ This function only affects data that has already been allocated.
+ You can call this function before calling after the png_set_*() functions
+ to control whether the user or png_destroy_*() is supposed to free the data.
+ When the user assumes responsibility for libpng-allocated data, the
+ application must use
+ png_free() to free it, and when the user transfers responsibility to libpng
+ for data that the user has allocated, the user must have used png_malloc()
+ or png_zalloc() to allocate it.
+ 
+ If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
+ separately, do not transfer responsibility for freeing text_ptr to libpng,
+ because when libpng fills a png_text structure it combines these members with
+ the key member, and png_free_data() will free only text_ptr.key.  Similarly,
+ if you transfer responsibility for free'ing text_ptr from libpng to your
+ application, your application must not separately free those members.
+ For a more compact example of writing a PNG image, see the file example.c.
+ 
+ .SH V. Modifying/Customizing libpng:
+ 
+ There are three issues here.  The first is changing how libpng does
+ standard things like memory allocation, input/output, and error handling.
+ The second deals with more complicated things like adding new chunks,
+ adding new transformations, and generally changing how libpng works.
+ Both of those are compile-time issues; that is, they are generally
+ determined at the time the code is written, and there is rarely a need
+ to provide the user with a means of changing them.  The third is a
+ run-time issue:  choosing between and/or tuning one or more alternate
+ versions of computationally intensive routines; specifically, optimized
+ assembly-language (and therefore compiler- and platform-dependent)
+ versions.
+ 
+ Memory allocation, input/output, and error handling
+ 
+ All of the memory allocation, input/output, and error handling in libpng
+ goes through callbacks that are user-settable.  The default routines are
+ in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively.  To change
+ these functions, call the appropriate png_set_*_fn() function.
+ 
+ Memory allocation is done through the functions png_malloc()
+ and png_free().  These currently just call the standard C functions.  If
+ your pointers can't access more then 64K at a time, you will want to set
+ MAXSEG_64K in zlib.h.  Since it is unlikely that the method of handling
+ memory allocation on a platform will change between applications, these
+ functions must be modified in the library at compile time.  If you prefer
+ to use a different method of allocating and freeing data, you can use
+ png_create_read_struct_2() or png_create_write_struct_2() to register
+ your own functions as described above.
+ 
+ These functions also provide a void pointer that can be retrieved via
+ 
+     mem_ptr=png_get_mem_ptr(png_ptr);
+ 
+ Your replacement memory functions must have prototypes as follows:
+ 
+     png_voidp malloc_fn(png_structp png_ptr,
+        png_size_t size);
+     void free_fn(png_structp png_ptr, png_voidp ptr);
+ 
+ Your malloc_fn() should return NULL in case of failure.  The png_malloc()
+ function will call png_error() if it receives a NULL from the system
+ memory allocator or from your replacement malloc_fn().
+ 
+ Input/Output in libpng is done through png_read() and png_write(),
+ which currently just call fread() and fwrite().  The FILE * is stored in
+ png_struct and is initialized via png_init_io().  If you wish to change
+ the method of I/O, the library supplies callbacks that you can set
+ through the function png_set_read_fn() and png_set_write_fn() at run
+ time, instead of calling the png_init_io() function.  These functions
+ also provide a void pointer that can be retrieved via the function
+ png_get_io_ptr().  For example:
+ 
+     png_set_read_fn(png_structp read_ptr,
+         voidp read_io_ptr, png_rw_ptr read_data_fn)
+ 
+     png_set_write_fn(png_structp write_ptr,
+         voidp write_io_ptr, png_rw_ptr write_data_fn,
+         png_flush_ptr output_flush_fn);
+ 
+     voidp read_io_ptr = png_get_io_ptr(read_ptr);
+     voidp write_io_ptr = png_get_io_ptr(write_ptr);
+ 
+ The replacement I/O functions must have prototypes as follows:
+ 
+     void user_read_data(png_structp png_ptr,
+         png_bytep data, png_size_t length);
+     void user_write_data(png_structp png_ptr,
+         png_bytep data, png_size_t length);
+     void user_flush_data(png_structp png_ptr);
+ 
+ Supplying NULL for the read, write, or flush functions sets them back
+ to using the default C stream functions.  It is an error to read from
+ a write stream, and vice versa.
+ 
+ Error handling in libpng is done through png_error() and png_warning().
+ Errors handled through png_error() are fatal, meaning that png_error()
+ should never return to its caller.  Currently, this is handled via
+ setjmp() and longjmp() (unless you have compiled libpng with
+ PNG_SETJMP_NOT_SUPPORTED, in which case it is handled via PNG_ABORT()),
+ but you could change this to do things like exit() if you should wish.
+ 
+ On non-fatal errors, png_warning() is called
+ to print a warning message, and then control returns to the calling code.
+ By default png_error() and png_warning() print a message on stderr via
+ fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
+ (because you don't want the messages) or PNG_NO_STDIO defined (because
+ fprintf() isn't available).  If you wish to change the behavior of the error
+ functions, you will need to set up your own message callbacks.  These
+ functions are normally supplied at the time that the png_struct is created.
+ It is also possible to redirect errors and warnings to your own replacement
+ functions after png_create_*_struct() has been called by calling:
+ 
+     png_set_error_fn(png_structp png_ptr,
+         png_voidp error_ptr, png_error_ptr error_fn,
+         png_error_ptr warning_fn);
+ 
+     png_voidp error_ptr = png_get_error_ptr(png_ptr);
+ 
+ If NULL is supplied for either error_fn or warning_fn, then the libpng
+ default function will be used, calling fprintf() and/or longjmp() if a
+ problem is encountered.  The replacement error functions should have
+ parameters as follows:
+ 
+     void user_error_fn(png_structp png_ptr,
+         png_const_charp error_msg);
+     void user_warning_fn(png_structp png_ptr,
+         png_const_charp warning_msg);
+ 
+ The motivation behind using setjmp() and longjmp() is the C++ throw and
+ catch exception handling methods.  This makes the code much easier to write,
+ as there is no need to check every return code of every function call.
+ However, there are some uncertainties about the status of local variables
+ after a longjmp, so the user may want to be careful about doing anything after
+ setjmp returns non-zero besides returning itself.  Consult your compiler
+ documentation for more details.  For an alternative approach, you may wish
+ to use the "cexcept" facility (see http://cexcept.sourceforge.net).
+ 
+ .SS Custom chunks
+ 
+ If you need to read or write custom chunks, you may need to get deeper
+ into the libpng code.  The library now has mechanisms for storing
+ and writing chunks of unknown type; you can even declare callbacks
+ for custom chunks.  Hoewver, this may not be good enough if the
+ library code itself needs to know about interactions between your
+ chunk and existing `intrinsic' chunks.
+ 
+ If you need to write a new intrinsic chunk, first read the PNG
+ specification. Acquire a first level of
+ understanding of how it works.  Pay particular attention to the
+ sections that describe chunk names, and look at how other chunks were
+ designed, so you can do things similarly.  Second, check out the
+ sections of libpng that read and write chunks.  Try to find a chunk
+ that is similar to yours and use it as a template.  More details can
+ be found in the comments inside the code.  It is best to handle unknown
+ chunks in a generic method, via callback functions, instead of by
+ modifying libpng functions.
+ 
+ If you wish to write your own transformation for the data, look through
+ the part of the code that does the transformations, and check out some of
+ the simpler ones to get an idea of how they work.  Try to find a similar
+ transformation to the one you want to add and copy off of it.  More details
+ can be found in the comments inside the code itself.
+ 
+ .SS Configuring for 16 bit platforms
+ 
+ You will want to look into zconf.h to tell zlib (and thus libpng) that
+ it cannot allocate more then 64K at a time.  Even if you can, the memory
+ won't be accessible.  So limit zlib and libpng to 64K by defining MAXSEG_64K.
+ 
+ .SS Configuring for DOS
+ 
+ For DOS users who only have access to the lower 640K, you will
+ have to limit zlib's memory usage via a png_set_compression_mem_level()
+ call.  See zlib.h or zconf.h in the zlib library for more information.
+ 
+ .SS Configuring for Medium Model
+ 
+ Libpng's support for medium model has been tested on most of the popular
+ compilers.  Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
+ defined, and FAR gets defined to far in pngconf.h, and you should be
+ all set.  Everything in the library (except for zlib's structure) is
+ expecting far data.  You must use the typedefs with the p or pp on
+ the end for pointers (or at least look at them and be careful).  Make
+ note that the rows of data are defined as png_bytepp, which is an
+ unsigned char far * far *.
+ 
+ .SS Configuring for gui/windowing platforms:
+ 
+ You will need to write new error and warning functions that use the GUI
+ interface, as described previously, and set them to be the error and
+ warning functions at the time that png_create_*_struct() is called,
+ in order to have them available during the structure initialization.
+ They can be changed later via png_set_error_fn().  On some compilers,
+ you may also have to change the memory allocators (png_malloc, etc.).
+ 
+ .SS Configuring for compiler xxx:
+ 
+ All includes for libpng are in pngconf.h.  If you need to add/change/delete
+ an include, this is the place to do it.  The includes that are not
+ needed outside libpng are protected by the PNG_INTERNAL definition,
+ which is only defined for those routines inside libpng itself.  The
+ files in libpng proper only include png.h, which includes pngconf.h.
+ 
+ .SS Configuring zlib:
+ 
+ There are special functions to configure the compression.  Perhaps the
+ most useful one changes the compression level, which currently uses
+ input compression values in the range 0 - 9.  The library normally
+ uses the default compression level (Z_DEFAULT_COMPRESSION = 6).  Tests
+ have shown that for a large majority of images, compression values in
+ the range 3-6 compress nearly as well as higher levels, and do so much
+ faster.  For online applications it may be desirable to have maximum speed
+ (Z_BEST_SPEED = 1).  With versions of zlib after v0.99, you can also
+ specify no compression (Z_NO_COMPRESSION = 0), but this would create
+ files larger than just storing the raw bitmap.  You can specify the
+ compression level by calling:
+ 
+     png_set_compression_level(png_ptr, level);
+ 
+ Another useful one is to reduce the memory level used by the library.
+ The memory level defaults to 8, but it can be lowered if you are
+ short on memory (running DOS, for example, where you only have 640K).
+ Note that the memory level does have an effect on compression; among
+ other things, lower levels will result in sections of incompressible
+ data being emitted in smaller stored blocks, with a correspondingly
+ larger relative overhead of up to 15% in the worst case.
+ 
+     png_set_compression_mem_level(png_ptr, level);
+ 
+ The other functions are for configuring zlib.  They are not recommended
+ for normal use and may result in writing an invalid PNG file.  See
+ zlib.h for more information on what these mean.
+ 
+     png_set_compression_strategy(png_ptr,
+         strategy);
+     png_set_compression_window_bits(png_ptr,
+         window_bits);
+     png_set_compression_method(png_ptr, method);
+     png_set_compression_buffer_size(png_ptr, size);
+ 
+ .SS Controlling row filtering
+ 
+ If you want to control whether libpng uses filtering or not, which
+ filters are used, and how it goes about picking row filters, you
+ can call one of these functions.  The selection and configuration
+ of row filters can have a significant impact on the size and
+ encoding speed and a somewhat lesser impact on the decoding speed
+ of an image.  Filtering is enabled by default for RGB and grayscale
+ images (with and without alpha), but not for paletted images nor
+ for any images with bit depths less than 8 bits/pixel.
+ 
+ The 'method' parameter sets the main filtering method, which is
+ currently only '0' in the PNG 1.2 specification.  The 'filters'
+ parameter sets which filter(s), if any, should be used for each
+ scanline.  Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+ to turn filtering on and off, respectively.
+ 
+ Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
+ PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
+ ORed together with '|' to specify one or more filters to use.
+ These filters are described in more detail in the PNG specification.
+ If you intend to change the filter type during the course of writing
+ the image, you should start with flags set for all of the filters
+ you intend to use so that libpng can initialize its internal
+ structures appropriately for all of the filter types.  (Note that this
+ means the first row must always be adaptively filtered, because libpng
+ currently does not allocate the filter buffers until png_write_row()
+ is called for the first time.)
+ 
+     filters = PNG_FILTER_NONE | PNG_FILTER_SUB
+               PNG_FILTER_UP | PNG_FILTER_AVE |
+               PNG_FILTER_PAETH | PNG_ALL_FILTERS;
+ 
+     png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
+        filters);
+               The second parameter can also be
+               PNG_INTRAPIXEL_DIFFERENCING if you are
+               writing a PNG to be embedded in a MNG
+               datastream.  This parameter must be the
+               same as the value of filter_method used
+               in png_set_IHDR().
+ 
+ It is also possible to influence how libpng chooses from among the
+ available filters.  This is done in one or both of two ways - by
+ telling it how important it is to keep the same filter for successive
+ rows, and by telling it the relative computational costs of the filters.
+ 
+     double weights[3] = {1.5, 1.3, 1.1},
+        costs[PNG_FILTER_VALUE_LAST] =
+        {1.0, 1.3, 1.3, 1.5, 1.7};
+ 
+     png_set_filter_heuristics(png_ptr,
+        PNG_FILTER_HEURISTIC_WEIGHTED, 3,
+        weights, costs);
+ 
+ The weights are multiplying factors that indicate to libpng that the
+ row filter should be the same for successive rows unless another row filter
+ is that many times better than the previous filter.  In the above example,
+ if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a
+ "sum of absolute differences" 1.5 x 1.3 times higher than other filters
+ and still be chosen, while the NONE filter could have a sum 1.1 times
+ higher than other filters and still be chosen.  Unspecified weights are
+ taken to be 1.0, and the specified weights should probably be declining
+ like those above in order to emphasize recent filters over older filters.
+ 
+ The filter costs specify for each filter type a relative decoding cost
+ to be considered when selecting row filters.  This means that filters
+ with higher costs are less likely to be chosen over filters with lower
+ costs, unless their "sum of absolute differences" is that much smaller.
+ The costs do not necessarily reflect the exact computational speeds of
+ the various filters, since this would unduly influence the final image
+ size.
+ 
+ Note that the numbers above were invented purely for this example and
+ are given only to help explain the function usage.  Little testing has
+ been done to find optimum values for either the costs or the weights.
+ 
+ .SS Removing unwanted object code
+ 
+ There are a bunch of #define's in pngconf.h that control what parts of
+ libpng are compiled.  All the defines end in _SUPPORTED.  If you are
+ never going to use a capability, you can change the #define to #undef
+ before recompiling libpng and save yourself code and data space, or
+ you can turn off individual capabilities with defines that begin with
+ PNG_NO_.
+ 
+ You can also turn all of the transforms and ancillary chunk capabilities
+ off en masse with compiler directives that define
+ PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
+ or all four,
+ along with directives to turn on any of the capabilities that you do
+ want.  The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable
+ the extra transformations but still leave the library fully capable of reading
+ and writing PNG files with all known public chunks
+ Use of the PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive
+ produces a library that is incapable of reading or writing ancillary chunks.
+ If you are not using the progressive reading capability, you can
+ turn that off with PNG_NO_PROGRESSIVE_READ (don't confuse
+ this with the INTERLACING capability, which you'll still have).
+ 
+ All the reading and writing specific code are in separate files, so the
+ linker should only grab the files it needs.  However, if you want to
+ make sure, or if you are building a stand alone library, all the
+ reading files start with pngr and all the writing files start with
+ pngw.  The files that don't match either (like png.c, pngtrans.c, etc.)
+ are used for both reading and writing, and always need to be included.
+ The progressive reader is in pngpread.c
+ 
+ If you are creating or distributing a dynamically linked library (a .so
+ or DLL file), you should not remove or disable any parts of the library,
+ as this will cause applications linked with different versions of the
+ library to fail if they call functions not available in your library.
+ The size of the library itself should not be an issue, because only
+ those sections that are actually used will be loaded into memory.
+ 
+ .SS Requesting debug printout
+ 
+ The macro definition PNG_DEBUG can be used to request debugging
+ printout.  Set it to an integer value in the range 0 to 3.  Higher
+ numbers result in increasing amounts of debugging information.  The
+ information is printed to the "stderr" file, unless another file
+ name is specified in the PNG_DEBUG_FILE macro definition.
+ 
+ When PNG_DEBUG > 0, the following functions (macros) become available:
+ 
+    png_debug(level, message)
+    png_debug1(level, message, p1)
+    png_debug2(level, message, p1, p2)
+ 
+ in which "level" is compared to PNG_DEBUG to decide whether to print
+ the message, "message" is the formatted string to be printed,
+ and p1 and p2 are parameters that are to be embedded in the string
+ according to printf-style formatting directives.  For example,
+ 
+    png_debug1(2, "foo=%d\n", foo);
+ 
+ is expanded to
+ 
+    if(PNG_DEBUG > 2)
+      fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
+ 
+ When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
+ can still use PNG_DEBUG to control your own debugging:
+ 
+    #ifdef PNG_DEBUG
+        fprintf(stderr, ...
+    #endif
+ 
+ When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
+ having level = 0 will be printed.  There aren't any such statements in
+ this version of libpng, but if you insert some they will be printed.
+ 
+ .SH VI.  Runtime optimization
+ 
+ A new feature in libpng 1.2.0 is the ability to dynamically switch between
+ standard and optimized versions of some routines.  Currently these are
+ limited to three computationally intensive tasks when reading PNG files:
+ decoding row filters, expanding interlacing, and combining interlaced or
+ transparent row data with previous row data.  Currently the optimized
+ versions are available only for x86 (Intel, AMD, etc.) platforms with
+ MMX support, though this may change in future versions.  (For example,
+ the non-MMX assembler optimizations for zlib might become similarly
+ runtime-selectable in future releases, in which case libpng could be
+ extended to support them.  Alternatively, the compile-time choice of
+ floating-point versus integer routines for gamma correction might become
+ runtime-selectable.)
+ 
+ Because such optimizations tend to be very platform- and compiler-dependent,
+ both in how they are written and in how they perform, the new runtime code
+ in libpng has been written to allow programs to query, enable, and disable
+ either specific optimizations or all such optimizations.  For example, to
+ enable all possible optimizations (bearing in mind that some "optimizations"
+ may actually run more slowly in rare cases):
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        png_uint_32 mask, flags;
+ 
+        flags = png_get_asm_flags(png_ptr);
+        mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
+        png_set_asm_flags(png_ptr, flags | mask);
+     #endif
+ 
+ To enable only optimizations relevant to reading PNGs, use PNG_SELECT_READ
+ by itself when calling png_get_asm_flagmask(); similarly for optimizing
+ only writing.  To disable all optimizations:
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        flags = png_get_asm_flags(png_ptr);
+        mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
+        png_set_asm_flags(png_ptr, flags & ~mask);
+     #endif
+ 
+ To enable or disable only MMX-related features, use png_get_mmx_flagmask()
+ in place of png_get_asm_flagmask().  The mmx version takes one additional
+ parameter:
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        int selection = PNG_SELECT_READ | PNG_SELECT_WRITE;
+        int compilerID;
+ 
+        mask = png_get_mmx_flagmask(selection, &compilerID);
+     #endif
+ 
+ On return, compilerID will indicate which version of the MMX assembler
+ optimizations was compiled.  Currently two flavors exist:  Microsoft
+ Visual C++ (compilerID == 1) and GNU C (a.k.a. gcc/gas, compilerID == 2).
+ On non-x86 platforms or on systems compiled without MMX optimizations, a
+ value of -1 is used.
+ 
+ Note that both png_get_asm_flagmask() and png_get_mmx_flagmask() return
+ all valid, settable optimization bits for the version of the library that's
+ currently in use.  In the case of shared (dynamically linked) libraries,
+ this may include optimizations that did not exist at the time the code was
+ written and compiled.  It is also possible, of course, to enable only known,
+ specific optimizations; for example:
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        flags = PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  \
+              | PNG_ASM_FLAG_MMX_READ_INTERLACE    \
+              | PNG_ASM_FLAG_MMX_READ_FILTER_SUB   \
+              | PNG_ASM_FLAG_MMX_READ_FILTER_UP    \
+              | PNG_ASM_FLAG_MMX_READ_FILTER_AVG   \
+              | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;
+        png_set_asm_flags(png_ptr, flags);
+     #endif
+ 
+ This method would enable only the MMX read-optimizations available at the
+ time of libpng 1.2.0's release, regardless of whether a later version of
+ the DLL were actually being used.  (Also note that these functions did not
+ exist in versions older than 1.2.0, so any attempt to run a dynamically
+ linked app on such an older version would fail.)
+ 
+ To determine whether the processor supports MMX instructions at all, use
+ the png_mmx_support() function:
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        mmxsupport = png_mmx_support();
+     #endif
+ 
+ It returns -1 if MMX support is not compiled into libpng, 0 if MMX code
+ is compiled but MMX is not supported by the processor, or 1 if MMX support
+ is fully available.  Note that png_mmx_support(), png_get_mmx_flagmask(),
+ and png_get_asm_flagmask() all may be called without allocating and ini-
+ tializing any PNG structures (for example, as part of a usage screen or
+ "about" box).
+ 
+ The following code can be used to prevent an application from using the
+ thread_unsafe features, even if libpng was built with PNG_THREAD_UNSAFE_OK
+ defined:
+ 
+ #if defined(PNG_USE_PNGGCCRD) && defined(PNG_ASSEMBLER_CODE_SUPPORTED) \
+   && defined(PNG_THREAD_UNSAFE_OK)
+     /* Disable thread-unsafe features of pnggccrd */
+     if (png_access_version() >= 10200)
+     {
+       png_uint_32 mmx_disable_mask = 0;
+       png_uint_32 asm_flags;
+ 
+       mmx_disable_mask |= ( PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  \
+                           | PNG_ASM_FLAG_MMX_READ_FILTER_SUB   \
+                           | PNG_ASM_FLAG_MMX_READ_FILTER_AVG   \
+                           | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH );
+       asm_flags = png_get_asm_flags(png_ptr);
+       png_set_asm_flags(png_ptr, asm_flags & ~mmx_disable_mask);
+     }
+ #endif
+ 
+ For more extensive examples of runtime querying, enabling and disabling
+ of optimized features, see contrib/gregbook/readpng2.c in the libpng
+ source-code distribution.
+ 
+ 
+ .SH VII.  MNG support
+ 
+ The MNG specification (available at http://www.libpng.org/pub/mng) allows
+ certain extensions to PNG for PNG images that are embedded in MNG datastreams.
+ Libpng can support some of these extensions.  To enable them, use the
+ png_permit_mng_features() function:
+ 
+    feature_set = png_permit_mng_features(png_ptr, mask)
+    mask is a png_uint_32 containing the logical OR of the
+         features you want to enable.  These include
+         PNG_FLAG_MNG_EMPTY_PLTE
+         PNG_FLAG_MNG_FILTER_64
+         PNG_ALL_MNG_FEATURES
+    feature_set is a png_32_uint that is the logical AND of
+       your mask with the set of MNG features that is
+       supported by the version of libpng that you are using.
+ 
+ It is an error to use this function when reading or writing a standalone
+ PNG file with the PNG 8-byte signature.  The PNG datastream must be wrapped
+ in a MNG datastream.  As a minimum, it must have the MNG 8-byte signature
+ and the MHDR and MEND chunks.  Libpng does not provide support for these
+ or any other MNG chunks; your application must provide its own support for
+ them.  You may wish to consider using libmng (available at
+ http://www.libmng.com) instead.
+ 
+ .SH VIII.  Changes to Libpng from version 0.88
+ 
+ It should be noted that versions of libpng later than 0.96 are not
+ distributed by the original libpng author, Guy Schalnat, nor by
+ Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
+ distributed versions 0.89 through 0.96, but rather by another member
+ of the original PNG Group, Glenn Randers-Pehrson.  Guy and Andreas are
+ still alive and well, but they have moved on to other things.
+ 
+ The old libpng functions png_read_init(), png_write_init(),
+ png_info_init(), png_read_destroy(), and png_write_destroy() have been
+ moved to PNG_INTERNAL in version 0.95 to discourage their use.  These
+ functions will be removed from libpng version 2.0.0.
+ 
+ The preferred method of creating and initializing the libpng structures is
+ via the png_create_read_struct(), png_create_write_struct(), and
+ png_create_info_struct() because they isolate the size of the structures
+ from the application, allow version error checking, and also allow the
+ use of custom error handling routines during the initialization, which
+ the old functions do not.  The functions png_read_destroy() and
+ png_write_destroy() do not actually free the memory that libpng
+ allocated for these structs, but just reset the data structures, so they
+ can be used instead of png_destroy_read_struct() and
+ png_destroy_write_struct() if you feel there is too much system overhead
+ allocating and freeing the png_struct for each image read.
+ 
+ Setting the error callbacks via png_set_message_fn() before
+ png_read_init() as was suggested in libpng-0.88 is no longer supported
+ because this caused applications that do not use custom error functions
+ to fail if the png_ptr was not initialized to zero.  It is still possible
+ to set the error callbacks AFTER png_read_init(), or to change them with
+ png_set_error_fn(), which is essentially the same function, but with a new
+ name to force compilation errors with applications that try to use the old
+ method.
+ 
+ Starting with version 1.0.7, you can find out which version of the library
+ you are using at run-time:
+ 
+    png_uint_32 libpng_vn = png_access_version_number();
+ 
+ The number libpng_vn is constructed from the major version, minor
+ version with leading zero, and release number with leading zero,
+ (e.g., libpng_vn for version 1.0.7 is 10007).
+ 
+ You can also check which version of png.h you used when compiling your
+ application:
+ 
+    png_uint_32 application_vn = PNG_LIBPNG_VER;
+ 
+ .SH IX. Y2K Compliance in libpng
+ 
+ October 3, 2002
+ 
+ Since the PNG Development group is an ad-hoc body, we can't make
+ an official declaration.
+ 
+ This is your unofficial assurance that libpng from version 0.71 and
+ upward through 1.2.5 are Y2K compliant.  It is my belief that earlier
+ versions were also Y2K compliant.
+ 
+ Libpng only has three year fields.  One is a 2-byte unsigned integer that
+ will hold years up to 65535.  The other two hold the date in text
+ format, and will hold years up to 9999.
+ 
+ The integer is
+     "png_uint_16 year" in png_time_struct.
+ 
+ The strings are
+     "png_charp time_buffer" in png_struct and
+     "near_time_buffer", which is a local character string in png.c.
+ 
+ There are seven time-related functions:
+ 
+     png_convert_to_rfc_1123() in png.c
+       (formerly png_convert_to_rfc_1152() in error)
+     png_convert_from_struct_tm() in pngwrite.c, called
+       in pngwrite.c
+     png_convert_from_time_t() in pngwrite.c
+     png_get_tIME() in pngget.c
+     png_handle_tIME() in pngrutil.c, called in pngread.c
+     png_set_tIME() in pngset.c
+     png_write_tIME() in pngwutil.c, called in pngwrite.c
+ 
+ All appear to handle dates properly in a Y2K environment.  The
+ png_convert_from_time_t() function calls gmtime() to convert from system
+ clock time, which returns (year - 1900), which we properly convert to
+ the full 4-digit year.  There is a possibility that applications using
+ libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
+ function, or that they are incorrectly passing only a 2-digit year
+ instead of "year - 1900" into the png_convert_from_struct_tm() function,
+ but this is not under our control.  The libpng documentation has always
+ stated that it works with 4-digit years, and the APIs have been
+ documented as such.
+ 
+ The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
+ integer to hold the year, and can hold years as large as 65535.
+ 
+ zlib, upon which libpng depends, is also Y2K compliant.  It contains
+ no date-related code.
+ 
+ 
+    Glenn Randers-Pehrson
+    libpng maintainer
+    PNG Development Group
+ 
+ .SH NOTE
+ 
+ Note about libpng version numbers:
+ 
+ Due to various miscommunications, unforeseen code incompatibilities
+ and occasional factors outside the authors' control, version numbering
+ on the library has not always been consistent and straightforward.
+ The following table summarizes matters since version 0.89c, which was
+ the first widely used release:
+ 
+  source             png.h  png.h  shared-lib
+  version            string   int  version
+  -------            ------  ----- ----------
+  0.89c ("beta 3")  0.89       89  1.0.89
+  0.90  ("beta 4")  0.90       90  0.90
+  0.95  ("beta 5")  0.95       95  0.95
+  0.96  ("beta 6")  0.96       96  0.96
+  0.97b ("beta 7")  1.00.97    97  1.0.1
+  0.97c             0.97       97  2.0.97
+  0.98              0.98       98  2.0.98
+  0.99              0.99       98  2.0.99
+  0.99a-m           0.99       99  2.0.99
+  1.00              1.00      100  2.1.0
+  1.0.0             1.0.0     100  2.1.0
+  1.0.0   (from here on, the  100  2.1.0
+  1.0.1    png.h string is  10001  2.1.0
+  1.0.1a-e identical to the 10002  from here on, the
+  1.0.2    source version)  10002  shared library is 2.V
+  1.0.2a-b                  10003  where V is the source
+  1.0.1                     10001  code version except as
+  1.0.1a-e                  10002  2.1.0.1a-e   noted.
+  1.0.2                     10002  2.1.0.2
+  1.0.2a-b                  10003  2.1.0.2a-b
+  1.0.3                     10003  2.1.0.3
+  1.0.3a-d                  10004  2.1.0.3a-d
+  1.0.4                     10004  2.1.0.4
+  1.0.4a-f                  10005  2.1.0.4a-f
+  1.0.5 (+ 2 patches)       10005  2.1.0.5
+  1.0.5a-d                  10006  2.1.0.5a-d
+  1.0.5e-r                  10100  2.1.0.5e-r
+  1.0.5s-v                  10006  2.1.0.5s-v
+  1.0.6 (+ 3 patches)       10006  2.1.0.6
+  1.0.6d-g                  10007  2.1.0.6d-g
+  1.0.6h                    10007  10.6h
+  1.0.6i                    10007  10.6i
+  1.0.6j                    10007  2.1.0.6j
+  1.0.7beta11-14    DLLNUM  10007  2.1.0.7beta11-14
+  1.0.7beta15-18       1    10007  2.1.0.7beta15-18
+  1.0.7rc1-2           1    10007  2.1.0.7rc1-2
+  1.0.7                1    10007  2.1.0.7
+  1.0.8beta1-4         1    10008  2.1.0.8beta1-4
+  1.0.8rc1             1    10008  2.1.0.8rc1
+  1.0.8                1    10008  2.1.0.8
+  1.0.9beta1-6         1    10009  2.1.0.9beta1-6
+  1.0.9rc1             1    10009  2.1.0.9rc1
+  1.0.9beta7-10        1    10009  2.1.0.9beta7-10
+  1.0.9rc2             1    10009  2.1.0.9rc2
+  1.0.9                1    10009  2.1.0.9
+  1.0.10beta1          1    10010  2.1.0.10beta1
+  1.0.10rc1            1    10010  2.1.0.10rc1
+  1.0.10               1    10010  2.1.0.10
+  1.0.11beta1-3        1    10011  2.1.0.11beta1-3
+  1.0.11rc1            1    10011  2.1.0.11rc1
+  1.0.11               1    10011  2.1.0.11
+  1.0.12beta1-2        2    10012  2.1.0.12beta1-2
+  1.0.12rc1            2    10012  2.1.0.12rc1
+  1.0.12               2    10012  2.1.0.12
+  1.1.0a-f             -    10100  2.1.1.0a-f abandoned
+  1.2.0beta1-2         2    10200  2.1.2.0beta1-2
+  1.2.0beta3-5         3    10200  3.1.2.0beta3-5
+  1.2.0rc1             3    10200  3.1.2.0rc1
+  1.2.0                3    10200  3.1.2.0
+  1.2.1beta-4          3    10201  3.1.2.1beta1-4
+  1.2.1rc1-2           3    10201  3.1.2.1rc1-2
+  1.2.1                3    10201  3.1.2.1
+  1.2.2beta1-6        12    10202  12.so.0.1.2.2beta1-6
+  1.0.13beta1         10    10013  10.so.0.1.0.13beta1
+  1.0.13rc1           10    10013  10.so.0.1.0.13rc1
+  1.2.2rc1            12    10202  12.so.0.1.2.2rc1
+  1.0.13              10    10013  10.so.0.1.0.13
+  1.2.2               12    10202  12.so.0.1.2.2
+  1.2.3rc1-6          12    10203  12.so.0.1.2.3rc1-6
+  1.2.3               12    10203  12.so.0.1.2.3
+  1.2.4beta1-3        13    10204  12.so.0.1.2.4beta1-3
+  1.2.4rc1            13    10204  12.so.0.1.2.4rc1
+  1.0.14              10    10014  10.so.0.1.0.14
+  1.2.4               13    10204  12.so.0.1.2.4
+  1.0.15rc1-3         10    10015  10.so.0.1.0.15rc1-3
+  1.2.5rc1-3          13    10205  12.so.0.1.2.5rc1-3
+  1.0.15              10    10015  10.so.0.1.0.15
+  1.2.5               13    10205  12.so.0.1.2.5
+ 
+ Henceforth the source version will match the shared-library minor
+ and patch numbers; the shared-library major version number will be
+ used for changes in backward compatibility, as it is intended.  The
+ PNG_PNGLIB_VER macro, which is not used within libpng but is available
+ for applications, is an unsigned integer of the form xyyzz corresponding
+ to the source version x.y.z (leading zeros in y and z).  Beta versions
+ were given the previous public release number plus a letter, until
+ version 1.0.6j; from then on they were given the upcoming public
+ release number plus "betaNN" or "rcN".
+ 
+ .SH "SEE ALSO"
+ libpngpf(3), png(5)
+ .LP
+ .IR libpng :
+ .IP
+ ftp://ftp.uu.net/graphics/png
+ http://www.libpng.org/pub/png
+ 
+ .LP
+ .IR zlib :
+ .IP
+ (generally) at the same location as
+ .I libpng
+ or at
+ .br
+ ftp://ftp.uu.net/pub/archiving/zip/zlib
+ .br
+ ftp://ftp.info-zip.org/pub/infozip/zlib
+ 
+ .LP
+ .IR PNG specification: RFC 2083
+ .IP
+ (generally) at the same location as
+ .I libpng
+ or at
+ .br
+ ftp://ds.internic.net/rfc/rfc2083.txt
+ .br
+ or (as a W3C Recommendation) at
+ .br
+ http://www.w3.org/TR/REC-png.html
+ 
+ .LP
+ In the case of any inconsistency between the PNG specification
+ and this library, the specification takes precedence.
+ 
+ .SH AUTHORS
+ This man page: Glenn Randers-Pehrson
+ <randeg at alum.rpi.edu>
+ 
+ The contributing authors would like to thank all those who helped
+ with testing, bug fixes, and patience.  This wouldn't have been
+ possible without all of you.
+ 
+ Thanks to Frank J. T. Wojcik for helping with the documentation.
+ 
+ Libpng version 1.2.5 - October 3, 2002:
+ Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
+ Currently maintained by Glenn Randers-Pehrson (randeg at alum.rpi.edu).
+ 
+ Supported by the PNG development group
+ .br
+ (png-implement at ccrc.wustl.edu).
+ 
+ .SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+ 
+ (This copy of the libpng notices is provided for your convenience.  In case of
+ any discrepancy between this copy and the notices in the file png.h that is
+ included in the libpng distribution, the latter shall prevail.)
+ 
+ If you modify libpng you may insert additional notices immediately following
+ this sentence.
+ 
+ libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
+ Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
+ distributed according to the same disclaimer and license as libpng-1.0.6
+ with the following individuals added to the list of Contributing Authors
+ 
+    Simon-Pierre Cadieux
+    Eric S. Raymond
+    Gilles Vollant
+ 
+ and with the following additions to the disclaimer:
+ 
+    There is no warranty against interference with your
+    enjoyment of the library or against infringement.
+    There is no warranty that our efforts or the library
+    will fulfill any of your particular purposes or needs.
+    This library is provided with all faults, and the entire
+    risk of satisfactory quality, performance, accuracy, and
+    effort is with the user.
+ 
+ libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
+ Copyright (c) 1998, 1999 Glenn Randers-Pehrson
+ Distributed according to the same disclaimer and license as libpng-0.96,
+ with the following individuals added to the list of Contributing Authors:
+ 
+    Tom Lane
+    Glenn Randers-Pehrson
+    Willem van Schaik
+ 
+ libpng versions 0.89, June 1996, through 0.96, May 1997, are
+ Copyright (c) 1996, 1997 Andreas Dilger
+ Distributed according to the same disclaimer and license as libpng-0.88,
+ with the following individuals added to the list of Contributing Authors:
+ 
+    John Bowler
+    Kevin Bracey
+    Sam Bushell
+    Magnus Holmgren
+    Greg Roelofs
+    Tom Tanner
+ 
+ libpng versions 0.5, May 1995, through 0.88, January 1996, are
+ Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ 
+ For the purposes of this copyright and license, "Contributing Authors"
+ is defined as the following set of individuals:
+ 
+    Andreas Dilger
+    Dave Martindale
+    Guy Eric Schalnat
+    Paul Schmidt
+    Tim Wegner
+ 
+ The PNG Reference Library is supplied "AS IS".  The Contributing Authors
+ and Group 42, Inc. disclaim all warranties, expressed or implied,
+ including, without limitation, the warranties of merchantability and of
+ fitness for any purpose.  The Contributing Authors and Group 42, Inc.
+ assume no liability for direct, indirect, incidental, special, exemplary,
+ or consequential damages, which may result from the use of the PNG
+ Reference Library, even if advised of the possibility of such damage.
+ 
+ Permission is hereby granted to use, copy, modify, and distribute this
+ source code, or portions hereof, for any purpose, without fee, subject
+ to the following restrictions:
+ 
+ 1. The origin of this source code must not be misrepresented.
+ 
+ 2. Altered versions must be plainly marked as such and
+    must not be misrepresented as being the original source.
+ 
+ 3. This Copyright notice may not be removed or altered from
+    any source or altered source distribution.
+ 
+ The Contributing Authors and Group 42, Inc. specifically permit, without
+ fee, and encourage the use of this source code as a component to
+ supporting the PNG file format in commercial products.  If you use this
+ source code in a product, acknowledgment is not required but would be
+ appreciated.
+ 
+ 
+ A "png_get_copyright" function is available, for convenient use in "about"
+ boxes and the like:
+ 
+    printf("%s",png_get_copyright(NULL));
+ 
+ Also, the PNG logo (in PNG format, of course) is supplied in the
+ files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
+ 
+ Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is a
+ certification mark of the Open Source Initiative.
+ 
+ Glenn Randers-Pehrson
+ randeg at alum.rpi.edu
+ October 3, 2002
+ 
+ .\" end of man page
+ 


Index: llvm/runtime/libpng/libpng.txt
diff -c /dev/null llvm/runtime/libpng/libpng.txt:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:55 2004
--- llvm/runtime/libpng/libpng.txt	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,2905 ----
+ libpng.txt - A description on how to use and modify libpng
+ 
+  libpng version 1.2.5 - October 3, 2002
+  Updated and distributed by Glenn Randers-Pehrson
+  <randeg at alum.rpi.edu>
+  Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  For conditions of distribution and use, see copyright
+  notice in png.h.
+ 
+  based on:
+ 
+  libpng 1.0 beta 6  version 0.96 May 28, 1997
+  Updated and distributed by Andreas Dilger
+  Copyright (c) 1996, 1997 Andreas Dilger
+ 
+  libpng 1.0 beta 2 - version 0.88  January 26, 1996
+  For conditions of distribution and use, see copyright
+  notice in png.h. Copyright (c) 1995, 1996 Guy Eric
+  Schalnat, Group 42, Inc.
+ 
+  Updated/rewritten per request in the libpng FAQ
+  Copyright (c) 1995, 1996 Frank J. T. Wojcik
+  December 18, 1995 & January 20, 1996
+ 
+ I. Introduction
+ 
+ This file describes how to use and modify the PNG reference library
+ (known as libpng) for your own use.  There are five sections to this
+ file: introduction, structures, reading, writing, and modification and
+ configuration notes for various special platforms.  In addition to this
+ file, example.c is a good starting point for using the library, as
+ it is heavily commented and should include everything most people
+ will need.  We assume that libpng is already installed; see the
+ INSTALL file for instructions on how to install libpng.
+ 
+ Libpng was written as a companion to the PNG specification, as a way
+ of reducing the amount of time and effort it takes to support the PNG
+ file format in application programs.
+ 
+ The PNG-1.2 specification is available at <http://www.libpng.org/pub/png>
+ and at <ftp://ftp.uu.net/graphics/png/documents/>.
+ 
+ The PNG-1.0 specification is available
+ as RFC 2083 <ftp://ftp.uu.net/graphics/png/documents/> and as a
+ W3C Recommendation <http://www.w3.org/TR/REC.png.html>. Some
+ additional chunks are described in the special-purpose public chunks
+ documents at <ftp://ftp.uu.net/graphics/png/documents/>.
+ 
+ Other information
+ about PNG, and the latest version of libpng, can be found at the PNG home
+ page, <http://www.libpng.org/pub/png/>
+ and at <ftp://ftp.uu.net/graphics/png/>.
+ 
+ Most users will not have to modify the library significantly; advanced
+ users may want to modify it more.  All attempts were made to make it as
+ complete as possible, while keeping the code easy to understand.
+ Currently, this library only supports C.  Support for other languages
+ is being considered.
+ 
+ Libpng has been designed to handle multiple sessions at one time,
+ to be easily modifiable, to be portable to the vast majority of
+ machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
+ to use.  The ultimate goal of libpng is to promote the acceptance of
+ the PNG file format in whatever way possible.  While there is still
+ work to be done (see the TODO file), libpng should cover the
+ majority of the needs of its users.
+ 
+ Libpng uses zlib for its compression and decompression of PNG files.
+ Further information about zlib, and the latest version of zlib, can
+ be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
+ The zlib compression utility is a general purpose utility that is
+ useful for more than PNG files, and can be used without libpng.
+ See the documentation delivered with zlib for more details.
+ You can usually find the source files for the zlib utility wherever you
+ find the libpng source files.
+ 
+ Libpng is thread safe, provided the threads are using different
+ instances of the structures.  Each thread should have its own
+ png_struct and png_info instances, and thus its own image.
+ Libpng does not protect itself against two threads using the
+ same instance of a structure.  Note: thread safety may be defeated
+ by use of some of the MMX assembler code in pnggccrd.c, which is only
+ compiled when the user defines PNG_THREAD_UNSAFE_OK.
+ 
+ 
+ II. Structures
+ 
+ There are two main structures that are important to libpng, png_struct
+ and png_info.  The first, png_struct, is an internal structure that
+ will not, for the most part, be used by a user except as the first
+ variable passed to every libpng function call.
+ 
+ The png_info structure is designed to provide information about the
+ PNG file.  At one time, the fields of png_info were intended to be
+ directly accessible to the user.  However, this tended to cause problems
+ with applications using dynamically loaded libraries, and as a result
+ a set of interface functions for png_info (the png_get_*() and png_set_*()
+ functions) was developed.  The fields of png_info are still available for
+ older applications, but it is suggested that applications use the new
+ interfaces if at all possible.
+ 
+ Applications that do make direct access to the members of png_struct (except
+ for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
+ and applications that make direct access to the members of png_info must
+ be recompiled if they were compiled or loaded with libpng version 1.0.6,
+ in which the members were in a different order.  In version 1.0.7, the
+ members of the png_info structure reverted to the old order, as they were
+ in versions 0.97c through 1.0.5.  Starting with version 2.0.0, both
+ structures are going to be hidden, and the contents of the structures will
+ only be accessible through the png_get/png_set functions.
+ 
+ The png.h header file is an invaluable reference for programming with libpng.
+ And while I'm on the topic, make sure you include the libpng header file:
+ 
+ #include <png.h>
+ 
+ III. Reading
+ 
+ We'll now walk you through the possible functions to call when reading
+ in a PNG file sequentially, briefly explaining the syntax and purpose
+ of each one.  See example.c and png.h for more detail.  While
+ progressive reading is covered in the next section, you will still
+ need some of the functions discussed in this section to read a PNG
+ file.
+ 
+ Setup
+ 
+ You will want to do the I/O initialization(*) before you get into libpng,
+ so if it doesn't work, you don't have much to undo.  Of course, you
+ will also want to insure that you are, in fact, dealing with a PNG
+ file.  Libpng provides a simple check to see if a file is a PNG file.
+ To use it, pass in the first 1 to 8 bytes of the file to the function
+ png_sig_cmp(), and it will return 0 if the bytes match the corresponding
+ bytes of the PNG signature, or nonzero otherwise.  Of course, the more bytes
+ you pass in, the greater the accuracy of the prediction.
+ 
+ If you are intending to keep the file pointer open for use in libpng,
+ you must ensure you don't read more than 8 bytes from the beginning
+ of the file, and you also have to make a call to png_set_sig_bytes_read()
+ with the number of bytes you read from the beginning.  Libpng will
+ then only check the bytes (if any) that your program didn't read.
+ 
+ (*): If you are not using the standard I/O functions, you will need
+ to replace them with custom functions.  See the discussion under
+ Customizing libpng.
+ 
+ 
+     FILE *fp = fopen(file_name, "rb");
+     if (!fp)
+     {
+         return (ERROR);
+     }
+     fread(header, 1, number, fp);
+     is_png = !png_sig_cmp(header, 0, number);
+     if (!is_png)
+     {
+         return (NOT_PNG);
+     }
+ 
+ 
+ Next, png_struct and png_info need to be allocated and initialized.  In
+ order to ensure that the size of these structures is correct even with a
+ dynamically linked libpng, there are functions to initialize and
+ allocate the structures.  We also pass the library version, optional
+ pointers to error handling functions, and a pointer to a data struct for
+ use by the error functions, if necessary (the pointer and functions can
+ be NULL if the default error handlers are to be used).  See the section
+ on Changes to Libpng below regarding the old initialization functions.
+ The structure allocation functions quietly return NULL if they fail to
+ create the structure, so your application should check for that.
+ 
+     png_structp png_ptr = png_create_read_struct
+        (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+         user_error_fn, user_warning_fn);
+     if (!png_ptr)
+         return (ERROR);
+ 
+     png_infop info_ptr = png_create_info_struct(png_ptr);
+     if (!info_ptr)
+     {
+         png_destroy_read_struct(&png_ptr,
+            (png_infopp)NULL, (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+     png_infop end_info = png_create_info_struct(png_ptr);
+     if (!end_info)
+     {
+         png_destroy_read_struct(&png_ptr, &info_ptr,
+           (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+ If you want to use your own memory allocation routines,
+ define PNG_USER_MEM_SUPPORTED and use
+ png_create_read_struct_2() instead of png_create_read_struct():
+ 
+     png_structp png_ptr = png_create_read_struct_2
+        (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+         user_error_fn, user_warning_fn, (png_voidp)
+         user_mem_ptr, user_malloc_fn, user_free_fn);
+ 
+ The error handling routines passed to png_create_read_struct()
+ and the memory alloc/free routines passed to png_create_struct_2()
+ are only necessary if you are not using the libpng supplied error
+ handling and memory alloc/free functions.
+ 
+ When libpng encounters an error, it expects to longjmp back
+ to your routine.  Therefore, you will need to call setjmp and pass
+ your png_jmpbuf(png_ptr).  If you read the file from different
+ routines, you will need to update the jmpbuf field every time you enter
+ a new routine that will call a png_*() function.
+ 
+ See your documentation of setjmp/longjmp for your compiler for more
+ information on setjmp/longjmp.  See the discussion on libpng error
+ handling in the Customizing Libpng section below for more information
+ on the libpng error handling.  If an error occurs, and libpng longjmp's
+ back to your setjmp, you will want to call png_destroy_read_struct() to
+ free any memory.
+ 
+     if (setjmp(png_jmpbuf(png_ptr)))
+     {
+         png_destroy_read_struct(&png_ptr, &info_ptr,
+            &end_info);
+         fclose(fp);
+         return (ERROR);
+     }
+ 
+ If you would rather avoid the complexity of setjmp/longjmp issues,
+ you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
+ errors will result in a call to PNG_ABORT() which defaults to abort().
+ 
+ Now you need to set up the input code.  The default for libpng is to
+ use the C function fread().  If you use this, you will need to pass a
+ valid FILE * in the function png_init_io().  Be sure that the file is
+ opened in binary mode.  If you wish to handle reading data in another
+ way, you need not call the png_init_io() function, but you must then
+ implement the libpng I/O methods discussed in the Customizing Libpng
+ section below.
+ 
+     png_init_io(png_ptr, fp);
+ 
+ If you had previously opened the file and read any of the signature from
+ the beginning in order to see if this was a PNG file, you need to let
+ libpng know that there are some bytes missing from the start of the file.
+ 
+     png_set_sig_bytes(png_ptr, number);
+ 
+ Setting up callback code
+ 
+ You can set up a callback function to handle any unknown chunks in the
+ input stream. You must supply the function
+ 
+     read_chunk_callback(png_ptr ptr,
+          png_unknown_chunkp chunk);
+     {
+        /* The unknown chunk structure contains your
+           chunk data: */
+            png_byte name[5];
+            png_byte *data;
+            png_size_t size;
+        /* Note that libpng has already taken care of
+           the CRC handling */
+ 
+        /* put your code here.  Return one of the
+           following: */
+ 
+        return (-n); /* chunk had an error */
+        return (0); /* did not recognize */
+        return (n); /* success */
+     }
+ 
+ (You can give your function another name that you like instead of
+ "read_chunk_callback")
+ 
+ To inform libpng about your function, use
+ 
+     png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
+         read_chunk_callback);
+ 
+ This names not only the callback function, but also a user pointer that
+ you can retrieve with
+ 
+     png_get_user_chunk_ptr(png_ptr);
+ 
+ At this point, you can set up a callback function that will be
+ called after each row has been read, which you can use to control
+ a progress meter or the like.  It's demonstrated in pngtest.c.
+ You must supply a function
+ 
+     void read_row_callback(png_ptr ptr, png_uint_32 row,
+        int pass);
+     {
+       /* put your code here */
+     }
+ 
+ (You can give it another name that you like instead of "read_row_callback")
+ 
+ To inform libpng about your function, use
+ 
+     png_set_read_status_fn(png_ptr, read_row_callback);
+ 
+ Unknown-chunk handling
+ 
+ Now you get to set the way the library processes unknown chunks in the
+ input PNG stream. Both known and unknown chunks will be read.  Normal
+ behavior is that known chunks will be parsed into information in
+ various info_ptr members; unknown chunks will be discarded. To change
+ this, you can call:
+ 
+     png_set_keep_unknown_chunks(png_ptr, info_ptr, keep,
+         chunk_list, num_chunks);
+     keep       - 0: do not keep
+                  1: keep only if safe-to-copy
+                  2: keep even if unsafe-to-copy
+     chunk_list - list of chunks affected (a byte string,
+                  five bytes per chunk, NULL or '\0' if
+                  num_chunks is 0)
+     num_chunks - number of chunks affected; if 0, all
+                  unknown chunks are affected
+ 
+ Unknown chunks declared in this way will be saved as raw data onto a
+ list of png_unknown_chunk structures.  If a chunk that is normally
+ known to libpng is named in the list, it will be handled as unknown,
+ according to the "keep" directive.  If a chunk is named in successive
+ instances of png_set_keep_unknown_chunks(), the final instance will
+ take precedence.
+ 
+ The high-level read interface
+ 
+ At this point there are two ways to proceed; through the high-level
+ read interface, or through a sequence of low-level read operations.
+ You can use the high-level interface if (a) you are willing to read
+ the entire image into memory, and (b) the input transformations
+ you want to do are limited to the following set:
+ 
+     PNG_TRANSFORM_IDENTITY      No transformation
+     PNG_TRANSFORM_STRIP_16      Strip 16-bit samples to
+                                 8 bits
+     PNG_TRANSFORM_STRIP_ALPHA   Discard the alpha channel
+     PNG_TRANSFORM_PACKING       Expand 1, 2 and 4-bit
+                                 samples to bytes
+     PNG_TRANSFORM_PACKSWAP      Change order of packed
+                                 pixels to LSB first
+     PNG_TRANSFORM_EXPAND        Perform set_expand()
+     PNG_TRANSFORM_INVERT_MONO   Invert monochrome images
+     PNG_TRANSFORM_SHIFT         Normalize pixels to the
+                                 sBIT depth
+     PNG_TRANSFORM_BGR           Flip RGB to BGR, RGBA
+                                 to BGRA
+     PNG_TRANSFORM_SWAP_ALPHA    Flip RGBA to ARGB or GA
+                                 to AG
+     PNG_TRANSFORM_INVERT_ALPHA  Change alpha from opacity
+                                 to transparency
+     PNG_TRANSFORM_SWAP_ENDIAN   Byte-swap 16-bit samples
+ 
+ (This excludes setting a background color, doing gamma transformation,
+ dithering, and setting filler.)  If this is the case, simply do this:
+ 
+     png_read_png(png_ptr, info_ptr, png_transforms, NULL)
+ 
+ where png_transforms is an integer containing the logical OR of
+ some set of transformation flags.  This call is equivalent to png_read_info(),
+ followed the set of transformations indicated by the transform mask,
+ then png_read_image(), and finally png_read_end().
+ 
+ (The final parameter of this call is not yet used.  Someday it might point
+ to transformation parameters required by some future input transform.)
+ 
+ After you have called png_read_png(), you can retrieve the image data
+ with
+ 
+    row_pointers = png_get_rows(png_ptr, info_ptr);
+ 
+ where row_pointers is an array of pointers to the pixel data for each row:
+ 
+    png_bytep row_pointers[height];
+ 
+ If you know your image size and pixel size ahead of time, you can allocate
+ row_pointers prior to calling png_read_png() with
+ 
+    row_pointers = png_malloc(png_ptr,
+       height*sizeof(png_bytep));
+    for (int i=0; i<height, i++)
+       row_pointers[i]=png_malloc(png_ptr,
+          width*pixel_size);
+    png_set_rows(png_ptr, info_ptr, &row_pointers);
+ 
+ Alternatively you could allocate your image in one big block and define
+ row_pointers[i] to point into the proper places in your block.
+ 
+ If you use png_set_rows(), the application is responsible for freeing
+ row_pointers (and row_pointers[i], if they were separately allocated).
+ 
+ If you don't allocate row_pointers ahead of time, png_read_png() will
+ do it, and it'll be free'ed when you call png_destroy_*().
+ 
+ The low-level read interface
+ 
+ If you are going the low-level route, you are now ready to read all
+ the file information up to the actual image data.  You do this with a
+ call to png_read_info().
+ 
+     png_read_info(png_ptr, info_ptr);
+ 
+ This will process all chunks up to but not including the image data.
+ 
+ Querying the info structure
+ 
+ Functions are used to get the information from the info_ptr once it
+ has been read.  Note that these fields may not be completely filled
+ in until png_read_end() has read the chunk data following the image.
+ 
+     png_get_IHDR(png_ptr, info_ptr, &width, &height,
+        &bit_depth, &color_type, &interlace_type,
+        &compression_type, &filter_method);
+ 
+     width          - holds the width of the image
+                      in pixels (up to 2^31).
+     height         - holds the height of the image
+                      in pixels (up to 2^31).
+     bit_depth      - holds the bit depth of one of the
+                      image channels.  (valid values are
+                      1, 2, 4, 8, 16 and depend also on
+                      the color_type.  See also
+                      significant bits (sBIT) below).
+     color_type     - describes which color/alpha channels
+                          are present.
+                      PNG_COLOR_TYPE_GRAY
+                         (bit depths 1, 2, 4, 8, 16)
+                      PNG_COLOR_TYPE_GRAY_ALPHA
+                         (bit depths 8, 16)
+                      PNG_COLOR_TYPE_PALETTE
+                         (bit depths 1, 2, 4, 8)
+                      PNG_COLOR_TYPE_RGB
+                         (bit_depths 8, 16)
+                      PNG_COLOR_TYPE_RGB_ALPHA
+                         (bit_depths 8, 16)
+ 
+                      PNG_COLOR_MASK_PALETTE
+                      PNG_COLOR_MASK_COLOR
+                      PNG_COLOR_MASK_ALPHA
+ 
+     filter_method  - (must be PNG_FILTER_TYPE_BASE
+                      for PNG 1.0, and can also be
+                      PNG_INTRAPIXEL_DIFFERENCING if
+                      the PNG datastream is embedded in
+                      a MNG-1.0 datastream)
+     compression_type - (must be PNG_COMPRESSION_TYPE_BASE
+                      for PNG 1.0)
+     interlace_type - (PNG_INTERLACE_NONE or
+                      PNG_INTERLACE_ADAM7)
+     Any or all of interlace_type, compression_type, of
+     filter_method can be NULL if you are
+     not interested in their values.
+ 
+     channels = png_get_channels(png_ptr, info_ptr);
+     channels       - number of channels of info for the
+                      color type (valid values are 1 (GRAY,
+                      PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
+                      4 (RGB_ALPHA or RGB + filler byte))
+     rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+     rowbytes       - number of bytes needed to hold a row
+ 
+     signature = png_get_signature(png_ptr, info_ptr);
+     signature      - holds the signature read from the
+                      file (if any).  The data is kept in
+                      the same offset it would be if the
+                      whole signature were read (i.e. if an
+                      application had already read in 4
+                      bytes of signature before starting
+                      libpng, the remaining 4 bytes would
+                      be in signature[4] through signature[7]
+                      (see png_set_sig_bytes())).
+ 
+ 
+     width            = png_get_image_width(png_ptr,
+                          info_ptr);
+     height           = png_get_image_height(png_ptr,
+                          info_ptr);
+     bit_depth        = png_get_bit_depth(png_ptr,
+                          info_ptr);
+     color_type       = png_get_color_type(png_ptr,
+                          info_ptr);
+     filter_method    = png_get_filter_type(png_ptr,
+                          info_ptr);
+     compression_type = png_get_compression_type(png_ptr,
+                          info_ptr);
+     interlace_type   = png_get_interlace_type(png_ptr,
+                          info_ptr);
+ 
+ 
+ These are also important, but their validity depends on whether the chunk
+ has been read.  The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
+ png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
+ data has been read, or zero if it is missing.  The parameters to the
+ png_get_<chunk> are set directly if they are simple data types, or a pointer
+ into the info_ptr is returned for any complex types.
+ 
+     png_get_PLTE(png_ptr, info_ptr, &palette,
+                      &num_palette);
+     palette        - the palette for the file
+                      (array of png_color)
+     num_palette    - number of entries in the palette
+ 
+     png_get_gAMA(png_ptr, info_ptr, &gamma);
+     gamma          - the gamma the file is written
+                      at (PNG_INFO_gAMA)
+ 
+     png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
+     srgb_intent    - the rendering intent (PNG_INFO_sRGB)
+                      The presence of the sRGB chunk
+                      means that the pixel data is in the
+                      sRGB color space.  This chunk also
+                      implies specific values of gAMA and
+                      cHRM.
+ 
+     png_get_iCCP(png_ptr, info_ptr, &name,
+        &compression_type, &profile, &proflen);
+     name            - The profile name.
+     compression     - The compression type; always
+                       PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
+                       You may give NULL to this argument to
+                       ignore it.
+     profile         - International Color Consortium color
+                       profile data. May contain NULs.
+     proflen         - length of profile data in bytes.
+ 
+     png_get_sBIT(png_ptr, info_ptr, &sig_bit);
+     sig_bit        - the number of significant bits for
+                      (PNG_INFO_sBIT) each of the gray,
+                      red, green, and blue channels,
+                      whichever are appropriate for the
+                      given color type (png_color_16)
+ 
+     png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans,
+                      &trans_values);
+     trans          - array of transparent entries for
+                      palette (PNG_INFO_tRNS)
+     trans_values   - graylevel or color sample values of
+                      the single transparent color for
+                      non-paletted images (PNG_INFO_tRNS)
+     num_trans      - number of transparent entries
+                      (PNG_INFO_tRNS)
+ 
+     png_get_hIST(png_ptr, info_ptr, &hist);
+                      (PNG_INFO_hIST)
+     hist           - histogram of palette (array of
+                      png_uint_16)
+ 
+     png_get_tIME(png_ptr, info_ptr, &mod_time);
+     mod_time       - time image was last modified
+                     (PNG_VALID_tIME)
+ 
+     png_get_bKGD(png_ptr, info_ptr, &background);
+     background     - background color (PNG_VALID_bKGD)
+                      valid 16-bit red, green and blue
+                      values, regardless of color_type
+ 
+     num_comments   = png_get_text(png_ptr, info_ptr,
+                      &text_ptr, &num_text);
+     num_comments   - number of comments
+     text_ptr       - array of png_text holding image
+                      comments
+     text_ptr[i].compression - type of compression used
+                  on "text" PNG_TEXT_COMPRESSION_NONE
+                            PNG_TEXT_COMPRESSION_zTXt
+                            PNG_ITXT_COMPRESSION_NONE
+                            PNG_ITXT_COMPRESSION_zTXt
+     text_ptr[i].key   - keyword for comment.  Must contain
+                          1-79 characters.
+     text_ptr[i].text  - text comments for current
+                          keyword.  Can be empty.
+     text_ptr[i].text_length - length of text string,
+                  after decompression, 0 for iTXt
+     text_ptr[i].itxt_length - length of itxt string,
+                  after decompression, 0 for tEXt/zTXt
+     text_ptr[i].lang  - language of comment (empty
+                          string for unknown).
+     text_ptr[i].lang_key  - keyword in UTF-8
+                          (empty string for unknown).
+     num_text       - number of comments (same as
+                      num_comments; you can put NULL here
+                      to avoid the duplication)
+     Note while png_set_text() will accept text, language,
+     and translated keywords that can be NULL pointers, the
+     structure returned by png_get_text will always contain
+     regular zero-terminated C strings.  They might be
+     empty strings but they will never be NULL pointers.
+ 
+     num_spalettes = png_get_sPLT(png_ptr, info_ptr,
+        &palette_ptr);
+     palette_ptr    - array of palette structures holding
+                      contents of one or more sPLT chunks
+                      read.
+     num_spalettes  - number of sPLT chunks read.
+ 
+     png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
+        &unit_type);
+     offset_x       - positive offset from the left edge
+                      of the screen
+     offset_y       - positive offset from the top edge
+                      of the screen
+     unit_type      - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
+ 
+     png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
+        &unit_type);
+     res_x          - pixels/unit physical resolution in
+                      x direction
+     res_y          - pixels/unit physical resolution in
+                      x direction
+     unit_type      - PNG_RESOLUTION_UNKNOWN,
+                      PNG_RESOLUTION_METER
+ 
+     png_get_sCAL(png_ptr, info_ptr, &unit, &width,
+        &height)
+     unit        - physical scale units (an integer)
+     width       - width of a pixel in physical scale units
+     height      - height of a pixel in physical scale units
+                  (width and height are doubles)
+ 
+     png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
+        &height)
+     unit        - physical scale units (an integer)
+     width       - width of a pixel in physical scale units
+     height      - height of a pixel in physical scale units
+                  (width and height are strings like "2.54")
+ 
+     num_unknown_chunks = png_get_unknown_chunks(png_ptr,
+        info_ptr, &unknowns)
+     unknowns          - array of png_unknown_chunk
+                         structures holding unknown chunks
+     unknowns[i].name  - name of unknown chunk
+     unknowns[i].data  - data of unknown chunk
+     unknowns[i].size  - size of unknown chunk's data
+     unknowns[i].location - position of chunk in file
+ 
+     The value of "i" corresponds to the order in which the
+     chunks were read from the PNG file or inserted with the
+     png_set_unknown_chunks() function.
+ 
+ The data from the pHYs chunk can be retrieved in several convenient
+ forms:
+ 
+     res_x = png_get_x_pixels_per_meter(png_ptr,
+        info_ptr)
+     res_y = png_get_y_pixels_per_meter(png_ptr,
+        info_ptr)
+     res_x_and_y = png_get_pixels_per_meter(png_ptr,
+        info_ptr)
+     res_x = png_get_x_pixels_per_inch(png_ptr,
+        info_ptr)
+     res_y = png_get_y_pixels_per_inch(png_ptr,
+        info_ptr)
+     res_x_and_y = png_get_pixels_per_inch(png_ptr,
+        info_ptr)
+     aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
+        info_ptr)
+ 
+    (Each of these returns 0 [signifying "unknown"] if
+        the data is not present or if res_x is 0;
+        res_x_and_y is 0 if res_x != res_y)
+ 
+ The data from the oFFs chunk can be retrieved in several convenient
+ forms:
+ 
+     x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
+     y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
+     x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
+     y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
+ 
+    (Each of these returns 0 [signifying "unknown" if both
+        x and y are 0] if the data is not present or if the
+        chunk is present but the unit is the pixel)
+ 
+ For more information, see the png_info definition in png.h and the
+ PNG specification for chunk contents.  Be careful with trusting
+ rowbytes, as some of the transformations could increase the space
+ needed to hold a row (expand, filler, gray_to_rgb, etc.).
+ See png_read_update_info(), below.
+ 
+ A quick word about text_ptr and num_text.  PNG stores comments in
+ keyword/text pairs, one pair per chunk, with no limit on the number
+ of text chunks, and a 2^31 byte limit on their size.  While there are
+ suggested keywords, there is no requirement to restrict the use to these
+ strings.  It is strongly suggested that keywords and text be sensible
+ to humans (that's the point), so don't use abbreviations.  Non-printing
+ symbols are not allowed.  See the PNG specification for more details.
+ There is also no requirement to have text after the keyword.
+ 
+ Keywords should be limited to 79 Latin-1 characters without leading or
+ trailing spaces, but non-consecutive spaces are allowed within the
+ keyword.  It is possible to have the same keyword any number of times.
+ The text_ptr is an array of png_text structures, each holding a
+ pointer to a language string, a pointer to a keyword and a pointer to
+ a text string.  The text string, language code, and translated
+ keyword may be empty or NULL pointers.  The keyword/text
+ pairs are put into the array in the order that they are received.
+ However, some or all of the text chunks may be after the image, so, to
+ make sure you have read all the text chunks, don't mess with these
+ until after you read the stuff after the image.  This will be
+ mentioned again below in the discussion that goes with png_read_end().
+ 
+ Input transformations
+ 
+ After you've read the header information, you can set up the library
+ to handle any special transformations of the image data.  The various
+ ways to transform the data will be described in the order that they
+ should occur.  This is important, as some of these change the color
+ type and/or bit depth of the data, and some others only work on
+ certain color types and bit depths.  Even though each transformation
+ checks to see if it has data that it can do something with, you should
+ make sure to only enable a transformation if it will be valid for the
+ data.  For example, don't swap red and blue on grayscale data.
+ 
+ The colors used for the background and transparency values should be
+ supplied in the same format/depth as the current image data.  They
+ are stored in the same format/depth as the image data in a bKGD or tRNS
+ chunk, so this is what libpng expects for this data.  The colors are
+ transformed to keep in sync with the image data when an application
+ calls the png_read_update_info() routine (see below).
+ 
+ Data will be decoded into the supplied row buffers packed into bytes
+ unless the library has been told to transform it into another format.
+ For example, 4 bit/pixel paletted or grayscale data will be returned
+ 2 pixels/byte with the leftmost pixel in the high-order bits of the
+ byte, unless png_set_packing() is called.  8-bit RGB data will be stored
+ in RGB RGB RGB format unless png_set_filler() is called to insert filler
+ bytes, either before or after each RGB triplet.  16-bit RGB data will
+ be returned RRGGBB RRGGBB, with the most significant byte of the color
+ value first, unless png_set_strip_16() is called to transform it to
+ regular RGB RGB triplets, or png_set_filler() is called to insert
+ filler bytes, either before or after each RRGGBB triplet.  Similarly,
+ 8-bit or 16-bit grayscale data can be modified with png_set_filler()
+ or png_set_strip_16().
+ 
+ The following code transforms grayscale images of less than 8 to 8 bits,
+ changes paletted images to RGB, and adds a full alpha channel if there is
+ transparency information in a tRNS chunk.  This is most useful on
+ grayscale images with bit depths of 2 or 4 or if there is a multiple-image
+ viewing application that wishes to treat all images in the same way.
+ 
+     if (color_type == PNG_COLOR_TYPE_PALETTE)
+         png_set_palette_to_rgb(png_ptr);
+ 
+     if (color_type == PNG_COLOR_TYPE_GRAY &&
+         bit_depth < 8) png_set_gray_1_2_4_to_8(png_ptr);
+ 
+     if (png_get_valid(png_ptr, info_ptr,
+         PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
+ 
+ These three functions are actually aliases for png_set_expand(), added
+ in libpng version 1.0.4, with the function names expanded to improve code
+ readability.  In some future version they may actually do different
+ things.
+ 
+ PNG can have files with 16 bits per channel.  If you only can handle
+ 8 bits per channel, this will strip the pixels down to 8 bit.
+ 
+     if (bit_depth == 16)
+         png_set_strip_16(png_ptr);
+ 
+ If, for some reason, you don't need the alpha channel on an image,
+ and you want to remove it rather than combining it with the background
+ (but the image author certainly had in mind that you *would* combine
+ it with the background, so that's what you should probably do):
+ 
+     if (color_type & PNG_COLOR_MASK_ALPHA)
+         png_set_strip_alpha(png_ptr);
+ 
+ In PNG files, the alpha channel in an image
+ is the level of opacity.  If you need the alpha channel in an image to
+ be the level of transparency instead of opacity, you can invert the
+ alpha channel (or the tRNS chunk data) after it's read, so that 0 is
+ fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
+ images) is fully transparent, with
+ 
+     png_set_invert_alpha(png_ptr);
+ 
+ PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
+ they can, resulting in, for example, 8 pixels per byte for 1 bit
+ files.  This code expands to 1 pixel per byte without changing the
+ values of the pixels:
+ 
+     if (bit_depth < 8)
+         png_set_packing(png_ptr);
+ 
+ PNG files have possible bit depths of 1, 2, 4, 8, and 16.  All pixels
+ stored in a PNG image have been "scaled" or "shifted" up to the next
+ higher possible bit depth (e.g. from 5 bits/sample in the range [0,31] to
+ 8 bits/sample in the range [0, 255]).  However, it is also possible to
+ convert the PNG pixel data back to the original bit depth of the image.
+ This call reduces the pixels back down to the original bit depth:
+ 
+     png_color_8p sig_bit;
+ 
+     if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
+         png_set_shift(png_ptr, sig_bit);
+ 
+ PNG files store 3-color pixels in red, green, blue order.  This code
+ changes the storage of the pixels to blue, green, red:
+ 
+     if (color_type == PNG_COLOR_TYPE_RGB ||
+         color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+         png_set_bgr(png_ptr);
+ 
+ PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
+ into 4 or 8 bytes for windowing systems that need them in this format:
+ 
+     if (color_type == PNG_COLOR_TYPE_RGB)
+         png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
+ 
+ where "filler" is the 8 or 16-bit number to fill with, and the location is
+ either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
+ you want the filler before the RGB or after.  This transformation
+ does not affect images that already have full alpha channels.  To add an
+ opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
+ will generate RGBA pixels.
+ 
+ If you are reading an image with an alpha channel, and you need the
+ data as ARGB instead of the normal PNG format RGBA:
+ 
+     if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+         png_set_swap_alpha(png_ptr);
+ 
+ For some uses, you may want a grayscale image to be represented as
+ RGB.  This code will do that conversion:
+ 
+     if (color_type == PNG_COLOR_TYPE_GRAY ||
+         color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+           png_set_gray_to_rgb(png_ptr);
+ 
+ Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
+ with alpha.
+ 
+     if (color_type == PNG_COLOR_TYPE_RGB ||
+         color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+           png_set_rgb_to_gray_fixed(png_ptr, error_action,
+              int red_weight, int green_weight);
+ 
+     error_action = 1: silently do the conversion
+     error_action = 2: issue a warning if the original
+                       image has any pixel where
+                       red != green or red != blue
+     error_action = 3: issue an error and abort the
+                       conversion if the original
+                       image has any pixel where
+                       red != green or red != blue
+ 
+     red_weight:       weight of red component times 100000
+     green_weight:     weight of green component times 100000
+                       If either weight is negative, default
+                       weights (21268, 71514) are used.
+ 
+ If you have set error_action = 1 or 2, you can
+ later check whether the image really was gray, after processing
+ the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
+ It will return a png_byte that is zero if the image was gray or
+ 1 if there were any non-gray pixels.  bKGD and sBIT data
+ will be silently converted to grayscale, using the green channel
+ data, regardless of the error_action setting.
+ 
+ With red_weight+green_weight<=100000,
+ the normalized graylevel is computed:
+ 
+     int rw = red_weight * 65536;
+     int gw = green_weight * 65536;
+     int bw = 65536 - (rw + gw);
+     gray = (rw*red + gw*green + bw*blue)/65536;
+ 
+ The default values approximate those recommended in the Charles
+ Poynton's Color FAQ, <http://www.inforamp.net/~poynton/>
+ Copyright (c) 1998-01-04 Charles Poynton poynton at inforamp.net
+ 
+     Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
+ 
+ Libpng approximates this with
+ 
+     Y = 0.21268 * R    + 0.7151 * G    + 0.07217 * B
+ 
+ which can be expressed with integers as
+ 
+     Y = (6969 * R + 23434 * G + 2365 * B)/32768
+ 
+ The calculation is done in a linear colorspace, if the image gamma
+ is known.
+ 
+ If you have a grayscale and you are using png_set_expand_depth(),
+ png_set_expand(), or png_set_gray_to_rgb to change to truecolor or to
+ a higher bit-depth, you must either supply the background color as a gray
+ value at the original file bit-depth (need_expand = 1) or else supply the
+ background color as an RGB triplet at the final, expanded bit depth
+ (need_expand = 0).  Similarly, if you are reading a paletted image, you
+ must either supply the background color as a palette index (need_expand = 1)
+ or as an RGB triplet that may or may not be in the palette (need_expand = 0).
+ 
+     png_color_16 my_background;
+     png_color_16p image_background;
+ 
+     if (png_get_bKGD(png_ptr, info_ptr, &image_background))
+         png_set_background(png_ptr, image_background,
+           PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
+     else
+         png_set_background(png_ptr, &my_background,
+           PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
+ 
+ The png_set_background() function tells libpng to composite images
+ with alpha or simple transparency against the supplied background
+ color.  If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
+ you may use this color, or supply another color more suitable for
+ the current display (e.g., the background color from a web page).  You
+ need to tell libpng whether the color is in the gamma space of the
+ display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
+ (PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
+ that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
+ know why anyone would use this, but it's here).
+ 
+ To properly display PNG images on any kind of system, the application needs
+ to know what the display gamma is.  Ideally, the user will know this, and
+ the application will allow them to set it.  One method of allowing the user
+ to set the display gamma separately for each system is to check for a
+ SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be
+ correctly set.
+ 
+ Note that display_gamma is the overall gamma correction required to produce
+ pleasing results, which depends on the lighting conditions in the surrounding
+ environment.  In a dim or brightly lit room, no compensation other than
+ the physical gamma exponent of the monitor is needed, while in a dark room
+ a slightly smaller exponent is better.
+ 
+    double gamma, screen_gamma;
+ 
+    if (/* We have a user-defined screen
+        gamma value */)
+    {
+       screen_gamma = user_defined_screen_gamma;
+    }
+    /* One way that applications can share the same
+       screen gamma value */
+    else if ((gamma_str = getenv("SCREEN_GAMMA"))
+       != NULL)
+    {
+       screen_gamma = (double)atof(gamma_str);
+    }
+    /* If we don't have another value */
+    else
+    {
+       screen_gamma = 2.2; /* A good guess for a
+            PC monitor in a bright office or a dim room */
+       screen_gamma = 2.0; /* A good guess for a
+            PC monitor in a dark room */
+       screen_gamma = 1.7 or 1.0;  /* A good
+            guess for Mac systems */
+    }
+ 
+ The png_set_gamma() function handles gamma transformations of the data.
+ Pass both the file gamma and the current screen_gamma.  If the file does
+ not have a gamma value, you can pass one anyway if you have an idea what
+ it is (usually 0.45455 is a good guess for GIF images on PCs).  Note
+ that file gammas are inverted from screen gammas.  See the discussions
+ on gamma in the PNG specification for an excellent description of what
+ gamma is, and why all applications should support it.  It is strongly
+ recommended that PNG viewers support gamma correction.
+ 
+    if (png_get_gAMA(png_ptr, info_ptr, &gamma))
+       png_set_gamma(png_ptr, screen_gamma, gamma);
+    else
+       png_set_gamma(png_ptr, screen_gamma, 0.45455);
+ 
+ If you need to reduce an RGB file to a paletted file, or if a paletted
+ file has more entries then will fit on your screen, png_set_dither()
+ will do that.  Note that this is a simple match dither that merely
+ finds the closest color available.  This should work fairly well with
+ optimized palettes, and fairly badly with linear color cubes.  If you
+ pass a palette that is larger then maximum_colors, the file will
+ reduce the number of colors in the palette so it will fit into
+ maximum_colors.  If there is a histogram, it will use it to make
+ more intelligent choices when reducing the palette.  If there is no
+ histogram, it may not do as good a job.
+ 
+    if (color_type & PNG_COLOR_MASK_COLOR)
+    {
+       if (png_get_valid(png_ptr, info_ptr,
+          PNG_INFO_PLTE))
+       {
+          png_uint_16p histogram = NULL;
+ 
+          png_get_hIST(png_ptr, info_ptr,
+             &histogram);
+          png_set_dither(png_ptr, palette, num_palette,
+             max_screen_colors, histogram, 1);
+       }
+       else
+       {
+          png_color std_color_cube[MAX_SCREEN_COLORS] =
+             { ... colors ... };
+ 
+          png_set_dither(png_ptr, std_color_cube,
+             MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
+             NULL,0);
+       }
+    }
+ 
+ PNG files describe monochrome as black being zero and white being one.
+ The following code will reverse this (make black be one and white be
+ zero):
+ 
+    if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
+       png_set_invert_mono(png_ptr);
+ 
+ This function can also be used to invert grayscale and gray-alpha images:
+ 
+    if (color_type == PNG_COLOR_TYPE_GRAY ||
+         color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+       png_set_invert_mono(png_ptr);
+ 
+ PNG files store 16 bit pixels in network byte order (big-endian,
+ ie. most significant bits first).  This code changes the storage to the
+ other way (little-endian, i.e. least significant bits first, the
+ way PCs store them):
+ 
+     if (bit_depth == 16)
+         png_set_swap(png_ptr);
+ 
+ If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
+ need to change the order the pixels are packed into bytes, you can use:
+ 
+     if (bit_depth < 8)
+        png_set_packswap(png_ptr);
+ 
+ Finally, you can write your own transformation function if none of
+ the existing ones meets your needs.  This is done by setting a callback
+ with
+ 
+     png_set_read_user_transform_fn(png_ptr,
+        read_transform_fn);
+ 
+ You must supply the function
+ 
+     void read_transform_fn(png_ptr ptr, row_info_ptr
+        row_info, png_bytep data)
+ 
+ See pngtest.c for a working example.  Your function will be called
+ after all of the other transformations have been processed.
+ 
+ You can also set up a pointer to a user structure for use by your
+ callback function, and you can inform libpng that your transform
+ function will change the number of channels or bit depth with the
+ function
+ 
+     png_set_user_transform_info(png_ptr, user_ptr,
+        user_depth, user_channels);
+ 
+ The user's application, not libpng, is responsible for allocating and
+ freeing any memory required for the user structure.
+ 
+ You can retrieve the pointer via the function
+ png_get_user_transform_ptr().  For example:
+ 
+     voidp read_user_transform_ptr =
+        png_get_user_transform_ptr(png_ptr);
+ 
+ The last thing to handle is interlacing; this is covered in detail below,
+ but you must call the function here if you want libpng to handle expansion
+ of the interlaced image.
+ 
+     number_of_passes = png_set_interlace_handling(png_ptr);
+ 
+ After setting the transformations, libpng can update your png_info
+ structure to reflect any transformations you've requested with this
+ call.  This is most useful to update the info structure's rowbytes
+ field so you can use it to allocate your image memory.  This function
+ will also update your palette with the correct screen_gamma and
+ background if these have been given with the calls above.
+ 
+     png_read_update_info(png_ptr, info_ptr);
+ 
+ After you call png_read_update_info(), you can allocate any
+ memory you need to hold the image.  The row data is simply
+ raw byte data for all forms of images.  As the actual allocation
+ varies among applications, no example will be given.  If you
+ are allocating one large chunk, you will need to build an
+ array of pointers to each row, as it will be needed for some
+ of the functions below.
+ 
+ Reading image data
+ 
+ After you've allocated memory, you can read the image data.
+ The simplest way to do this is in one function call.  If you are
+ allocating enough memory to hold the whole image, you can just
+ call png_read_image() and libpng will read in all the image data
+ and put it in the memory area supplied.  You will need to pass in
+ an array of pointers to each row.
+ 
+ This function automatically handles interlacing, so you don't need
+ to call png_set_interlace_handling() or call this function multiple
+ times, or any of that other stuff necessary with png_read_rows().
+ 
+    png_read_image(png_ptr, row_pointers);
+ 
+ where row_pointers is:
+ 
+    png_bytep row_pointers[height];
+ 
+ You can point to void or char or whatever you use for pixels.
+ 
+ If you don't want to read in the whole image at once, you can
+ use png_read_rows() instead.  If there is no interlacing (check
+ interlace_type == PNG_INTERLACE_NONE), this is simple:
+ 
+     png_read_rows(png_ptr, row_pointers, NULL,
+        number_of_rows);
+ 
+ where row_pointers is the same as in the png_read_image() call.
+ 
+ If you are doing this just one row at a time, you can do this with
+ a single row_pointer instead of an array of row_pointers:
+ 
+     png_bytep row_pointer = row;
+     png_read_row(png_ptr, row_pointer, NULL);
+ 
+ If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
+ get somewhat harder.  The only current (PNG Specification version 1.2)
+ interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7)
+ is a somewhat complicated 2D interlace scheme, known as Adam7, that
+ breaks down an image into seven smaller images of varying size, based
+ on an 8x8 grid.
+ 
+ libpng can fill out those images or it can give them to you "as is".
+ If you want them filled out, there are two ways to do that.  The one
+ mentioned in the PNG specification is to expand each pixel to cover
+ those pixels that have not been read yet (the "rectangle" method).
+ This results in a blocky image for the first pass, which gradually
+ smooths out as more pixels are read.  The other method is the "sparkle"
+ method, where pixels are drawn only in their final locations, with the
+ rest of the image remaining whatever colors they were initialized to
+ before the start of the read.  The first method usually looks better,
+ but tends to be slower, as there are more pixels to put in the rows.
+ 
+ If you don't want libpng to handle the interlacing details, just call
+ png_read_rows() seven times to read in all seven images.  Each of the
+ images is a valid image by itself, or they can all be combined on an
+ 8x8 grid to form a single image (although if you intend to combine them
+ you would be far better off using the libpng interlace handling).
+ 
+ The first pass will return an image 1/8 as wide as the entire image
+ (every 8th column starting in column 0) and 1/8 as high as the original
+ (every 8th row starting in row 0), the second will be 1/8 as wide
+ (starting in column 4) and 1/8 as high (also starting in row 0).  The
+ third pass will be 1/4 as wide (every 4th pixel starting in column 0) and
+ 1/8 as high (every 8th row starting in row 4), and the fourth pass will
+ be 1/4 as wide and 1/4 as high (every 4th column starting in column 2,
+ and every 4th row starting in row 0).  The fifth pass will return an
+ image 1/2 as wide, and 1/4 as high (starting at column 0 and row 2),
+ while the sixth pass will be 1/2 as wide and 1/2 as high as the original
+ (starting in column 1 and row 0).  The seventh and final pass will be as
+ wide as the original, and 1/2 as high, containing all of the odd
+ numbered scanlines.  Phew!
+ 
+ If you want libpng to expand the images, call this before calling
+ png_start_read_image() or png_read_update_info():
+ 
+     if (interlace_type == PNG_INTERLACE_ADAM7)
+         number_of_passes
+            = png_set_interlace_handling(png_ptr);
+ 
+ This will return the number of passes needed.  Currently, this
+ is seven, but may change if another interlace type is added.
+ This function can be called even if the file is not interlaced,
+ where it will return one pass.
+ 
+ If you are not going to display the image after each pass, but are
+ going to wait until the entire image is read in, use the sparkle
+ effect.  This effect is faster and the end result of either method
+ is exactly the same.  If you are planning on displaying the image
+ after each pass, the "rectangle" effect is generally considered the
+ better looking one.
+ 
+ If you only want the "sparkle" effect, just call png_read_rows() as
+ normal, with the third parameter NULL.  Make sure you make pass over
+ the image number_of_passes times, and you don't change the data in the
+ rows between calls.  You can change the locations of the data, just
+ not the data.  Each pass only writes the pixels appropriate for that
+ pass, and assumes the data from previous passes is still valid.
+ 
+     png_read_rows(png_ptr, row_pointers, NULL,
+        number_of_rows);
+ 
+ If you only want the first effect (the rectangles), do the same as
+ before except pass the row buffer in the third parameter, and leave
+ the second parameter NULL.
+ 
+     png_read_rows(png_ptr, NULL, row_pointers,
+        number_of_rows);
+ 
+ Finishing a sequential read
+ 
+ After you are finished reading the image through either the high- or
+ low-level interfaces, you can finish reading the file.  If you are
+ interested in comments or time, which may be stored either before or
+ after the image data, you should pass the separate png_info struct if
+ you want to keep the comments from before and after the image
+ separate.  If you are not interested, you can pass NULL.
+ 
+    png_read_end(png_ptr, end_info);
+ 
+ When you are done, you can free all memory allocated by libpng like this:
+ 
+    png_destroy_read_struct(&png_ptr, &info_ptr,
+        &end_info);
+ 
+ It is also possible to individually free the info_ptr members that
+ point to libpng-allocated storage with the following function:
+ 
+     png_free_data(png_ptr, info_ptr, mask, seq)
+     mask - identifies data to be freed, a mask
+            containing the logical OR of one or
+            more of
+              PNG_FREE_PLTE, PNG_FREE_TRNS,
+              PNG_FREE_HIST, PNG_FREE_ICCP,
+              PNG_FREE_PCAL, PNG_FREE_ROWS,
+              PNG_FREE_SCAL, PNG_FREE_SPLT,
+              PNG_FREE_TEXT, PNG_FREE_UNKN,
+            or simply PNG_FREE_ALL
+     seq  - sequence number of item to be freed
+            (-1 for all items)
+ 
+ This function may be safely called when the relevant storage has
+ already been freed, or has not yet been allocated, or was allocated
+ by the user and not by libpng,  and will in those
+ cases do nothing.  The "seq" parameter is ignored if only one item
+ of the selected data type, such as PLTE, is allowed.  If "seq" is not
+ -1, and multiple items are allowed for the data type identified in
+ the mask, such as text or sPLT, only the n'th item in the structure
+ is freed, where n is "seq".
+ 
+ The default behavior is only to free data that was allocated internally
+ by libpng.  This can be changed, so that libpng will not free the data,
+ or so that it will free data that was allocated by the user with png_malloc()
+ or png_zalloc() and passed in via a png_set_*() function, with
+ 
+     png_data_freer(png_ptr, info_ptr, freer, mask)
+     mask   - which data elements are affected
+              same choices as in png_free_data()
+     freer  - one of
+                PNG_DESTROY_WILL_FREE_DATA
+                PNG_SET_WILL_FREE_DATA
+                PNG_USER_WILL_FREE_DATA
+ 
+ This function only affects data that has already been allocated.
+ You can call this function after reading the PNG data but before calling
+ any png_set_*() functions, to control whether the user or the png_set_*()
+ function is responsible for freeing any existing data that might be present,
+ and again after the png_set_*() functions to control whether the user
+ or png_destroy_*() is supposed to free the data.  When the user assumes
+ responsibility for libpng-allocated data, the application must use
+ png_free() to free it, and when the user transfers responsibility to libpng
+ for data that the user has allocated, the user must have used png_malloc()
+ or png_zalloc() to allocate it.
+ 
+ If you allocated your row_pointers in a single block, as suggested above in
+ the description of the high level read interface, you must not transfer
+ responsibility for freeing it to the png_set_rows or png_read_destroy function,
+ because they would also try to free the individual row_pointers[i].
+ 
+ If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
+ separately, do not transfer responsibility for freeing text_ptr to libpng,
+ because when libpng fills a png_text structure it combines these members with
+ the key member, and png_free_data() will free only text_ptr.key.  Similarly,
+ if you transfer responsibility for free'ing text_ptr from libpng to your
+ application, your application must not separately free those members.
+ 
+ The png_free_data() function will turn off the "valid" flag for anything
+ it frees.  If you need to turn the flag off for a chunk that was freed by your
+ application instead of by libpng, you can use
+ 
+     png_set_invalid(png_ptr, info_ptr, mask);
+     mask - identifies the chunks to be made invalid,
+            containing the logical OR of one or
+            more of
+              PNG_INFO_gAMA, PNG_INFO_sBIT,
+              PNG_INFO_cHRM, PNG_INFO_PLTE,
+              PNG_INFO_tRNS, PNG_INFO_bKGD,
+              PNG_INFO_hIST, PNG_INFO_pHYs,
+              PNG_INFO_oFFs, PNG_INFO_tIME,
+              PNG_INFO_pCAL, PNG_INFO_sRGB,
+              PNG_INFO_iCCP, PNG_INFO_sPLT,
+              PNG_INFO_sCAL, PNG_INFO_IDAT
+ 
+ For a more compact example of reading a PNG image, see the file example.c.
+ 
+ Reading PNG files progressively
+ 
+ The progressive reader is slightly different then the non-progressive
+ reader.  Instead of calling png_read_info(), png_read_rows(), and
+ png_read_end(), you make one call to png_process_data(), which calls
+ callbacks when it has the info, a row, or the end of the image.  You
+ set up these callbacks with png_set_progressive_read_fn().  You don't
+ have to worry about the input/output functions of libpng, as you are
+ giving the library the data directly in png_process_data().  I will
+ assume that you have read the section on reading PNG files above,
+ so I will only highlight the differences (although I will show
+ all of the code).
+ 
+ png_structp png_ptr;
+ png_infop info_ptr;
+ 
+  /*  An example code fragment of how you would
+      initialize the progressive reader in your
+      application. */
+  int
+  initialize_png_reader()
+  {
+     png_ptr = png_create_read_struct
+         (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+          user_error_fn, user_warning_fn);
+     if (!png_ptr)
+         return (ERROR);
+     info_ptr = png_create_info_struct(png_ptr);
+     if (!info_ptr)
+     {
+         png_destroy_read_struct(&png_ptr, (png_infopp)NULL,
+            (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+     if (setjmp(png_jmpbuf(png_ptr)))
+     {
+         png_destroy_read_struct(&png_ptr, &info_ptr,
+            (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+     /* This one's new.  You can provide functions
+        to be called when the header info is valid,
+        when each row is completed, and when the image
+        is finished.  If you aren't using all functions,
+        you can specify NULL parameters.  Even when all
+        three functions are NULL, you need to call
+        png_set_progressive_read_fn().  You can use
+        any struct as the user_ptr (cast to a void pointer
+        for the function call), and retrieve the pointer
+        from inside the callbacks using the function
+ 
+           png_get_progressive_ptr(png_ptr);
+ 
+        which will return a void pointer, which you have
+        to cast appropriately.
+      */
+     png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
+         info_callback, row_callback, end_callback);
+ 
+     return 0;
+  }
+ 
+  /* A code fragment that you call as you receive blocks
+    of data */
+  int
+  process_data(png_bytep buffer, png_uint_32 length)
+  {
+     if (setjmp(png_jmpbuf(png_ptr)))
+     {
+         png_destroy_read_struct(&png_ptr, &info_ptr,
+            (png_infopp)NULL);
+         return (ERROR);
+     }
+ 
+     /* This one's new also.  Simply give it a chunk
+        of data from the file stream (in order, of
+        course).  On machines with segmented memory
+        models machines, don't give it any more than
+        64K.  The library seems to run fine with sizes
+        of 4K. Although you can give it much less if
+        necessary (I assume you can give it chunks of
+        1 byte, I haven't tried less then 256 bytes
+        yet).  When this function returns, you may
+        want to display any rows that were generated
+        in the row callback if you don't already do
+        so there.
+      */
+     png_process_data(png_ptr, info_ptr, buffer, length);
+     return 0;
+  }
+ 
+  /* This function is called (as set by
+     png_set_progressive_read_fn() above) when enough data
+     has been supplied so all of the header has been
+     read.
+  */
+  void
+  info_callback(png_structp png_ptr, png_infop info)
+  {
+     /* Do any setup here, including setting any of
+        the transformations mentioned in the Reading
+        PNG files section.  For now, you _must_ call
+        either png_start_read_image() or
+        png_read_update_info() after all the
+        transformations are set (even if you don't set
+        any).  You may start getting rows before
+        png_process_data() returns, so this is your
+        last chance to prepare for that.
+      */
+  }
+ 
+  /* This function is called when each row of image
+     data is complete */
+  void
+  row_callback(png_structp png_ptr, png_bytep new_row,
+     png_uint_32 row_num, int pass)
+  {
+     /* If the image is interlaced, and you turned
+        on the interlace handler, this function will
+        be called for every row in every pass.  Some
+        of these rows will not be changed from the
+        previous pass.  When the row is not changed,
+        the new_row variable will be NULL.  The rows
+        and passes are called in order, so you don't
+        really need the row_num and pass, but I'm
+        supplying them because it may make your life
+        easier.
+ 
+        For the non-NULL rows of interlaced images,
+        you must call png_progressive_combine_row()
+        passing in the row and the old row.  You can
+        call this function for NULL rows (it will just
+        return) and for non-interlaced images (it just
+        does the memcpy for you) if it will make the
+        code easier.  Thus, you can just do this for
+        all cases:
+      */
+ 
+         png_progressive_combine_row(png_ptr, old_row,
+           new_row);
+ 
+     /* where old_row is what was displayed for
+        previously for the row.  Note that the first
+        pass (pass == 0, really) will completely cover
+        the old row, so the rows do not have to be
+        initialized.  After the first pass (and only
+        for interlaced images), you will have to pass
+        the current row, and the function will combine
+        the old row and the new row.
+     */
+  }
+ 
+  void
+  end_callback(png_structp png_ptr, png_infop info)
+  {
+     /* This function is called after the whole image
+        has been read, including any chunks after the
+        image (up to and including the IEND).  You
+        will usually have the same info chunk as you
+        had in the header, although some data may have
+        been added to the comments and time fields.
+ 
+        Most people won't do much here, perhaps setting
+        a flag that marks the image as finished.
+      */
+  }
+ 
+ 
+ 
+ IV. Writing
+ 
+ Much of this is very similar to reading.  However, everything of
+ importance is repeated here, so you won't have to constantly look
+ back up in the reading section to understand writing.
+ 
+ Setup
+ 
+ You will want to do the I/O initialization before you get into libpng,
+ so if it doesn't work, you don't have anything to undo. If you are not
+ using the standard I/O functions, you will need to replace them with
+ custom writing functions.  See the discussion under Customizing libpng.
+ 
+     FILE *fp = fopen(file_name, "wb");
+     if (!fp)
+     {
+        return (ERROR);
+     }
+ 
+ Next, png_struct and png_info need to be allocated and initialized.
+ As these can be both relatively large, you may not want to store these
+ on the stack, unless you have stack space to spare.  Of course, you
+ will want to check if they return NULL.  If you are also reading,
+ you won't want to name your read structure and your write structure
+ both "png_ptr"; you can call them anything you like, such as
+ "read_ptr" and "write_ptr".  Look at pngtest.c, for example.
+ 
+     png_structp png_ptr = png_create_write_struct
+        (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+         user_error_fn, user_warning_fn);
+     if (!png_ptr)
+        return (ERROR);
+ 
+     png_infop info_ptr = png_create_info_struct(png_ptr);
+     if (!info_ptr)
+     {
+        png_destroy_write_struct(&png_ptr,
+          (png_infopp)NULL);
+        return (ERROR);
+     }
+ 
+ If you want to use your own memory allocation routines,
+ define PNG_USER_MEM_SUPPORTED and use
+ png_create_write_struct_2() instead of png_create_write_struct():
+ 
+     png_structp png_ptr = png_create_write_struct_2
+        (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+         user_error_fn, user_warning_fn, (png_voidp)
+         user_mem_ptr, user_malloc_fn, user_free_fn);
+ 
+ After you have these structures, you will need to set up the
+ error handling.  When libpng encounters an error, it expects to
+ longjmp() back to your routine.  Therefore, you will need to call
+ setjmp() and pass the png_jmpbuf(png_ptr).  If you
+ write the file from different routines, you will need to update
+ the png_jmpbuf(png_ptr) every time you enter a new routine that will
+ call a png_*() function.  See your documentation of setjmp/longjmp
+ for your compiler for more information on setjmp/longjmp.  See
+ the discussion on libpng error handling in the Customizing Libpng
+ section below for more information on the libpng error handling.
+ 
+     if (setjmp(png_jmpbuf(png_ptr)))
+     {
+        png_destroy_write_struct(&png_ptr, &info_ptr);
+        fclose(fp);
+        return (ERROR);
+     }
+     ...
+     return;
+ 
+ If you would rather avoid the complexity of setjmp/longjmp issues,
+ you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
+ errors will result in a call to PNG_ABORT() which defaults to abort().
+ 
+ Now you need to set up the output code.  The default for libpng is to
+ use the C function fwrite().  If you use this, you will need to pass a
+ valid FILE * in the function png_init_io().  Be sure that the file is
+ opened in binary mode.  Again, if you wish to handle writing data in
+ another way, see the discussion on libpng I/O handling in the Customizing
+ Libpng section below.
+ 
+     png_init_io(png_ptr, fp);
+ 
+ Write callbacks
+ 
+ At this point, you can set up a callback function that will be
+ called after each row has been written, which you can use to control
+ a progress meter or the like.  It's demonstrated in pngtest.c.
+ You must supply a function
+ 
+     void write_row_callback(png_ptr, png_uint_32 row,
+        int pass);
+     {
+       /* put your code here */
+     }
+ 
+ (You can give it another name that you like instead of "write_row_callback")
+ 
+ To inform libpng about your function, use
+ 
+     png_set_write_status_fn(png_ptr, write_row_callback);
+ 
+ You now have the option of modifying how the compression library will
+ run.  The following functions are mainly for testing, but may be useful
+ in some cases, like if you need to write PNG files extremely fast and
+ are willing to give up some compression, or if you want to get the
+ maximum possible compression at the expense of slower writing.  If you
+ have no special needs in this area, let the library do what it wants by
+ not calling this function at all, as it has been tuned to deliver a good
+ speed/compression ratio. The second parameter to png_set_filter() is
+ the filter method, for which the only valid values are 0 (as of the
+ July 1999 PNG specification, version 1.2) or 64 (if you are writing
+ a PNG datastream that is to be embedded in a MNG datastream).  The third
+ parameter is a flag that indicates which filter type(s) are to be tested
+ for each scanline.  See the PNG specification for details on the specific filter
+ types.
+ 
+ 
+     /* turn on or off filtering, and/or choose
+        specific filters.  You can use either a single
+        PNG_FILTER_VALUE_NAME or the logical OR of one
+        or more PNG_FILTER_NAME masks. */
+     png_set_filter(png_ptr, 0,
+        PNG_FILTER_NONE  | PNG_FILTER_VALUE_NONE |
+        PNG_FILTER_SUB   | PNG_FILTER_VALUE_SUB  |
+        PNG_FILTER_UP    | PNG_FILTER_VALUE_UP   |
+        PNG_FILTER_AVE   | PNG_FILTER_VALUE_AVE  |
+        PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
+        PNG_ALL_FILTERS);
+ 
+ If an application
+ wants to start and stop using particular filters during compression,
+ it should start out with all of the filters (to ensure that the previous
+ row of pixels will be stored in case it's needed later), and then add
+ and remove them after the start of compression.
+ 
+ If you are writing a PNG datastream that is to be embedded in a MNG
+ datastream, the second parameter can be either 0 or 64.
+ 
+ The png_set_compression_*() functions interface to the zlib compression
+ library, and should mostly be ignored unless you really know what you are
+ doing.  The only generally useful call is png_set_compression_level()
+ which changes how much time zlib spends on trying to compress the image
+ data.  See the Compression Library (zlib.h and algorithm.txt, distributed
+ with zlib) for details on the compression levels.
+ 
+     /* set the zlib compression level */
+     png_set_compression_level(png_ptr,
+         Z_BEST_COMPRESSION);
+ 
+     /* set other zlib parameters */
+     png_set_compression_mem_level(png_ptr, 8);
+     png_set_compression_strategy(png_ptr,
+         Z_DEFAULT_STRATEGY);
+     png_set_compression_window_bits(png_ptr, 15);
+     png_set_compression_method(png_ptr, 8);
+     png_set_compression_buffer_size(png_ptr, 8192)
+ 
+ extern PNG_EXPORT(void,png_set_zbuf_size)
+ 
+ Setting the contents of info for output
+ 
+ You now need to fill in the png_info structure with all the data you
+ wish to write before the actual image.  Note that the only thing you
+ are allowed to write after the image is the text chunks and the time
+ chunk (as of PNG Specification 1.2, anyway).  See png_write_end() and
+ the latest PNG specification for more information on that.  If you
+ wish to write them before the image, fill them in now, and flag that
+ data as being valid.  If you want to wait until after the data, don't
+ fill them until png_write_end().  For all the fields in png_info and
+ their data types, see png.h.  For explanations of what the fields
+ contain, see the PNG specification.
+ 
+ Some of the more important parts of the png_info are:
+ 
+     png_set_IHDR(png_ptr, info_ptr, width, height,
+        bit_depth, color_type, interlace_type,
+        compression_type, filter_method)
+     width          - holds the width of the image
+                      in pixels (up to 2^31).
+     height         - holds the height of the image
+                      in pixels (up to 2^31).
+     bit_depth      - holds the bit depth of one of the
+                      image channels.
+                      (valid values are 1, 2, 4, 8, 16
+                      and depend also on the
+                      color_type.  See also significant
+                      bits (sBIT) below).
+     color_type     - describes which color/alpha
+                      channels are present.
+                      PNG_COLOR_TYPE_GRAY
+                         (bit depths 1, 2, 4, 8, 16)
+                      PNG_COLOR_TYPE_GRAY_ALPHA
+                         (bit depths 8, 16)
+                      PNG_COLOR_TYPE_PALETTE
+                         (bit depths 1, 2, 4, 8)
+                      PNG_COLOR_TYPE_RGB
+                         (bit_depths 8, 16)
+                      PNG_COLOR_TYPE_RGB_ALPHA
+                         (bit_depths 8, 16)
+ 
+                      PNG_COLOR_MASK_PALETTE
+                      PNG_COLOR_MASK_COLOR
+                      PNG_COLOR_MASK_ALPHA
+ 
+     interlace_type - PNG_INTERLACE_NONE or
+                      PNG_INTERLACE_ADAM7
+     compression_type - (must be
+                      PNG_COMPRESSION_TYPE_DEFAULT)
+     filter_method  - (must be PNG_FILTER_TYPE_DEFAULT
+                      or, if you are writing a PNG to
+                      be embedded in a MNG datastream,
+                      can also be
+                      PNG_INTRAPIXEL_DIFFERENCING)
+ 
+     png_set_PLTE(png_ptr, info_ptr, palette,
+        num_palette);
+     palette        - the palette for the file
+                      (array of png_color)
+     num_palette    - number of entries in the palette
+ 
+     png_set_gAMA(png_ptr, info_ptr, gamma);
+     gamma          - the gamma the image was created
+                      at (PNG_INFO_gAMA)
+ 
+     png_set_sRGB(png_ptr, info_ptr, srgb_intent);
+     srgb_intent    - the rendering intent
+                      (PNG_INFO_sRGB) The presence of
+                      the sRGB chunk means that the pixel
+                      data is in the sRGB color space.
+                      This chunk also implies specific
+                      values of gAMA and cHRM.  Rendering
+                      intent is the CSS-1 property that
+                      has been defined by the International
+                      Color Consortium
+                      (http://www.color.org).
+                      It can be one of
+                      PNG_sRGB_INTENT_SATURATION,
+                      PNG_sRGB_INTENT_PERCEPTUAL,
+                      PNG_sRGB_INTENT_ABSOLUTE, or
+                      PNG_sRGB_INTENT_RELATIVE.
+ 
+ 
+     png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
+        srgb_intent);
+     srgb_intent    - the rendering intent
+                      (PNG_INFO_sRGB) The presence of the
+                      sRGB chunk means that the pixel
+                      data is in the sRGB color space.
+                      This function also causes gAMA and
+                      cHRM chunks with the specific values
+                      that are consistent with sRGB to be
+                      written.
+ 
+     png_set_iCCP(png_ptr, info_ptr, name, compression_type,
+                       profile, proflen);
+     name            - The profile name.
+     compression     - The compression type; always
+                       PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
+                       You may give NULL to this argument to
+                       ignore it.
+     profile         - International Color Consortium color
+                       profile data. May contain NULs.
+     proflen         - length of profile data in bytes.
+ 
+     png_set_sBIT(png_ptr, info_ptr, sig_bit);
+     sig_bit        - the number of significant bits for
+                      (PNG_INFO_sBIT) each of the gray, red,
+                      green, and blue channels, whichever are
+                      appropriate for the given color type
+                      (png_color_16)
+ 
+     png_set_tRNS(png_ptr, info_ptr, trans, num_trans,
+        trans_values);
+     trans          - array of transparent entries for
+                      palette (PNG_INFO_tRNS)
+     trans_values   - graylevel or color sample values of
+                      the single transparent color for
+                      non-paletted images (PNG_INFO_tRNS)
+     num_trans      - number of transparent entries
+                      (PNG_INFO_tRNS)
+ 
+     png_set_hIST(png_ptr, info_ptr, hist);
+                     (PNG_INFO_hIST)
+     hist           - histogram of palette (array of
+                      png_uint_16)
+ 
+     png_set_tIME(png_ptr, info_ptr, mod_time);
+     mod_time       - time image was last modified
+                      (PNG_VALID_tIME)
+ 
+     png_set_bKGD(png_ptr, info_ptr, background);
+     background     - background color (PNG_VALID_bKGD)
+ 
+     png_set_text(png_ptr, info_ptr, text_ptr, num_text);
+     text_ptr       - array of png_text holding image
+                      comments
+     text_ptr[i].compression - type of compression used
+                  on "text" PNG_TEXT_COMPRESSION_NONE
+                            PNG_TEXT_COMPRESSION_zTXt
+                            PNG_ITXT_COMPRESSION_NONE
+                            PNG_ITXT_COMPRESSION_zTXt
+     text_ptr[i].key   - keyword for comment.  Must contain
+                  1-79 characters.
+     text_ptr[i].text  - text comments for current
+                          keyword.  Can be NULL or empty.
+     text_ptr[i].text_length - length of text string,
+                  after decompression, 0 for iTXt
+     text_ptr[i].itxt_length - length of itxt string,
+                  after decompression, 0 for tEXt/zTXt
+     text_ptr[i].lang  - language of comment (NULL or
+                          empty for unknown).
+     text_ptr[i].translated_keyword  - keyword in UTF-8 (NULL
+                          or empty for unknown).
+     num_text       - number of comments
+ 
+     png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
+        num_spalettes);
+     palette_ptr    - array of png_sPLT_struct structures
+                      to be added to the list of palettes
+                      in the info structure.
+     num_spalettes  - number of palette structures to be
+                      added.
+ 
+     png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
+         unit_type);
+     offset_x  - positive offset from the left
+                      edge of the screen
+     offset_y  - positive offset from the top
+                      edge of the screen
+     unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
+ 
+     png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
+         unit_type);
+     res_x       - pixels/unit physical resolution
+                   in x direction
+     res_y       - pixels/unit physical resolution
+                   in y direction
+     unit_type   - PNG_RESOLUTION_UNKNOWN,
+                   PNG_RESOLUTION_METER
+ 
+     png_set_sCAL(png_ptr, info_ptr, unit, width, height)
+     unit        - physical scale units (an integer)
+     width       - width of a pixel in physical scale units
+     height      - height of a pixel in physical scale units
+                   (width and height are doubles)
+ 
+     png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
+     unit        - physical scale units (an integer)
+     width       - width of a pixel in physical scale units
+     height      - height of a pixel in physical scale units
+                  (width and height are strings like "2.54")
+ 
+     png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
+        num_unknowns)
+     unknowns          - array of png_unknown_chunk
+                         structures holding unknown chunks
+     unknowns[i].name  - name of unknown chunk
+     unknowns[i].data  - data of unknown chunk
+     unknowns[i].size  - size of unknown chunk's data
+     unknowns[i].location - position to write chunk in file
+                            0: do not write chunk
+                            PNG_HAVE_IHDR: before PLTE
+                            PNG_HAVE_PLTE: before IDAT
+                            PNG_AFTER_IDAT: after IDAT
+ 
+ The "location" member is set automatically according to
+ what part of the output file has already been written.
+ You can change its value after calling png_set_unknown_chunks()
+ as demonstrated in pngtest.c.  Within each of the "locations",
+ the chunks are sequenced according to their position in the
+ structure (that is, the value of "i", which is the order in which
+ the chunk was either read from the input file or defined with
+ png_set_unknown_chunks).
+ 
+ A quick word about text and num_text.  text is an array of png_text
+ structures.  num_text is the number of valid structures in the array.
+ Each png_text structure holds a language code, a keyword, a text value,
+ and a compression type.
+ 
+ The compression types have the same valid numbers as the compression
+ types of the image data.  Currently, the only valid number is zero.
+ However, you can store text either compressed or uncompressed, unlike
+ images, which always have to be compressed.  So if you don't want the
+ text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
+ Because tEXt and zTXt chunks don't have a language field, if you
+ specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
+ any language code or translated keyword will not be written out.
+ 
+ Until text gets around 1000 bytes, it is not worth compressing it.
+ After the text has been written out to the file, the compression type
+ is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
+ so that it isn't written out again at the end (in case you are calling
+ png_write_end() with the same struct.
+ 
+ The keywords that are given in the PNG Specification are:
+ 
+     Title            Short (one line) title or
+                      caption for image
+     Author           Name of image's creator
+     Description      Description of image (possibly long)
+     Copyright        Copyright notice
+     Creation Time    Time of original image creation
+                      (usually RFC 1123 format, see below)
+     Software         Software used to create the image
+     Disclaimer       Legal disclaimer
+     Warning          Warning of nature of content
+     Source           Device used to create the image
+     Comment          Miscellaneous comment; conversion
+                      from other image format
+ 
+ The keyword-text pairs work like this.  Keywords should be short
+ simple descriptions of what the comment is about.  Some typical
+ keywords are found in the PNG specification, as is some recommendations
+ on keywords.  You can repeat keywords in a file.  You can even write
+ some text before the image and some after.  For example, you may want
+ to put a description of the image before the image, but leave the
+ disclaimer until after, so viewers working over modem connections
+ don't have to wait for the disclaimer to go over the modem before
+ they start seeing the image.  Finally, keywords should be full
+ words, not abbreviations.  Keywords and text are in the ISO 8859-1
+ (Latin-1) character set (a superset of regular ASCII) and can not
+ contain NUL characters, and should not contain control or other
+ unprintable characters.  To make the comments widely readable, stick
+ with basic ASCII, and avoid machine specific character set extensions
+ like the IBM-PC character set.  The keyword must be present, but
+ you can leave off the text string on non-compressed pairs.
+ Compressed pairs must have a text string, as only the text string
+ is compressed anyway, so the compression would be meaningless.
+ 
+ PNG supports modification time via the png_time structure.  Two
+ conversion routines are provided, png_convert_from_time_t() for
+ time_t and png_convert_from_struct_tm() for struct tm.  The
+ time_t routine uses gmtime().  You don't have to use either of
+ these, but if you wish to fill in the png_time structure directly,
+ you should provide the time in universal time (GMT) if possible
+ instead of your local time.  Note that the year number is the full
+ year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
+ that months start with 1.
+ 
+ If you want to store the time of the original image creation, you should
+ use a plain tEXt chunk with the "Creation Time" keyword.  This is
+ necessary because the "creation time" of a PNG image is somewhat vague,
+ depending on whether you mean the PNG file, the time the image was
+ created in a non-PNG format, a still photo from which the image was
+ scanned, or possibly the subject matter itself.  In order to facilitate
+ machine-readable dates, it is recommended that the "Creation Time"
+ tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
+ although this isn't a requirement.  Unlike the tIME chunk, the
+ "Creation Time" tEXt chunk is not expected to be automatically changed
+ by the software.  To facilitate the use of RFC 1123 dates, a function
+ png_convert_to_rfc1123(png_timep) is provided to convert from PNG
+ time to an RFC 1123 format string.
+ 
+ Writing unknown chunks
+ 
+ You can use the png_set_unknown_chunks function to queue up chunks
+ for writing.  You give it a chunk name, raw data, and a size; that's
+ all there is to it.  The chunks will be written by the next following
+ png_write_info_before_PLTE, png_write_info, or png_write_end function.
+ Any chunks previously read into the info structure's unknown-chunk
+ list will also be written out in a sequence that satisfies the PNG
+ specification's ordering rules.
+ 
+ The high-level write interface
+ 
+ At this point there are two ways to proceed; through the high-level
+ write interface, or through a sequence of low-level write operations.
+ You can use the high-level interface if your image data is present
+ in the info structure.  All defined output
+ transformations are permitted, enabled by the following masks.
+ 
+     PNG_TRANSFORM_IDENTITY      No transformation
+     PNG_TRANSFORM_PACKING       Pack 1, 2 and 4-bit samples
+     PNG_TRANSFORM_PACKSWAP      Change order of packed
+                                 pixels to LSB first
+     PNG_TRANSFORM_INVERT_MONO   Invert monochrome images
+     PNG_TRANSFORM_SHIFT         Normalize pixels to the
+                                 sBIT depth
+     PNG_TRANSFORM_BGR           Flip RGB to BGR, RGBA
+                                 to BGRA
+     PNG_TRANSFORM_SWAP_ALPHA    Flip RGBA to ARGB or GA
+                                 to AG
+     PNG_TRANSFORM_INVERT_ALPHA  Change alpha from opacity
+                                 to transparency
+     PNG_TRANSFORM_SWAP_ENDIAN   Byte-swap 16-bit samples
+     PNG_TRANSFORM_STRIP_FILLER  Strip out filler bytes.
+ 
+ If you have valid image data in the info structure (you can use
+ png_set_rows() to put image data in the info structure), simply do this:
+ 
+     png_write_png(png_ptr, info_ptr, png_transforms, NULL)
+ 
+ where png_transforms is an integer containing the logical OR of some set of
+ transformation flags.  This call is equivalent to png_write_info(),
+ followed the set of transformations indicated by the transform mask,
+ then png_write_image(), and finally png_write_end().
+ 
+ (The final parameter of this call is not yet used.  Someday it might point
+ to transformation parameters required by some future output transform.)
+ 
+ The low-level write interface
+ 
+ If you are going the low-level route instead, you are now ready to
+ write all the file information up to the actual image data.  You do
+ this with a call to png_write_info().
+ 
+     png_write_info(png_ptr, info_ptr);
+ 
+ Note that there is one transformation you may need to do before
+ png_write_info().  In PNG files, the alpha channel in an image is the
+ level of opacity.  If your data is supplied as a level of
+ transparency, you can invert the alpha channel before you write it, so
+ that 0 is fully transparent and 255 (in 8-bit or paletted images) or
+ 65535 (in 16-bit images) is fully opaque, with
+ 
+     png_set_invert_alpha(png_ptr);
+ 
+ This must appear before png_write_info() instead of later with the
+ other transformations because in the case of paletted images the tRNS
+ chunk data has to be inverted before the tRNS chunk is written.  If
+ your image is not a paletted image, the tRNS data (which in such cases
+ represents a single color to be rendered as transparent) won't need to
+ be changed, and you can safely do this transformation after your
+ png_write_info() call.
+ 
+ If you need to write a private chunk that you want to appear before
+ the PLTE chunk when PLTE is present, you can write the PNG info in
+ two steps, and insert code to write your own chunk between them:
+ 
+     png_write_info_before_PLTE(png_ptr, info_ptr);
+     png_set_unknown_chunks(png_ptr, info_ptr, ...);
+     png_write_info(png_ptr, info_ptr);
+ 
+ After you've written the file information, you can set up the library
+ to handle any special transformations of the image data.  The various
+ ways to transform the data will be described in the order that they
+ should occur.  This is important, as some of these change the color
+ type and/or bit depth of the data, and some others only work on
+ certain color types and bit depths.  Even though each transformation
+ checks to see if it has data that it can do something with, you should
+ make sure to only enable a transformation if it will be valid for the
+ data.  For example, don't swap red and blue on grayscale data.
+ 
+ PNG files store RGB pixels packed into 3 or 6 bytes.  This code tells
+ the library to strip input data that has 4 or 8 bytes per pixel down
+ to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
+ bytes per pixel).
+ 
+     png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+ 
+ where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
+ PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
+ is stored XRGB or RGBX.
+ 
+ PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
+ they can, resulting in, for example, 8 pixels per byte for 1 bit files.
+ If the data is supplied at 1 pixel per byte, use this code, which will
+ correctly pack the pixels into a single byte:
+ 
+     png_set_packing(png_ptr);
+ 
+ PNG files reduce possible bit depths to 1, 2, 4, 8, and 16.  If your
+ data is of another bit depth, you can write an sBIT chunk into the
+ file so that decoders can recover the original data if desired.
+ 
+     /* Set the true bit depth of the image data */
+     if (color_type & PNG_COLOR_MASK_COLOR)
+     {
+         sig_bit.red = true_bit_depth;
+         sig_bit.green = true_bit_depth;
+         sig_bit.blue = true_bit_depth;
+     }
+     else
+     {
+         sig_bit.gray = true_bit_depth;
+     }
+     if (color_type & PNG_COLOR_MASK_ALPHA)
+     {
+         sig_bit.alpha = true_bit_depth;
+     }
+ 
+     png_set_sBIT(png_ptr, info_ptr, &sig_bit);
+ 
+ If the data is stored in the row buffer in a bit depth other than
+ one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
+ this will scale the values to appear to be the correct bit depth as
+ is required by PNG.
+ 
+     png_set_shift(png_ptr, &sig_bit);
+ 
+ PNG files store 16 bit pixels in network byte order (big-endian,
+ ie. most significant bits first).  This code would be used if they are
+ supplied the other way (little-endian, i.e. least significant bits
+ first, the way PCs store them):
+ 
+     if (bit_depth > 8)
+        png_set_swap(png_ptr);
+ 
+ If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
+ need to change the order the pixels are packed into bytes, you can use:
+ 
+     if (bit_depth < 8)
+        png_set_packswap(png_ptr);
+ 
+ PNG files store 3 color pixels in red, green, blue order.  This code
+ would be used if they are supplied as blue, green, red:
+ 
+     png_set_bgr(png_ptr);
+ 
+ PNG files describe monochrome as black being zero and white being
+ one. This code would be used if the pixels are supplied with this reversed
+ (black being one and white being zero):
+ 
+     png_set_invert_mono(png_ptr);
+ 
+ Finally, you can write your own transformation function if none of
+ the existing ones meets your needs.  This is done by setting a callback
+ with
+ 
+     png_set_write_user_transform_fn(png_ptr,
+        write_transform_fn);
+ 
+ You must supply the function
+ 
+     void write_transform_fn(png_ptr ptr, row_info_ptr
+        row_info, png_bytep data)
+ 
+ See pngtest.c for a working example.  Your function will be called
+ before any of the other transformations are processed.
+ 
+ You can also set up a pointer to a user structure for use by your
+ callback function.
+ 
+     png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
+ 
+ The user_channels and user_depth parameters of this function are ignored
+ when writing; you can set them to zero as shown.
+ 
+ You can retrieve the pointer via the function png_get_user_transform_ptr().
+ For example:
+ 
+     voidp write_user_transform_ptr =
+        png_get_user_transform_ptr(png_ptr);
+ 
+ It is possible to have libpng flush any pending output, either manually,
+ or automatically after a certain number of lines have been written.  To
+ flush the output stream a single time call:
+ 
+     png_write_flush(png_ptr);
+ 
+ and to have libpng flush the output stream periodically after a certain
+ number of scanlines have been written, call:
+ 
+     png_set_flush(png_ptr, nrows);
+ 
+ Note that the distance between rows is from the last time png_write_flush()
+ was called, or the first row of the image if it has never been called.
+ So if you write 50 lines, and then png_set_flush 25, it will flush the
+ output on the next scanline, and every 25 lines thereafter, unless
+ png_write_flush() is called before 25 more lines have been written.
+ If nrows is too small (less than about 10 lines for a 640 pixel wide
+ RGB image) the image compression may decrease noticeably (although this
+ may be acceptable for real-time applications).  Infrequent flushing will
+ only degrade the compression performance by a few percent over images
+ that do not use flushing.
+ 
+ Writing the image data
+ 
+ That's it for the transformations.  Now you can write the image data.
+ The simplest way to do this is in one function call.  If you have the
+ whole image in memory, you can just call png_write_image() and libpng
+ will write the image.  You will need to pass in an array of pointers to
+ each row.  This function automatically handles interlacing, so you don't
+ need to call png_set_interlace_handling() or call this function multiple
+ times, or any of that other stuff necessary with png_write_rows().
+ 
+     png_write_image(png_ptr, row_pointers);
+ 
+ where row_pointers is:
+ 
+     png_byte *row_pointers[height];
+ 
+ You can point to void or char or whatever you use for pixels.
+ 
+ If you don't want to write the whole image at once, you can
+ use png_write_rows() instead.  If the file is not interlaced,
+ this is simple:
+ 
+     png_write_rows(png_ptr, row_pointers,
+        number_of_rows);
+ 
+ row_pointers is the same as in the png_write_image() call.
+ 
+ If you are just writing one row at a time, you can do this with
+ a single row_pointer instead of an array of row_pointers:
+ 
+     png_bytep row_pointer = row;
+ 
+     png_write_row(png_ptr, row_pointer);
+ 
+ When the file is interlaced, things can get a good deal more
+ complicated.  The only currently (as of the PNG Specification
+ version 1.2, dated July 1999) defined interlacing scheme for PNG files
+ is the "Adam7" interlace scheme, that breaks down an
+ image into seven smaller images of varying size.  libpng will build
+ these images for you, or you can do them yourself.  If you want to
+ build them yourself, see the PNG specification for details of which
+ pixels to write when.
+ 
+ If you don't want libpng to handle the interlacing details, just
+ use png_set_interlace_handling() and call png_write_rows() the
+ correct number of times to write all seven sub-images.
+ 
+ If you want libpng to build the sub-images, call this before you start
+ writing any rows:
+ 
+     number_of_passes =
+        png_set_interlace_handling(png_ptr);
+ 
+ This will return the number of passes needed.  Currently, this
+ is seven, but may change if another interlace type is added.
+ 
+ Then write the complete image number_of_passes times.
+ 
+     png_write_rows(png_ptr, row_pointers,
+        number_of_rows);
+ 
+ As some of these rows are not used, and thus return immediately,
+ you may want to read about interlacing in the PNG specification,
+ and only update the rows that are actually used.
+ 
+ Finishing a sequential write
+ 
+ After you are finished writing the image, you should finish writing
+ the file.  If you are interested in writing comments or time, you should
+ pass an appropriately filled png_info pointer.  If you are not interested,
+ you can pass NULL.
+ 
+     png_write_end(png_ptr, info_ptr);
+ 
+ When you are done, you can free all memory used by libpng like this:
+ 
+     png_destroy_write_struct(&png_ptr, &info_ptr);
+ 
+ It is also possible to individually free the info_ptr members that
+ point to libpng-allocated storage with the following function:
+ 
+     png_free_data(png_ptr, info_ptr, mask, seq)
+     mask  - identifies data to be freed, a mask
+             containing the logical OR of one or
+             more of
+               PNG_FREE_PLTE, PNG_FREE_TRNS,
+               PNG_FREE_HIST, PNG_FREE_ICCP,
+               PNG_FREE_PCAL, PNG_FREE_ROWS,
+               PNG_FREE_SCAL, PNG_FREE_SPLT,
+               PNG_FREE_TEXT, PNG_FREE_UNKN,
+             or simply PNG_FREE_ALL
+     seq   - sequence number of item to be freed
+             (-1 for all items)
+ 
+ This function may be safely called when the relevant storage has
+ already been freed, or has not yet been allocated, or was allocated
+ by the user  and not by libpng,  and will in those
+ cases do nothing.  The "seq" parameter is ignored if only one item
+ of the selected data type, such as PLTE, is allowed.  If "seq" is not
+ -1, and multiple items are allowed for the data type identified in
+ the mask, such as text or sPLT, only the n'th item in the structure
+ is freed, where n is "seq".
+ 
+ If you allocated data such as a palette that you passed
+ in to libpng with png_set_*, you must not free it until just before the call to
+ png_destroy_write_struct().
+ 
+ The default behavior is only to free data that was allocated internally
+ by libpng.  This can be changed, so that libpng will not free the data,
+ or so that it will free data that was allocated by the user with png_malloc()
+ or png_zalloc() and passed in via a png_set_*() function, with
+ 
+     png_data_freer(png_ptr, info_ptr, freer, mask)
+     mask   - which data elements are affected
+              same choices as in png_free_data()
+     freer  - one of
+                PNG_DESTROY_WILL_FREE_DATA
+                PNG_SET_WILL_FREE_DATA
+                PNG_USER_WILL_FREE_DATA
+ 
+ For example, to transfer responsibility for some data from a read structure
+ to a write structure, you could use
+ 
+     png_data_freer(read_ptr, read_info_ptr,
+        PNG_USER_WILL_FREE_DATA,
+        PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
+     png_data_freer(write_ptr, write_info_ptr,
+        PNG_DESTROY_WILL_FREE_DATA,
+        PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
+ 
+ thereby briefly reassigning responsibility for freeing to the user but
+ immediately afterwards reassigning it once more to the write_destroy
+ function.  Having done this, it would then be safe to destroy the read
+ structure and continue to use the PLTE, tRNS, and hIST data in the write
+ structure.
+ 
+ This function only affects data that has already been allocated.
+ You can call this function before calling after the png_set_*() functions
+ to control whether the user or png_destroy_*() is supposed to free the data.
+ When the user assumes responsibility for libpng-allocated data, the
+ application must use
+ png_free() to free it, and when the user transfers responsibility to libpng
+ for data that the user has allocated, the user must have used png_malloc()
+ or png_zalloc() to allocate it.
+ 
+ If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
+ separately, do not transfer responsibility for freeing text_ptr to libpng,
+ because when libpng fills a png_text structure it combines these members with
+ the key member, and png_free_data() will free only text_ptr.key.  Similarly,
+ if you transfer responsibility for free'ing text_ptr from libpng to your
+ application, your application must not separately free those members.
+ For a more compact example of writing a PNG image, see the file example.c.
+ 
+ V. Modifying/Customizing libpng:
+ 
+ There are three issues here.  The first is changing how libpng does
+ standard things like memory allocation, input/output, and error handling.
+ The second deals with more complicated things like adding new chunks,
+ adding new transformations, and generally changing how libpng works.
+ Both of those are compile-time issues; that is, they are generally
+ determined at the time the code is written, and there is rarely a need
+ to provide the user with a means of changing them.  The third is a
+ run-time issue:  choosing between and/or tuning one or more alternate
+ versions of computationally intensive routines; specifically, optimized
+ assembly-language (and therefore compiler- and platform-dependent)
+ versions.
+ 
+ Memory allocation, input/output, and error handling
+ 
+ All of the memory allocation, input/output, and error handling in libpng
+ goes through callbacks that are user-settable.  The default routines are
+ in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively.  To change
+ these functions, call the appropriate png_set_*_fn() function.
+ 
+ Memory allocation is done through the functions png_malloc()
+ and png_free().  These currently just call the standard C functions.  If
+ your pointers can't access more then 64K at a time, you will want to set
+ MAXSEG_64K in zlib.h.  Since it is unlikely that the method of handling
+ memory allocation on a platform will change between applications, these
+ functions must be modified in the library at compile time.  If you prefer
+ to use a different method of allocating and freeing data, you can use
+ png_create_read_struct_2() or png_create_write_struct_2() to register
+ your own functions as described above.
+ 
+ These functions also provide a void pointer that can be retrieved via
+ 
+     mem_ptr=png_get_mem_ptr(png_ptr);
+ 
+ Your replacement memory functions must have prototypes as follows:
+ 
+     png_voidp malloc_fn(png_structp png_ptr,
+        png_size_t size);
+     void free_fn(png_structp png_ptr, png_voidp ptr);
+ 
+ Your malloc_fn() should return NULL in case of failure.  The png_malloc()
+ function will call png_error() if it receives a NULL from the system
+ memory allocator or from your replacement malloc_fn().
+ 
+ Input/Output in libpng is done through png_read() and png_write(),
+ which currently just call fread() and fwrite().  The FILE * is stored in
+ png_struct and is initialized via png_init_io().  If you wish to change
+ the method of I/O, the library supplies callbacks that you can set
+ through the function png_set_read_fn() and png_set_write_fn() at run
+ time, instead of calling the png_init_io() function.  These functions
+ also provide a void pointer that can be retrieved via the function
+ png_get_io_ptr().  For example:
+ 
+     png_set_read_fn(png_structp read_ptr,
+         voidp read_io_ptr, png_rw_ptr read_data_fn)
+ 
+     png_set_write_fn(png_structp write_ptr,
+         voidp write_io_ptr, png_rw_ptr write_data_fn,
+         png_flush_ptr output_flush_fn);
+ 
+     voidp read_io_ptr = png_get_io_ptr(read_ptr);
+     voidp write_io_ptr = png_get_io_ptr(write_ptr);
+ 
+ The replacement I/O functions must have prototypes as follows:
+ 
+     void user_read_data(png_structp png_ptr,
+         png_bytep data, png_size_t length);
+     void user_write_data(png_structp png_ptr,
+         png_bytep data, png_size_t length);
+     void user_flush_data(png_structp png_ptr);
+ 
+ Supplying NULL for the read, write, or flush functions sets them back
+ to using the default C stream functions.  It is an error to read from
+ a write stream, and vice versa.
+ 
+ Error handling in libpng is done through png_error() and png_warning().
+ Errors handled through png_error() are fatal, meaning that png_error()
+ should never return to its caller.  Currently, this is handled via
+ setjmp() and longjmp() (unless you have compiled libpng with
+ PNG_SETJMP_NOT_SUPPORTED, in which case it is handled via PNG_ABORT()),
+ but you could change this to do things like exit() if you should wish.
+ 
+ On non-fatal errors, png_warning() is called
+ to print a warning message, and then control returns to the calling code.
+ By default png_error() and png_warning() print a message on stderr via
+ fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
+ (because you don't want the messages) or PNG_NO_STDIO defined (because
+ fprintf() isn't available).  If you wish to change the behavior of the error
+ functions, you will need to set up your own message callbacks.  These
+ functions are normally supplied at the time that the png_struct is created.
+ It is also possible to redirect errors and warnings to your own replacement
+ functions after png_create_*_struct() has been called by calling:
+ 
+     png_set_error_fn(png_structp png_ptr,
+         png_voidp error_ptr, png_error_ptr error_fn,
+         png_error_ptr warning_fn);
+ 
+     png_voidp error_ptr = png_get_error_ptr(png_ptr);
+ 
+ If NULL is supplied for either error_fn or warning_fn, then the libpng
+ default function will be used, calling fprintf() and/or longjmp() if a
+ problem is encountered.  The replacement error functions should have
+ parameters as follows:
+ 
+     void user_error_fn(png_structp png_ptr,
+         png_const_charp error_msg);
+     void user_warning_fn(png_structp png_ptr,
+         png_const_charp warning_msg);
+ 
+ The motivation behind using setjmp() and longjmp() is the C++ throw and
+ catch exception handling methods.  This makes the code much easier to write,
+ as there is no need to check every return code of every function call.
+ However, there are some uncertainties about the status of local variables
+ after a longjmp, so the user may want to be careful about doing anything after
+ setjmp returns non-zero besides returning itself.  Consult your compiler
+ documentation for more details.  For an alternative approach, you may wish
+ to use the "cexcept" facility (see http://cexcept.sourceforge.net).
+ 
+ Custom chunks
+ 
+ If you need to read or write custom chunks, you may need to get deeper
+ into the libpng code.  The library now has mechanisms for storing
+ and writing chunks of unknown type; you can even declare callbacks
+ for custom chunks.  Hoewver, this may not be good enough if the
+ library code itself needs to know about interactions between your
+ chunk and existing `intrinsic' chunks.
+ 
+ If you need to write a new intrinsic chunk, first read the PNG
+ specification. Acquire a first level of
+ understanding of how it works.  Pay particular attention to the
+ sections that describe chunk names, and look at how other chunks were
+ designed, so you can do things similarly.  Second, check out the
+ sections of libpng that read and write chunks.  Try to find a chunk
+ that is similar to yours and use it as a template.  More details can
+ be found in the comments inside the code.  It is best to handle unknown
+ chunks in a generic method, via callback functions, instead of by
+ modifying libpng functions.
+ 
+ If you wish to write your own transformation for the data, look through
+ the part of the code that does the transformations, and check out some of
+ the simpler ones to get an idea of how they work.  Try to find a similar
+ transformation to the one you want to add and copy off of it.  More details
+ can be found in the comments inside the code itself.
+ 
+ Configuring for 16 bit platforms
+ 
+ You will want to look into zconf.h to tell zlib (and thus libpng) that
+ it cannot allocate more then 64K at a time.  Even if you can, the memory
+ won't be accessible.  So limit zlib and libpng to 64K by defining MAXSEG_64K.
+ 
+ Configuring for DOS
+ 
+ For DOS users who only have access to the lower 640K, you will
+ have to limit zlib's memory usage via a png_set_compression_mem_level()
+ call.  See zlib.h or zconf.h in the zlib library for more information.
+ 
+ Configuring for Medium Model
+ 
+ Libpng's support for medium model has been tested on most of the popular
+ compilers.  Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
+ defined, and FAR gets defined to far in pngconf.h, and you should be
+ all set.  Everything in the library (except for zlib's structure) is
+ expecting far data.  You must use the typedefs with the p or pp on
+ the end for pointers (or at least look at them and be careful).  Make
+ note that the rows of data are defined as png_bytepp, which is an
+ unsigned char far * far *.
+ 
+ Configuring for gui/windowing platforms:
+ 
+ You will need to write new error and warning functions that use the GUI
+ interface, as described previously, and set them to be the error and
+ warning functions at the time that png_create_*_struct() is called,
+ in order to have them available during the structure initialization.
+ They can be changed later via png_set_error_fn().  On some compilers,
+ you may also have to change the memory allocators (png_malloc, etc.).
+ 
+ Configuring for compiler xxx:
+ 
+ All includes for libpng are in pngconf.h.  If you need to add/change/delete
+ an include, this is the place to do it.  The includes that are not
+ needed outside libpng are protected by the PNG_INTERNAL definition,
+ which is only defined for those routines inside libpng itself.  The
+ files in libpng proper only include png.h, which includes pngconf.h.
+ 
+ Configuring zlib:
+ 
+ There are special functions to configure the compression.  Perhaps the
+ most useful one changes the compression level, which currently uses
+ input compression values in the range 0 - 9.  The library normally
+ uses the default compression level (Z_DEFAULT_COMPRESSION = 6).  Tests
+ have shown that for a large majority of images, compression values in
+ the range 3-6 compress nearly as well as higher levels, and do so much
+ faster.  For online applications it may be desirable to have maximum speed
+ (Z_BEST_SPEED = 1).  With versions of zlib after v0.99, you can also
+ specify no compression (Z_NO_COMPRESSION = 0), but this would create
+ files larger than just storing the raw bitmap.  You can specify the
+ compression level by calling:
+ 
+     png_set_compression_level(png_ptr, level);
+ 
+ Another useful one is to reduce the memory level used by the library.
+ The memory level defaults to 8, but it can be lowered if you are
+ short on memory (running DOS, for example, where you only have 640K).
+ Note that the memory level does have an effect on compression; among
+ other things, lower levels will result in sections of incompressible
+ data being emitted in smaller stored blocks, with a correspondingly
+ larger relative overhead of up to 15% in the worst case.
+ 
+     png_set_compression_mem_level(png_ptr, level);
+ 
+ The other functions are for configuring zlib.  They are not recommended
+ for normal use and may result in writing an invalid PNG file.  See
+ zlib.h for more information on what these mean.
+ 
+     png_set_compression_strategy(png_ptr,
+         strategy);
+     png_set_compression_window_bits(png_ptr,
+         window_bits);
+     png_set_compression_method(png_ptr, method);
+     png_set_compression_buffer_size(png_ptr, size);
+ 
+ Controlling row filtering
+ 
+ If you want to control whether libpng uses filtering or not, which
+ filters are used, and how it goes about picking row filters, you
+ can call one of these functions.  The selection and configuration
+ of row filters can have a significant impact on the size and
+ encoding speed and a somewhat lesser impact on the decoding speed
+ of an image.  Filtering is enabled by default for RGB and grayscale
+ images (with and without alpha), but not for paletted images nor
+ for any images with bit depths less than 8 bits/pixel.
+ 
+ The 'method' parameter sets the main filtering method, which is
+ currently only '0' in the PNG 1.2 specification.  The 'filters'
+ parameter sets which filter(s), if any, should be used for each
+ scanline.  Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+ to turn filtering on and off, respectively.
+ 
+ Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
+ PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
+ ORed together with '|' to specify one or more filters to use.
+ These filters are described in more detail in the PNG specification.
+ If you intend to change the filter type during the course of writing
+ the image, you should start with flags set for all of the filters
+ you intend to use so that libpng can initialize its internal
+ structures appropriately for all of the filter types.  (Note that this
+ means the first row must always be adaptively filtered, because libpng
+ currently does not allocate the filter buffers until png_write_row()
+ is called for the first time.)
+ 
+     filters = PNG_FILTER_NONE | PNG_FILTER_SUB
+               PNG_FILTER_UP | PNG_FILTER_AVE |
+               PNG_FILTER_PAETH | PNG_ALL_FILTERS;
+ 
+     png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
+        filters);
+               The second parameter can also be
+               PNG_INTRAPIXEL_DIFFERENCING if you are
+               writing a PNG to be embedded in a MNG
+               datastream.  This parameter must be the
+               same as the value of filter_method used
+               in png_set_IHDR().
+ 
+ It is also possible to influence how libpng chooses from among the
+ available filters.  This is done in one or both of two ways - by
+ telling it how important it is to keep the same filter for successive
+ rows, and by telling it the relative computational costs of the filters.
+ 
+     double weights[3] = {1.5, 1.3, 1.1},
+        costs[PNG_FILTER_VALUE_LAST] =
+        {1.0, 1.3, 1.3, 1.5, 1.7};
+ 
+     png_set_filter_heuristics(png_ptr,
+        PNG_FILTER_HEURISTIC_WEIGHTED, 3,
+        weights, costs);
+ 
+ The weights are multiplying factors that indicate to libpng that the
+ row filter should be the same for successive rows unless another row filter
+ is that many times better than the previous filter.  In the above example,
+ if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a
+ "sum of absolute differences" 1.5 x 1.3 times higher than other filters
+ and still be chosen, while the NONE filter could have a sum 1.1 times
+ higher than other filters and still be chosen.  Unspecified weights are
+ taken to be 1.0, and the specified weights should probably be declining
+ like those above in order to emphasize recent filters over older filters.
+ 
+ The filter costs specify for each filter type a relative decoding cost
+ to be considered when selecting row filters.  This means that filters
+ with higher costs are less likely to be chosen over filters with lower
+ costs, unless their "sum of absolute differences" is that much smaller.
+ The costs do not necessarily reflect the exact computational speeds of
+ the various filters, since this would unduly influence the final image
+ size.
+ 
+ Note that the numbers above were invented purely for this example and
+ are given only to help explain the function usage.  Little testing has
+ been done to find optimum values for either the costs or the weights.
+ 
+ Removing unwanted object code
+ 
+ There are a bunch of #define's in pngconf.h that control what parts of
+ libpng are compiled.  All the defines end in _SUPPORTED.  If you are
+ never going to use a capability, you can change the #define to #undef
+ before recompiling libpng and save yourself code and data space, or
+ you can turn off individual capabilities with defines that begin with
+ PNG_NO_.
+ 
+ You can also turn all of the transforms and ancillary chunk capabilities
+ off en masse with compiler directives that define
+ PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
+ or all four,
+ along with directives to turn on any of the capabilities that you do
+ want.  The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable
+ the extra transformations but still leave the library fully capable of reading
+ and writing PNG files with all known public chunks
+ Use of the PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive
+ produces a library that is incapable of reading or writing ancillary chunks.
+ If you are not using the progressive reading capability, you can
+ turn that off with PNG_NO_PROGRESSIVE_READ (don't confuse
+ this with the INTERLACING capability, which you'll still have).
+ 
+ All the reading and writing specific code are in separate files, so the
+ linker should only grab the files it needs.  However, if you want to
+ make sure, or if you are building a stand alone library, all the
+ reading files start with pngr and all the writing files start with
+ pngw.  The files that don't match either (like png.c, pngtrans.c, etc.)
+ are used for both reading and writing, and always need to be included.
+ The progressive reader is in pngpread.c
+ 
+ If you are creating or distributing a dynamically linked library (a .so
+ or DLL file), you should not remove or disable any parts of the library,
+ as this will cause applications linked with different versions of the
+ library to fail if they call functions not available in your library.
+ The size of the library itself should not be an issue, because only
+ those sections that are actually used will be loaded into memory.
+ 
+ Requesting debug printout
+ 
+ The macro definition PNG_DEBUG can be used to request debugging
+ printout.  Set it to an integer value in the range 0 to 3.  Higher
+ numbers result in increasing amounts of debugging information.  The
+ information is printed to the "stderr" file, unless another file
+ name is specified in the PNG_DEBUG_FILE macro definition.
+ 
+ When PNG_DEBUG > 0, the following functions (macros) become available:
+ 
+    png_debug(level, message)
+    png_debug1(level, message, p1)
+    png_debug2(level, message, p1, p2)
+ 
+ in which "level" is compared to PNG_DEBUG to decide whether to print
+ the message, "message" is the formatted string to be printed,
+ and p1 and p2 are parameters that are to be embedded in the string
+ according to printf-style formatting directives.  For example,
+ 
+    png_debug1(2, "foo=%d\n", foo);
+ 
+ is expanded to
+ 
+    if(PNG_DEBUG > 2)
+      fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
+ 
+ When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
+ can still use PNG_DEBUG to control your own debugging:
+ 
+    #ifdef PNG_DEBUG
+        fprintf(stderr, ...
+    #endif
+ 
+ When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
+ having level = 0 will be printed.  There aren't any such statements in
+ this version of libpng, but if you insert some they will be printed.
+ 
+ VI.  Runtime optimization
+ 
+ A new feature in libpng 1.2.0 is the ability to dynamically switch between
+ standard and optimized versions of some routines.  Currently these are
+ limited to three computationally intensive tasks when reading PNG files:
+ decoding row filters, expanding interlacing, and combining interlaced or
+ transparent row data with previous row data.  Currently the optimized
+ versions are available only for x86 (Intel, AMD, etc.) platforms with
+ MMX support, though this may change in future versions.  (For example,
+ the non-MMX assembler optimizations for zlib might become similarly
+ runtime-selectable in future releases, in which case libpng could be
+ extended to support them.  Alternatively, the compile-time choice of
+ floating-point versus integer routines for gamma correction might become
+ runtime-selectable.)
+ 
+ Because such optimizations tend to be very platform- and compiler-dependent,
+ both in how they are written and in how they perform, the new runtime code
+ in libpng has been written to allow programs to query, enable, and disable
+ either specific optimizations or all such optimizations.  For example, to
+ enable all possible optimizations (bearing in mind that some "optimizations"
+ may actually run more slowly in rare cases):
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        png_uint_32 mask, flags;
+ 
+        flags = png_get_asm_flags(png_ptr);
+        mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
+        png_set_asm_flags(png_ptr, flags | mask);
+     #endif
+ 
+ To enable only optimizations relevant to reading PNGs, use PNG_SELECT_READ
+ by itself when calling png_get_asm_flagmask(); similarly for optimizing
+ only writing.  To disable all optimizations:
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        flags = png_get_asm_flags(png_ptr);
+        mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
+        png_set_asm_flags(png_ptr, flags & ~mask);
+     #endif
+ 
+ To enable or disable only MMX-related features, use png_get_mmx_flagmask()
+ in place of png_get_asm_flagmask().  The mmx version takes one additional
+ parameter:
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        int selection = PNG_SELECT_READ | PNG_SELECT_WRITE;
+        int compilerID;
+ 
+        mask = png_get_mmx_flagmask(selection, &compilerID);
+     #endif
+ 
+ On return, compilerID will indicate which version of the MMX assembler
+ optimizations was compiled.  Currently two flavors exist:  Microsoft
+ Visual C++ (compilerID == 1) and GNU C (a.k.a. gcc/gas, compilerID == 2).
+ On non-x86 platforms or on systems compiled without MMX optimizations, a
+ value of -1 is used.
+ 
+ Note that both png_get_asm_flagmask() and png_get_mmx_flagmask() return
+ all valid, settable optimization bits for the version of the library that's
+ currently in use.  In the case of shared (dynamically linked) libraries,
+ this may include optimizations that did not exist at the time the code was
+ written and compiled.  It is also possible, of course, to enable only known,
+ specific optimizations; for example:
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        flags = PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  \
+              | PNG_ASM_FLAG_MMX_READ_INTERLACE    \
+              | PNG_ASM_FLAG_MMX_READ_FILTER_SUB   \
+              | PNG_ASM_FLAG_MMX_READ_FILTER_UP    \
+              | PNG_ASM_FLAG_MMX_READ_FILTER_AVG   \
+              | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;
+        png_set_asm_flags(png_ptr, flags);
+     #endif
+ 
+ This method would enable only the MMX read-optimizations available at the
+ time of libpng 1.2.0's release, regardless of whether a later version of
+ the DLL were actually being used.  (Also note that these functions did not
+ exist in versions older than 1.2.0, so any attempt to run a dynamically
+ linked app on such an older version would fail.)
+ 
+ To determine whether the processor supports MMX instructions at all, use
+ the png_mmx_support() function:
+ 
+     #if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
+        mmxsupport = png_mmx_support();
+     #endif
+ 
+ It returns -1 if MMX support is not compiled into libpng, 0 if MMX code
+ is compiled but MMX is not supported by the processor, or 1 if MMX support
+ is fully available.  Note that png_mmx_support(), png_get_mmx_flagmask(),
+ and png_get_asm_flagmask() all may be called without allocating and ini-
+ tializing any PNG structures (for example, as part of a usage screen or
+ "about" box).
+ 
+ The following code can be used to prevent an application from using the
+ thread_unsafe features, even if libpng was built with PNG_THREAD_UNSAFE_OK
+ defined:
+ 
+ #if defined(PNG_USE_PNGGCCRD) && defined(PNG_ASSEMBLER_CODE_SUPPORTED) \
+   && defined(PNG_THREAD_UNSAFE_OK)
+     /* Disable thread-unsafe features of pnggccrd */
+     if (png_access_version() >= 10200)
+     {
+       png_uint_32 mmx_disable_mask = 0;
+       png_uint_32 asm_flags;
+ 
+       mmx_disable_mask |= ( PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  \
+                           | PNG_ASM_FLAG_MMX_READ_FILTER_SUB   \
+                           | PNG_ASM_FLAG_MMX_READ_FILTER_AVG   \
+                           | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH );
+       asm_flags = png_get_asm_flags(png_ptr);
+       png_set_asm_flags(png_ptr, asm_flags & ~mmx_disable_mask);
+     }
+ #endif
+ 
+ For more extensive examples of runtime querying, enabling and disabling
+ of optimized features, see contrib/gregbook/readpng2.c in the libpng
+ source-code distribution.
+ 
+ 
+ VII.  MNG support
+ 
+ The MNG specification (available at http://www.libpng.org/pub/mng) allows
+ certain extensions to PNG for PNG images that are embedded in MNG datastreams.
+ Libpng can support some of these extensions.  To enable them, use the
+ png_permit_mng_features() function:
+ 
+    feature_set = png_permit_mng_features(png_ptr, mask)
+    mask is a png_uint_32 containing the logical OR of the
+         features you want to enable.  These include
+         PNG_FLAG_MNG_EMPTY_PLTE
+         PNG_FLAG_MNG_FILTER_64
+         PNG_ALL_MNG_FEATURES
+    feature_set is a png_32_uint that is the logical AND of
+       your mask with the set of MNG features that is
+       supported by the version of libpng that you are using.
+ 
+ It is an error to use this function when reading or writing a standalone
+ PNG file with the PNG 8-byte signature.  The PNG datastream must be wrapped
+ in a MNG datastream.  As a minimum, it must have the MNG 8-byte signature
+ and the MHDR and MEND chunks.  Libpng does not provide support for these
+ or any other MNG chunks; your application must provide its own support for
+ them.  You may wish to consider using libmng (available at
+ http://www.libmng.com) instead.
+ 
+ VIII.  Changes to Libpng from version 0.88
+ 
+ It should be noted that versions of libpng later than 0.96 are not
+ distributed by the original libpng author, Guy Schalnat, nor by
+ Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
+ distributed versions 0.89 through 0.96, but rather by another member
+ of the original PNG Group, Glenn Randers-Pehrson.  Guy and Andreas are
+ still alive and well, but they have moved on to other things.
+ 
+ The old libpng functions png_read_init(), png_write_init(),
+ png_info_init(), png_read_destroy(), and png_write_destroy() have been
+ moved to PNG_INTERNAL in version 0.95 to discourage their use.  These
+ functions will be removed from libpng version 2.0.0.
+ 
+ The preferred method of creating and initializing the libpng structures is
+ via the png_create_read_struct(), png_create_write_struct(), and
+ png_create_info_struct() because they isolate the size of the structures
+ from the application, allow version error checking, and also allow the
+ use of custom error handling routines during the initialization, which
+ the old functions do not.  The functions png_read_destroy() and
+ png_write_destroy() do not actually free the memory that libpng
+ allocated for these structs, but just reset the data structures, so they
+ can be used instead of png_destroy_read_struct() and
+ png_destroy_write_struct() if you feel there is too much system overhead
+ allocating and freeing the png_struct for each image read.
+ 
+ Setting the error callbacks via png_set_message_fn() before
+ png_read_init() as was suggested in libpng-0.88 is no longer supported
+ because this caused applications that do not use custom error functions
+ to fail if the png_ptr was not initialized to zero.  It is still possible
+ to set the error callbacks AFTER png_read_init(), or to change them with
+ png_set_error_fn(), which is essentially the same function, but with a new
+ name to force compilation errors with applications that try to use the old
+ method.
+ 
+ Starting with version 1.0.7, you can find out which version of the library
+ you are using at run-time:
+ 
+    png_uint_32 libpng_vn = png_access_version_number();
+ 
+ The number libpng_vn is constructed from the major version, minor
+ version with leading zero, and release number with leading zero,
+ (e.g., libpng_vn for version 1.0.7 is 10007).
+ 
+ You can also check which version of png.h you used when compiling your
+ application:
+ 
+    png_uint_32 application_vn = PNG_LIBPNG_VER;
+ 
+ IX. Y2K Compliance in libpng
+ 
+ October 3, 2002
+ 
+ Since the PNG Development group is an ad-hoc body, we can't make
+ an official declaration.
+ 
+ This is your unofficial assurance that libpng from version 0.71 and
+ upward through 1.2.5 are Y2K compliant.  It is my belief that earlier
+ versions were also Y2K compliant.
+ 
+ Libpng only has three year fields.  One is a 2-byte unsigned integer that
+ will hold years up to 65535.  The other two hold the date in text
+ format, and will hold years up to 9999.
+ 
+ The integer is
+     "png_uint_16 year" in png_time_struct.
+ 
+ The strings are
+     "png_charp time_buffer" in png_struct and
+     "near_time_buffer", which is a local character string in png.c.
+ 
+ There are seven time-related functions:
+ 
+     png_convert_to_rfc_1123() in png.c
+       (formerly png_convert_to_rfc_1152() in error)
+     png_convert_from_struct_tm() in pngwrite.c, called
+       in pngwrite.c
+     png_convert_from_time_t() in pngwrite.c
+     png_get_tIME() in pngget.c
+     png_handle_tIME() in pngrutil.c, called in pngread.c
+     png_set_tIME() in pngset.c
+     png_write_tIME() in pngwutil.c, called in pngwrite.c
+ 
+ All appear to handle dates properly in a Y2K environment.  The
+ png_convert_from_time_t() function calls gmtime() to convert from system
+ clock time, which returns (year - 1900), which we properly convert to
+ the full 4-digit year.  There is a possibility that applications using
+ libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
+ function, or that they are incorrectly passing only a 2-digit year
+ instead of "year - 1900" into the png_convert_from_struct_tm() function,
+ but this is not under our control.  The libpng documentation has always
+ stated that it works with 4-digit years, and the APIs have been
+ documented as such.
+ 
+ The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
+ integer to hold the year, and can hold years as large as 65535.
+ 
+ zlib, upon which libpng depends, is also Y2K compliant.  It contains
+ no date-related code.
+ 
+ 
+    Glenn Randers-Pehrson
+    libpng maintainer
+    PNG Development Group


Index: llvm/runtime/libpng/libpngpf.3
diff -c /dev/null llvm/runtime/libpng/libpngpf.3:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/libpngpf.3	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,552 ----
+ .TH LIBPNGPF 3 "October 3, 2002"
+ .SH NAME
+ libpng \- Portable Network Graphics (PNG) Reference Library 1.2.5
+ (private functions)
+ .SH SYNOPSIS
+ \fB#include <png.h>\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_build_gamma_table (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_build_grayscale_palette (int \fP\fIbit_depth\fP\fB, png_colorp \fIpalette\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_calculate_crc (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIptr\fP\fB, png_size_t \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_check_chunk_name (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_size_t png_check_keyword (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIkey\fP\fB, png_charpp \fInew_key\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, int \fImask\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_correct_palette (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_crc_error (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_crc_finish (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIskip\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_crc_read (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIbuf\fP\fB, png_size_t \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_create_struct (int \fItype\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_voidp png_create_struct_2 (int \fP\fItype\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_voidp \fImem_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_charp png_decompress_chunk (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcomp_type\fP\fB, png_charp \fP\fIchunkdata\fP\fB, png_size_t \fP\fIchunklength\fP\fB, png_size_t \fP\fIprefix_length\fP\fB, png_size_t \fI*data_length\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_destroy_struct (png_voidp \fIstruct_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_destroy_struct_2 (png_voidp \fP\fIstruct_ptr\fP\fB, png_free_ptr \fP\fIfree_fn\fP\fB, png_voidp \fImem_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_background (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_color_16p \fP\fItrans_values\fP\fB, png_color_16p \fP\fIbackground\fP\fB, png_color_16p \fP\fIbackground_1\fP\fB, png_bytep \fP\fIgamma_table\fP\fB, png_bytep \fP\fIgamma_from_1\fP\fB, png_bytep \fP\fIgamma_to_1\fP\fB, png_uint_16pp \fP\fIgamma_16\fP\fB, png_uint_16pp \fP\fIgamma_16_from_1\fP\fB, png_uint_16pp \fP\fIgamma_16_to_1\fP\fB, int \fIgamma_shift\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_bgr (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_chop (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_dither (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fP\fIpalette_lookup\fP\fB, png_bytep \fIdither_lookup\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_expand (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_color_16p \fItrans_value\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_expand_palette (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_colorp \fP\fIpalette\fP\fB, png_bytep \fP\fItrans\fP\fB, int \fInum_trans\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_gamma (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fP\fIgamma_table\fP\fB, png_uint_16pp \fP\fIgamma_16_table\fP\fB, int \fIgamma_shift\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_gray_to_rgb (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_invert (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_pack (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_uint_32 \fIbit_depth\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_packswap (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_read_filler (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, png_uint_32 \fIflags\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_read_interlace (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, int \fP\fIpass\fP\fB, png_uint_32 \fItransformations\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_read_invert_alpha (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_read_swap_alpha (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_read_transformations (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_do_rgb_to_gray (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_shift (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_color_8p \fIbit_depth\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_strip_filler (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_uint_32 \fIflags\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_swap (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_unpack (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_unshift (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_color_8p \fIsig_bits\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_write_interlace (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, int \fIpass\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_write_invert_alpha (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_write_swap_alpha (png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_do_write_transformations (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid *png_far_to_near (png_structp png_ptr,png_voidp \fP\fIptr\fP\fB, int \fIcheck\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_flush (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_IEND (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_iTXt (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_tEXt (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_handle_zTXt (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_info_destroy (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_init_mmx_flags (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_init_read_transformations (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_process_IDAT_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_length\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_process_some_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_check_crc (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_crc_finish (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_crc_skip (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_fill_buffer (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_handle_tEXt (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_handle_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_handle_zTXt (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_have_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_have_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_have_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_process_row (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_read_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_read_IDAT (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_read_sig (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_read_tEXt (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_read_zTXt (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_restore_buffer (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_length\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_push_save_buffer (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_filter_row (png_structp \fP\fIpng_ptr\fP\fB, png_row_infop \fP\fIrow_info\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fP\fIprev_row\fP\fB, int \fIfilter\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_finish_row (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_push_finish_row (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_start_row (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_read_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_reset_crc (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBint png_set_text_2 (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text)\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_cHRM (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_filtered_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIfiltered_row\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_find_filter (png_structp \fP\fIpng_ptr\fP\fB, png_row_infop \fIrow_info\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_finish_row (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_gAMA (png_structp \fP\fIpng_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIint_file_gamma\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_uint_16p \fP\fIhist\fP\fB, int \fInum_hist\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_charp \fP\fIprofile\fP\fB, int \fIproflen\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_IDAT (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_IEND (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fP\fIfilter_type\fP\fB, int \fIinterlace_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_iTXt (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcompression\fP\fB, png_charp \fP\fIkey\fP\fB, png_charp \fP\fIlang\fP\fB, png_charp \fP\fItranslated_key\fP\fB, png_charp \fItext)\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIx_offset\fP\fB, png_uint_32 \fP\fIy_offset\fP\fB, int \fIunit_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIx_pixels_per_unit\fP\fB, png_uint_32 \fP\fIy_pixels_per_unit\fP\fB, int \fIunit_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, png_uint_32 \fInum_pal\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fP\fIsbit\fP\fB, int \fIcolor_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_sRGB (png_structp \fP\fIpng_ptr\fP\fB, int \fIintent\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_spalette_p \fIpalette\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_start_row (png_structp \fIpng_ptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_tEXt (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIkey\fP\fB, png_charp \fP\fItext\fP\fB, png_size_t \fItext_len\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fItrans\fP\fB, png_color_16p \fP\fIvalues\fP\fB, int \fP\fInumber\fP\fB, int \fIcolor_type\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_write_zTXt (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIkey\fP\fB, png_charp \fP\fItext\fP\fB, png_size_t \fP\fItext_len\fP\fB, int \fIcompression\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoidpf png_zalloc (voidpf \fP\fIpng_ptr\fP\fB, uInt \fP\fIitems\fP\fB, uInt \fIsize\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ \fBvoid png_zfree (voidpf \fP\fIpng_ptr\fP\fB, voidpf \fIptr\fP\fB);\fP
+ 
+ \fI\fB
+ 
+ .SH DESCRIPTION
+ The functions listed above are used privately by libpng
+ and are not recommended for use by applications.  They are
+ not "exported" to applications using shared libraries.  They
+ are listed alphabetically here as an aid to libpng maintainers.
+ See png.h for more information on these functions.
+ 
+ .SH SEE ALSO
+ libpng(3), png(5)
+ .SH AUTHOR
+ Glenn Randers-Pehrson


Index: llvm/runtime/libpng/png.5
diff -c /dev/null llvm/runtime/libpng/png.5:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/png.5	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,60 ----
+ .TH PNG 5 "October 3, 2002"
+ .SH NAME
+ png \- Portable Network Graphics (PNG) format
+ .SH DESCRIPTION
+ PNG (Portable Network Graphics) is an extensible file format for the
+ lossless, portable, well-compressed storage of raster images. PNG provides
+ a patent-free replacement for GIF and can also replace many
+ common uses of TIFF. Indexed-color, grayscale, and truecolor images are
+ supported, plus an optional alpha channel. Sample depths range from
+ 1 to 16 bits.
+ .br
+ 
+ PNG is designed to work well in online viewing applications, such as the
+ World Wide Web, so it is fully streamable with a progressive display
+ option. PNG is robust, providing both full file integrity checking and
+ fast, simple detection of common transmission errors. Also, PNG can store
+ gamma and chromaticity data for improved color matching on heterogeneous
+ platforms.
+ 
+ .SH "SEE ALSO"
+ .IR libpng(3), zlib(3), deflate(5), and zlib(5)
+ .LP
+ PNG 1.2 specification, July 1999:
+ .IP
+ .br
+ http://www.libpng.org/pub/png
+ .br
+ or ftp://ftp.uu.net/graphics/png/documents
+ .LP
+ PNG 1.0 specification, October 1996:
+ .IP
+ .br
+ RFC 2083
+ .IP
+ .br
+ ftp://ds.internic.net/rfc/rfc2083.txt
+ .br
+ or (as a W3C Recommendation) at
+ .br
+ http://www.w3.org/TR/REC-png.html
+ .SH AUTHORS
+ This man page: Glenn Randers-Pehrson
+ .LP
+ Portable Network Graphics (PNG) Specification Version 1.2 (July 8, 1999):
+ Glenn Randers-Pehrson and others (png-list at ccrc.wustl.edu).
+ .LP
+ Portable Network Graphics (PNG) Specification Version 1.0 (October 1, 1996):
+ Thomas Boutell and others (png-list at ccrc.wustl.edu).
+ .LP
+ 
+ 
+ .SH COPYRIGHT NOTICE
+ The PNG-1.2 specification is copyright (c) 1999 Glenn Randers-Pehrson.
+ See the specification for conditions of use and distribution.
+ .LP
+ The PNG-1.0 specification is copyright (c) 1996 Massachusetts Institute of
+ Technology.  See the specification for conditions of use and distribution.
+ .LP
+ .\" end of man page
+ 


Index: llvm/runtime/libpng/png.c
diff -c /dev/null llvm/runtime/libpng/png.c:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/png.c	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,805 ----
+ 
+ /* png.c - location for general purpose libpng functions
+  *
+  * libpng version 1.2.5 - October 3, 2002
+  * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+  *
+  */
+ 
+ #define PNG_INTERNAL
+ #define PNG_NO_EXTERN
+ #include "png.h"
+ 
+ /* Generate a compiler error if there is an old png.h in the search path. */
+ typedef version_1_2_5 Your_png_h_is_not_version_1_2_5;
+ 
+ /* Version information for C files.  This had better match the version
+  * string defined in png.h.  */
+ 
+ #ifdef PNG_USE_GLOBAL_ARRAYS
+ /* png_libpng_ver was changed to a function in version 1.0.5c */
+ const char png_libpng_ver[18] = "1.2.5";
+ 
+ /* png_sig was changed to a function in version 1.0.5c */
+ /* Place to hold the signature string for a PNG file. */
+ const png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
+ 
+ /* Invoke global declarations for constant strings for known chunk types */
+ PNG_IHDR;
+ PNG_IDAT;
+ PNG_IEND;
+ PNG_PLTE;
+ PNG_bKGD;
+ PNG_cHRM;
+ PNG_gAMA;
+ PNG_hIST;
+ PNG_iCCP;
+ PNG_iTXt;
+ PNG_oFFs;
+ PNG_pCAL;
+ PNG_sCAL;
+ PNG_pHYs;
+ PNG_sBIT;
+ PNG_sPLT;
+ PNG_sRGB;
+ PNG_tEXt;
+ PNG_tIME;
+ PNG_tRNS;
+ PNG_zTXt;
+ 
+ /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+ 
+ /* start of interlace block */
+ const int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
+ 
+ /* offset to next interlace block */
+ const int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
+ 
+ /* start of interlace block in the y direction */
+ const int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
+ 
+ /* offset to next interlace block in the y direction */
+ const int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
+ 
+ /* width of interlace block (used in assembler routines only) */
+ #ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW
+ const int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1};
+ #endif
+ 
+ /* Height of interlace block.  This is not currently used - if you need
+  * it, uncomment it here and in png.h
+ const int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
+ */
+ 
+ /* Mask to determine which pixels are valid in a pass */
+ const int FARDATA png_pass_mask[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
+ 
+ /* Mask to determine which pixels to overwrite while displaying */
+ const int FARDATA png_pass_dsp_mask[]
+    = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
+ 
+ #endif
+ 
+ /* Tells libpng that we have already handled the first "num_bytes" bytes
+  * of the PNG file signature.  If the PNG data is embedded into another
+  * stream we can set num_bytes = 8 so that libpng will not attempt to read
+  * or write any of the magic bytes before it starts on the IHDR.
+  */
+ 
+ void PNGAPI
+ png_set_sig_bytes(png_structp png_ptr, int num_bytes)
+ {
+    png_debug(1, "in png_set_sig_bytes\n");
+    if (num_bytes > 8)
+       png_error(png_ptr, "Too many bytes for PNG signature.");
+ 
+    png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
+ }
+ 
+ /* Checks whether the supplied bytes match the PNG signature.  We allow
+  * checking less than the full 8-byte signature so that those apps that
+  * already read the first few bytes of a file to determine the file type
+  * can simply check the remaining bytes for extra assurance.  Returns
+  * an integer less than, equal to, or greater than zero if sig is found,
+  * respectively, to be less than, to match, or be greater than the correct
+  * PNG signature (this is the same behaviour as strcmp, memcmp, etc).
+  */
+ int PNGAPI
+ png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)
+ {
+    png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
+    if (num_to_check > 8)
+       num_to_check = 8;
+    else if (num_to_check < 1)
+       return (0);
+ 
+    if (start > 7)
+       return (0);
+ 
+    if (start + num_to_check > 8)
+       num_to_check = 8 - start;
+ 
+    return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
+ }
+ 
+ /* (Obsolete) function to check signature bytes.  It does not allow one
+  * to check a partial signature.  This function might be removed in the
+  * future - use png_sig_cmp().  Returns true (nonzero) if the file is a PNG.
+  */
+ int PNGAPI
+ png_check_sig(png_bytep sig, int num)
+ {
+   return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));
+ }
+ 
+ /* Function to allocate memory for zlib and clear it to 0. */
+ #ifdef PNG_1_0_X
+ voidpf PNGAPI
+ #else
+ voidpf /* private */
+ #endif
+ png_zalloc(voidpf png_ptr, uInt items, uInt size)
+ {
+    png_uint_32 num_bytes = (png_uint_32)items * size;
+    png_voidp ptr;
+    png_structp p=png_ptr;
+    png_uint_32 save_flags=p->flags;
+ 
+    p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
+    ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
+    p->flags=save_flags;
+ 
+ #ifndef PNG_NO_ZALLOC_ZERO
+    if (ptr == NULL)
+        return ((voidpf)ptr);
+ 
+    if (num_bytes > (png_uint_32)0x8000L)
+    {
+       png_memset(ptr, 0, (png_size_t)0x8000L);
+       png_memset((png_bytep)ptr + (png_size_t)0x8000L, 0,
+          (png_size_t)(num_bytes - (png_uint_32)0x8000L));
+    }
+    else
+    {
+       png_memset(ptr, 0, (png_size_t)num_bytes);
+    }
+ #endif
+    return ((voidpf)ptr);
+ }
+ 
+ /* function to free memory for zlib */
+ #ifdef PNG_1_0_X
+ void PNGAPI
+ #else
+ void /* private */
+ #endif
+ png_zfree(voidpf png_ptr, voidpf ptr)
+ {
+    png_free((png_structp)png_ptr, (png_voidp)ptr);
+ }
+ 
+ /* Reset the CRC variable to 32 bits of 1's.  Care must be taken
+  * in case CRC is > 32 bits to leave the top bits 0.
+  */
+ void /* PRIVATE */
+ png_reset_crc(png_structp png_ptr)
+ {
+    png_ptr->crc = crc32(0, Z_NULL, 0);
+ }
+ 
+ /* Calculate the CRC over a section of data.  We can only pass as
+  * much data to this routine as the largest single buffer size.  We
+  * also check that this data will actually be used before going to the
+  * trouble of calculating it.
+  */
+ void /* PRIVATE */
+ png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)
+ {
+    int need_crc = 1;
+ 
+    if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
+    {
+       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
+           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
+          need_crc = 0;
+    }
+    else                                                    /* critical */
+    {
+       if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
+          need_crc = 0;
+    }
+ 
+    if (need_crc)
+       png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length);
+ }
+ 
+ /* Allocate the memory for an info_struct for the application.  We don't
+  * really need the png_ptr, but it could potentially be useful in the
+  * future.  This should be used in favour of malloc(sizeof(png_info))
+  * and png_info_init() so that applications that want to use a shared
+  * libpng don't have to be recompiled if png_info changes size.
+  */
+ png_infop PNGAPI
+ png_create_info_struct(png_structp png_ptr)
+ {
+    png_infop info_ptr;
+ 
+    png_debug(1, "in png_create_info_struct\n");
+    if(png_ptr == NULL) return (NULL);
+ #ifdef PNG_USER_MEM_SUPPORTED
+    info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
+       png_ptr->malloc_fn, png_ptr->mem_ptr);
+ #else
+    info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
+ #endif
+    if (info_ptr != NULL)
+       png_info_init_3(&info_ptr, sizeof(png_info));
+ 
+    return (info_ptr);
+ }
+ 
+ /* This function frees the memory associated with a single info struct.
+  * Normally, one would use either png_destroy_read_struct() or
+  * png_destroy_write_struct() to free an info struct, but this may be
+  * useful for some applications.
+  */
+ void PNGAPI
+ png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
+ {
+    png_infop info_ptr = NULL;
+ 
+    png_debug(1, "in png_destroy_info_struct\n");
+    if (info_ptr_ptr != NULL)
+       info_ptr = *info_ptr_ptr;
+ 
+    if (info_ptr != NULL)
+    {
+       png_info_destroy(png_ptr, info_ptr);
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+       png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,
+           png_ptr->mem_ptr);
+ #else
+       png_destroy_struct((png_voidp)info_ptr);
+ #endif
+       *info_ptr_ptr = NULL;
+    }
+ }
+ 
+ /* Initialize the info structure.  This is now an internal function (0.89)
+  * and applications using it are urged to use png_create_info_struct()
+  * instead.
+  */
+ #undef png_info_init
+ void PNGAPI
+ png_info_init(png_infop info_ptr)
+ {
+    /* We only come here via pre-1.0.12-compiled applications */
+    png_info_init_3(&info_ptr, 0);
+ }
+ 
+ void PNGAPI
+ png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
+ {
+    png_infop info_ptr = *ptr_ptr;
+ 
+    png_debug(1, "in png_info_init_3\n");
+ 
+    if(sizeof(png_info) > png_info_struct_size)
+      {
+        png_destroy_struct(info_ptr);
+        info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
+        *ptr_ptr = info_ptr;
+      }
+ 
+    /* set everything to 0 */
+    png_memset(info_ptr, 0, sizeof (png_info));
+ }
+ 
+ #ifdef PNG_FREE_ME_SUPPORTED
+ void PNGAPI
+ png_data_freer(png_structp png_ptr, png_infop info_ptr,
+    int freer, png_uint_32 mask)
+ {
+    png_debug(1, "in png_data_freer\n");
+    if (png_ptr == NULL || info_ptr == NULL)
+       return;
+    if(freer == PNG_DESTROY_WILL_FREE_DATA)
+       info_ptr->free_me |= mask;
+    else if(freer == PNG_USER_WILL_FREE_DATA)
+       info_ptr->free_me &= ~mask;
+    else
+       png_warning(png_ptr,
+          "Unknown freer parameter in png_data_freer.");
+ }
+ #endif
+ 
+ void PNGAPI
+ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
+    int num)
+ {
+    png_debug(1, "in png_free_data\n");
+    if (png_ptr == NULL || info_ptr == NULL)
+       return;
+ 
+ #if defined(PNG_TEXT_SUPPORTED)
+ /* free text item num or (if num == -1) all text items */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
+ #else
+ if (mask & PNG_FREE_TEXT)
+ #endif
+ {
+    if (num != -1)
+    {
+      if (info_ptr->text && info_ptr->text[num].key)
+      {
+          png_free(png_ptr, info_ptr->text[num].key);
+          info_ptr->text[num].key = NULL;
+      }
+    }
+    else
+    {
+        int i;
+        for (i = 0; i < info_ptr->num_text; i++)
+            png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
+        png_free(png_ptr, info_ptr->text);
+        info_ptr->text = NULL;
+        info_ptr->num_text=0;
+    }
+ }
+ #endif
+ 
+ #if defined(PNG_tRNS_SUPPORTED)
+ /* free any tRNS entry */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
+ #else
+ if ((mask & PNG_FREE_TRNS) && (png_ptr->flags & PNG_FLAG_FREE_TRNS))
+ #endif
+ {
+     png_free(png_ptr, info_ptr->trans);
+     info_ptr->valid &= ~PNG_INFO_tRNS;
+ #ifndef PNG_FREE_ME_SUPPORTED
+     png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;
+ #endif
+     info_ptr->trans = NULL;
+ }
+ #endif
+ 
+ #if defined(PNG_sCAL_SUPPORTED)
+ /* free any sCAL entry */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
+ #else
+ if (mask & PNG_FREE_SCAL)
+ #endif
+ {
+ #if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
+     png_free(png_ptr, info_ptr->scal_s_width);
+     png_free(png_ptr, info_ptr->scal_s_height);
+     info_ptr->scal_s_width = NULL;
+     info_ptr->scal_s_height = NULL;
+ #endif
+     info_ptr->valid &= ~PNG_INFO_sCAL;
+ }
+ #endif
+ 
+ #if defined(PNG_pCAL_SUPPORTED)
+ /* free any pCAL entry */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
+ #else
+ if (mask & PNG_FREE_PCAL)
+ #endif
+ {
+     png_free(png_ptr, info_ptr->pcal_purpose);
+     png_free(png_ptr, info_ptr->pcal_units);
+     info_ptr->pcal_purpose = NULL;
+     info_ptr->pcal_units = NULL;
+     if (info_ptr->pcal_params != NULL)
+     {
+         int i;
+         for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
+         {
+           png_free(png_ptr, info_ptr->pcal_params[i]);
+           info_ptr->pcal_params[i]=NULL;
+         }
+         png_free(png_ptr, info_ptr->pcal_params);
+         info_ptr->pcal_params = NULL;
+     }
+     info_ptr->valid &= ~PNG_INFO_pCAL;
+ }
+ #endif
+ 
+ #if defined(PNG_iCCP_SUPPORTED)
+ /* free any iCCP entry */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
+ #else
+ if (mask & PNG_FREE_ICCP)
+ #endif
+ {
+     png_free(png_ptr, info_ptr->iccp_name);
+     png_free(png_ptr, info_ptr->iccp_profile);
+     info_ptr->iccp_name = NULL;
+     info_ptr->iccp_profile = NULL;
+     info_ptr->valid &= ~PNG_INFO_iCCP;
+ }
+ #endif
+ 
+ #if defined(PNG_sPLT_SUPPORTED)
+ /* free a given sPLT entry, or (if num == -1) all sPLT entries */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
+ #else
+ if (mask & PNG_FREE_SPLT)
+ #endif
+ {
+    if (num != -1)
+    {
+       if(info_ptr->splt_palettes)
+       {
+           png_free(png_ptr, info_ptr->splt_palettes[num].name);
+           png_free(png_ptr, info_ptr->splt_palettes[num].entries);
+           info_ptr->splt_palettes[num].name = NULL;
+           info_ptr->splt_palettes[num].entries = NULL;
+       }
+    }
+    else
+    {
+        if(info_ptr->splt_palettes_num)
+        {
+          int i;
+          for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
+             png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);
+ 
+          png_free(png_ptr, info_ptr->splt_palettes);
+          info_ptr->splt_palettes = NULL;
+          info_ptr->splt_palettes_num = 0;
+        }
+        info_ptr->valid &= ~PNG_INFO_sPLT;
+    }
+ }
+ #endif
+ 
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
+ #else
+ if (mask & PNG_FREE_UNKN)
+ #endif
+ {
+    if (num != -1)
+    {
+        if(info_ptr->unknown_chunks)
+        {
+           png_free(png_ptr, info_ptr->unknown_chunks[num].data);
+           info_ptr->unknown_chunks[num].data = NULL;
+        }
+    }
+    else
+    {
+        int i;
+ 
+        if(info_ptr->unknown_chunks_num)
+        {
+          for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)
+             png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);
+ 
+          png_free(png_ptr, info_ptr->unknown_chunks);
+          info_ptr->unknown_chunks = NULL;
+          info_ptr->unknown_chunks_num = 0;
+        }
+    }
+ }
+ #endif
+ 
+ #if defined(PNG_hIST_SUPPORTED)
+ /* free any hIST entry */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
+ #else
+ if ((mask & PNG_FREE_HIST) && (png_ptr->flags & PNG_FLAG_FREE_HIST))
+ #endif
+ {
+     png_free(png_ptr, info_ptr->hist);
+     info_ptr->hist = NULL;
+     info_ptr->valid &= ~PNG_INFO_hIST;
+ #ifndef PNG_FREE_ME_SUPPORTED
+     png_ptr->flags &= ~PNG_FLAG_FREE_HIST;
+ #endif
+ }
+ #endif
+ 
+ /* free any PLTE entry that was internally allocated */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
+ #else
+ if ((mask & PNG_FREE_PLTE) && (png_ptr->flags & PNG_FLAG_FREE_PLTE))
+ #endif
+ {
+     png_zfree(png_ptr, info_ptr->palette);
+     info_ptr->palette = NULL;
+     info_ptr->valid &= ~PNG_INFO_PLTE;
+ #ifndef PNG_FREE_ME_SUPPORTED
+     png_ptr->flags &= ~PNG_FLAG_FREE_PLTE;
+ #endif
+     info_ptr->num_palette = 0;
+ }
+ 
+ #if defined(PNG_INFO_IMAGE_SUPPORTED)
+ /* free any image bits attached to the info structure */
+ #ifdef PNG_FREE_ME_SUPPORTED
+ if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
+ #else
+ if (mask & PNG_FREE_ROWS)
+ #endif
+ {
+     if(info_ptr->row_pointers)
+     {
+        int row;
+        for (row = 0; row < (int)info_ptr->height; row++)
+        {
+           png_free(png_ptr, info_ptr->row_pointers[row]);
+           info_ptr->row_pointers[row]=NULL;
+        }
+        png_free(png_ptr, info_ptr->row_pointers);
+        info_ptr->row_pointers=NULL;
+     }
+     info_ptr->valid &= ~PNG_INFO_IDAT;
+ }
+ #endif
+ 
+ #ifdef PNG_FREE_ME_SUPPORTED
+    if(num == -1)
+      info_ptr->free_me &= ~mask;
+    else
+      info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);
+ #endif
+ }
+ 
+ /* This is an internal routine to free any memory that the info struct is
+  * pointing to before re-using it or freeing the struct itself.  Recall
+  * that png_free() checks for NULL pointers for us.
+  */
+ void /* PRIVATE */
+ png_info_destroy(png_structp png_ptr, png_infop info_ptr)
+ {
+    png_debug(1, "in png_info_destroy\n");
+ 
+    png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
+ 
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+    if (png_ptr->num_chunk_list)
+    {
+        png_free(png_ptr, png_ptr->chunk_list);
+        png_ptr->chunk_list=NULL;
+        png_ptr->num_chunk_list=0;
+    }
+ #endif
+ 
+    png_info_init_3(&info_ptr, sizeof(png_info));
+ }
+ 
+ /* This function returns a pointer to the io_ptr associated with the user
+  * functions.  The application should free any memory associated with this
+  * pointer before png_write_destroy() or png_read_destroy() are called.
+  */
+ png_voidp PNGAPI
+ png_get_io_ptr(png_structp png_ptr)
+ {
+    return (png_ptr->io_ptr);
+ }
+ 
+ #if !defined(PNG_NO_STDIO)
+ /* Initialize the default input/output functions for the PNG file.  If you
+  * use your own read or write routines, you can call either png_set_read_fn()
+  * or png_set_write_fn() instead of png_init_io().  If you have defined
+  * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't
+  * necessarily available.
+  */
+ void PNGAPI
+ png_init_io(png_structp png_ptr, png_FILE_p fp)
+ {
+    png_debug(1, "in png_init_io\n");
+    png_ptr->io_ptr = (png_voidp)fp;
+ }
+ #endif
+ 
+ #if defined(PNG_TIME_RFC1123_SUPPORTED)
+ /* Convert the supplied time into an RFC 1123 string suitable for use in
+  * a "Creation Time" or other text-based time string.
+  */
+ png_charp PNGAPI
+ png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
+ {
+    static PNG_CONST char short_months[12][4] =
+         {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
+ 
+    if (png_ptr->time_buffer == NULL)
+    {
+       png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
+          sizeof(char)));
+    }
+ 
+ #if defined(_WIN32_WCE)
+    {
+       wchar_t time_buf[29];
+       wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"),
+           ptime->day % 32, short_months[(ptime->month - 1) % 12],
+         ptime->year, ptime->hour % 24, ptime->minute % 60,
+           ptime->second % 61);
+       WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer, 29,
+           NULL, NULL);
+    }
+ #else
+ #ifdef USE_FAR_KEYWORD
+    {
+       char near_time_buf[29];
+       sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000",
+           ptime->day % 32, short_months[(ptime->month - 1) % 12],
+           ptime->year, ptime->hour % 24, ptime->minute % 60,
+           ptime->second % 61);
+       png_memcpy(png_ptr->time_buffer, near_time_buf,
+           29*sizeof(char));
+    }
+ #else
+    sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000",
+        ptime->day % 32, short_months[(ptime->month - 1) % 12],
+        ptime->year, ptime->hour % 24, ptime->minute % 60,
+        ptime->second % 61);
+ #endif
+ #endif /* _WIN32_WCE */
+    return ((png_charp)png_ptr->time_buffer);
+ }
+ #endif /* PNG_TIME_RFC1123_SUPPORTED */
+ 
+ #if 0
+ /* Signature string for a PNG file. */
+ png_bytep PNGAPI
+ png_sig_bytes(void)
+ {
+    return ((png_bytep)"\211\120\116\107\015\012\032\012");
+ }
+ #endif
+ 
+ png_charp PNGAPI
+ png_get_copyright(png_structp png_ptr)
+ {
+    if (png_ptr != NULL || png_ptr == NULL)  /* silence compiler warning */
+    return ((png_charp) "\n libpng version 1.2.5 - October 3, 2002\n\
+    Copyright (c) 1998-2002 Glenn Randers-Pehrson\n\
+    Copyright (c) 1996-1997 Andreas Dilger\n\
+    Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.\n");
+    return ((png_charp) "");
+ }
+ 
+ /* The following return the library version as a short string in the
+  * format 1.0.0 through 99.99.99zz.  To get the version of *.h files used
+  * with your application, print out PNG_LIBPNG_VER_STRING, which is defined
+  * in png.h.
+  */
+ 
+ png_charp PNGAPI
+ png_get_libpng_ver(png_structp png_ptr)
+ {
+    /* Version of *.c files used when building libpng */
+    if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */
+       return((png_charp) "1.2.5");
+    return((png_charp) "1.2.5");
+ }
+ 
+ png_charp PNGAPI
+ png_get_header_ver(png_structp png_ptr)
+ {
+    /* Version of *.h files used when building libpng */
+    if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */
+       return((png_charp) PNG_LIBPNG_VER_STRING);
+    return((png_charp) PNG_LIBPNG_VER_STRING);
+ }
+ 
+ png_charp PNGAPI
+ png_get_header_version(png_structp png_ptr)
+ {
+    /* Returns longer string containing both version and date */
+    if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */
+       return((png_charp) PNG_HEADER_VERSION_STRING);
+    return((png_charp) PNG_HEADER_VERSION_STRING);
+ }
+ 
+ #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+ int PNGAPI
+ png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
+ {
+    /* check chunk_name and return "keep" value if it's on the list, else 0 */
+    int i;
+    png_bytep p;
+    if((png_ptr == NULL && chunk_name == NULL) || png_ptr->num_chunk_list<=0)
+       return 0;
+    p=png_ptr->chunk_list+png_ptr->num_chunk_list*5-5;
+    for (i = png_ptr->num_chunk_list; i; i--, p-=5)
+       if (!png_memcmp(chunk_name, p, 4))
+         return ((int)*(p+4));
+    return 0;
+ }
+ #endif
+ 
+ /* This function, added to libpng-1.0.6g, is untested. */
+ int PNGAPI
+ png_reset_zstream(png_structp png_ptr)
+ {
+    return (inflateReset(&png_ptr->zstream));
+ }
+ 
+ /* This function was added to libpng-1.0.7 */
+ png_uint_32 PNGAPI
+ png_access_version_number(void)
+ {
+    /* Version of *.c files used when building libpng */
+    return((png_uint_32) 10205L);
+ }
+ 
+ 
+ #if !defined(PNG_1_0_X)
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+     /* GRR:  could add this:   && defined(PNG_MMX_CODE_SUPPORTED) */
+ /* this INTERNAL function was added to libpng 1.2.0 */
+ void /* PRIVATE */
+ png_init_mmx_flags (png_structp png_ptr)
+ {
+     png_ptr->mmx_rowbytes_threshold = 0;
+     png_ptr->mmx_bitdepth_threshold = 0;
+ 
+ #  if (defined(PNG_USE_PNGVCRD) || defined(PNG_USE_PNGGCCRD))
+ 
+     png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_COMPILED;
+ 
+     if (png_mmx_support() > 0) {
+         png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
+ #    ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW
+                               | PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
+ #    endif
+ #    ifdef PNG_HAVE_ASSEMBLER_READ_INTERLACE
+                               | PNG_ASM_FLAG_MMX_READ_INTERLACE
+ #    endif
+ #    ifndef PNG_HAVE_ASSEMBLER_READ_FILTER_ROW
+                               ;
+ #    else
+                               | PNG_ASM_FLAG_MMX_READ_FILTER_SUB
+                               | PNG_ASM_FLAG_MMX_READ_FILTER_UP
+                               | PNG_ASM_FLAG_MMX_READ_FILTER_AVG
+                               | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;
+ 
+         png_ptr->mmx_rowbytes_threshold = PNG_MMX_ROWBYTES_THRESHOLD_DEFAULT;
+         png_ptr->mmx_bitdepth_threshold = PNG_MMX_BITDEPTH_THRESHOLD_DEFAULT;
+ #    endif
+     } else {
+         png_ptr->asm_flags &= ~( PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
+                                | PNG_MMX_READ_FLAGS
+                                | PNG_MMX_WRITE_FLAGS );
+     }
+ 
+ #  else /* !((PNGVCRD || PNGGCCRD) && PNG_ASSEMBLER_CODE_SUPPORTED)) */
+ 
+     /* clear all MMX flags; no support is compiled in */
+     png_ptr->asm_flags &= ~( PNG_MMX_FLAGS );
+ 
+ #  endif /* ?(PNGVCRD || PNGGCCRD) */
+ }
+ 
+ #endif /* !(PNG_ASSEMBLER_CODE_SUPPORTED) */
+ 
+ /* this function was added to libpng 1.2.0 */
+ #if !defined(PNG_USE_PNGGCCRD) && \
+     !(defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_USE_PNGVCRD))
+ int PNGAPI
+ png_mmx_support(void)
+ {
+     return -1;
+ }
+ #endif
+ #endif /* PNG_1_0_X */


Index: llvm/runtime/libpng/png.h
diff -c /dev/null llvm/runtime/libpng/png.h:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/png.h	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,3283 ----
+ /* png.h - header file for PNG reference library
+  *
+  * libpng version 1.2.5 - October 3, 2002
+  * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+  *
+  * Authors and maintainers:
+  *  libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
+  *  libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
+  *  libpng versions 0.97, January 1998, through 1.2.5 - October 3, 2002: Glenn
+  *  See also "Contributing Authors", below.
+  *
+  * Note about libpng version numbers:
+  *
+  *    Due to various miscommunications, unforeseen code incompatibilities
+  *    and occasional factors outside the authors' control, version numbering
+  *    on the library has not always been consistent and straightforward.
+  *    The following table summarizes matters since version 0.89c, which was
+  *    the first widely used release:
+  *
+  *    source                 png.h  png.h  shared-lib
+  *    version                string   int  version
+  *    -------                ------ -----  ----------
+  *    0.89c "1.0 beta 3"     0.89      89  1.0.89
+  *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
+  *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
+  *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
+  *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
+  *    0.97c                  0.97      97  2.0.97
+  *    0.98                   0.98      98  2.0.98
+  *    0.99                   0.99      98  2.0.99
+  *    0.99a-m                0.99      99  2.0.99
+  *    1.00                   1.00     100  2.1.0 [100 should be 10000]
+  *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
+  *    1.0.1       png.h string is   10001  2.1.0
+  *    1.0.1a-e    identical to the  10002  from here on, the shared library
+  *    1.0.2       source version)   10002  is 2.V where V is the source code
+  *    1.0.2a-b                      10003  version, except as noted.
+  *    1.0.3                         10003
+  *    1.0.3a-d                      10004
+  *    1.0.4                         10004
+  *    1.0.4a-f                      10005
+  *    1.0.5 (+ 2 patches)           10005
+  *    1.0.5a-d                      10006
+  *    1.0.5e-r                      10100 (not source compatible)
+  *    1.0.5s-v                      10006 (not binary compatible)
+  *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
+  *    1.0.6d-f                      10007 (still binary incompatible)
+  *    1.0.6g                        10007
+  *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
+  *    1.0.6i                        10007  10.6i
+  *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
+  *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
+  *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
+  *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
+  *    1.0.7                    1    10007  (still compatible)
+  *    1.0.8beta1-4             1    10008  2.1.0.8beta1-4
+  *    1.0.8rc1                 1    10008  2.1.0.8rc1
+  *    1.0.8                    1    10008  2.1.0.8
+  *    1.0.9beta1-6             1    10009  2.1.0.9beta1-6
+  *    1.0.9rc1                 1    10009  2.1.0.9rc1
+  *    1.0.9beta7-10            1    10009  2.1.0.9beta7-10
+  *    1.0.9rc2                 1    10009  2.1.0.9rc2
+  *    1.0.9                    1    10009  2.1.0.9
+  *    1.0.10beta1              1    10010  2.1.0.10beta1
+  *    1.0.10rc1                1    10010  2.1.0.10rc1
+  *    1.0.10                   1    10010  2.1.0.10
+  *    1.0.11beta1-3            1    10011  2.1.0.11beta1-3
+  *    1.0.11rc1                1    10011  2.1.0.11rc1
+  *    1.0.11                   1    10011  2.1.0.11
+  *    1.0.12beta1-2            2    10012  2.1.0.12beta1-2
+  *    1.0.12rc1                2    10012  2.1.0.12rc1
+  *    1.0.12                   2    10012  2.1.0.12
+  *    1.1.0a-f                 -    10100  2.1.1.0a-f (branch abandoned)
+  *    1.2.0beta1-2             2    10200  2.1.2.0beta1-2
+  *    1.2.0beta3-5             3    10200  3.1.2.0beta3-5
+  *    1.2.0rc1                 3    10200  3.1.2.0rc1
+  *    1.2.0                    3    10200  3.1.2.0
+  *    1.2.1beta1-4             3    10201  3.1.2.1beta1-4
+  *    1.2.1rc1-2               3    10201  3.1.2.1rc1-2
+  *    1.2.1                    3    10201  3.1.2.1
+  *    1.2.2beta1-6            12    10202  12.so.0.1.2.2beta1-6
+  *    1.0.13beta1             10    10013  10.so.0.1.0.13beta1
+  *    1.0.13rc1               10    10013  10.so.0.1.0.13rc1
+  *    1.2.2rc1                12    10202  12.so.0.1.2.2rc1
+  *    1.0.13                  10    10013  10.so.0.1.0.13
+  *    1.2.2                   12    10202  12.so.0.1.2.2
+  *    1.2.3rc1-6              12    10203  12.so.0.1.2.3rc1-6
+  *    1.2.3                   12    10203  12.so.0.1.2.3
+  *    1.2.4beta1-3            13    10204  12.so.0.1.2.4beta1-3
+  *    1.0.14rc1               13    10014  10.so.0.1.0.14rc1
+  *    1.2.4rc1                13    10204  12.so.0.1.2.4rc1
+  *    1.0.14                  10    10014  10.so.0.1.0.14
+  *    1.2.4                   13    10204  12.so.0.1.2.4
+  *    1.2.5beta1-2            13    10205  12.so.0.1.2.5beta1-2
+  *    1.0.15rc1-3             10    10015  10.so.0.1.0.15rc1-3
+  *    1.2.5rc1-3              13    10205  12.so.0.1.2.5rc1-3
+  *    1.0.15                  10    10015  10.so.0.1.0.15
+  *    1.2.5                   13    10205  12.so.0.1.2.5
+  *
+  *    Henceforth the source version will match the shared-library major
+  *    and minor numbers; the shared-library major version number will be
+  *    used for changes in backward compatibility, as it is intended.  The
+  *    PNG_LIBPNG_VER macro, which is not used within libpng but is available
+  *    for applications, is an unsigned integer of the form xyyzz corresponding
+  *    to the source version x.y.z (leading zeros in y and z).  Beta versions
+  *    were given the previous public release number plus a letter, until
+  *    version 1.0.6j; from then on they were given the upcoming public
+  *    release number plus "betaNN" or "rcN".
+  *
+  *    Binary incompatibility exists only when applications make direct access
+  *    to the info_ptr or png_ptr members through png.h, and the compiled
+  *    application is loaded with a different version of the library.
+  *
+  *    DLLNUM will change each time there are forward or backward changes
+  *    in binary compatibility (e.g., when a new feature is added).
+  *
+  * See libpng.txt or libpng.3 for more information.  The PNG specification
+  * is available as RFC 2083 <ftp://ftp.uu.net/graphics/png/documents/>
+  * and as a W3C Recommendation <http://www.w3.org/TR/REC.png.html>
+  */
+ 
+ /*
+  * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+  *
+  * If you modify libpng you may insert additional notices immediately following
+  * this sentence.
+  *
+  * libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
+  * Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
+  * distributed according to the same disclaimer and license as libpng-1.0.6
+  * with the following individuals added to the list of Contributing Authors
+  *
+  *    Simon-Pierre Cadieux
+  *    Eric S. Raymond
+  *    Gilles Vollant
+  *
+  * and with the following additions to the disclaimer:
+  *
+  *    There is no warranty against interference with your enjoyment of the
+  *    library or against infringement.  There is no warranty that our
+  *    efforts or the library will fulfill any of your particular purposes
+  *    or needs.  This library is provided with all faults, and the entire
+  *    risk of satisfactory quality, performance, accuracy, and effort is with
+  *    the user.
+  *
+  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
+  * Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson
+  * Distributed according to the same disclaimer and license as libpng-0.96,
+  * with the following individuals added to the list of Contributing Authors:
+  *
+  *    Tom Lane
+  *    Glenn Randers-Pehrson
+  *    Willem van Schaik
+  *
+  * libpng versions 0.89, June 1996, through 0.96, May 1997, are
+  * Copyright (c) 1996, 1997 Andreas Dilger
+  * Distributed according to the same disclaimer and license as libpng-0.88,
+  * with the following individuals added to the list of Contributing Authors:
+  *
+  *    John Bowler
+  *    Kevin Bracey
+  *    Sam Bushell
+  *    Magnus Holmgren
+  *    Greg Roelofs
+  *    Tom Tanner
+  *
+  * libpng versions 0.5, May 1995, through 0.88, January 1996, are
+  * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+  *
+  * For the purposes of this copyright and license, "Contributing Authors"
+  * is defined as the following set of individuals:
+  *
+  *    Andreas Dilger
+  *    Dave Martindale
+  *    Guy Eric Schalnat
+  *    Paul Schmidt
+  *    Tim Wegner
+  *
+  * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
+  * and Group 42, Inc. disclaim all warranties, expressed or implied,
+  * including, without limitation, the warranties of merchantability and of
+  * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
+  * assume no liability for direct, indirect, incidental, special, exemplary,
+  * or consequential damages, which may result from the use of the PNG
+  * Reference Library, even if advised of the possibility of such damage.
+  *
+  * Permission is hereby granted to use, copy, modify, and distribute this
+  * source code, or portions hereof, for any purpose, without fee, subject
+  * to the following restrictions:
+  *
+  * 1. The origin of this source code must not be misrepresented.
+  *
+  * 2. Altered versions must be plainly marked as such and
+  * must not be misrepresented as being the original source.
+  *
+  * 3. This Copyright notice may not be removed or altered from
+  *    any source or altered source distribution.
+  *
+  * The Contributing Authors and Group 42, Inc. specifically permit, without
+  * fee, and encourage the use of this source code as a component to
+  * supporting the PNG file format in commercial products.  If you use this
+  * source code in a product, acknowledgment is not required but would be
+  * appreciated.
+  */
+ 
+ /*
+  * A "png_get_copyright" function is available, for convenient use in "about"
+  * boxes and the like:
+  *
+  * printf("%s",png_get_copyright(NULL));
+  *
+  * Also, the PNG logo (in PNG format, of course) is supplied in the
+  * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
+  */
+ 
+ /*
+  * Libpng is OSI Certified Open Source Software.  OSI Certified is a
+  * certification mark of the Open Source Initiative.
+  */
+ 
+ /*
+  * The contributing authors would like to thank all those who helped
+  * with testing, bug fixes, and patience.  This wouldn't have been
+  * possible without all of you.
+  *
+  * Thanks to Frank J. T. Wojcik for helping with the documentation.
+  */
+ 
+ /*
+  * Y2K compliance in libpng:
+  * =========================
+  *
+  *    October 3, 2002
+  *
+  *    Since the PNG Development group is an ad-hoc body, we can't make
+  *    an official declaration.
+  *
+  *    This is your unofficial assurance that libpng from version 0.71 and
+  *    upward through 1.2.5 are Y2K compliant.  It is my belief that earlier
+  *    versions were also Y2K compliant.
+  *
+  *    Libpng only has three year fields.  One is a 2-byte unsigned integer
+  *    that will hold years up to 65535.  The other two hold the date in text
+  *    format, and will hold years up to 9999.
+  *
+  *    The integer is
+  *        "png_uint_16 year" in png_time_struct.
+  *
+  *    The strings are
+  *        "png_charp time_buffer" in png_struct and
+  *        "near_time_buffer", which is a local character string in png.c.
+  *
+  *    There are seven time-related functions:
+  *        png.c: png_convert_to_rfc_1123() in png.c
+  *          (formerly png_convert_to_rfc_1152() in error)
+  *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
+  *        png_convert_from_time_t() in pngwrite.c
+  *        png_get_tIME() in pngget.c
+  *        png_handle_tIME() in pngrutil.c, called in pngread.c
+  *        png_set_tIME() in pngset.c
+  *        png_write_tIME() in pngwutil.c, called in pngwrite.c
+  *
+  *    All handle dates properly in a Y2K environment.  The
+  *    png_convert_from_time_t() function calls gmtime() to convert from system
+  *    clock time, which returns (year - 1900), which we properly convert to
+  *    the full 4-digit year.  There is a possibility that applications using
+  *    libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
+  *    function, or that they are incorrectly passing only a 2-digit year
+  *    instead of "year - 1900" into the png_convert_from_struct_tm() function,
+  *    but this is not under our control.  The libpng documentation has always
+  *    stated that it works with 4-digit years, and the APIs have been
+  *    documented as such.
+  *
+  *    The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
+  *    integer to hold the year, and can hold years as large as 65535.
+  *
+  *    zlib, upon which libpng depends, is also Y2K compliant.  It contains
+  *    no date-related code.
+  *
+  *       Glenn Randers-Pehrson
+  *       libpng maintainer
+  *       PNG Development Group
+  */
+ 
+ #ifndef PNG_H
+ #define PNG_H
+ 
+ /* This is not the place to learn how to use libpng.  The file libpng.txt
+  * describes how to use libpng, and the file example.c summarizes it
+  * with some code on which to build.  This file is useful for looking
+  * at the actual function definitions and structure components.
+  */
+ 
+ /* Version information for png.h - this should match the version in png.c */
+ #define PNG_LIBPNG_VER_STRING "1.2.5"
+ 
+ #define PNG_LIBPNG_VER_SONUM   0
+ #define PNG_LIBPNG_VER_DLLNUM  %DLLNUM%
+ 
+ /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
+ #define PNG_LIBPNG_VER_MAJOR   1
+ #define PNG_LIBPNG_VER_MINOR   2
+ #define PNG_LIBPNG_VER_RELEASE 5
+ /* This should match the numeric part of the final component of
+  * PNG_LIBPNG_VER_STRING, omitting any leading zero: */
+ 
+ #define PNG_LIBPNG_VER_BUILD  0
+ 
+ #define PNG_LIBPNG_BUILD_ALPHA    1
+ #define PNG_LIBPNG_BUILD_BETA     2
+ #define PNG_LIBPNG_BUILD_RC       3
+ #define PNG_LIBPNG_BUILD_STABLE   4
+ #define PNG_LIBPNG_BUILD_TYPEMASK 7
+ #define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with STABLE only */
+ #define PNG_LIBPNG_BUILD_TYPE 4
+ 
+ /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
+  * We must not include leading zeros.
+  * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
+  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
+  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release */
+ #define PNG_LIBPNG_VER 10205 /* 1.2.5 */
+ 
+ #ifndef PNG_VERSION_INFO_ONLY
+ 
+ /* include the compression library's header */
+ #include "zlib.h"
+ 
+ /* include all user configurable info, including optional assembler routines */
+ #include "pngconf.h"
+ 
+ /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
+ #ifdef __cplusplus
+ extern "C" {
+ #endif /* __cplusplus */
+ 
+ /* This file is arranged in several sections.  The first section contains
+  * structure and type definitions.  The second section contains the external
+  * library functions, while the third has the internal library functions,
+  * which applications aren't expected to use directly.
+  */
+ 
+ #ifndef PNG_NO_TYPECAST_NULL
+ #define int_p_NULL                (int *)NULL
+ #define png_bytep_NULL            (png_bytep)NULL
+ #define png_bytepp_NULL           (png_bytepp)NULL
+ #define png_doublep_NULL          (png_doublep)NULL
+ #define png_error_ptr_NULL        (png_error_ptr)NULL
+ #define png_flush_ptr_NULL        (png_flush_ptr)NULL
+ #define png_free_ptr_NULL         (png_free_ptr)NULL
+ #define png_infopp_NULL           (png_infopp)NULL
+ #define png_malloc_ptr_NULL       (png_malloc_ptr)NULL
+ #define png_read_status_ptr_NULL  (png_read_status_ptr)NULL
+ #define png_rw_ptr_NULL           (png_rw_ptr)NULL
+ #define png_structp_NULL          (png_structp)NULL
+ #define png_uint_16p_NULL         (png_uint_16p)NULL
+ #define png_voidp_NULL            (png_voidp)NULL
+ #define png_write_status_ptr_NULL (png_write_status_ptr)NULL
+ #else
+ #define int_p_NULL                NULL
+ #define png_bytep_NULL            NULL
+ #define png_bytepp_NULL           NULL
+ #define png_doublep_NULL          NULL
+ #define png_error_ptr_NULL        NULL
+ #define png_flush_ptr_NULL        NULL
+ #define png_free_ptr_NULL         NULL
+ #define png_infopp_NULL           NULL
+ #define png_malloc_ptr_NULL       NULL
+ #define png_read_status_ptr_NULL  NULL
+ #define png_rw_ptr_NULL           NULL
+ #define png_structp_NULL          NULL
+ #define png_uint_16p_NULL         NULL
+ #define png_voidp_NULL            NULL
+ #define png_write_status_ptr_NULL NULL
+ #endif
+ 
+ /* variables declared in png.c - only it needs to define PNG_NO_EXTERN */
+ #if !defined(PNG_NO_EXTERN) || defined(PNG_ALWAYS_EXTERN)
+ /* Version information for C files, stored in png.c.  This had better match
+  * the version above.
+  */
+ #ifdef PNG_USE_GLOBAL_ARRAYS
+ PNG_EXPORT_VAR (const char) png_libpng_ver[18];
+   /* need room for 99.99.99beta99z */
+ #else
+ #define png_libpng_ver png_get_header_ver(NULL)
+ #endif
+ 
+ #ifdef PNG_USE_GLOBAL_ARRAYS
+ /* This was removed in version 1.0.5c */
+ /* Structures to facilitate easy interlacing.  See png.c for more details */
+ PNG_EXPORT_VAR (const int FARDATA) png_pass_start[7];
+ PNG_EXPORT_VAR (const int FARDATA) png_pass_inc[7];
+ PNG_EXPORT_VAR (const int FARDATA) png_pass_ystart[7];
+ PNG_EXPORT_VAR (const int FARDATA) png_pass_yinc[7];
+ PNG_EXPORT_VAR (const int FARDATA) png_pass_mask[7];
+ PNG_EXPORT_VAR (const int FARDATA) png_pass_dsp_mask[7];
+ #ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW
+ PNG_EXPORT_VAR (const int FARDATA) png_pass_width[7];
+ #endif
+ /* This isn't currently used.  If you need it, see png.c for more details.
+ PNG_EXPORT_VAR (const int FARDATA) png_pass_height[7];
+ */
+ #endif
+ 
+ #endif /* PNG_NO_EXTERN */
+ 
+ /* Three color definitions.  The order of the red, green, and blue, (and the
+  * exact size) is not important, although the size of the fields need to
+  * be png_byte or png_uint_16 (as defined below).
+  */
+ typedef struct png_color_struct
+ {
+    png_byte red;
+    png_byte green;
+    png_byte blue;
+ } png_color;
+ typedef png_color FAR * png_colorp;
+ typedef png_color FAR * FAR * png_colorpp;
+ 
+ typedef struct png_color_16_struct
+ {
+    png_byte index;    /* used for palette files */
+    png_uint_16 red;   /* for use in red green blue files */
+    png_uint_16 green;
+    png_uint_16 blue;
+    png_uint_16 gray;  /* for use in grayscale files */
+ } png_color_16;
+ typedef png_color_16 FAR * png_color_16p;
+ typedef png_color_16 FAR * FAR * png_color_16pp;
+ 
+ typedef struct png_color_8_struct
+ {
+    png_byte red;   /* for use in red green blue files */
+    png_byte green;
+    png_byte blue;
+    png_byte gray;  /* for use in grayscale files */
+    png_byte alpha; /* for alpha channel files */
+ } png_color_8;
+ typedef png_color_8 FAR * png_color_8p;
+ typedef png_color_8 FAR * FAR * png_color_8pp;
+ 
+ /*
+  * The following two structures are used for the in-core representation
+  * of sPLT chunks.
+  */
+ typedef struct png_sPLT_entry_struct
+ {
+    png_uint_16 red;
+    png_uint_16 green;
+    png_uint_16 blue;
+    png_uint_16 alpha;
+    png_uint_16 frequency;
+ } png_sPLT_entry;
+ typedef png_sPLT_entry FAR * png_sPLT_entryp;
+ typedef png_sPLT_entry FAR * FAR * png_sPLT_entrypp;
+ 
+ /*  When the depth of the sPLT palette is 8 bits, the color and alpha samples
+  *  occupy the LSB of their respective members, and the MSB of each member
+  *  is zero-filled.  The frequency member always occupies the full 16 bits.
+  */
+ 
+ typedef struct png_sPLT_struct
+ {
+    png_charp name;           /* palette name */
+    png_byte depth;           /* depth of palette samples */
+    png_sPLT_entryp entries;  /* palette entries */
+    png_int_32 nentries;      /* number of palette entries */
+ } png_sPLT_t;
+ typedef png_sPLT_t FAR * png_sPLT_tp;
+ typedef png_sPLT_t FAR * FAR * png_sPLT_tpp;
+ 
+ #ifdef PNG_TEXT_SUPPORTED
+ /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
+  * and whether that contents is compressed or not.  The "key" field
+  * points to a regular zero-terminated C string.  The "text", "lang", and
+  * "lang_key" fields can be regular C strings, empty strings, or NULL pointers.
+  * However, the * structure returned by png_get_text() will always contain
+  * regular zero-terminated C strings (possibly empty), never NULL pointers,
+  * so they can be safely used in printf() and other string-handling functions.
+  */
+ typedef struct png_text_struct
+ {
+    int  compression;       /* compression value:
+                              -1: tEXt, none
+                               0: zTXt, deflate
+                               1: iTXt, none
+                               2: iTXt, deflate  */
+    png_charp key;          /* keyword, 1-79 character description of "text" */
+    png_charp text;         /* comment, may be an empty string (ie "")
+                               or a NULL pointer */
+    png_size_t text_length; /* length of the text string */
+ #ifdef PNG_iTXt_SUPPORTED
+    png_size_t itxt_length; /* length of the itxt string */
+    png_charp lang;         /* language code, 0-79 characters
+                               or a NULL pointer */
+    png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more
+                               chars or a NULL pointer */
+ #endif
+ } png_text;
+ typedef png_text FAR * png_textp;
+ typedef png_text FAR * FAR * png_textpp;
+ #endif
+ 
+ /* Supported compression types for text in PNG files (tEXt, and zTXt).
+  * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
+ #define PNG_TEXT_COMPRESSION_NONE_WR -3
+ #define PNG_TEXT_COMPRESSION_zTXt_WR -2
+ #define PNG_TEXT_COMPRESSION_NONE    -1
+ #define PNG_TEXT_COMPRESSION_zTXt     0
+ #define PNG_ITXT_COMPRESSION_NONE     1
+ #define PNG_ITXT_COMPRESSION_zTXt     2
+ #define PNG_TEXT_COMPRESSION_LAST     3  /* Not a valid value */
+ 
+ /* png_time is a way to hold the time in an machine independent way.
+  * Two conversions are provided, both from time_t and struct tm.  There
+  * is no portable way to convert to either of these structures, as far
+  * as I know.  If you know of a portable way, send it to me.  As a side
+  * note - PNG has always been Year 2000 compliant!
+  */
+ typedef struct png_time_struct
+ {
+    png_uint_16 year; /* full year, as in, 1995 */
+    png_byte month;   /* month of year, 1 - 12 */
+    png_byte day;     /* day of month, 1 - 31 */
+    png_byte hour;    /* hour of day, 0 - 23 */
+    png_byte minute;  /* minute of hour, 0 - 59 */
+    png_byte second;  /* second of minute, 0 - 60 (for leap seconds) */
+ } png_time;
+ typedef png_time FAR * png_timep;
+ typedef png_time FAR * FAR * png_timepp;
+ 
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ /* png_unknown_chunk is a structure to hold queued chunks for which there is
+  * no specific support.  The idea is that we can use this to queue
+  * up private chunks for output even though the library doesn't actually
+  * know about their semantics.
+  */
+ typedef struct png_unknown_chunk_t
+ {
+     png_byte name[5];
+     png_byte *data;
+     png_size_t size;
+ 
+     /* libpng-using applications should NOT directly modify this byte. */
+     png_byte location; /* mode of operation at read time */
+ }
+ png_unknown_chunk;
+ typedef png_unknown_chunk FAR * png_unknown_chunkp;
+ typedef png_unknown_chunk FAR * FAR * png_unknown_chunkpp;
+ #endif
+ 
+ /* png_info is a structure that holds the information in a PNG file so
+  * that the application can find out the characteristics of the image.
+  * If you are reading the file, this structure will tell you what is
+  * in the PNG file.  If you are writing the file, fill in the information
+  * you want to put into the PNG file, then call png_write_info().
+  * The names chosen should be very close to the PNG specification, so
+  * consult that document for information about the meaning of each field.
+  *
+  * With libpng < 0.95, it was only possible to directly set and read the
+  * the values in the png_info_struct, which meant that the contents and
+  * order of the values had to remain fixed.  With libpng 0.95 and later,
+  * however, there are now functions that abstract the contents of
+  * png_info_struct from the application, so this makes it easier to use
+  * libpng with dynamic libraries, and even makes it possible to use
+  * libraries that don't have all of the libpng ancillary chunk-handing
+  * functionality.
+  *
+  * In any case, the order of the parameters in png_info_struct should NOT
+  * be changed for as long as possible to keep compatibility with applications
+  * that use the old direct-access method with png_info_struct.
+  *
+  * The following members may have allocated storage attached that should be
+  * cleaned up before the structure is discarded: palette, trans, text,
+  * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile,
+  * splt_palettes, scal_unit, row_pointers, and unknowns.   By default, these
+  * are automatically freed when the info structure is deallocated, if they were
+  * allocated internally by libpng.  This behavior can be changed by means
+  * of the png_data_freer() function.
+  *
+  * More allocation details: all the chunk-reading functions that
+  * change these members go through the corresponding png_set_*
+  * functions.  A function to clear these members is available: see
+  * png_free_data().  The png_set_* functions do not depend on being
+  * able to point info structure members to any of the storage they are
+  * passed (they make their own copies), EXCEPT that the png_set_text
+  * functions use the same storage passed to them in the text_ptr or
+  * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns
+  * functions do not make their own copies.
+  */
+ typedef struct png_info_struct
+ {
+    /* the following are necessary for every PNG file */
+    png_uint_32 width;       /* width of image in pixels (from IHDR) */
+    png_uint_32 height;      /* height of image in pixels (from IHDR) */
+    png_uint_32 valid;       /* valid chunk data (see PNG_INFO_ below) */
+    png_uint_32 rowbytes;    /* bytes needed to hold an untransformed row */
+    png_colorp palette;      /* array of color values (valid & PNG_INFO_PLTE) */
+    png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */
+    png_uint_16 num_trans;   /* number of transparent palette color (tRNS) */
+    png_byte bit_depth;      /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */
+    png_byte color_type;     /* see PNG_COLOR_TYPE_ below (from IHDR) */
+    /* The following three should have been named *_method not *_type */
+    png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */
+    png_byte filter_type;    /* must be PNG_FILTER_TYPE_BASE (from IHDR) */
+    png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
+ 
+    /* The following is informational only on read, and not used on writes. */
+    png_byte channels;       /* number of data channels per pixel (1, 2, 3, 4) */
+    png_byte pixel_depth;    /* number of bits per pixel */
+    png_byte spare_byte;     /* to align the data, and for future use */
+    png_byte signature[8];   /* magic bytes read by libpng from start of file */
+ 
+    /* The rest of the data is optional.  If you are reading, check the
+     * valid field to see if the information in these are valid.  If you
+     * are writing, set the valid field to those chunks you want written,
+     * and initialize the appropriate fields below.
+     */
+ 
+ #if defined(PNG_gAMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
+    /* The gAMA chunk describes the gamma characteristics of the system
+     * on which the image was created, normally in the range [1.0, 2.5].
+     * Data is valid if (valid & PNG_INFO_gAMA) is non-zero.
+     */
+    float gamma; /* gamma value of image, if (valid & PNG_INFO_gAMA) */
+ #endif
+ 
+ #if defined(PNG_sRGB_SUPPORTED)
+     /* GR-P, 0.96a */
+     /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */
+    png_byte srgb_intent; /* sRGB rendering intent [0, 1, 2, or 3] */
+ #endif
+ 
+ #if defined(PNG_TEXT_SUPPORTED)
+    /* The tEXt, and zTXt chunks contain human-readable textual data in
+     * uncompressed, compressed, and optionally compressed forms, respectively.
+     * The data in "text" is an array of pointers to uncompressed,
+     * null-terminated C strings. Each chunk has a keyword that describes the
+     * textual data contained in that chunk.  Keywords are not required to be
+     * unique, and the text string may be empty.  Any number of text chunks may
+     * be in an image.
+     */
+    int num_text; /* number of comments read/to write */
+    int max_text; /* current size of text array */
+    png_textp text; /* array of comments read/to write */
+ #endif /* PNG_TEXT_SUPPORTED */
+ 
+ #if defined(PNG_tIME_SUPPORTED)
+    /* The tIME chunk holds the last time the displayed image data was
+     * modified.  See the png_time struct for the contents of this struct.
+     */
+    png_time mod_time;
+ #endif
+ 
+ #if defined(PNG_sBIT_SUPPORTED)
+    /* The sBIT chunk specifies the number of significant high-order bits
+     * in the pixel data.  Values are in the range [1, bit_depth], and are
+     * only specified for the channels in the pixel data.  The contents of
+     * the low-order bits is not specified.  Data is valid if
+     * (valid & PNG_INFO_sBIT) is non-zero.
+     */
+    png_color_8 sig_bit; /* significant bits in color channels */
+ #endif
+ 
+ #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \
+ defined(PNG_READ_BACKGROUND_SUPPORTED)
+    /* The tRNS chunk supplies transparency data for paletted images and
+     * other image types that don't need a full alpha channel.  There are
+     * "num_trans" transparency values for a paletted image, stored in the
+     * same order as the palette colors, starting from index 0.  Values
+     * for the data are in the range [0, 255], ranging from fully transparent
+     * to fully opaque, respectively.  For non-paletted images, there is a
+     * single color specified that should be treated as fully transparent.
+     * Data is valid if (valid & PNG_INFO_tRNS) is non-zero.
+     */
+    png_bytep trans; /* transparent values for paletted image */
+    png_color_16 trans_values; /* transparent color for non-palette image */
+ #endif
+ 
+ #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+    /* The bKGD chunk gives the suggested image background color if the
+     * display program does not have its own background color and the image
+     * is needs to composited onto a background before display.  The colors
+     * in "background" are normally in the same color space/depth as the
+     * pixel data.  Data is valid if (valid & PNG_INFO_bKGD) is non-zero.
+     */
+    png_color_16 background;
+ #endif
+ 
+ #if defined(PNG_oFFs_SUPPORTED)
+    /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
+     * and downwards from the top-left corner of the display, page, or other
+     * application-specific co-ordinate space.  See the PNG_OFFSET_ defines
+     * below for the unit types.  Valid if (valid & PNG_INFO_oFFs) non-zero.
+     */
+    png_int_32 x_offset; /* x offset on page */
+    png_int_32 y_offset; /* y offset on page */
+    png_byte offset_unit_type; /* offset units type */
+ #endif
+ 
+ #if defined(PNG_pHYs_SUPPORTED)
+    /* The pHYs chunk gives the physical pixel density of the image for
+     * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
+     * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
+     */
+    png_uint_32 x_pixels_per_unit; /* horizontal pixel density */
+    png_uint_32 y_pixels_per_unit; /* vertical pixel density */
+    png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
+ #endif
+ 
+ #if defined(PNG_hIST_SUPPORTED)
+    /* The hIST chunk contains the relative frequency or importance of the
+     * various palette entries, so that a viewer can intelligently select a
+     * reduced-color palette, if required.  Data is an array of "num_palette"
+     * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
+     * is non-zero.
+     */
+    png_uint_16p hist;
+ #endif
+ 
+ #ifdef PNG_cHRM_SUPPORTED
+    /* The cHRM chunk describes the CIE color characteristics of the monitor
+     * on which the PNG was created.  This data allows the viewer to do gamut
+     * mapping of the input image to ensure that the viewer sees the same
+     * colors in the image as the creator.  Values are in the range
+     * [0.0, 0.8].  Data valid if (valid & PNG_INFO_cHRM) non-zero.
+     */
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+    float x_white;
+    float y_white;
+    float x_red;
+    float y_red;
+    float x_green;
+    float y_green;
+    float x_blue;
+    float y_blue;
+ #endif
+ #endif
+ 
+ #if defined(PNG_pCAL_SUPPORTED)
+    /* The pCAL chunk describes a transformation between the stored pixel
+     * values and original physical data values used to create the image.
+     * The integer range [0, 2^bit_depth - 1] maps to the floating-point
+     * range given by [pcal_X0, pcal_X1], and are further transformed by a
+     * (possibly non-linear) transformation function given by "pcal_type"
+     * and "pcal_params" into "pcal_units".  Please see the PNG_EQUATION_
+     * defines below, and the PNG-Group's PNG extensions document for a
+     * complete description of the transformations and how they should be
+     * implemented, and for a description of the ASCII parameter strings.
+     * Data values are valid if (valid & PNG_INFO_pCAL) non-zero.
+     */
+    png_charp pcal_purpose;  /* pCAL chunk description string */
+    png_int_32 pcal_X0;      /* minimum value */
+    png_int_32 pcal_X1;      /* maximum value */
+    png_charp pcal_units;    /* Latin-1 string giving physical units */
+    png_charpp pcal_params;  /* ASCII strings containing parameter values */
+    png_byte pcal_type;      /* equation type (see PNG_EQUATION_ below) */
+    png_byte pcal_nparams;   /* number of parameters given in pcal_params */
+ #endif
+ 
+ /* New members added in libpng-1.0.6 */
+ #ifdef PNG_FREE_ME_SUPPORTED
+    png_uint_32 free_me;     /* flags items libpng is responsible for freeing */
+ #endif
+ 
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+    /* storage for unknown chunks that the library doesn't recognize. */
+    png_unknown_chunkp unknown_chunks;
+    png_size_t unknown_chunks_num;
+ #endif
+ 
+ #if defined(PNG_iCCP_SUPPORTED)
+    /* iCCP chunk data. */
+    png_charp iccp_name;     /* profile name */
+    png_charp iccp_profile;  /* International Color Consortium profile data */
+                             /* Note to maintainer: should be png_bytep */
+    png_uint_32 iccp_proflen;  /* ICC profile data length */
+    png_byte iccp_compression; /* Always zero */
+ #endif
+ 
+ #if defined(PNG_sPLT_SUPPORTED)
+    /* data on sPLT chunks (there may be more than one). */
+    png_sPLT_tp splt_palettes;
+    png_uint_32 splt_palettes_num;
+ #endif
+ 
+ #if defined(PNG_sCAL_SUPPORTED)
+    /* The sCAL chunk describes the actual physical dimensions of the
+     * subject matter of the graphic.  The chunk contains a unit specification
+     * a byte value, and two ASCII strings representing floating-point
+     * values.  The values are width and height corresponsing to one pixel
+     * in the image.  This external representation is converted to double
+     * here.  Data values are valid if (valid & PNG_INFO_sCAL) is non-zero.
+     */
+    png_byte scal_unit;         /* unit of physical scale */
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+    double scal_pixel_width;    /* width of one pixel */
+    double scal_pixel_height;   /* height of one pixel */
+ #endif
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+    png_charp scal_s_width;     /* string containing height */
+    png_charp scal_s_height;    /* string containing width */
+ #endif
+ #endif
+ 
+ #if defined(PNG_INFO_IMAGE_SUPPORTED)
+    /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) non-zero */
+    /* Data valid if (valid & PNG_INFO_IDAT) non-zero */
+    png_bytepp row_pointers;        /* the image bits */
+ #endif
+ 
+ #if defined(PNG_FIXED_POINT_SUPPORTED) && defined(PNG_gAMA_SUPPORTED)
+    png_fixed_point int_gamma; /* gamma of image, if (valid & PNG_INFO_gAMA) */
+ #endif
+ 
+ #if defined(PNG_cHRM_SUPPORTED) && defined(PNG_FIXED_POINT_SUPPORTED)
+    png_fixed_point int_x_white;
+    png_fixed_point int_y_white;
+    png_fixed_point int_x_red;
+    png_fixed_point int_y_red;
+    png_fixed_point int_x_green;
+    png_fixed_point int_y_green;
+    png_fixed_point int_x_blue;
+    png_fixed_point int_y_blue;
+ #endif
+ 
+ } png_info;
+ 
+ typedef png_info FAR * png_infop;
+ typedef png_info FAR * FAR * png_infopp;
+ 
+ /* Maximum positive integer used in PNG is (2^31)-1 */
+ #define PNG_MAX_UINT ((png_uint_32)0x7fffffffL)
+ 
+ /* These describe the color_type field in png_info. */
+ /* color type masks */
+ #define PNG_COLOR_MASK_PALETTE    1
+ #define PNG_COLOR_MASK_COLOR      2
+ #define PNG_COLOR_MASK_ALPHA      4
+ 
+ /* color types.  Note that not all combinations are legal */
+ #define PNG_COLOR_TYPE_GRAY 0
+ #define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
+ #define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
+ #define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
+ #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
+ /* aliases */
+ #define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA
+ #define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA
+ 
+ /* This is for compression type. PNG 1.0-1.2 only define the single type. */
+ #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
+ #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
+ 
+ /* This is for filter type. PNG 1.0-1.2 only define the single type. */
+ #define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */
+ #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
+ #define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE
+ 
+ /* These are for the interlacing type.  These values should NOT be changed. */
+ #define PNG_INTERLACE_NONE        0 /* Non-interlaced image */
+ #define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */
+ #define PNG_INTERLACE_LAST        2 /* Not a valid value */
+ 
+ /* These are for the oFFs chunk.  These values should NOT be changed. */
+ #define PNG_OFFSET_PIXEL          0 /* Offset in pixels */
+ #define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */
+ #define PNG_OFFSET_LAST           2 /* Not a valid value */
+ 
+ /* These are for the pCAL chunk.  These values should NOT be changed. */
+ #define PNG_EQUATION_LINEAR       0 /* Linear transformation */
+ #define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */
+ #define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */
+ #define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */
+ #define PNG_EQUATION_LAST         4 /* Not a valid value */
+ 
+ /* These are for the sCAL chunk.  These values should NOT be changed. */
+ #define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */
+ #define PNG_SCALE_METER           1 /* meters per pixel */
+ #define PNG_SCALE_RADIAN          2 /* radians per pixel */
+ #define PNG_SCALE_LAST            3 /* Not a valid value */
+ 
+ /* These are for the pHYs chunk.  These values should NOT be changed. */
+ #define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */
+ #define PNG_RESOLUTION_METER      1 /* pixels/meter */
+ #define PNG_RESOLUTION_LAST       2 /* Not a valid value */
+ 
+ /* These are for the sRGB chunk.  These values should NOT be changed. */
+ #define PNG_sRGB_INTENT_PERCEPTUAL 0
+ #define PNG_sRGB_INTENT_RELATIVE   1
+ #define PNG_sRGB_INTENT_SATURATION 2
+ #define PNG_sRGB_INTENT_ABSOLUTE   3
+ #define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */
+ 
+ /* This is for text chunks */
+ #define PNG_KEYWORD_MAX_LENGTH     79
+ 
+ /* Maximum number of entries in PLTE/sPLT/tRNS arrays */
+ #define PNG_MAX_PALETTE_LENGTH    256
+ 
+ /* These determine if an ancillary chunk's data has been successfully read
+  * from the PNG header, or if the application has filled in the corresponding
+  * data in the info_struct to be written into the output file.  The values
+  * of the PNG_INFO_<chunk> defines should NOT be changed.
+  */
+ #define PNG_INFO_gAMA 0x0001
+ #define PNG_INFO_sBIT 0x0002
+ #define PNG_INFO_cHRM 0x0004
+ #define PNG_INFO_PLTE 0x0008
+ #define PNG_INFO_tRNS 0x0010
+ #define PNG_INFO_bKGD 0x0020
+ #define PNG_INFO_hIST 0x0040
+ #define PNG_INFO_pHYs 0x0080
+ #define PNG_INFO_oFFs 0x0100
+ #define PNG_INFO_tIME 0x0200
+ #define PNG_INFO_pCAL 0x0400
+ #define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */
+ #define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */
+ #define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */
+ #define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */
+ #define PNG_INFO_IDAT 0x8000L  /* ESR, 1.0.6 */
+ 
+ /* This is used for the transformation routines, as some of them
+  * change these values for the row.  It also should enable using
+  * the routines for other purposes.
+  */
+ typedef struct png_row_info_struct
+ {
+    png_uint_32 width; /* width of row */
+    png_uint_32 rowbytes; /* number of bytes in row */
+    png_byte color_type; /* color type of row */
+    png_byte bit_depth; /* bit depth of row */
+    png_byte channels; /* number of channels (1, 2, 3, or 4) */
+    png_byte pixel_depth; /* bits per pixel (depth * channels) */
+ } png_row_info;
+ 
+ typedef png_row_info FAR * png_row_infop;
+ typedef png_row_info FAR * FAR * png_row_infopp;
+ 
+ /* These are the function types for the I/O functions and for the functions
+  * that allow the user to override the default I/O functions with his or her
+  * own.  The png_error_ptr type should match that of user-supplied warning
+  * and error functions, while the png_rw_ptr type should match that of the
+  * user read/write data functions.
+  */
+ typedef struct png_struct_def png_struct;
+ typedef png_struct FAR * png_structp;
+ 
+ typedef void (PNGAPI *png_error_ptr) PNGARG((png_structp, png_const_charp));
+ typedef void (PNGAPI *png_rw_ptr) PNGARG((png_structp, png_bytep, png_size_t));
+ typedef void (PNGAPI *png_flush_ptr) PNGARG((png_structp));
+ typedef void (PNGAPI *png_read_status_ptr) PNGARG((png_structp, png_uint_32,
+    int));
+ typedef void (PNGAPI *png_write_status_ptr) PNGARG((png_structp, png_uint_32,
+    int));
+ 
+ #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+ typedef void (PNGAPI *png_progressive_info_ptr) PNGARG((png_structp, png_infop));
+ typedef void (PNGAPI *png_progressive_end_ptr) PNGARG((png_structp, png_infop));
+ typedef void (PNGAPI *png_progressive_row_ptr) PNGARG((png_structp, png_bytep,
+    png_uint_32, int));
+ #endif
+ 
+ #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
+     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
+     defined(PNG_LEGACY_SUPPORTED)
+ typedef void (PNGAPI *png_user_transform_ptr) PNGARG((png_structp,
+     png_row_infop, png_bytep));
+ #endif
+ 
+ #if defined(PNG_USER_CHUNKS_SUPPORTED)
+ typedef int (PNGAPI *png_user_chunk_ptr) PNGARG((png_structp, png_unknown_chunkp));
+ #endif
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ typedef void (PNGAPI *png_unknown_chunk_ptr) PNGARG((png_structp));
+ #endif
+ 
+ /* Transform masks for the high-level interface */
+ #define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */
+ #define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */
+ #define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */
+ #define PNG_TRANSFORM_PACKING        0x0004    /* read and write */
+ #define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */
+ #define PNG_TRANSFORM_EXPAND         0x0010    /* read only */
+ #define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */
+ #define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */
+ #define PNG_TRANSFORM_BGR            0x0080    /* read and write */
+ #define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */
+ #define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */
+ #define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */
+ #define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* WRITE only */
+ 
+ /* Flags for MNG supported features */
+ #define PNG_FLAG_MNG_EMPTY_PLTE     0x01
+ #define PNG_FLAG_MNG_FILTER_64      0x04
+ #define PNG_ALL_MNG_FEATURES        0x05
+ 
+ typedef png_voidp (*png_malloc_ptr) PNGARG((png_structp, png_size_t));
+ typedef void (*png_free_ptr) PNGARG((png_structp, png_voidp));
+ 
+ /* The structure that holds the information to read and write PNG files.
+  * The only people who need to care about what is inside of this are the
+  * people who will be modifying the library for their own special needs.
+  * It should NOT be accessed directly by an application, except to store
+  * the jmp_buf.
+  */
+ 
+ struct png_struct_def
+ {
+ #ifdef PNG_SETJMP_SUPPORTED
+    jmp_buf jmpbuf;            /* used in png_error */
+ #endif
+    png_error_ptr error_fn;    /* function for printing errors and aborting */
+    png_error_ptr warning_fn;  /* function for printing warnings */
+    png_voidp error_ptr;       /* user supplied struct for error functions */
+    png_rw_ptr write_data_fn;  /* function for writing output data */
+    png_rw_ptr read_data_fn;   /* function for reading input data */
+    png_voidp io_ptr;          /* ptr to application struct for I/O functions */
+ 
+ #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
+    png_user_transform_ptr read_user_transform_fn; /* user read transform */
+ #endif
+ 
+ #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
+    png_user_transform_ptr write_user_transform_fn; /* user write transform */
+ #endif
+ 
+ /* These were added in libpng-1.0.2 */
+ #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
+ #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
+     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
+    png_voidp user_transform_ptr; /* user supplied struct for user transform */
+    png_byte user_transform_depth;    /* bit depth of user transformed pixels */
+    png_byte user_transform_channels; /* channels in user transformed pixels */
+ #endif
+ #endif
+ 
+    png_uint_32 mode;          /* tells us where we are in the PNG file */
+    png_uint_32 flags;         /* flags indicating various things to libpng */
+    png_uint_32 transformations; /* which transformations to perform */
+ 
+    z_stream zstream;          /* pointer to decompression structure (below) */
+    png_bytep zbuf;            /* buffer for zlib */
+    png_size_t zbuf_size;      /* size of zbuf */
+    int zlib_level;            /* holds zlib compression level */
+    int zlib_method;           /* holds zlib compression method */
+    int zlib_window_bits;      /* holds zlib compression window bits */
+    int zlib_mem_level;        /* holds zlib compression memory level */
+    int zlib_strategy;         /* holds zlib compression strategy */
+ 
+    png_uint_32 width;         /* width of image in pixels */
+    png_uint_32 height;        /* height of image in pixels */
+    png_uint_32 num_rows;      /* number of rows in current pass */
+    png_uint_32 usr_width;     /* width of row at start of write */
+    png_uint_32 rowbytes;      /* size of row in bytes */
+    png_uint_32 irowbytes;     /* size of current interlaced row in bytes */
+    png_uint_32 iwidth;        /* width of current interlaced row in pixels */
+    png_uint_32 row_number;    /* current row in interlace pass */
+    png_bytep prev_row;        /* buffer to save previous (unfiltered) row */
+    png_bytep row_buf;         /* buffer to save current (unfiltered) row */
+    png_bytep sub_row;         /* buffer to save "sub" row when filtering */
+    png_bytep up_row;          /* buffer to save "up" row when filtering */
+    png_bytep avg_row;         /* buffer to save "avg" row when filtering */
+    png_bytep paeth_row;       /* buffer to save "Paeth" row when filtering */
+    png_row_info row_info;     /* used for transformation routines */
+ 
+    png_uint_32 idat_size;     /* current IDAT size for read */
+    png_uint_32 crc;           /* current chunk CRC value */
+    png_colorp palette;        /* palette from the input file */
+    png_uint_16 num_palette;   /* number of color entries in palette */
+    png_uint_16 num_trans;     /* number of transparency values */
+    png_byte chunk_name[5];    /* null-terminated name of current chunk */
+    png_byte compression;      /* file compression type (always 0) */
+    png_byte filter;           /* file filter type (always 0) */
+    png_byte interlaced;       /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
+    png_byte pass;             /* current interlace pass (0 - 6) */
+    png_byte do_filter;        /* row filter flags (see PNG_FILTER_ below ) */
+    png_byte color_type;       /* color type of file */
+    png_byte bit_depth;        /* bit depth of file */
+    png_byte usr_bit_depth;    /* bit depth of users row */
+    png_byte pixel_depth;      /* number of bits per pixel */
+    png_byte channels;         /* number of channels in file */
+    png_byte usr_channels;     /* channels at start of write */
+    png_byte sig_bytes;        /* magic bytes read/written from start of file */
+ 
+ #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
+ #ifdef PNG_LEGACY_SUPPORTED
+    png_byte filler;           /* filler byte for pixel expansion */
+ #else
+    png_uint_16 filler;           /* filler bytes for pixel expansion */
+ #endif
+ #endif
+ 
+ #if defined(PNG_bKGD_SUPPORTED)
+    png_byte background_gamma_type;
+ #  ifdef PNG_FLOATING_POINT_SUPPORTED
+    float background_gamma;
+ #  endif
+    png_color_16 background;   /* background color in screen gamma space */
+ #if defined(PNG_READ_GAMMA_SUPPORTED)
+    png_color_16 background_1; /* background normalized to gamma 1.0 */
+ #endif
+ #endif /* PNG_bKGD_SUPPORTED */
+ 
+ #if defined(PNG_WRITE_FLUSH_SUPPORTED)
+    png_flush_ptr output_flush_fn;/* Function for flushing output */
+    png_uint_32 flush_dist;    /* how many rows apart to flush, 0 - no flush */
+    png_uint_32 flush_rows;    /* number of rows written since last flush */
+ #endif
+ 
+ #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+    int gamma_shift;      /* number of "insignificant" bits 16-bit gamma */
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+    float gamma;          /* file gamma value */
+    float screen_gamma;   /* screen gamma value (display_exponent) */
+ #endif
+ #endif
+ 
+ #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+    png_bytep gamma_table;     /* gamma table for 8-bit depth files */
+    png_bytep gamma_from_1;    /* converts from 1.0 to screen */
+    png_bytep gamma_to_1;      /* converts from file to 1.0 */
+    png_uint_16pp gamma_16_table; /* gamma table for 16-bit depth files */
+    png_uint_16pp gamma_16_from_1; /* converts from 1.0 to screen */
+    png_uint_16pp gamma_16_to_1; /* converts from file to 1.0 */
+ #endif
+ 
+ #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_sBIT_SUPPORTED)
+    png_color_8 sig_bit;       /* significant bits in each available channel */
+ #endif
+ 
+ #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
+    png_color_8 shift;         /* shift for significant bit tranformation */
+ #endif
+ 
+ #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) \
+  || defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+    png_bytep trans;           /* transparency values for paletted files */
+    png_color_16 trans_values; /* transparency values for non-paletted files */
+ #endif
+ 
+    png_read_status_ptr read_row_fn;   /* called after each row is decoded */
+    png_write_status_ptr write_row_fn; /* called after each row is encoded */
+ #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+    png_progressive_info_ptr info_fn; /* called after header data fully read */
+    png_progressive_row_ptr row_fn;   /* called after each prog. row is decoded */
+    png_progressive_end_ptr end_fn;   /* called after image is complete */
+    png_bytep save_buffer_ptr;        /* current location in save_buffer */
+    png_bytep save_buffer;            /* buffer for previously read data */
+    png_bytep current_buffer_ptr;     /* current location in current_buffer */
+    png_bytep current_buffer;         /* buffer for recently used data */
+    png_uint_32 push_length;          /* size of current input chunk */
+    png_uint_32 skip_length;          /* bytes to skip in input data */
+    png_size_t save_buffer_size;      /* amount of data now in save_buffer */
+    png_size_t save_buffer_max;       /* total size of save_buffer */
+    png_size_t buffer_size;           /* total amount of available input data */
+    png_size_t current_buffer_size;   /* amount of data now in current_buffer */
+    int process_mode;                 /* what push library is currently doing */
+    int cur_palette;                  /* current push library palette index */
+ 
+ #  if defined(PNG_TEXT_SUPPORTED)
+      png_size_t current_text_size;   /* current size of text input data */
+      png_size_t current_text_left;   /* how much text left to read in input */
+      png_charp current_text;         /* current text chunk buffer */
+      png_charp current_text_ptr;     /* current location in current_text */
+ #  endif /* PNG_PROGRESSIVE_READ_SUPPORTED && PNG_TEXT_SUPPORTED */
+ 
+ #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+ 
+ #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
+ /* for the Borland special 64K segment handler */
+    png_bytepp offset_table_ptr;
+    png_bytep offset_table;
+    png_uint_16 offset_table_number;
+    png_uint_16 offset_table_count;
+    png_uint_16 offset_table_count_free;
+ #endif
+ 
+ #if defined(PNG_READ_DITHER_SUPPORTED)
+    png_bytep palette_lookup;         /* lookup table for dithering */
+    png_bytep dither_index;           /* index translation for palette files */
+ #endif
+ 
+ #if defined(PNG_READ_DITHER_SUPPORTED) || defined(PNG_hIST_SUPPORTED)
+    png_uint_16p hist;                /* histogram */
+ #endif
+ 
+ #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+    png_byte heuristic_method;        /* heuristic for row filter selection */
+    png_byte num_prev_filters;        /* number of weights for previous rows */
+    png_bytep prev_filters;           /* filter type(s) of previous row(s) */
+    png_uint_16p filter_weights;      /* weight(s) for previous line(s) */
+    png_uint_16p inv_filter_weights;  /* 1/weight(s) for previous line(s) */
+    png_uint_16p filter_costs;        /* relative filter calculation cost */
+    png_uint_16p inv_filter_costs;    /* 1/relative filter calculation cost */
+ #endif
+ 
+ #if defined(PNG_TIME_RFC1123_SUPPORTED)
+    png_charp time_buffer;            /* String to hold RFC 1123 time text */
+ #endif
+ 
+ /* New members added in libpng-1.0.6 */
+ 
+ #ifdef PNG_FREE_ME_SUPPORTED
+    png_uint_32 free_me;       /* flags items libpng is responsible for freeing */
+ #endif
+ 
+ #if defined(PNG_USER_CHUNKS_SUPPORTED)
+    png_voidp user_chunk_ptr;
+    png_user_chunk_ptr read_user_chunk_fn; /* user read chunk handler */
+ #endif
+ 
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+    int num_chunk_list;
+    png_bytep chunk_list;
+ #endif
+ 
+ /* New members added in libpng-1.0.3 */
+ #if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+    png_byte rgb_to_gray_status;
+    /* These were changed from png_byte in libpng-1.0.6 */
+    png_uint_16 rgb_to_gray_red_coeff;
+    png_uint_16 rgb_to_gray_green_coeff;
+    png_uint_16 rgb_to_gray_blue_coeff;
+ #endif
+ 
+ /* New member added in libpng-1.0.4 (renamed in 1.0.9) */
+ #if defined(PNG_MNG_FEATURES_SUPPORTED) || \
+     defined(PNG_READ_EMPTY_PLTE_SUPPORTED) || \
+     defined(PNG_WRITE_EMPTY_PLTE_SUPPORTED)
+ /* changed from png_byte to png_uint_32 at version 1.2.0 */
+ #ifdef PNG_1_0_X
+    png_byte mng_features_permitted;
+ #else
+    png_uint_32 mng_features_permitted;
+ #endif /* PNG_1_0_X */
+ #endif
+ 
+ /* New member added in libpng-1.0.7 */
+ #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+    png_fixed_point int_gamma;
+ #endif
+ 
+ /* New member added in libpng-1.0.9, ifdef'ed out in 1.0.12, enabled in 1.2.0 */
+ #if defined(PNG_MNG_FEATURES_SUPPORTED)
+    png_byte filter_type;
+ #endif
+ 
+ #if defined(PNG_1_0_X) || (defined(PNG_DEBUG) && defined(PNG_USE_PNGGCCRD))
+ /* New member added in libpng-1.0.10, ifdef'ed out in 1.2.0 */
+    png_uint_32 row_buf_size;
+ #endif
+ 
+ /* New members added in libpng-1.2.0 */
+ #if !defined(PNG_1_0_X) && defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+    png_byte     mmx_bitdepth_threshold;
+    png_uint_32  mmx_rowbytes_threshold;
+    png_uint_32  asm_flags;
+ #endif
+ 
+ /* New members added in libpng-1.0.2 but first enabled by default in 1.2.0 */
+ #ifdef PNG_USER_MEM_SUPPORTED
+    png_voidp mem_ptr;                /* user supplied struct for mem functions */
+    png_malloc_ptr malloc_fn;         /* function for allocating memory */
+    png_free_ptr free_fn;             /* function for freeing memory */
+ #endif
+ 
+ /* New member added in libpng-1.0.13 and 1.2.0 */
+    png_bytep big_row_buf;         /* buffer to save current (unfiltered) row */
+ 
+ #if defined(PNG_READ_DITHER_SUPPORTED)
+ /* The following three members were added at version 1.0.14 and 1.2.4 */
+    png_bytep dither_sort;            /* working sort array */
+    png_bytep index_to_palette;       /* where the original index currently is */
+                                      /* in the palette */
+    png_bytep palette_to_index;       /* which original index points to this */
+                                      /* palette color */
+ #endif
+ 
+ };
+ 
+ 
+ /* This prevents a compiler error in png.c if png.c and png.h are both at
+    version 1.2.5
+  */
+ typedef png_structp version_1_2_5;
+ 
+ typedef png_struct FAR * FAR * png_structpp;
+ 
+ /* Here are the function definitions most commonly used.  This is not
+  * the place to find out how to use libpng.  See libpng.txt for the
+  * full explanation, see example.c for the summary.  This just provides
+  * a simple one line description of the use of each function.
+  */
+ 
+ /* Returns the version number of the library */
+ extern PNG_EXPORT(png_uint_32,png_access_version_number) PNGARG((void));
+ 
+ /* Tell lib we have already handled the first <num_bytes> magic bytes.
+  * Handling more than 8 bytes from the beginning of the file is an error.
+  */
+ extern PNG_EXPORT(void,png_set_sig_bytes) PNGARG((png_structp png_ptr,
+    int num_bytes));
+ 
+ /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
+  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
+  * signature, and non-zero otherwise.  Having num_to_check == 0 or
+  * start > 7 will always fail (ie return non-zero).
+  */
+ extern PNG_EXPORT(int,png_sig_cmp) PNGARG((png_bytep sig, png_size_t start,
+    png_size_t num_to_check));
+ 
+ /* Simple signature checking function.  This is the same as calling
+  * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
+  */
+ extern PNG_EXPORT(int,png_check_sig) PNGARG((png_bytep sig, int num));
+ 
+ /* Allocate and initialize png_ptr struct for reading, and any other memory. */
+ extern PNG_EXPORT(png_structp,png_create_read_struct)
+    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
+    png_error_ptr error_fn, png_error_ptr warn_fn));
+ 
+ /* Allocate and initialize png_ptr struct for writing, and any other memory */
+ extern PNG_EXPORT(png_structp,png_create_write_struct)
+    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
+    png_error_ptr error_fn, png_error_ptr warn_fn));
+ 
+ extern PNG_EXPORT(png_uint_32,png_get_compression_buffer_size)
+    PNGARG((png_structp png_ptr));
+ 
+ extern PNG_EXPORT(void,png_set_compression_buffer_size)
+    PNGARG((png_structp png_ptr, png_uint_32 size));
+ 
+ /* Reset the compression stream */
+ extern PNG_EXPORT(int,png_reset_zstream) PNGARG((png_structp png_ptr));
+ 
+ /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
+ #ifdef PNG_USER_MEM_SUPPORTED
+ extern PNG_EXPORT(png_structp,png_create_read_struct_2)
+    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
+    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
+    png_malloc_ptr malloc_fn, png_free_ptr free_fn));
+ extern PNG_EXPORT(png_structp,png_create_write_struct_2)
+    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
+    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
+    png_malloc_ptr malloc_fn, png_free_ptr free_fn));
+ #endif
+ 
+ /* Write a PNG chunk - size, type, (optional) data, CRC. */
+ extern PNG_EXPORT(void,png_write_chunk) PNGARG((png_structp png_ptr,
+    png_bytep chunk_name, png_bytep data, png_size_t length));
+ 
+ /* Write the start of a PNG chunk - length and chunk name. */
+ extern PNG_EXPORT(void,png_write_chunk_start) PNGARG((png_structp png_ptr,
+    png_bytep chunk_name, png_uint_32 length));
+ 
+ /* Write the data of a PNG chunk started with png_write_chunk_start(). */
+ extern PNG_EXPORT(void,png_write_chunk_data) PNGARG((png_structp png_ptr,
+    png_bytep data, png_size_t length));
+ 
+ /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
+ extern PNG_EXPORT(void,png_write_chunk_end) PNGARG((png_structp png_ptr));
+ 
+ /* Allocate and initialize the info structure */
+ extern PNG_EXPORT(png_infop,png_create_info_struct)
+    PNGARG((png_structp png_ptr));
+ 
+ /* Initialize the info structure (old interface - DEPRECATED) */
+ extern PNG_EXPORT(void,png_info_init) PNGARG((png_infop info_ptr));
+ #undef png_info_init
+ #define png_info_init(info_ptr) png_info_init_3(&info_ptr, sizeof(png_info));
+ extern PNG_EXPORT(void,png_info_init_3) PNGARG((png_infopp info_ptr,
+     png_size_t png_info_struct_size));
+ 
+ /* Writes all the PNG information before the image. */
+ extern PNG_EXPORT(void,png_write_info_before_PLTE) PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ extern PNG_EXPORT(void,png_write_info) PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ 
+ /* read the information before the actual image data. */
+ extern PNG_EXPORT(void,png_read_info) PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ 
+ #if defined(PNG_TIME_RFC1123_SUPPORTED)
+ extern PNG_EXPORT(png_charp,png_convert_to_rfc1123)
+    PNGARG((png_structp png_ptr, png_timep ptime));
+ #endif
+ 
+ #if !defined(_WIN32_WCE)
+ /* "time.h" functions are not supported on WindowsCE */
+ #if defined(PNG_WRITE_tIME_SUPPORTED)
+ /* convert from a struct tm to png_time */
+ extern PNG_EXPORT(void,png_convert_from_struct_tm) PNGARG((png_timep ptime,
+    struct tm FAR * ttime));
+ 
+ /* convert from time_t to png_time.  Uses gmtime() */
+ extern PNG_EXPORT(void,png_convert_from_time_t) PNGARG((png_timep ptime,
+    time_t ttime));
+ #endif /* PNG_WRITE_tIME_SUPPORTED */
+ #endif /* _WIN32_WCE */
+ 
+ #if defined(PNG_READ_EXPAND_SUPPORTED)
+ /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
+ extern PNG_EXPORT(void,png_set_expand) PNGARG((png_structp png_ptr));
+ extern PNG_EXPORT(void,png_set_gray_1_2_4_to_8) PNGARG((png_structp png_ptr));
+ extern PNG_EXPORT(void,png_set_palette_to_rgb) PNGARG((png_structp png_ptr));
+ extern PNG_EXPORT(void,png_set_tRNS_to_alpha) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
+ /* Use blue, green, red order for pixels. */
+ extern PNG_EXPORT(void,png_set_bgr) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+ /* Expand the grayscale to 24-bit RGB if necessary. */
+ extern PNG_EXPORT(void,png_set_gray_to_rgb) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ /* Reduce RGB to grayscale. */
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_rgb_to_gray) PNGARG((png_structp png_ptr,
+    int error_action, double red, double green ));
+ #endif
+ extern PNG_EXPORT(void,png_set_rgb_to_gray_fixed) PNGARG((png_structp png_ptr,
+    int error_action, png_fixed_point red, png_fixed_point green ));
+ extern PNG_EXPORT(png_byte,png_get_rgb_to_gray_status) PNGARG((png_structp
+    png_ptr));
+ #endif
+ 
+ extern PNG_EXPORT(void,png_build_grayscale_palette) PNGARG((int bit_depth,
+    png_colorp palette));
+ 
+ #if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_strip_alpha) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
+     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_swap_alpha) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
+     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_invert_alpha) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
+ /* Add a filler byte to 24-bit RGB images. */
+ extern PNG_EXPORT(void,png_set_filler) PNGARG((png_structp png_ptr,
+    png_uint_32 filler, int flags));
+ /* The values of the PNG_FILLER_ defines should NOT be changed */
+ #define PNG_FILLER_BEFORE 0
+ #define PNG_FILLER_AFTER 1
+ #endif /* PNG_READ_FILLER_SUPPORTED || PNG_WRITE_FILLER_SUPPORTED */
+ 
+ #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
+ /* Swap bytes in 16-bit depth files. */
+ extern PNG_EXPORT(void,png_set_swap) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
+ /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
+ extern PNG_EXPORT(void,png_set_packing) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED) || defined(PNG_WRITE_PACKSWAP_SUPPORTED)
+ /* Swap packing order of pixels in bytes. */
+ extern PNG_EXPORT(void,png_set_packswap) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
+ /* Converts files to legal bit depths. */
+ extern PNG_EXPORT(void,png_set_shift) PNGARG((png_structp png_ptr,
+    png_color_8p true_bits));
+ #endif
+ 
+ #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
+     defined(PNG_WRITE_INTERLACING_SUPPORTED)
+ /* Have the code handle the interlacing.  Returns the number of passes. */
+ extern PNG_EXPORT(int,png_set_interlace_handling) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
+ /* Invert monochrome files */
+ extern PNG_EXPORT(void,png_set_invert_mono) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_BACKGROUND_SUPPORTED)
+ /* Handle alpha and tRNS by replacing with a background color. */
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_background) PNGARG((png_structp png_ptr,
+    png_color_16p background_color, int background_gamma_code,
+    int need_expand, double background_gamma));
+ #endif
+ #define PNG_BACKGROUND_GAMMA_UNKNOWN 0
+ #define PNG_BACKGROUND_GAMMA_SCREEN  1
+ #define PNG_BACKGROUND_GAMMA_FILE    2
+ #define PNG_BACKGROUND_GAMMA_UNIQUE  3
+ #endif
+ 
+ #if defined(PNG_READ_16_TO_8_SUPPORTED)
+ /* strip the second byte of information from a 16-bit depth file. */
+ extern PNG_EXPORT(void,png_set_strip_16) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_DITHER_SUPPORTED)
+ /* Turn on dithering, and reduce the palette to the number of colors available. */
+ extern PNG_EXPORT(void,png_set_dither) PNGARG((png_structp png_ptr,
+    png_colorp palette, int num_palette, int maximum_colors,
+    png_uint_16p histogram, int full_dither));
+ #endif
+ 
+ #if defined(PNG_READ_GAMMA_SUPPORTED)
+ /* Handle gamma correction. Screen_gamma=(display_exponent) */
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_gamma) PNGARG((png_structp png_ptr,
+    double screen_gamma, double default_file_gamma));
+ #endif
+ #endif
+ 
+ #if defined(PNG_READ_EMPTY_PLTE_SUPPORTED) || \
+     defined(PNG_WRITE_EMPTY_PLTE_SUPPORTED)
+ /* Permit or disallow empty PLTE (0: not permitted, 1: permitted) */
+ /* Deprecated and will be removed.  Use png_permit_mng_features() instead. */
+ extern PNG_EXPORT(void,png_permit_empty_plte) PNGARG((png_structp png_ptr,
+    int empty_plte_permitted));
+ #endif
+ 
+ #if defined(PNG_WRITE_FLUSH_SUPPORTED)
+ /* Set how many lines between output flushes - 0 for no flushing */
+ extern PNG_EXPORT(void,png_set_flush) PNGARG((png_structp png_ptr, int nrows));
+ /* Flush the current PNG output buffer */
+ extern PNG_EXPORT(void,png_write_flush) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ /* optional update palette with requested transformations */
+ extern PNG_EXPORT(void,png_start_read_image) PNGARG((png_structp png_ptr));
+ 
+ /* optional call to update the users info structure */
+ extern PNG_EXPORT(void,png_read_update_info) PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ 
+ /* read one or more rows of image data. */
+ extern PNG_EXPORT(void,png_read_rows) PNGARG((png_structp png_ptr,
+    png_bytepp row, png_bytepp display_row, png_uint_32 num_rows));
+ 
+ /* read a row of data. */
+ extern PNG_EXPORT(void,png_read_row) PNGARG((png_structp png_ptr,
+    png_bytep row,
+    png_bytep display_row));
+ 
+ /* read the whole image into memory at once. */
+ extern PNG_EXPORT(void,png_read_image) PNGARG((png_structp png_ptr,
+    png_bytepp image));
+ 
+ /* write a row of image data */
+ extern PNG_EXPORT(void,png_write_row) PNGARG((png_structp png_ptr,
+    png_bytep row));
+ 
+ /* write a few rows of image data */
+ extern PNG_EXPORT(void,png_write_rows) PNGARG((png_structp png_ptr,
+    png_bytepp row, png_uint_32 num_rows));
+ 
+ /* write the image data */
+ extern PNG_EXPORT(void,png_write_image) PNGARG((png_structp png_ptr,
+    png_bytepp image));
+ 
+ /* writes the end of the PNG file. */
+ extern PNG_EXPORT(void,png_write_end) PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ 
+ /* read the end of the PNG file. */
+ extern PNG_EXPORT(void,png_read_end) PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ 
+ /* free any memory associated with the png_info_struct */
+ extern PNG_EXPORT(void,png_destroy_info_struct) PNGARG((png_structp png_ptr,
+    png_infopp info_ptr_ptr));
+ 
+ /* free any memory associated with the png_struct and the png_info_structs */
+ extern PNG_EXPORT(void,png_destroy_read_struct) PNGARG((png_structpp
+    png_ptr_ptr, png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
+ 
+ /* free all memory used by the read (old method - NOT DLL EXPORTED) */
+ extern void png_read_destroy PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_infop end_info_ptr));
+ 
+ /* free any memory associated with the png_struct and the png_info_structs */
+ extern PNG_EXPORT(void,png_destroy_write_struct)
+    PNGARG((png_structpp png_ptr_ptr, png_infopp info_ptr_ptr));
+ 
+ /* free any memory used in png_ptr struct (old method - NOT DLL EXPORTED) */
+ extern void png_write_destroy PNGARG((png_structp png_ptr));
+ 
+ /* set the libpng method of handling chunk CRC errors */
+ extern PNG_EXPORT(void,png_set_crc_action) PNGARG((png_structp png_ptr,
+    int crit_action, int ancil_action));
+ 
+ /* Values for png_set_crc_action() to say how to handle CRC errors in
+  * ancillary and critical chunks, and whether to use the data contained
+  * therein.  Note that it is impossible to "discard" data in a critical
+  * chunk.  For versions prior to 0.90, the action was always error/quit,
+  * whereas in version 0.90 and later, the action for CRC errors in ancillary
+  * chunks is warn/discard.  These values should NOT be changed.
+  *
+  *      value                       action:critical     action:ancillary
+  */
+ #define PNG_CRC_DEFAULT       0  /* error/quit          warn/discard data */
+ #define PNG_CRC_ERROR_QUIT    1  /* error/quit          error/quit        */
+ #define PNG_CRC_WARN_DISCARD  2  /* (INVALID)           warn/discard data */
+ #define PNG_CRC_WARN_USE      3  /* warn/use data       warn/use data     */
+ #define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */
+ #define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */
+ 
+ /* These functions give the user control over the scan-line filtering in
+  * libpng and the compression methods used by zlib.  These functions are
+  * mainly useful for testing, as the defaults should work with most users.
+  * Those users who are tight on memory or want faster performance at the
+  * expense of compression can modify them.  See the compression library
+  * header file (zlib.h) for an explination of the compression functions.
+  */
+ 
+ /* set the filtering method(s) used by libpng.  Currently, the only valid
+  * value for "method" is 0.
+  */
+ extern PNG_EXPORT(void,png_set_filter) PNGARG((png_structp png_ptr, int method,
+    int filters));
+ 
+ /* Flags for png_set_filter() to say which filters to use.  The flags
+  * are chosen so that they don't conflict with real filter types
+  * below, in case they are supplied instead of the #defined constants.
+  * These values should NOT be changed.
+  */
+ #define PNG_NO_FILTERS     0x00
+ #define PNG_FILTER_NONE    0x08
+ #define PNG_FILTER_SUB     0x10
+ #define PNG_FILTER_UP      0x20
+ #define PNG_FILTER_AVG     0x40
+ #define PNG_FILTER_PAETH   0x80
+ #define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
+                          PNG_FILTER_AVG | PNG_FILTER_PAETH)
+ 
+ /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
+  * These defines should NOT be changed.
+  */
+ #define PNG_FILTER_VALUE_NONE  0
+ #define PNG_FILTER_VALUE_SUB   1
+ #define PNG_FILTER_VALUE_UP    2
+ #define PNG_FILTER_VALUE_AVG   3
+ #define PNG_FILTER_VALUE_PAETH 4
+ #define PNG_FILTER_VALUE_LAST  5
+ 
+ #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) /* EXPERIMENTAL */
+ /* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
+  * defines, either the default (minimum-sum-of-absolute-differences), or
+  * the experimental method (weighted-minimum-sum-of-absolute-differences).
+  *
+  * Weights are factors >= 1.0, indicating how important it is to keep the
+  * filter type consistent between rows.  Larger numbers mean the current
+  * filter is that many times as likely to be the same as the "num_weights"
+  * previous filters.  This is cumulative for each previous row with a weight.
+  * There needs to be "num_weights" values in "filter_weights", or it can be
+  * NULL if the weights aren't being specified.  Weights have no influence on
+  * the selection of the first row filter.  Well chosen weights can (in theory)
+  * improve the compression for a given image.
+  *
+  * Costs are factors >= 1.0 indicating the relative decoding costs of a
+  * filter type.  Higher costs indicate more decoding expense, and are
+  * therefore less likely to be selected over a filter with lower computational
+  * costs.  There needs to be a value in "filter_costs" for each valid filter
+  * type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't
+  * setting the costs.  Costs try to improve the speed of decompression without
+  * unduly increasing the compressed image size.
+  *
+  * A negative weight or cost indicates the default value is to be used, and
+  * values in the range [0.0, 1.0) indicate the value is to remain unchanged.
+  * The default values for both weights and costs are currently 1.0, but may
+  * change if good general weighting/cost heuristics can be found.  If both
+  * the weights and costs are set to 1.0, this degenerates the WEIGHTED method
+  * to the UNWEIGHTED method, but with added encoding time/computation.
+  */
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_filter_heuristics) PNGARG((png_structp png_ptr,
+    int heuristic_method, int num_weights, png_doublep filter_weights,
+    png_doublep filter_costs));
+ #endif
+ #endif /*  PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
+ 
+ /* Heuristic used for row filter selection.  These defines should NOT be
+  * changed.
+  */
+ #define PNG_FILTER_HEURISTIC_DEFAULT    0  /* Currently "UNWEIGHTED" */
+ #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1  /* Used by libpng < 0.95 */
+ #define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */
+ #define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */
+ 
+ /* Set the library compression level.  Currently, valid values range from
+  * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
+  * (0 - no compression, 9 - "maximal" compression).  Note that tests have
+  * shown that zlib compression levels 3-6 usually perform as well as level 9
+  * for PNG images, and do considerably fewer caclulations.  In the future,
+  * these values may not correspond directly to the zlib compression levels.
+  */
+ extern PNG_EXPORT(void,png_set_compression_level) PNGARG((png_structp png_ptr,
+    int level));
+ 
+ extern PNG_EXPORT(void,png_set_compression_mem_level)
+    PNGARG((png_structp png_ptr, int mem_level));
+ 
+ extern PNG_EXPORT(void,png_set_compression_strategy)
+    PNGARG((png_structp png_ptr, int strategy));
+ 
+ extern PNG_EXPORT(void,png_set_compression_window_bits)
+    PNGARG((png_structp png_ptr, int window_bits));
+ 
+ extern PNG_EXPORT(void,png_set_compression_method) PNGARG((png_structp png_ptr,
+    int method));
+ 
+ /* These next functions are called for input/output, memory, and error
+  * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c,
+  * and call standard C I/O routines such as fread(), fwrite(), and
+  * fprintf().  These functions can be made to use other I/O routines
+  * at run time for those applications that need to handle I/O in a
+  * different manner by calling png_set_???_fn().  See libpng.txt for
+  * more information.
+  */
+ 
+ #if !defined(PNG_NO_STDIO)
+ /* Initialize the input/output for the PNG file to the default functions. */
+ extern PNG_EXPORT(void,png_init_io) PNGARG((png_structp png_ptr, png_FILE_p fp));
+ #endif
+ 
+ /* Replace the (error and abort), and warning functions with user
+  * supplied functions.  If no messages are to be printed you must still
+  * write and use replacement functions. The replacement error_fn should
+  * still do a longjmp to the last setjmp location if you are using this
+  * method of error handling.  If error_fn or warning_fn is NULL, the
+  * default function will be used.
+  */
+ 
+ extern PNG_EXPORT(void,png_set_error_fn) PNGARG((png_structp png_ptr,
+    png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
+ 
+ /* Return the user pointer associated with the error functions */
+ extern PNG_EXPORT(png_voidp,png_get_error_ptr) PNGARG((png_structp png_ptr));
+ 
+ /* Replace the default data output functions with a user supplied one(s).
+  * If buffered output is not used, then output_flush_fn can be set to NULL.
+  * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
+  * output_flush_fn will be ignored (and thus can be NULL).
+  */
+ extern PNG_EXPORT(void,png_set_write_fn) PNGARG((png_structp png_ptr,
+    png_voidp io_ptr, png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
+ 
+ /* Replace the default data input function with a user supplied one. */
+ extern PNG_EXPORT(void,png_set_read_fn) PNGARG((png_structp png_ptr,
+    png_voidp io_ptr, png_rw_ptr read_data_fn));
+ 
+ /* Return the user pointer associated with the I/O functions */
+ extern PNG_EXPORT(png_voidp,png_get_io_ptr) PNGARG((png_structp png_ptr));
+ 
+ extern PNG_EXPORT(void,png_set_read_status_fn) PNGARG((png_structp png_ptr,
+    png_read_status_ptr read_row_fn));
+ 
+ extern PNG_EXPORT(void,png_set_write_status_fn) PNGARG((png_structp png_ptr,
+    png_write_status_ptr write_row_fn));
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+ /* Replace the default memory allocation functions with user supplied one(s). */
+ extern PNG_EXPORT(void,png_set_mem_fn) PNGARG((png_structp png_ptr,
+    png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn));
+ /* Return the user pointer associated with the memory functions */
+ extern PNG_EXPORT(png_voidp,png_get_mem_ptr) PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
+     defined(PNG_LEGACY_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_read_user_transform_fn) PNGARG((png_structp
+    png_ptr, png_user_transform_ptr read_user_transform_fn));
+ #endif
+ 
+ #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
+     defined(PNG_LEGACY_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_write_user_transform_fn) PNGARG((png_structp
+    png_ptr, png_user_transform_ptr write_user_transform_fn));
+ #endif
+ 
+ #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
+     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
+     defined(PNG_LEGACY_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_user_transform_info) PNGARG((png_structp
+    png_ptr, png_voidp user_transform_ptr, int user_transform_depth,
+    int user_transform_channels));
+ /* Return the user pointer associated with the user transform functions */
+ extern PNG_EXPORT(png_voidp,png_get_user_transform_ptr)
+    PNGARG((png_structp png_ptr));
+ #endif
+ 
+ #ifdef PNG_USER_CHUNKS_SUPPORTED
+ extern PNG_EXPORT(void,png_set_read_user_chunk_fn) PNGARG((png_structp png_ptr,
+    png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
+ extern PNG_EXPORT(png_voidp,png_get_user_chunk_ptr) PNGARG((png_structp
+    png_ptr));
+ #endif
+ 
+ #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+ /* Sets the function callbacks for the push reader, and a pointer to a
+  * user-defined structure available to the callback functions.
+  */
+ extern PNG_EXPORT(void,png_set_progressive_read_fn) PNGARG((png_structp png_ptr,
+    png_voidp progressive_ptr,
+    png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
+    png_progressive_end_ptr end_fn));
+ 
+ /* returns the user pointer associated with the push read functions */
+ extern PNG_EXPORT(png_voidp,png_get_progressive_ptr)
+    PNGARG((png_structp png_ptr));
+ 
+ /* function to be called when data becomes available */
+ extern PNG_EXPORT(void,png_process_data) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_bytep buffer, png_size_t buffer_size));
+ 
+ /* function that combines rows.  Not very much different than the
+  * png_combine_row() call.  Is this even used?????
+  */
+ extern PNG_EXPORT(void,png_progressive_combine_row) PNGARG((png_structp png_ptr,
+    png_bytep old_row, png_bytep new_row));
+ #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+ 
+ extern PNG_EXPORT(png_voidp,png_malloc) PNGARG((png_structp png_ptr,
+    png_uint_32 size));
+ 
+ #if defined(PNG_1_0_X)
+ #  define png_malloc_warn png_malloc
+ #else
+ /* Added at libpng version 1.2.4 */
+ extern PNG_EXPORT(png_voidp,png_malloc_warn) PNGARG((png_structp png_ptr,
+    png_uint_32 size));
+ #endif
+ 
+ /* frees a pointer allocated by png_malloc() */
+ extern PNG_EXPORT(void,png_free) PNGARG((png_structp png_ptr, png_voidp ptr));
+ 
+ #if defined(PNG_1_0_X)
+ /* Function to allocate memory for zlib. */
+ extern PNG_EXPORT(voidpf,png_zalloc) PNGARG((voidpf png_ptr, uInt items,
+    uInt size));
+ 
+ /* Function to free memory for zlib */
+ extern PNG_EXPORT(void,png_zfree) PNGARG((voidpf png_ptr, voidpf ptr));
+ #endif
+ 
+ /* Free data that was allocated internally */
+ extern PNG_EXPORT(void,png_free_data) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 free_me, int num));
+ #ifdef PNG_FREE_ME_SUPPORTED
+ /* Reassign responsibility for freeing existing data, whether allocated
+  * by libpng or by the application */
+ extern PNG_EXPORT(void,png_data_freer) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int freer, png_uint_32 mask));
+ #endif
+ /* assignments for png_data_freer */
+ #define PNG_DESTROY_WILL_FREE_DATA 1
+ #define PNG_SET_WILL_FREE_DATA 1
+ #define PNG_USER_WILL_FREE_DATA 2
+ /* Flags for png_ptr->free_me and info_ptr->free_me */
+ #define PNG_FREE_HIST 0x0008
+ #define PNG_FREE_ICCP 0x0010
+ #define PNG_FREE_SPLT 0x0020
+ #define PNG_FREE_ROWS 0x0040
+ #define PNG_FREE_PCAL 0x0080
+ #define PNG_FREE_SCAL 0x0100
+ #define PNG_FREE_UNKN 0x0200
+ #define PNG_FREE_LIST 0x0400
+ #define PNG_FREE_PLTE 0x1000
+ #define PNG_FREE_TRNS 0x2000
+ #define PNG_FREE_TEXT 0x4000
+ #define PNG_FREE_ALL  0x7fff
+ #define PNG_FREE_MUL  0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+ extern PNG_EXPORT(png_voidp,png_malloc_default) PNGARG((png_structp png_ptr,
+    png_uint_32 size));
+ extern PNG_EXPORT(void,png_free_default) PNGARG((png_structp png_ptr,
+    png_voidp ptr));
+ #endif
+ 
+ extern PNG_EXPORT(png_voidp,png_memcpy_check) PNGARG((png_structp png_ptr,
+    png_voidp s1, png_voidp s2, png_uint_32 size));
+ 
+ extern PNG_EXPORT(png_voidp,png_memset_check) PNGARG((png_structp png_ptr,
+    png_voidp s1, int value, png_uint_32 size));
+ 
+ #if defined(USE_FAR_KEYWORD)  /* memory model conversion function */
+ extern void *png_far_to_near PNGARG((png_structp png_ptr,png_voidp ptr,
+    int check));
+ #endif /* USE_FAR_KEYWORD */
+ 
+ /* Fatal error in PNG image of libpng - can't continue */
+ extern PNG_EXPORT(void,png_error) PNGARG((png_structp png_ptr,
+    png_const_charp error_message));
+ 
+ /* The same, but the chunk name is prepended to the error string. */
+ extern PNG_EXPORT(void,png_chunk_error) PNGARG((png_structp png_ptr,
+    png_const_charp error_message));
+ 
+ /* Non-fatal error in libpng.  Can continue, but may have a problem. */
+ extern PNG_EXPORT(void,png_warning) PNGARG((png_structp png_ptr,
+    png_const_charp warning_message));
+ 
+ /* Non-fatal error in libpng, chunk name is prepended to message. */
+ extern PNG_EXPORT(void,png_chunk_warning) PNGARG((png_structp png_ptr,
+    png_const_charp warning_message));
+ 
+ /* The png_set_<chunk> functions are for storing values in the png_info_struct.
+  * Similarly, the png_get_<chunk> calls are used to read values from the
+  * png_info_struct, either storing the parameters in the passed variables, or
+  * setting pointers into the png_info_struct where the data is stored.  The
+  * png_get_<chunk> functions return a non-zero value if the data was available
+  * in info_ptr, or return zero and do not change any of the parameters if the
+  * data was not available.
+  *
+  * These functions should be used instead of directly accessing png_info
+  * to avoid problems with future changes in the size and internal layout of
+  * png_info_struct.
+  */
+ /* Returns "flag" if chunk data is valid in info_ptr. */
+ extern PNG_EXPORT(png_uint_32,png_get_valid) PNGARG((png_structp png_ptr,
+ png_infop info_ptr, png_uint_32 flag));
+ 
+ /* Returns number of bytes needed to hold a transformed row. */
+ extern PNG_EXPORT(png_uint_32,png_get_rowbytes) PNGARG((png_structp png_ptr,
+ png_infop info_ptr));
+ 
+ #if defined(PNG_INFO_IMAGE_SUPPORTED)
+ /* Returns row_pointers, which is an array of pointers to scanlines that was
+ returned from png_read_png(). */
+ extern PNG_EXPORT(png_bytepp,png_get_rows) PNGARG((png_structp png_ptr,
+ png_infop info_ptr));
+ /* Set row_pointers, which is an array of pointers to scanlines for use
+ by png_write_png(). */
+ extern PNG_EXPORT(void,png_set_rows) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_bytepp row_pointers));
+ #endif
+ 
+ /* Returns number of color channels in image. */
+ extern PNG_EXPORT(png_byte,png_get_channels) PNGARG((png_structp png_ptr,
+ png_infop info_ptr));
+ 
+ #ifdef PNG_EASY_ACCESS_SUPPORTED
+ /* Returns image width in pixels. */
+ extern PNG_EXPORT(png_uint_32, png_get_image_width) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ /* Returns image height in pixels. */
+ extern PNG_EXPORT(png_uint_32, png_get_image_height) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ /* Returns image bit_depth. */
+ extern PNG_EXPORT(png_byte, png_get_bit_depth) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ /* Returns image color_type. */
+ extern PNG_EXPORT(png_byte, png_get_color_type) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ /* Returns image filter_type. */
+ extern PNG_EXPORT(png_byte, png_get_filter_type) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ /* Returns image interlace_type. */
+ extern PNG_EXPORT(png_byte, png_get_interlace_type) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ /* Returns image compression_type. */
+ extern PNG_EXPORT(png_byte, png_get_compression_type) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ /* Returns image resolution in pixels per meter, from pHYs chunk data. */
+ extern PNG_EXPORT(png_uint_32, png_get_pixels_per_meter) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ extern PNG_EXPORT(png_uint_32, png_get_x_pixels_per_meter) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ extern PNG_EXPORT(png_uint_32, png_get_y_pixels_per_meter) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ /* Returns pixel aspect ratio, computed from pHYs chunk data.  */
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(float, png_get_pixel_aspect_ratio) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ #endif
+ 
+ /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
+ extern PNG_EXPORT(png_int_32, png_get_x_offset_pixels) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ extern PNG_EXPORT(png_int_32, png_get_y_offset_pixels) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ extern PNG_EXPORT(png_int_32, png_get_x_offset_microns) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ extern PNG_EXPORT(png_int_32, png_get_y_offset_microns) PNGARG((png_structp
+ png_ptr, png_infop info_ptr));
+ 
+ #endif /* PNG_EASY_ACCESS_SUPPORTED */
+ 
+ /* Returns pointer to signature string read from PNG header */
+ extern PNG_EXPORT(png_bytep,png_get_signature) PNGARG((png_structp png_ptr,
+ png_infop info_ptr));
+ 
+ #if defined(PNG_bKGD_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_bKGD) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_color_16p *background));
+ #endif
+ 
+ #if defined(PNG_bKGD_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_bKGD) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_color_16p background));
+ #endif
+ 
+ #if defined(PNG_cHRM_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(png_uint_32,png_get_cHRM) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, double *white_x, double *white_y, double *red_x,
+    double *red_y, double *green_x, double *green_y, double *blue_x,
+    double *blue_y));
+ #endif
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ extern PNG_EXPORT(png_uint_32,png_get_cHRM_fixed) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_fixed_point *int_white_x, png_fixed_point
+    *int_white_y, png_fixed_point *int_red_x, png_fixed_point *int_red_y,
+    png_fixed_point *int_green_x, png_fixed_point *int_green_y, png_fixed_point
+    *int_blue_x, png_fixed_point *int_blue_y));
+ #endif
+ #endif
+ 
+ #if defined(PNG_cHRM_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_cHRM) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, double white_x, double white_y, double red_x,
+    double red_y, double green_x, double green_y, double blue_x, double blue_y));
+ #endif
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_cHRM_fixed) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_fixed_point int_white_x, png_fixed_point int_white_y,
+    png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
+    int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
+    png_fixed_point int_blue_y));
+ #endif
+ #endif
+ 
+ #if defined(PNG_gAMA_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(png_uint_32,png_get_gAMA) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, double *file_gamma));
+ #endif
+ extern PNG_EXPORT(png_uint_32,png_get_gAMA_fixed) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_fixed_point *int_file_gamma));
+ #endif
+ 
+ #if defined(PNG_gAMA_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_gAMA) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, double file_gamma));
+ #endif
+ extern PNG_EXPORT(void,png_set_gAMA_fixed) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_fixed_point int_file_gamma));
+ #endif
+ 
+ #if defined(PNG_hIST_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_hIST) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_16p *hist));
+ #endif
+ 
+ #if defined(PNG_hIST_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_hIST) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_16p hist));
+ #endif
+ 
+ extern PNG_EXPORT(png_uint_32,png_get_IHDR) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 *width, png_uint_32 *height,
+    int *bit_depth, int *color_type, int *interlace_method,
+    int *compression_method, int *filter_method));
+ 
+ extern PNG_EXPORT(void,png_set_IHDR) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
+    int color_type, int interlace_method, int compression_method,
+    int filter_method));
+ 
+ #if defined(PNG_oFFs_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_oFFs) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
+    int *unit_type));
+ #endif
+ 
+ #if defined(PNG_oFFs_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_oFFs) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_int_32 offset_x, png_int_32 offset_y,
+    int unit_type));
+ #endif
+ 
+ #if defined(PNG_pCAL_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_pCAL) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_charp *purpose, png_int_32 *X0, png_int_32 *X1,
+    int *type, int *nparams, png_charp *units, png_charpp *params));
+ #endif
+ 
+ #if defined(PNG_pCAL_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_pCAL) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_charp purpose, png_int_32 X0, png_int_32 X1,
+    int type, int nparams, png_charp units, png_charpp params));
+ #endif
+ 
+ #if defined(PNG_pHYs_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_pHYs) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type));
+ #endif
+ 
+ #if defined(PNG_pHYs_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_pHYs) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
+ #endif
+ 
+ extern PNG_EXPORT(png_uint_32,png_get_PLTE) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_colorp *palette, int *num_palette));
+ 
+ extern PNG_EXPORT(void,png_set_PLTE) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_colorp palette, int num_palette));
+ 
+ #if defined(PNG_sBIT_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_sBIT) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_color_8p *sig_bit));
+ #endif
+ 
+ #if defined(PNG_sBIT_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_sBIT) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_color_8p sig_bit));
+ #endif
+ 
+ #if defined(PNG_sRGB_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_sRGB) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int *intent));
+ #endif
+ 
+ #if defined(PNG_sRGB_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_sRGB) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int intent));
+ extern PNG_EXPORT(void,png_set_sRGB_gAMA_and_cHRM) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int intent));
+ #endif
+ 
+ #if defined(PNG_iCCP_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_iCCP) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_charpp name, int *compression_type,
+    png_charpp profile, png_uint_32 *proflen));
+    /* Note to maintainer: profile should be png_bytepp */
+ #endif
+ 
+ #if defined(PNG_iCCP_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_iCCP) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_charp name, int compression_type,
+    png_charp profile, png_uint_32 proflen));
+    /* Note to maintainer: profile should be png_bytep */
+ #endif
+ 
+ #if defined(PNG_sPLT_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_sPLT) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_sPLT_tpp entries));
+ #endif
+ 
+ #if defined(PNG_sPLT_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_sPLT) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_sPLT_tp entries, int nentries));
+ #endif
+ 
+ #if defined(PNG_TEXT_SUPPORTED)
+ /* png_get_text also returns the number of text chunks in *num_text */
+ extern PNG_EXPORT(png_uint_32,png_get_text) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_textp *text_ptr, int *num_text));
+ #endif
+ 
+ /*
+  *  Note while png_set_text() will accept a structure whose text,
+  *  language, and  translated keywords are NULL pointers, the structure
+  *  returned by png_get_text will always contain regular
+  *  zero-terminated C strings.  They might be empty strings but
+  *  they will never be NULL pointers.
+  */
+ 
+ #if defined(PNG_TEXT_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_text) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_textp text_ptr, int num_text));
+ #endif
+ 
+ #if defined(PNG_tIME_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_tIME) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_timep *mod_time));
+ #endif
+ 
+ #if defined(PNG_tIME_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_tIME) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_timep mod_time));
+ #endif
+ 
+ #if defined(PNG_tRNS_SUPPORTED)
+ extern PNG_EXPORT(png_uint_32,png_get_tRNS) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_bytep *trans, int *num_trans,
+    png_color_16p *trans_values));
+ #endif
+ 
+ #if defined(PNG_tRNS_SUPPORTED)
+ extern PNG_EXPORT(void,png_set_tRNS) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_bytep trans, int num_trans,
+    png_color_16p trans_values));
+ #endif
+ 
+ #if defined(PNG_tRNS_SUPPORTED)
+ #endif
+ 
+ #if defined(PNG_sCAL_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(png_uint_32,png_get_sCAL) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int *unit, double *width, double *height));
+ #else
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ extern PNG_EXPORT(png_uint_32,png_get_sCAL_s) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int *unit, png_charpp swidth, png_charpp sheight));
+ #endif
+ #endif
+ #endif /* PNG_sCAL_SUPPORTED */
+ 
+ #if defined(PNG_sCAL_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_sCAL) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int unit, double width, double height));
+ #endif
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ extern PNG_EXPORT(void,png_set_sCAL_s) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int unit, png_charp swidth, png_charp sheight));
+ #endif
+ #endif /* PNG_sCAL_SUPPORTED || PNG_WRITE_sCAL_SUPPORTED */
+ 
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ /* provide a list of chunks and how they are to be handled, if the built-in
+    handling or default unknown chunk handling is not desired.  Any chunks not
+    listed will be handled in the default manner.  The IHDR and IEND chunks
+    must not be listed.
+       keep = 0: follow default behavour
+            = 1: do not keep
+            = 2: keep only if safe-to-copy
+            = 3: keep even if unsafe-to-copy
+ */
+ extern PNG_EXPORT(void, png_set_keep_unknown_chunks) PNGARG((png_structp
+    png_ptr, int keep, png_bytep chunk_list, int num_chunks));
+ extern PNG_EXPORT(void, png_set_unknown_chunks) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_unknown_chunkp unknowns, int num_unknowns));
+ extern PNG_EXPORT(void, png_set_unknown_chunk_location)
+    PNGARG((png_structp png_ptr, png_infop info_ptr, int chunk, int location));
+ extern PNG_EXPORT(png_uint_32,png_get_unknown_chunks) PNGARG((png_structp
+    png_ptr, png_infop info_ptr, png_unknown_chunkpp entries));
+ #endif
+ #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+ PNG_EXPORT(int,png_handle_as_unknown) PNGARG((png_structp png_ptr, png_bytep
+    chunk_name));
+ #endif
+ 
+ /* Png_free_data() will turn off the "valid" flag for anything it frees.
+    If you need to turn it off for a chunk that your application has freed,
+    you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK); */
+ extern PNG_EXPORT(void, png_set_invalid) PNGARG((png_structp png_ptr,
+    png_infop info_ptr, int mask));
+ 
+ #if defined(PNG_INFO_IMAGE_SUPPORTED)
+ /* The "params" pointer is currently not used and is for future expansion. */
+ extern PNG_EXPORT(void, png_read_png) PNGARG((png_structp png_ptr,
+                         png_infop info_ptr,
+                         int transforms,
+                         png_voidp params));
+ extern PNG_EXPORT(void, png_write_png) PNGARG((png_structp png_ptr,
+                         png_infop info_ptr,
+                         int transforms,
+                         png_voidp params));
+ #endif
+ 
+ /* Define PNG_DEBUG at compile time for debugging information.  Higher
+  * numbers for PNG_DEBUG mean more debugging information.  This has
+  * only been added since version 0.95 so it is not implemented throughout
+  * libpng yet, but more support will be added as needed.
+  */
+ #ifdef PNG_DEBUG
+ #if (PNG_DEBUG > 0)
+ #if !defined(PNG_DEBUG_FILE) && defined(_MSC_VER)
+ #include <crtdbg.h>
+ #if (PNG_DEBUG > 1)
+ #define png_debug(l,m)  _RPT0(_CRT_WARN,m)
+ #define png_debug1(l,m,p1)  _RPT1(_CRT_WARN,m,p1)
+ #define png_debug2(l,m,p1,p2) _RPT2(_CRT_WARN,m,p1,p2)
+ #endif
+ #else /* PNG_DEBUG_FILE || !_MSC_VER */
+ #ifndef PNG_DEBUG_FILE
+ #define PNG_DEBUG_FILE stderr
+ #endif /* PNG_DEBUG_FILE */
+ #if (PNG_DEBUG > 1)
+ #define png_debug(l,m) \
+ { \
+      int num_tabs=l; \
+      fprintf(PNG_DEBUG_FILE,"%s"m,(num_tabs==1 ? "\t" : \
+        (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":"")))); \
+ }
+ #define png_debug1(l,m,p1) \
+ { \
+      int num_tabs=l; \
+      fprintf(PNG_DEBUG_FILE,"%s"m,(num_tabs==1 ? "\t" : \
+        (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1); \
+ }
+ #define png_debug2(l,m,p1,p2) \
+ { \
+      int num_tabs=l; \
+      fprintf(PNG_DEBUG_FILE,"%s"m,(num_tabs==1 ? "\t" : \
+        (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1,p2); \
+ }
+ #endif /* (PNG_DEBUG > 1) */
+ #endif /* _MSC_VER */
+ #endif /* (PNG_DEBUG > 0) */
+ #endif /* PNG_DEBUG */
+ #ifndef png_debug
+ #define png_debug(l, m)
+ #endif
+ #ifndef png_debug1
+ #define png_debug1(l, m, p1)
+ #endif
+ #ifndef png_debug2
+ #define png_debug2(l, m, p1, p2)
+ #endif
+ 
+ extern PNG_EXPORT(png_bytep,png_sig_bytes) PNGARG((void));
+ 
+ extern PNG_EXPORT(png_charp,png_get_copyright) PNGARG((png_structp png_ptr));
+ extern PNG_EXPORT(png_charp,png_get_header_ver) PNGARG((png_structp png_ptr));
+ extern PNG_EXPORT(png_charp,png_get_header_version) PNGARG((png_structp png_ptr));
+ extern PNG_EXPORT(png_charp,png_get_libpng_ver) PNGARG((png_structp png_ptr));
+ 
+ #ifdef PNG_MNG_FEATURES_SUPPORTED
+ extern PNG_EXPORT(png_uint_32,png_permit_mng_features) PNGARG((png_structp
+    png_ptr, png_uint_32 mng_features_permitted));
+ #endif
+ 
+ /* Added to version 1.2.0 */
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+ #define PNG_ASM_FLAG_MMX_SUPPORT_COMPILED  0x01  /* not user-settable */
+ #define PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU    0x02  /* not user-settable */
+ #define PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  0x04
+ #define PNG_ASM_FLAG_MMX_READ_INTERLACE    0x08
+ #define PNG_ASM_FLAG_MMX_READ_FILTER_SUB   0x10
+ #define PNG_ASM_FLAG_MMX_READ_FILTER_UP    0x20
+ #define PNG_ASM_FLAG_MMX_READ_FILTER_AVG   0x40
+ #define PNG_ASM_FLAG_MMX_READ_FILTER_PAETH 0x80
+ #define PNG_ASM_FLAGS_INITIALIZED          0x80000000  /* not user-settable */
+ 
+ #define PNG_MMX_READ_FLAGS ( PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  \
+                            | PNG_ASM_FLAG_MMX_READ_INTERLACE    \
+                            | PNG_ASM_FLAG_MMX_READ_FILTER_SUB   \
+                            | PNG_ASM_FLAG_MMX_READ_FILTER_UP    \
+                            | PNG_ASM_FLAG_MMX_READ_FILTER_AVG   \
+                            | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH )
+ #define PNG_MMX_WRITE_FLAGS ( 0 )
+ 
+ #define PNG_MMX_FLAGS ( PNG_ASM_FLAG_MMX_SUPPORT_COMPILED \
+                       | PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU   \
+                       | PNG_MMX_READ_FLAGS                \
+                       | PNG_MMX_WRITE_FLAGS )
+ 
+ #define PNG_SELECT_READ   1
+ #define PNG_SELECT_WRITE  2
+ 
+ 
+ #if !defined(PNG_1_0_X)
+ /* pngget.c */
+ extern PNG_EXPORT(png_uint_32,png_get_mmx_flagmask)
+    PNGARG((int flag_select, int *compilerID));
+ 
+ /* pngget.c */
+ extern PNG_EXPORT(png_uint_32,png_get_asm_flagmask)
+    PNGARG((int flag_select));
+ 
+ /* pngget.c */
+ extern PNG_EXPORT(png_uint_32,png_get_asm_flags)
+    PNGARG((png_structp png_ptr));
+ 
+ /* pngget.c */
+ extern PNG_EXPORT(png_byte,png_get_mmx_bitdepth_threshold)
+    PNGARG((png_structp png_ptr));
+ 
+ /* pngget.c */
+ extern PNG_EXPORT(png_uint_32,png_get_mmx_rowbytes_threshold)
+    PNGARG((png_structp png_ptr));
+ 
+ /* pngset.c */
+ extern PNG_EXPORT(void,png_set_asm_flags)
+    PNGARG((png_structp png_ptr, png_uint_32 asm_flags));
+ 
+ /* pngset.c */
+ extern PNG_EXPORT(void,png_set_mmx_thresholds)
+    PNGARG((png_structp png_ptr, png_byte mmx_bitdepth_threshold,
+    png_uint_32 mmx_rowbytes_threshold));
+ 
+ #endif /* PNG_1_0_X */
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+ 
+ #if !defined(PNG_1_0_X)
+ /* png.c, pnggccrd.c, or pngvcrd.c */
+ extern PNG_EXPORT(int,png_mmx_support) PNGARG((void));
+ 
+ /* Strip the prepended error numbers ("#nnn ") from error and warning
+  * messages before passing them to the error or warning handler. */
+ #ifdef PNG_ERROR_NUMBERS_SUPPORTED
+ extern PNG_EXPORT(void,png_set_strip_error_numbers) PNGARG((png_structp
+    png_ptr, png_uint_32 strip_mode));
+ #endif
+ #endif /* PNG_1_0_X */
+ 
+ /* Maintainer: Put new public prototypes here ^, in libpng.3, and project defs */
+ 
+ #define PNG_HEADER_VERSION_STRING \
+    " libpng version 1.2.5 - October 3, 2002 (header)\n"
+ 
+ #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
+ /* With these routines we avoid an integer divide, which will be slower on
+  * most machines.  However, it does take more operations than the corresponding
+  * divide method, so it may be slower on a few RISC systems.  There are two
+  * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
+  *
+  * Note that the rounding factors are NOT supposed to be the same!  128 and
+  * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
+  * standard method.
+  *
+  * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
+  */
+ 
+  /* fg and bg should be in `gamma 1.0' space; alpha is the opacity          */
+ 
+ #  define png_composite(composite, fg, alpha, bg)                            \
+      { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) * (png_uint_16)(alpha) \
+                         +        (png_uint_16)(bg)*(png_uint_16)(255 -       \
+                         (png_uint_16)(alpha)) + (png_uint_16)128);           \
+        (composite) = (png_byte)((temp + (temp >> 8)) >> 8); }
+ 
+ #  define png_composite_16(composite, fg, alpha, bg)                         \
+      { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) * (png_uint_32)(alpha) \
+                         + (png_uint_32)(bg)*(png_uint_32)(65535L -           \
+                         (png_uint_32)(alpha)) + (png_uint_32)32768L);        \
+        (composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); }
+ 
+ #else  /* standard method using integer division */
+ 
+ #  define png_composite(composite, fg, alpha, bg)                            \
+      (composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) +    \
+        (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) +       \
+        (png_uint_16)127) / 255)
+ 
+ #  define png_composite_16(composite, fg, alpha, bg)                         \
+      (composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
+        (png_uint_32)(bg)*(png_uint_32)(65535L - (png_uint_32)(alpha)) +      \
+        (png_uint_32)32767) / (png_uint_32)65535L)
+ 
+ #endif /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */
+ 
+ /* These next functions are used internally in the code.  They generally
+  * shouldn't be used unless you are writing code to add or replace some
+  * functionality in libpng.  More information about most functions can
+  * be found in the files where the functions are located.
+  */
+ 
+ #if defined(PNG_INTERNAL)
+ 
+ /* Various modes of operation.  Note that after an init, mode is set to
+  * zero automatically when the structure is created.
+  */
+ #define PNG_HAVE_IHDR               0x01
+ #define PNG_HAVE_PLTE               0x02
+ #define PNG_HAVE_IDAT               0x04
+ #define PNG_AFTER_IDAT              0x08
+ #define PNG_HAVE_IEND               0x10
+ #define PNG_HAVE_gAMA               0x20
+ #define PNG_HAVE_cHRM               0x40
+ #define PNG_HAVE_sRGB               0x80
+ #define PNG_HAVE_CHUNK_HEADER      0x100
+ #define PNG_WROTE_tIME             0x200
+ #define PNG_WROTE_INFO_BEFORE_PLTE 0x400
+ #define PNG_BACKGROUND_IS_GRAY     0x800
+ #define PNG_HAVE_PNG_SIGNATURE    0x1000
+ 
+ /* flags for the transformations the PNG library does on the image data */
+ #define PNG_BGR                0x0001
+ #define PNG_INTERLACE          0x0002
+ #define PNG_PACK               0x0004
+ #define PNG_SHIFT              0x0008
+ #define PNG_SWAP_BYTES         0x0010
+ #define PNG_INVERT_MONO        0x0020
+ #define PNG_DITHER             0x0040
+ #define PNG_BACKGROUND         0x0080
+ #define PNG_BACKGROUND_EXPAND  0x0100
+                           /*   0x0200 unused */
+ #define PNG_16_TO_8            0x0400
+ #define PNG_RGBA               0x0800
+ #define PNG_EXPAND             0x1000
+ #define PNG_GAMMA              0x2000
+ #define PNG_GRAY_TO_RGB        0x4000
+ #define PNG_FILLER             0x8000L
+ #define PNG_PACKSWAP          0x10000L
+ #define PNG_SWAP_ALPHA        0x20000L
+ #define PNG_STRIP_ALPHA       0x40000L
+ #define PNG_INVERT_ALPHA      0x80000L
+ #define PNG_USER_TRANSFORM   0x100000L
+ #define PNG_RGB_TO_GRAY_ERR  0x200000L
+ #define PNG_RGB_TO_GRAY_WARN 0x400000L
+ #define PNG_RGB_TO_GRAY      0x600000L  /* two bits, RGB_TO_GRAY_ERR|WARN */
+ 
+ /* flags for png_create_struct */
+ #define PNG_STRUCT_PNG   0x0001
+ #define PNG_STRUCT_INFO  0x0002
+ 
+ /* Scaling factor for filter heuristic weighting calculations */
+ #define PNG_WEIGHT_SHIFT 8
+ #define PNG_WEIGHT_FACTOR (1<<(PNG_WEIGHT_SHIFT))
+ #define PNG_COST_SHIFT 3
+ #define PNG_COST_FACTOR (1<<(PNG_COST_SHIFT))
+ 
+ /* flags for the png_ptr->flags rather than declaring a byte for each one */
+ #define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
+ #define PNG_FLAG_ZLIB_CUSTOM_LEVEL        0x0002
+ #define PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL    0x0004
+ #define PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS  0x0008
+ #define PNG_FLAG_ZLIB_CUSTOM_METHOD       0x0010
+ #define PNG_FLAG_ZLIB_FINISHED            0x0020
+ #define PNG_FLAG_ROW_INIT                 0x0040
+ #define PNG_FLAG_FILLER_AFTER             0x0080
+ #define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
+ #define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
+ #define PNG_FLAG_CRC_CRITICAL_USE         0x0400
+ #define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
+ #define PNG_FLAG_FREE_PLTE                0x1000
+ #define PNG_FLAG_FREE_TRNS                0x2000
+ #define PNG_FLAG_FREE_HIST                0x4000
+ #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000L
+ #define PNG_FLAG_KEEP_UNSAFE_CHUNKS       0x10000L
+ #define PNG_FLAG_LIBRARY_MISMATCH         0x20000L
+ #define PNG_FLAG_STRIP_ERROR_NUMBERS      0x40000L
+ #define PNG_FLAG_STRIP_ERROR_TEXT         0x80000L
+ #define PNG_FLAG_MALLOC_NULL_MEM_OK       0x100000L
+ 
+ /* For use in png_set_keep_unknown, png_handle_as_unknown */
+ #define HANDLE_CHUNK_AS_DEFAULT   0
+ #define HANDLE_CHUNK_NEVER        1
+ #define HANDLE_CHUNK_IF_SAFE      2
+ #define HANDLE_CHUNK_ALWAYS       3
+ 
+ #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
+                                      PNG_FLAG_CRC_ANCILLARY_NOWARN)
+ 
+ #define PNG_FLAG_CRC_CRITICAL_MASK  (PNG_FLAG_CRC_CRITICAL_USE | \
+                                      PNG_FLAG_CRC_CRITICAL_IGNORE)
+ 
+ #define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
+                                      PNG_FLAG_CRC_CRITICAL_MASK)
+ 
+ /* save typing and make code easier to understand */
+ #define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
+    abs((int)((c1).green) - (int)((c2).green)) + \
+    abs((int)((c1).blue) - (int)((c2).blue)))
+ 
+ /* variables declared in png.c - only it needs to define PNG_NO_EXTERN */
+ #if !defined(PNG_NO_EXTERN) || defined(PNG_ALWAYS_EXTERN)
+ /* place to hold the signature string for a PNG file. */
+ #ifdef PNG_USE_GLOBAL_ARRAYS
+    PNG_EXPORT_VAR (const png_byte FARDATA) png_sig[8];
+ #else
+ #define png_sig png_sig_bytes(NULL)
+ #endif
+ #endif /* PNG_NO_EXTERN */
+ 
+ /* Constant strings for known chunk types.  If you need to add a chunk,
+  * define the name here, and add an invocation of the macro in png.c and
+  * wherever it's needed.
+  */
+ #define PNG_IHDR const png_byte png_IHDR[5] = { 73,  72,  68,  82, '\0'}
+ #define PNG_IDAT const png_byte png_IDAT[5] = { 73,  68,  65,  84, '\0'}
+ #define PNG_IEND const png_byte png_IEND[5] = { 73,  69,  78,  68, '\0'}
+ #define PNG_PLTE const png_byte png_PLTE[5] = { 80,  76,  84,  69, '\0'}
+ #define PNG_bKGD const png_byte png_bKGD[5] = { 98,  75,  71,  68, '\0'}
+ #define PNG_cHRM const png_byte png_cHRM[5] = { 99,  72,  82,  77, '\0'}
+ #define PNG_gAMA const png_byte png_gAMA[5] = {103,  65,  77,  65, '\0'}
+ #define PNG_hIST const png_byte png_hIST[5] = {104,  73,  83,  84, '\0'}
+ #define PNG_iCCP const png_byte png_iCCP[5] = {105,  67,  67,  80, '\0'}
+ #define PNG_iTXt const png_byte png_iTXt[5] = {105,  84,  88, 116, '\0'}
+ #define PNG_oFFs const png_byte png_oFFs[5] = {111,  70,  70, 115, '\0'}
+ #define PNG_pCAL const png_byte png_pCAL[5] = {112,  67,  65,  76, '\0'}
+ #define PNG_sCAL const png_byte png_sCAL[5] = {115,  67,  65,  76, '\0'}
+ #define PNG_pHYs const png_byte png_pHYs[5] = {112,  72,  89, 115, '\0'}
+ #define PNG_sBIT const png_byte png_sBIT[5] = {115,  66,  73,  84, '\0'}
+ #define PNG_sPLT const png_byte png_sPLT[5] = {115,  80,  76,  84, '\0'}
+ #define PNG_sRGB const png_byte png_sRGB[5] = {115,  82,  71,  66, '\0'}
+ #define PNG_tEXt const png_byte png_tEXt[5] = {116,  69,  88, 116, '\0'}
+ #define PNG_tIME const png_byte png_tIME[5] = {116,  73,  77,  69, '\0'}
+ #define PNG_tRNS const png_byte png_tRNS[5] = {116,  82,  78,  83, '\0'}
+ #define PNG_zTXt const png_byte png_zTXt[5] = {122,  84,  88, 116, '\0'}
+ 
+ #ifdef PNG_USE_GLOBAL_ARRAYS
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_IHDR[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_IDAT[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_IEND[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_PLTE[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_bKGD[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_cHRM[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_gAMA[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_hIST[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_iCCP[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_iTXt[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_oFFs[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_pCAL[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_sCAL[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_pHYs[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_sBIT[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_sPLT[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_sRGB[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_tEXt[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_tIME[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_tRNS[5];
+ PNG_EXPORT_VAR (const png_byte FARDATA) png_zTXt[5];
+ #endif /* PNG_USE_GLOBAL_ARRAYS */
+ 
+ 
+ /* Inline macros to do direct reads of bytes from the input buffer.  These
+  * require that you are using an architecture that uses PNG byte ordering
+  * (MSB first) and supports unaligned data storage.  I think that PowerPC
+  * in big-endian mode and 680x0 are the only ones that will support this.
+  * The x86 line of processors definitely do not.  The png_get_int_32()
+  * routine also assumes we are using two's complement format for negative
+  * values, which is almost certainly true.
+  */
+ #if defined(PNG_READ_BIG_ENDIAN_SUPPORTED)
+ #  if defined(PNG_pCAL_SUPPORTED) || defined(PNG_oFFs_SUPPORTED)
+ #    define png_get_int_32(buf) ( *((png_int_32p) (buf)))
+ #  endif
+ #  define png_get_uint_32(buf) ( *((png_uint_32p) (buf)))
+ #  define png_get_uint_16(buf) ( *((png_uint_16p) (buf)))
+ #else
+ #  if defined(PNG_pCAL_SUPPORTED) || defined(PNG_oFFs_SUPPORTED)
+ PNG_EXTERN png_int_32 png_get_int_32 PNGARG((png_bytep buf));
+ #  endif
+ PNG_EXTERN png_uint_32 png_get_uint_32 PNGARG((png_bytep buf));
+ PNG_EXTERN png_uint_16 png_get_uint_16 PNGARG((png_bytep buf));
+ #endif /* !PNG_READ_BIG_ENDIAN_SUPPORTED */
+ 
+ /* Initialize png_ptr struct for reading, and allocate any other memory.
+  * (old interface - DEPRECATED - use png_create_read_struct instead).
+  */
+ extern PNG_EXPORT(void,png_read_init) PNGARG((png_structp png_ptr));
+ #undef png_read_init
+ #define png_read_init(png_ptr) png_read_init_3(&png_ptr, \
+     PNG_LIBPNG_VER_STRING,  sizeof(png_struct));
+ extern PNG_EXPORT(void,png_read_init_3) PNGARG((png_structpp ptr_ptr,
+     png_const_charp user_png_ver, png_size_t png_struct_size));
+ extern PNG_EXPORT(void,png_read_init_2) PNGARG((png_structp png_ptr,
+     png_const_charp user_png_ver, png_size_t png_struct_size, png_size_t
+     png_info_size));
+ 
+ /* Initialize png_ptr struct for writing, and allocate any other memory.
+  * (old interface - DEPRECATED - use png_create_write_struct instead).
+  */
+ extern PNG_EXPORT(void,png_write_init) PNGARG((png_structp png_ptr));
+ #undef png_write_init
+ #define png_write_init(png_ptr) png_write_init_3(&png_ptr, \
+     PNG_LIBPNG_VER_STRING, sizeof(png_struct));
+ extern PNG_EXPORT(void,png_write_init_3) PNGARG((png_structpp ptr_ptr,
+     png_const_charp user_png_ver, png_size_t png_struct_size));
+ extern PNG_EXPORT(void,png_write_init_2) PNGARG((png_structp png_ptr,
+     png_const_charp user_png_ver, png_size_t png_struct_size, png_size_t
+     png_info_size));
+ 
+ /* Allocate memory for an internal libpng struct */
+ PNG_EXTERN png_voidp png_create_struct PNGARG((int type));
+ 
+ /* Free memory from internal libpng struct */
+ PNG_EXTERN void png_destroy_struct PNGARG((png_voidp struct_ptr));
+ 
+ PNG_EXTERN png_voidp png_create_struct_2 PNGARG((int type, png_malloc_ptr
+   malloc_fn, png_voidp mem_ptr));
+ PNG_EXTERN void png_destroy_struct_2 PNGARG((png_voidp struct_ptr,
+    png_free_ptr free_fn, png_voidp mem_ptr));
+ 
+ /* Free any memory that info_ptr points to and reset struct. */
+ PNG_EXTERN void png_info_destroy PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ 
+ #ifndef PNG_1_0_X
+ /* Function to allocate memory for zlib. */
+ PNG_EXTERN voidpf png_zalloc PNGARG((voidpf png_ptr, uInt items, uInt size));
+ 
+ /* Function to free memory for zlib */
+ PNG_EXTERN void png_zfree PNGARG((voidpf png_ptr, voidpf ptr));
+ 
+ /* Next four functions are used internally as callbacks.  PNGAPI is required
+  * but not PNG_EXPORT.  PNGAPI added at libpng version 1.2.3. */
+ 
+ PNG_EXTERN void PNGAPI png_default_read_data PNGARG((png_structp png_ptr,
+    png_bytep data, png_size_t length));
+ 
+ #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+ PNG_EXTERN void PNGAPI png_push_fill_buffer PNGARG((png_structp png_ptr,
+    png_bytep buffer, png_size_t length));
+ #endif
+ 
+ PNG_EXTERN void PNGAPI png_default_write_data PNGARG((png_structp png_ptr,
+    png_bytep data, png_size_t length));
+ 
+ #if defined(PNG_WRITE_FLUSH_SUPPORTED)
+ #if !defined(PNG_NO_STDIO)
+ PNG_EXTERN void PNGAPI png_default_flush PNGARG((png_structp png_ptr));
+ #endif
+ #endif
+ #else /* PNG_1_0_X */
+ #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+ PNG_EXTERN void png_push_fill_buffer PNGARG((png_structp png_ptr,
+    png_bytep buffer, png_size_t length));
+ #endif
+ #endif /* PNG_1_0_X */
+ 
+ /* Reset the CRC variable */
+ PNG_EXTERN void png_reset_crc PNGARG((png_structp png_ptr));
+ 
+ /* Write the "data" buffer to whatever output you are using. */
+ PNG_EXTERN void png_write_data PNGARG((png_structp png_ptr, png_bytep data,
+    png_size_t length));
+ 
+ /* Read data from whatever input you are using into the "data" buffer */
+ PNG_EXTERN void png_read_data PNGARG((png_structp png_ptr, png_bytep data,
+    png_size_t length));
+ 
+ /* Read bytes into buf, and update png_ptr->crc */
+ PNG_EXTERN void png_crc_read PNGARG((png_structp png_ptr, png_bytep buf,
+    png_size_t length));
+ 
+ /* Decompress data in a chunk that uses compression */
+ #if defined(PNG_zTXt_SUPPORTED) || defined(PNG_iTXt_SUPPORTED) || \
+     defined(PNG_iCCP_SUPPORTED) || defined(PNG_sPLT_SUPPORTED)
+ PNG_EXTERN png_charp png_decompress_chunk PNGARG((png_structp png_ptr,
+    int comp_type, png_charp chunkdata, png_size_t chunklength,
+    png_size_t prefix_length, png_size_t *data_length));
+ #endif
+ 
+ /* Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc */
+ PNG_EXTERN int png_crc_finish PNGARG((png_structp png_ptr, png_uint_32 skip));
+ 
+ /* Read the CRC from the file and compare it to the libpng calculated CRC */
+ PNG_EXTERN int png_crc_error PNGARG((png_structp png_ptr));
+ 
+ /* Calculate the CRC over a section of data.  Note that we are only
+  * passing a maximum of 64K on systems that have this as a memory limit,
+  * since this is the maximum buffer size we can specify.
+  */
+ PNG_EXTERN void png_calculate_crc PNGARG((png_structp png_ptr, png_bytep ptr,
+    png_size_t length));
+ 
+ #if defined(PNG_WRITE_FLUSH_SUPPORTED)
+ PNG_EXTERN void png_flush PNGARG((png_structp png_ptr));
+ #endif
+ 
+ 
+ /* Place a 32-bit number into a buffer in PNG byte order (big-endian).
+  * The only currently known PNG chunks that use signed numbers are
+  * the ancillary extension chunks, oFFs and pCAL.
+  */
+ PNG_EXTERN void png_save_uint_32 PNGARG((png_bytep buf, png_uint_32 i));
+ 
+ #if defined(PNG_WRITE_pCAL_SUPPORTED) || defined(PNG_WRITE_oFFs_SUPPORTED)
+ PNG_EXTERN void png_save_int_32 PNGARG((png_bytep buf, png_int_32 i));
+ #endif
+ 
+ /* Place a 16-bit number into a buffer in PNG byte order.
+  * The parameter is declared unsigned int, not png_uint_16,
+  * just to avoid potential problems on pre-ANSI C compilers.
+  */
+ PNG_EXTERN void png_save_uint_16 PNGARG((png_bytep buf, unsigned int i));
+ 
+ /* simple function to write the signature */
+ PNG_EXTERN void png_write_sig PNGARG((png_structp png_ptr));
+ 
+ /* write various chunks */
+ 
+ /* Write the IHDR chunk, and update the png_struct with the necessary
+  * information.
+  */
+ PNG_EXTERN void png_write_IHDR PNGARG((png_structp png_ptr, png_uint_32 width,
+    png_uint_32 height,
+    int bit_depth, int color_type, int compression_method, int filter_method,
+    int interlace_method));
+ 
+ PNG_EXTERN void png_write_PLTE PNGARG((png_structp png_ptr, png_colorp palette,
+    png_uint_32 num_pal));
+ 
+ PNG_EXTERN void png_write_IDAT PNGARG((png_structp png_ptr, png_bytep data,
+    png_size_t length));
+ 
+ PNG_EXTERN void png_write_IEND PNGARG((png_structp png_ptr));
+ 
+ #if defined(PNG_WRITE_gAMA_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ PNG_EXTERN void png_write_gAMA PNGARG((png_structp png_ptr, double file_gamma));
+ #endif
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ PNG_EXTERN void png_write_gAMA_fixed PNGARG((png_structp png_ptr, png_fixed_point
+     file_gamma));
+ #endif
+ #endif
+ 
+ #if defined(PNG_WRITE_sBIT_SUPPORTED)
+ PNG_EXTERN void png_write_sBIT PNGARG((png_structp png_ptr, png_color_8p sbit,
+    int color_type));
+ #endif
+ 
+ #if defined(PNG_WRITE_cHRM_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ PNG_EXTERN void png_write_cHRM PNGARG((png_structp png_ptr,
+    double white_x, double white_y,
+    double red_x, double red_y, double green_x, double green_y,
+    double blue_x, double blue_y));
+ #endif
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ PNG_EXTERN void png_write_cHRM_fixed PNGARG((png_structp png_ptr,
+    png_fixed_point int_white_x, png_fixed_point int_white_y,
+    png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
+    int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
+    png_fixed_point int_blue_y));
+ #endif
+ #endif
+ 
+ #if defined(PNG_WRITE_sRGB_SUPPORTED)
+ PNG_EXTERN void png_write_sRGB PNGARG((png_structp png_ptr,
+    int intent));
+ #endif
+ 
+ #if defined(PNG_WRITE_iCCP_SUPPORTED)
+ PNG_EXTERN void png_write_iCCP PNGARG((png_structp png_ptr,
+    png_charp name, int compression_type,
+    png_charp profile, int proflen));
+    /* Note to maintainer: profile should be png_bytep */
+ #endif
+ 
+ #if defined(PNG_WRITE_sPLT_SUPPORTED)
+ PNG_EXTERN void png_write_sPLT PNGARG((png_structp png_ptr,
+    png_sPLT_tp palette));
+ #endif
+ 
+ #if defined(PNG_WRITE_tRNS_SUPPORTED)
+ PNG_EXTERN void png_write_tRNS PNGARG((png_structp png_ptr, png_bytep trans,
+    png_color_16p values, int number, int color_type));
+ #endif
+ 
+ #if defined(PNG_WRITE_bKGD_SUPPORTED)
+ PNG_EXTERN void png_write_bKGD PNGARG((png_structp png_ptr,
+    png_color_16p values, int color_type));
+ #endif
+ 
+ #if defined(PNG_WRITE_hIST_SUPPORTED)
+ PNG_EXTERN void png_write_hIST PNGARG((png_structp png_ptr, png_uint_16p hist,
+    int num_hist));
+ #endif
+ 
+ #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
+     defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
+ PNG_EXTERN png_size_t png_check_keyword PNGARG((png_structp png_ptr,
+    png_charp key, png_charpp new_key));
+ #endif
+ 
+ #if defined(PNG_WRITE_tEXt_SUPPORTED)
+ PNG_EXTERN void png_write_tEXt PNGARG((png_structp png_ptr, png_charp key,
+    png_charp text, png_size_t text_len));
+ #endif
+ 
+ #if defined(PNG_WRITE_zTXt_SUPPORTED)
+ PNG_EXTERN void png_write_zTXt PNGARG((png_structp png_ptr, png_charp key,
+    png_charp text, png_size_t text_len, int compression));
+ #endif
+ 
+ #if defined(PNG_WRITE_iTXt_SUPPORTED)
+ PNG_EXTERN void png_write_iTXt PNGARG((png_structp png_ptr,
+    int compression, png_charp key, png_charp lang, png_charp lang_key,
+    png_charp text));
+ #endif
+ 
+ #if defined(PNG_TEXT_SUPPORTED)  /* Added at version 1.0.14 and 1.2.4 */
+ PNG_EXTERN int png_set_text_2 PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_textp text_ptr, int num_text));
+ #endif
+ 
+ #if defined(PNG_WRITE_oFFs_SUPPORTED)
+ PNG_EXTERN void png_write_oFFs PNGARG((png_structp png_ptr,
+    png_int_32 x_offset, png_int_32 y_offset, int unit_type));
+ #endif
+ 
+ #if defined(PNG_WRITE_pCAL_SUPPORTED)
+ PNG_EXTERN void png_write_pCAL PNGARG((png_structp png_ptr, png_charp purpose,
+    png_int_32 X0, png_int_32 X1, int type, int nparams,
+    png_charp units, png_charpp params));
+ #endif
+ 
+ #if defined(PNG_WRITE_pHYs_SUPPORTED)
+ PNG_EXTERN void png_write_pHYs PNGARG((png_structp png_ptr,
+    png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
+    int unit_type));
+ #endif
+ 
+ #if defined(PNG_WRITE_tIME_SUPPORTED)
+ PNG_EXTERN void png_write_tIME PNGARG((png_structp png_ptr,
+    png_timep mod_time));
+ #endif
+ 
+ #if defined(PNG_WRITE_sCAL_SUPPORTED)
+ #if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
+ PNG_EXTERN void png_write_sCAL PNGARG((png_structp png_ptr,
+    int unit, double width, double height));
+ #else
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ PNG_EXTERN void png_write_sCAL_s PNGARG((png_structp png_ptr,
+    int unit, png_charp width, png_charp height));
+ #endif
+ #endif
+ #endif
+ 
+ /* Called when finished processing a row of data */
+ PNG_EXTERN void png_write_finish_row PNGARG((png_structp png_ptr));
+ 
+ /* Internal use only.   Called before first row of data */
+ PNG_EXTERN void png_write_start_row PNGARG((png_structp png_ptr));
+ 
+ #if defined(PNG_READ_GAMMA_SUPPORTED)
+ PNG_EXTERN void png_build_gamma_table PNGARG((png_structp png_ptr));
+ #endif
+ 
+ /* combine a row of data, dealing with alpha, etc. if requested */
+ PNG_EXTERN void png_combine_row PNGARG((png_structp png_ptr, png_bytep row,
+    int mask));
+ 
+ #if defined(PNG_READ_INTERLACING_SUPPORTED)
+ /* expand an interlaced row */
+ /* OLD pre-1.0.9 interface:
+ PNG_EXTERN void png_do_read_interlace PNGARG((png_row_infop row_info,
+    png_bytep row, int pass, png_uint_32 transformations));
+  */
+ PNG_EXTERN void png_do_read_interlace PNGARG((png_structp png_ptr));
+ #endif
+ 
+ /* GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces */
+ 
+ #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
+ /* grab pixels out of a row for an interlaced pass */
+ PNG_EXTERN void png_do_write_interlace PNGARG((png_row_infop row_info,
+    png_bytep row, int pass));
+ #endif
+ 
+ /* unfilter a row */
+ PNG_EXTERN void png_read_filter_row PNGARG((png_structp png_ptr,
+    png_row_infop row_info, png_bytep row, png_bytep prev_row, int filter));
+ 
+ /* Choose the best filter to use and filter the row data */
+ PNG_EXTERN void png_write_find_filter PNGARG((png_structp png_ptr,
+    png_row_infop row_info));
+ 
+ /* Write out the filtered row. */
+ PNG_EXTERN void png_write_filtered_row PNGARG((png_structp png_ptr,
+    png_bytep filtered_row));
+ /* finish a row while reading, dealing with interlacing passes, etc. */
+ PNG_EXTERN void png_read_finish_row PNGARG((png_structp png_ptr));
+ 
+ /* initialize the row buffers, etc. */
+ PNG_EXTERN void png_read_start_row PNGARG((png_structp png_ptr));
+ /* optional call to update the users info structure */
+ PNG_EXTERN void png_read_transform_info PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ 
+ /* these are the functions that do the transformations */
+ #if defined(PNG_READ_FILLER_SUPPORTED)
+ PNG_EXTERN void png_do_read_filler PNGARG((png_row_infop row_info,
+    png_bytep row, png_uint_32 filler, png_uint_32 flags));
+ #endif
+ 
+ #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
+ PNG_EXTERN void png_do_read_swap_alpha PNGARG((png_row_infop row_info,
+    png_bytep row));
+ #endif
+ 
+ #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
+ PNG_EXTERN void png_do_write_swap_alpha PNGARG((png_row_infop row_info,
+    png_bytep row));
+ #endif
+ 
+ #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+ PNG_EXTERN void png_do_read_invert_alpha PNGARG((png_row_infop row_info,
+    png_bytep row));
+ #endif
+ 
+ #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+ PNG_EXTERN void png_do_write_invert_alpha PNGARG((png_row_infop row_info,
+    png_bytep row));
+ #endif
+ 
+ #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
+     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
+ PNG_EXTERN void png_do_strip_filler PNGARG((png_row_infop row_info,
+    png_bytep row, png_uint_32 flags));
+ #endif
+ 
+ #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
+ PNG_EXTERN void png_do_swap PNGARG((png_row_infop row_info, png_bytep row));
+ #endif
+ 
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED) || defined(PNG_WRITE_PACKSWAP_SUPPORTED)
+ PNG_EXTERN void png_do_packswap PNGARG((png_row_infop row_info, png_bytep row));
+ #endif
+ 
+ #if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ PNG_EXTERN int png_do_rgb_to_gray PNGARG((png_structp png_ptr, png_row_infop
+    row_info, png_bytep row));
+ #endif
+ 
+ #if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+ PNG_EXTERN void png_do_gray_to_rgb PNGARG((png_row_infop row_info,
+    png_bytep row));
+ #endif
+ 
+ #if defined(PNG_READ_PACK_SUPPORTED)
+ PNG_EXTERN void png_do_unpack PNGARG((png_row_infop row_info, png_bytep row));
+ #endif
+ 
+ #if defined(PNG_READ_SHIFT_SUPPORTED)
+ PNG_EXTERN void png_do_unshift PNGARG((png_row_infop row_info, png_bytep row,
+    png_color_8p sig_bits));
+ #endif
+ 
+ #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
+ PNG_EXTERN void png_do_invert PNGARG((png_row_infop row_info, png_bytep row));
+ #endif
+ 
+ #if defined(PNG_READ_16_TO_8_SUPPORTED)
+ PNG_EXTERN void png_do_chop PNGARG((png_row_infop row_info, png_bytep row));
+ #endif
+ 
+ #if defined(PNG_READ_DITHER_SUPPORTED)
+ PNG_EXTERN void png_do_dither PNGARG((png_row_infop row_info,
+    png_bytep row, png_bytep palette_lookup, png_bytep dither_lookup));
+ 
+ #  if defined(PNG_CORRECT_PALETTE_SUPPORTED)
+ PNG_EXTERN void png_correct_palette PNGARG((png_structp png_ptr,
+    png_colorp palette, int num_palette));
+ #  endif
+ #endif
+ 
+ #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
+ PNG_EXTERN void png_do_bgr PNGARG((png_row_infop row_info, png_bytep row));
+ #endif
+ 
+ #if defined(PNG_WRITE_PACK_SUPPORTED)
+ PNG_EXTERN void png_do_pack PNGARG((png_row_infop row_info,
+    png_bytep row, png_uint_32 bit_depth));
+ #endif
+ 
+ #if defined(PNG_WRITE_SHIFT_SUPPORTED)
+ PNG_EXTERN void png_do_shift PNGARG((png_row_infop row_info, png_bytep row,
+    png_color_8p bit_depth));
+ #endif
+ 
+ #if defined(PNG_READ_BACKGROUND_SUPPORTED)
+ #if defined(PNG_READ_GAMMA_SUPPORTED)
+ PNG_EXTERN void png_do_background PNGARG((png_row_infop row_info, png_bytep row,
+    png_color_16p trans_values, png_color_16p background,
+    png_color_16p background_1,
+    png_bytep gamma_table, png_bytep gamma_from_1, png_bytep gamma_to_1,
+    png_uint_16pp gamma_16, png_uint_16pp gamma_16_from_1,
+    png_uint_16pp gamma_16_to_1, int gamma_shift));
+ #else
+ PNG_EXTERN void png_do_background PNGARG((png_row_infop row_info, png_bytep row,
+    png_color_16p trans_values, png_color_16p background));
+ #endif
+ #endif
+ 
+ #if defined(PNG_READ_GAMMA_SUPPORTED)
+ PNG_EXTERN void png_do_gamma PNGARG((png_row_infop row_info, png_bytep row,
+    png_bytep gamma_table, png_uint_16pp gamma_16_table,
+    int gamma_shift));
+ #endif
+ 
+ #if defined(PNG_READ_EXPAND_SUPPORTED)
+ PNG_EXTERN void png_do_expand_palette PNGARG((png_row_infop row_info,
+    png_bytep row, png_colorp palette, png_bytep trans, int num_trans));
+ PNG_EXTERN void png_do_expand PNGARG((png_row_infop row_info,
+    png_bytep row, png_color_16p trans_value));
+ #endif
+ 
+ /* The following decodes the appropriate chunks, and does error correction,
+  * then calls the appropriate callback for the chunk if it is valid.
+  */
+ 
+ /* decode the IHDR chunk */
+ PNG_EXTERN void png_handle_IHDR PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ PNG_EXTERN void png_handle_PLTE PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ PNG_EXTERN void png_handle_IEND PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ 
+ #if defined(PNG_READ_bKGD_SUPPORTED)
+ PNG_EXTERN void png_handle_bKGD PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_cHRM_SUPPORTED)
+ PNG_EXTERN void png_handle_cHRM PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_gAMA_SUPPORTED)
+ PNG_EXTERN void png_handle_gAMA PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_hIST_SUPPORTED)
+ PNG_EXTERN void png_handle_hIST PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_iCCP_SUPPORTED)
+ extern void png_handle_iCCP PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif /* PNG_READ_iCCP_SUPPORTED */
+ 
+ #if defined(PNG_READ_iTXt_SUPPORTED)
+ PNG_EXTERN void png_handle_iTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_oFFs_SUPPORTED)
+ PNG_EXTERN void png_handle_oFFs PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_pCAL_SUPPORTED)
+ PNG_EXTERN void png_handle_pCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_pHYs_SUPPORTED)
+ PNG_EXTERN void png_handle_pHYs PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_sBIT_SUPPORTED)
+ PNG_EXTERN void png_handle_sBIT PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_sCAL_SUPPORTED)
+ PNG_EXTERN void png_handle_sCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_sPLT_SUPPORTED)
+ extern void png_handle_sPLT PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif /* PNG_READ_sPLT_SUPPORTED */
+ 
+ #if defined(PNG_READ_sRGB_SUPPORTED)
+ PNG_EXTERN void png_handle_sRGB PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_tEXt_SUPPORTED)
+ PNG_EXTERN void png_handle_tEXt PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_tIME_SUPPORTED)
+ PNG_EXTERN void png_handle_tIME PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_tRNS_SUPPORTED)
+ PNG_EXTERN void png_handle_tRNS PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ #if defined(PNG_READ_zTXt_SUPPORTED)
+ PNG_EXTERN void png_handle_zTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 length));
+ #endif
+ 
+ PNG_EXTERN void png_handle_unknown PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 length));
+ 
+ PNG_EXTERN void png_check_chunk_name PNGARG((png_structp png_ptr,
+    png_bytep chunk_name));
+ 
+ /* handle the transformations for reading and writing */
+ PNG_EXTERN void png_do_read_transformations PNGARG((png_structp png_ptr));
+ PNG_EXTERN void png_do_write_transformations PNGARG((png_structp png_ptr));
+ 
+ PNG_EXTERN void png_init_read_transformations PNGARG((png_structp png_ptr));
+ 
+ #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+ PNG_EXTERN void png_push_read_chunk PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ PNG_EXTERN void png_push_read_sig PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ PNG_EXTERN void png_push_check_crc PNGARG((png_structp png_ptr));
+ PNG_EXTERN void png_push_crc_skip PNGARG((png_structp png_ptr,
+    png_uint_32 length));
+ PNG_EXTERN void png_push_crc_finish PNGARG((png_structp png_ptr));
+ PNG_EXTERN void png_push_save_buffer PNGARG((png_structp png_ptr));
+ PNG_EXTERN void png_push_restore_buffer PNGARG((png_structp png_ptr,
+    png_bytep buffer, png_size_t buffer_length));
+ PNG_EXTERN void png_push_read_IDAT PNGARG((png_structp png_ptr));
+ PNG_EXTERN void png_process_IDAT_data PNGARG((png_structp png_ptr,
+    png_bytep buffer, png_size_t buffer_length));
+ PNG_EXTERN void png_push_process_row PNGARG((png_structp png_ptr));
+ PNG_EXTERN void png_push_handle_unknown PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 length));
+ PNG_EXTERN void png_push_have_info PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ PNG_EXTERN void png_push_have_end PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ PNG_EXTERN void png_push_have_row PNGARG((png_structp png_ptr, png_bytep row));
+ PNG_EXTERN void png_push_read_end PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ PNG_EXTERN void png_process_some_data PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ PNG_EXTERN void png_read_push_finish_row PNGARG((png_structp png_ptr));
+ #if defined(PNG_READ_tEXt_SUPPORTED)
+ PNG_EXTERN void png_push_handle_tEXt PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 length));
+ PNG_EXTERN void png_push_read_tEXt PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ #endif
+ #if defined(PNG_READ_zTXt_SUPPORTED)
+ PNG_EXTERN void png_push_handle_zTXt PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 length));
+ PNG_EXTERN void png_push_read_zTXt PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ #endif
+ #if defined(PNG_READ_iTXt_SUPPORTED)
+ PNG_EXTERN void png_push_handle_iTXt PNGARG((png_structp png_ptr,
+    png_infop info_ptr, png_uint_32 length));
+ PNG_EXTERN void png_push_read_iTXt PNGARG((png_structp png_ptr,
+    png_infop info_ptr));
+ #endif
+ 
+ #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+ 
+ #ifdef PNG_MNG_FEATURES_SUPPORTED
+ PNG_EXTERN void png_do_read_intrapixel PNGARG((png_row_infop row_info,
+    png_bytep row));
+ PNG_EXTERN void png_do_write_intrapixel PNGARG((png_row_infop row_info,
+    png_bytep row));
+ #endif
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+ /* png.c */ /* PRIVATE */
+ PNG_EXTERN void png_init_mmx_flags PNGARG((png_structp png_ptr));
+ #endif
+ /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
+ 
+ #endif /* PNG_INTERNAL */
+ 
+ #ifdef __cplusplus
+ }
+ #endif
+ 
+ #endif /* PNG_VERSION_INFO_ONLY */
+ /* do not put anything past this line */
+ #endif /* PNG_H */


Index: llvm/runtime/libpng/pngasmrd.h
diff -c /dev/null llvm/runtime/libpng/pngasmrd.h:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/pngasmrd.h	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,11 ----
+ /* pngasmrd.h - assembler version of utilities to read a PNG file
+  *
+  * libpng 1.2.5 - October 3, 2002
+  * For conditions of distribution and use, see copyright notice in png.h
+  * Copyright (c) 2002 Glenn Randers-Pehrson
+  *
+  */
+ 
+ /* This file is obsolete in libpng-1.0.9 and later; its contents now appear
+  * at the end of pngconf.h.
+  */


Index: llvm/runtime/libpng/pngbar.jpg


Index: llvm/runtime/libpng/pngbar.png


Index: llvm/runtime/libpng/pngconf.h
diff -c /dev/null llvm/runtime/libpng/pngconf.h:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/pngconf.h	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,1348 ----
+ /* pngconf.h - machine configurable file for libpng
+  *
+  * libpng 1.2.5 - October 3, 2002
+  * For conditions of distribution and use, see copyright notice in png.h
+  * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+  */
+ 
+ /* Any machine specific code is near the front of this file, so if you
+  * are configuring libpng for a machine, you may want to read the section
+  * starting here down to where it starts to typedef png_color, png_text,
+  * and png_info.
+  */
+ 
+ #ifndef PNGCONF_H
+ #define PNGCONF_H
+ 
+ /* This is the size of the compression buffer, and thus the size of
+  * an IDAT chunk.  Make this whatever size you feel is best for your
+  * machine.  One of these will be allocated per png_struct.  When this
+  * is full, it writes the data to the disk, and does some other
+  * calculations.  Making this an extremely small size will slow
+  * the library down, but you may want to experiment to determine
+  * where it becomes significant, if you are concerned with memory
+  * usage.  Note that zlib allocates at least 32Kb also.  For readers,
+  * this describes the size of the buffer available to read the data in.
+  * Unless this gets smaller than the size of a row (compressed),
+  * it should not make much difference how big this is.
+  */
+ 
+ #ifndef PNG_ZBUF_SIZE
+ #  define PNG_ZBUF_SIZE 8192
+ #endif
+ 
+ /* Enable if you want a write-only libpng */
+ 
+ #ifndef PNG_NO_READ_SUPPORTED
+ #  define PNG_READ_SUPPORTED
+ #endif
+ 
+ /* Enable if you want a read-only libpng */
+ 
+ #ifndef PNG_NO_WRITE_SUPPORTED
+ #  define PNG_WRITE_SUPPORTED
+ #endif
+ 
+ /* Enabled by default in 1.2.0.  You can disable this if you don't need to
+    support PNGs that are embedded in MNG datastreams */
+ #if !defined(PNG_1_0_X) && !defined(PNG_NO_MNG_FEATURES)
+ #  ifndef PNG_MNG_FEATURES_SUPPORTED
+ #    define PNG_MNG_FEATURES_SUPPORTED
+ #  endif
+ #endif
+ 
+ #ifndef PNG_NO_FLOATING_POINT_SUPPORTED
+ #  ifndef PNG_FLOATING_POINT_SUPPORTED
+ #    define PNG_FLOATING_POINT_SUPPORTED
+ #  endif
+ #endif
+ 
+ /* If you are running on a machine where you cannot allocate more
+  * than 64K of memory at once, uncomment this.  While libpng will not
+  * normally need that much memory in a chunk (unless you load up a very
+  * large file), zlib needs to know how big of a chunk it can use, and
+  * libpng thus makes sure to check any memory allocation to verify it
+  * will fit into memory.
+ #define PNG_MAX_MALLOC_64K
+  */
+ #if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
+ #  define PNG_MAX_MALLOC_64K
+ #endif
+ 
+ /* Special munging to support doing things the 'cygwin' way:
+  * 'Normal' png-on-win32 defines/defaults:
+  *   PNG_BUILD_DLL -- building dll
+  *   PNG_USE_DLL   -- building an application, linking to dll
+  *   (no define)   -- building static library, or building an
+  *                    application and linking to the static lib
+  * 'Cygwin' defines/defaults:
+  *   PNG_BUILD_DLL -- (ignored) building the dll
+  *   (no define)   -- (ignored) building an application, linking to the dll
+  *   PNG_STATIC    -- (ignored) building the static lib, or building an 
+  *                    application that links to the static lib.
+  *   ALL_STATIC    -- (ignored) building various static libs, or building an 
+  *                    application that links to the static libs.
+  * Thus,
+  * a cygwin user should define either PNG_BUILD_DLL or PNG_STATIC, and
+  * this bit of #ifdefs will define the 'correct' config variables based on
+  * that. If a cygwin user *wants* to define 'PNG_USE_DLL' that's okay, but
+  * unnecessary.
+  *
+  * Also, the precedence order is:
+  *   ALL_STATIC (since we can't #undef something outside our namespace)
+  *   PNG_BUILD_DLL
+  *   PNG_STATIC
+  *   (nothing) == PNG_USE_DLL
+  * 
+  * CYGWIN (2002-01-20): The preceding is now obsolete. With the advent
+  *   of auto-import in binutils, we no longer need to worry about 
+  *   __declspec(dllexport) / __declspec(dllimport) and friends.  Therefore,
+  *   we don't need to worry about PNG_STATIC or ALL_STATIC when it comes
+  *   to __declspec() stuff.  However, we DO need to worry about 
+  *   PNG_BUILD_DLL and PNG_STATIC because those change some defaults
+  *   such as CONSOLE_IO and whether GLOBAL_ARRAYS are allowed.
+  */
+ #if defined(__CYGWIN__)
+ #  if defined(ALL_STATIC)
+ #    if defined(PNG_BUILD_DLL)
+ #      undef PNG_BUILD_DLL
+ #    endif
+ #    if defined(PNG_USE_DLL)
+ #      undef PNG_USE_DLL
+ #    endif
+ #    if defined(PNG_DLL)
+ #      undef PNG_DLL
+ #    endif
+ #    if !defined(PNG_STATIC)
+ #      define PNG_STATIC
+ #    endif
+ #  else
+ #    if defined (PNG_BUILD_DLL)
+ #      if defined(PNG_STATIC)
+ #        undef PNG_STATIC
+ #      endif
+ #      if defined(PNG_USE_DLL)
+ #        undef PNG_USE_DLL
+ #      endif
+ #      if !defined(PNG_DLL)
+ #        define PNG_DLL
+ #      endif
+ #    else
+ #      if defined(PNG_STATIC)
+ #        if defined(PNG_USE_DLL)
+ #          undef PNG_USE_DLL
+ #        endif
+ #        if defined(PNG_DLL)
+ #          undef PNG_DLL
+ #        endif
+ #      else
+ #        if !defined(PNG_USE_DLL)
+ #          define PNG_USE_DLL
+ #        endif
+ #        if !defined(PNG_DLL)
+ #          define PNG_DLL
+ #        endif
+ #      endif  
+ #    endif  
+ #  endif
+ #endif
+ 
+ /* This protects us against compilers that run on a windowing system
+  * and thus don't have or would rather us not use the stdio types:
+  * stdin, stdout, and stderr.  The only one currently used is stderr
+  * in png_error() and png_warning().  #defining PNG_NO_CONSOLE_IO will
+  * prevent these from being compiled and used. #defining PNG_NO_STDIO
+  * will also prevent these, plus will prevent the entire set of stdio
+  * macros and functions (FILE *, printf, etc.) from being compiled and used,
+  * unless (PNG_DEBUG > 0) has been #defined.
+  *
+  * #define PNG_NO_CONSOLE_IO
+  * #define PNG_NO_STDIO
+  */
+ 
+ #if defined(_WIN32_WCE)
+ #  include <windows.h>
+    /* Console I/O functions are not supported on WindowsCE */
+ #  define PNG_NO_CONSOLE_IO
+ #  ifdef PNG_DEBUG
+ #    undef PNG_DEBUG
+ #  endif
+ #endif
+ 
+ #ifdef PNG_BUILD_DLL
+ #  ifndef PNG_CONSOLE_IO_SUPPORTED
+ #    ifndef PNG_NO_CONSOLE_IO
+ #      define PNG_NO_CONSOLE_IO
+ #    endif
+ #  endif
+ #endif
+ 
+ #  ifdef PNG_NO_STDIO
+ #    ifndef PNG_NO_CONSOLE_IO
+ #      define PNG_NO_CONSOLE_IO
+ #    endif
+ #    ifdef PNG_DEBUG
+ #      if (PNG_DEBUG > 0)
+ #        include <stdio.h>
+ #      endif
+ #    endif
+ #  else
+ #    if !defined(_WIN32_WCE)
+ /* "stdio.h" functions are not supported on WindowsCE */
+ #      include <stdio.h>
+ #    endif
+ #  endif
+ 
+ /* This macro protects us against machines that don't have function
+  * prototypes (ie K&R style headers).  If your compiler does not handle
+  * function prototypes, define this macro and use the included ansi2knr.
+  * I've always been able to use _NO_PROTO as the indicator, but you may
+  * need to drag the empty declaration out in front of here, or change the
+  * ifdef to suit your own needs.
+  */
+ #ifndef PNGARG
+ 
+ #ifdef OF /* zlib prototype munger */
+ #  define PNGARG(arglist) OF(arglist)
+ #else
+ 
+ #ifdef _NO_PROTO
+ #  define PNGARG(arglist) ()
+ #  ifndef PNG_TYPECAST_NULL
+ #     define PNG_TYPECAST_NULL
+ #  endif
+ #else
+ #  define PNGARG(arglist) arglist
+ #endif /* _NO_PROTO */
+ 
+ #endif /* OF */
+ 
+ #endif /* PNGARG */
+ 
+ /* Try to determine if we are compiling on a Mac.  Note that testing for
+  * just __MWERKS__ is not good enough, because the Codewarrior is now used
+  * on non-Mac platforms.
+  */
+ #ifndef MACOS
+ #  if (defined(__MWERKS__) && defined(macintosh)) || defined(applec) || \
+       defined(THINK_C) || defined(__SC__) || defined(TARGET_OS_MAC)
+ #    define MACOS
+ #  endif
+ #endif
+ 
+ /* enough people need this for various reasons to include it here */
+ #if !defined(MACOS) && !defined(RISCOS) && !defined(_WIN32_WCE)
+ #  include <sys/types.h>
+ #endif
+ 
+ #if !defined(PNG_SETJMP_NOT_SUPPORTED) && !defined(PNG_NO_SETJMP_SUPPORTED)
+ #  define PNG_SETJMP_SUPPORTED
+ #endif
+ 
+ #ifdef PNG_SETJMP_SUPPORTED
+ /* This is an attempt to force a single setjmp behaviour on Linux.  If
+  * the X config stuff didn't define _BSD_SOURCE we wouldn't need this.
+  */
+ 
+ #  ifdef __linux__
+ #    ifdef _BSD_SOURCE
+ #      define PNG_SAVE_BSD_SOURCE
+ #      undef _BSD_SOURCE
+ #    endif
+ #    ifdef _SETJMP_H
+       __png.h__ already includes setjmp.h;
+       __dont__ include it again.;
+ #    endif
+ #  endif /* __linux__ */
+ 
+    /* include setjmp.h for error handling */
+ #  include <setjmp.h>
+ 
+ #  ifdef __linux__
+ #    ifdef PNG_SAVE_BSD_SOURCE
+ #      define _BSD_SOURCE
+ #      undef PNG_SAVE_BSD_SOURCE
+ #    endif
+ #  endif /* __linux__ */
+ #endif /* PNG_SETJMP_SUPPORTED */
+ 
+ #ifdef BSD
+ #  include <strings.h>
+ #else
+ #  include <string.h>
+ #endif
+ 
+ /* Other defines for things like memory and the like can go here.  */
+ #ifdef PNG_INTERNAL
+ 
+ #include <stdlib.h>
+ 
+ /* The functions exported by PNG_EXTERN are PNG_INTERNAL functions, which
+  * aren't usually used outside the library (as far as I know), so it is
+  * debatable if they should be exported at all.  In the future, when it is
+  * possible to have run-time registry of chunk-handling functions, some of
+  * these will be made available again.
+ #define PNG_EXTERN extern
+  */
+ #define PNG_EXTERN
+ 
+ /* Other defines specific to compilers can go here.  Try to keep
+  * them inside an appropriate ifdef/endif pair for portability.
+  */
+ 
+ #if defined(PNG_FLOATING_POINT_SUPPORTED)
+ #  if defined(MACOS)
+      /* We need to check that <math.h> hasn't already been included earlier
+       * as it seems it doesn't agree with <fp.h>, yet we should really use
+       * <fp.h> if possible.
+       */
+ #    if !defined(__MATH_H__) && !defined(__MATH_H) && !defined(__cmath__)
+ #      include <fp.h>
+ #    endif
+ #  else
+ #    include <math.h>
+ #  endif
+ #  if defined(_AMIGA) && defined(__SASC) && defined(_M68881)
+      /* Amiga SAS/C: We must include builtin FPU functions when compiling using
+       * MATH=68881
+       */
+ #    include <m68881.h>
+ #  endif
+ #endif
+ 
+ /* Codewarrior on NT has linking problems without this. */
+ #if (defined(__MWERKS__) && defined(WIN32)) || defined(__STDC__)
+ #  define PNG_ALWAYS_EXTERN
+ #endif
+ 
+ /* For some reason, Borland C++ defines memcmp, etc. in mem.h, not
+  * stdlib.h like it should (I think).  Or perhaps this is a C++
+  * "feature"?
+  */
+ #ifdef __TURBOC__
+ #  include <mem.h>
+ #  include "alloc.h"
+ #endif
+ 
+ #if defined(_MSC_VER) && (defined(WIN32) || defined(_Windows) || \
+     defined(_WINDOWS) || defined(_WIN32) || defined(__WIN32__))
+ #  include <malloc.h>
+ #endif
+ 
+ /* This controls how fine the dithering gets.  As this allocates
+  * a largish chunk of memory (32K), those who are not as concerned
+  * with dithering quality can decrease some or all of these.
+  */
+ #ifndef PNG_DITHER_RED_BITS
+ #  define PNG_DITHER_RED_BITS 5
+ #endif
+ #ifndef PNG_DITHER_GREEN_BITS
+ #  define PNG_DITHER_GREEN_BITS 5
+ #endif
+ #ifndef PNG_DITHER_BLUE_BITS
+ #  define PNG_DITHER_BLUE_BITS 5
+ #endif
+ 
+ /* This controls how fine the gamma correction becomes when you
+  * are only interested in 8 bits anyway.  Increasing this value
+  * results in more memory being used, and more pow() functions
+  * being called to fill in the gamma tables.  Don't set this value
+  * less then 8, and even that may not work (I haven't tested it).
+  */
+ 
+ #ifndef PNG_MAX_GAMMA_8
+ #  define PNG_MAX_GAMMA_8 11
+ #endif
+ 
+ /* This controls how much a difference in gamma we can tolerate before
+  * we actually start doing gamma conversion.
+  */
+ #ifndef PNG_GAMMA_THRESHOLD
+ #  define PNG_GAMMA_THRESHOLD 0.05
+ #endif
+ 
+ #endif /* PNG_INTERNAL */
+ 
+ /* The following uses const char * instead of char * for error
+  * and warning message functions, so some compilers won't complain.
+  * If you do not want to use const, define PNG_NO_CONST here.
+  */
+ 
+ #ifndef PNG_NO_CONST
+ #  define PNG_CONST const
+ #else
+ #  define PNG_CONST
+ #endif
+ 
+ /* The following defines give you the ability to remove code from the
+  * library that you will not be using.  I wish I could figure out how to
+  * automate this, but I can't do that without making it seriously hard
+  * on the users.  So if you are not using an ability, change the #define
+  * to and #undef, and that part of the library will not be compiled.  If
+  * your linker can't find a function, you may want to make sure the
+  * ability is defined here.  Some of these depend upon some others being
+  * defined.  I haven't figured out all the interactions here, so you may
+  * have to experiment awhile to get everything to compile.  If you are
+  * creating or using a shared library, you probably shouldn't touch this,
+  * as it will affect the size of the structures, and this will cause bad
+  * things to happen if the library and/or application ever change.
+  */
+ 
+ /* Any features you will not be using can be undef'ed here */
+ 
+ /* GR-P, 0.96a: Set "*TRANSFORMS_SUPPORTED as default but allow user
+  * to turn it off with "*TRANSFORMS_NOT_SUPPORTED" or *PNG_NO_*_TRANSFORMS
+  * on the compile line, then pick and choose which ones to define without
+  * having to edit this file. It is safe to use the *TRANSFORMS_NOT_SUPPORTED
+  * if you only want to have a png-compliant reader/writer but don't need
+  * any of the extra transformations.  This saves about 80 kbytes in a
+  * typical installation of the library. (PNG_NO_* form added in version
+  * 1.0.1c, for consistency)
+  */
+ 
+ /* The size of the png_text structure changed in libpng-1.0.6 when
+  * iTXt is supported.  It is turned off by default, to support old apps
+  * that malloc the png_text structure instead of calling png_set_text()
+  * and letting libpng malloc it.  It will be turned on by default in
+  * libpng-1.3.0.
+  */
+ 
+ #ifndef PNG_iTXt_SUPPORTED
+ #  if !defined(PNG_READ_iTXt_SUPPORTED) && !defined(PNG_NO_READ_iTXt)
+ #    define PNG_NO_READ_iTXt
+ #  endif
+ #  if !defined(PNG_WRITE_iTXt_SUPPORTED) && !defined(PNG_NO_WRITE_iTXt)
+ #    define PNG_NO_WRITE_iTXt
+ #  endif
+ #endif
+ 
+ /* The following support, added after version 1.0.0, can be turned off here en
+  * masse by defining PNG_LEGACY_SUPPORTED in case you need binary compatibility
+  * with old applications that require the length of png_struct and png_info
+  * to remain unchanged.
+  */
+ 
+ #ifdef PNG_LEGACY_SUPPORTED
+ #  define PNG_NO_FREE_ME
+ #  define PNG_NO_READ_UNKNOWN_CHUNKS
+ #  define PNG_NO_WRITE_UNKNOWN_CHUNKS
+ #  define PNG_NO_READ_USER_CHUNKS
+ #  define PNG_NO_READ_iCCP
+ #  define PNG_NO_WRITE_iCCP
+ #  define PNG_NO_READ_iTXt
+ #  define PNG_NO_WRITE_iTXt
+ #  define PNG_NO_READ_sCAL
+ #  define PNG_NO_WRITE_sCAL
+ #  define PNG_NO_READ_sPLT
+ #  define PNG_NO_WRITE_sPLT
+ #  define PNG_NO_INFO_IMAGE
+ #  define PNG_NO_READ_RGB_TO_GRAY
+ #  define PNG_NO_READ_USER_TRANSFORM
+ #  define PNG_NO_WRITE_USER_TRANSFORM
+ #  define PNG_NO_USER_MEM
+ #  define PNG_NO_READ_EMPTY_PLTE
+ #  define PNG_NO_MNG_FEATURES
+ #  define PNG_NO_FIXED_POINT_SUPPORTED
+ #endif
+ 
+ /* Ignore attempt to turn off both floating and fixed point support */
+ #if !defined(PNG_FLOATING_POINT_SUPPORTED) || \
+     !defined(PNG_NO_FIXED_POINT_SUPPORTED)
+ #  define PNG_FIXED_POINT_SUPPORTED
+ #endif
+ 
+ #ifndef PNG_NO_FREE_ME
+ #  define PNG_FREE_ME_SUPPORTED
+ #endif
+ 
+ #if defined(PNG_READ_SUPPORTED)
+ 
+ #if !defined(PNG_READ_TRANSFORMS_NOT_SUPPORTED) && \
+       !defined(PNG_NO_READ_TRANSFORMS)
+ #  define PNG_READ_TRANSFORMS_SUPPORTED
+ #endif
+ 
+ #ifdef PNG_READ_TRANSFORMS_SUPPORTED
+ #  ifndef PNG_NO_READ_EXPAND
+ #    define PNG_READ_EXPAND_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_SHIFT
+ #    define PNG_READ_SHIFT_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_PACK
+ #    define PNG_READ_PACK_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_BGR
+ #    define PNG_READ_BGR_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_SWAP
+ #    define PNG_READ_SWAP_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_PACKSWAP
+ #    define PNG_READ_PACKSWAP_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_INVERT
+ #    define PNG_READ_INVERT_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_DITHER
+ #    define PNG_READ_DITHER_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_BACKGROUND
+ #    define PNG_READ_BACKGROUND_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_16_TO_8
+ #    define PNG_READ_16_TO_8_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_FILLER
+ #    define PNG_READ_FILLER_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_GAMMA
+ #    define PNG_READ_GAMMA_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_GRAY_TO_RGB
+ #    define PNG_READ_GRAY_TO_RGB_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_SWAP_ALPHA
+ #    define PNG_READ_SWAP_ALPHA_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_INVERT_ALPHA
+ #    define PNG_READ_INVERT_ALPHA_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_STRIP_ALPHA
+ #    define PNG_READ_STRIP_ALPHA_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_USER_TRANSFORM
+ #    define PNG_READ_USER_TRANSFORM_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_READ_RGB_TO_GRAY
+ #    define PNG_READ_RGB_TO_GRAY_SUPPORTED
+ #  endif
+ #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+ 
+ #if !defined(PNG_NO_PROGRESSIVE_READ) && \
+  !defined(PNG_PROGRESSIVE_READ_NOT_SUPPORTED)  /* if you don't do progressive */
+ #  define PNG_PROGRESSIVE_READ_SUPPORTED     /* reading.  This is not talking */
+ #endif                               /* about interlacing capability!  You'll */
+               /* still have interlacing unless you change the following line: */
+ 
+ #define PNG_READ_INTERLACING_SUPPORTED /* required for PNG-compliant decoders */
+ 
+ #ifndef PNG_NO_READ_COMPOSITE_NODIV
+ #  ifndef PNG_NO_READ_COMPOSITED_NODIV  /* libpng-1.0.x misspelling */
+ #    define PNG_READ_COMPOSITE_NODIV_SUPPORTED   /* well tested on Intel, SGI */
+ #  endif
+ #endif
+ 
+ /* Deprecated, will be removed from version 2.0.0.
+    Use PNG_MNG_FEATURES_SUPPORTED instead. */
+ #ifndef PNG_NO_READ_EMPTY_PLTE
+ #  define PNG_READ_EMPTY_PLTE_SUPPORTED
+ #endif
+ 
+ #endif /* PNG_READ_SUPPORTED */
+ 
+ #if defined(PNG_WRITE_SUPPORTED)
+ 
+ # if !defined(PNG_WRITE_TRANSFORMS_NOT_SUPPORTED) && \
+     !defined(PNG_NO_WRITE_TRANSFORMS)
+ #  define PNG_WRITE_TRANSFORMS_SUPPORTED
+ #endif
+ 
+ #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
+ #  ifndef PNG_NO_WRITE_SHIFT
+ #    define PNG_WRITE_SHIFT_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_WRITE_PACK
+ #    define PNG_WRITE_PACK_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_WRITE_BGR
+ #    define PNG_WRITE_BGR_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_WRITE_SWAP
+ #    define PNG_WRITE_SWAP_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_WRITE_PACKSWAP
+ #    define PNG_WRITE_PACKSWAP_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_WRITE_INVERT
+ #    define PNG_WRITE_INVERT_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_WRITE_FILLER
+ #    define PNG_WRITE_FILLER_SUPPORTED   /* same as WRITE_STRIP_ALPHA */
+ #  endif
+ #  ifndef PNG_NO_WRITE_SWAP_ALPHA
+ #    define PNG_WRITE_SWAP_ALPHA_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_WRITE_INVERT_ALPHA
+ #    define PNG_WRITE_INVERT_ALPHA_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_WRITE_USER_TRANSFORM
+ #    define PNG_WRITE_USER_TRANSFORM_SUPPORTED
+ #  endif
+ #endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
+ 
+ #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
+     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
+ #  ifndef PNG_NO_USER_TRANSFORM_PTR
+ #    define PNG_USER_TRANSFORM_PTR_SUPPORTED
+ #  endif
+ #endif
+ 
+ #define PNG_WRITE_INTERLACING_SUPPORTED  /* not required for PNG-compliant
+                                             encoders, but can cause trouble
+                                             if left undefined */
+ 
+ #if !defined(PNG_NO_WRITE_WEIGHTED_FILTER) && \
+      defined(PNG_FLOATING_POINT_SUPPORTED)
+ #  define PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+ #endif
+ 
+ #ifndef PNG_1_0_X
+ #ifndef PNG_NO_ERROR_NUMBERS
+ #define PNG_ERROR_NUMBERS_SUPPORTED
+ #endif
+ #endif /* PNG_1_0_X */
+ 
+ #ifndef PNG_NO_WRITE_FLUSH
+ #  define PNG_WRITE_FLUSH_SUPPORTED
+ #endif
+ 
+ /* Deprecated, see PNG_MNG_FEATURES_SUPPORTED, above */
+ #ifndef PNG_NO_WRITE_EMPTY_PLTE
+ #  define PNG_WRITE_EMPTY_PLTE_SUPPORTED
+ #endif
+ 
+ #endif /* PNG_WRITE_SUPPORTED */
+ 
+ #ifndef PNG_NO_STDIO
+ #  define PNG_TIME_RFC1123_SUPPORTED
+ #endif
+ 
+ /* This adds extra functions in pngget.c for accessing data from the
+  * info pointer (added in version 0.99)
+  * png_get_image_width()
+  * png_get_image_height()
+  * png_get_bit_depth()
+  * png_get_color_type()
+  * png_get_compression_type()
+  * png_get_filter_type()
+  * png_get_interlace_type()
+  * png_get_pixel_aspect_ratio()
+  * png_get_pixels_per_meter()
+  * png_get_x_offset_pixels()
+  * png_get_y_offset_pixels()
+  * png_get_x_offset_microns()
+  * png_get_y_offset_microns()
+  */
+ #if !defined(PNG_NO_EASY_ACCESS) && !defined(PNG_EASY_ACCESS_SUPPORTED)
+ #  define PNG_EASY_ACCESS_SUPPORTED
+ #endif
+ 
+ /* PNG_ASSEMBLER_CODE was enabled by default in version 1.2.0 
+    even when PNG_USE_PNGVCRD or PNG_USE_PNGGCCRD is not defined */
+ #if defined(PNG_READ_SUPPORTED) && !defined(PNG_NO_ASSEMBLER_CODE)
+ #  ifndef PNG_ASSEMBLER_CODE_SUPPORTED
+ #    define PNG_ASSEMBLER_CODE_SUPPORTED
+ #  endif
+ #  if !defined(PNG_MMX_CODE_SUPPORTED) && !defined(PNG_NO_MMX_CODE)
+ #    define PNG_MMX_CODE_SUPPORTED
+ #  endif
+ #endif
+ 
+ /* If you are sure that you don't need thread safety and you are compiling
+    with PNG_USE_PNGCCRD for an MMX application, you can define this for
+    faster execution.  See pnggccrd.c.
+ #define PNG_THREAD_UNSAFE_OK
+ */
+ 
+ #if !defined(PNG_1_0_X)
+ #if !defined(PNG_NO_USER_MEM) && !defined(PNG_USER_MEM_SUPPORTED)
+ #  define PNG_USER_MEM_SUPPORTED
+ #endif
+ #endif /* PNG_1_0_X */
+ 
+ /* These are currently experimental features, define them if you want */
+ 
+ /* very little testing */
+ /*
+ #ifdef PNG_READ_SUPPORTED
+ #  ifndef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+ #    define PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+ #  endif
+ #endif
+ */
+ 
+ /* This is only for PowerPC big-endian and 680x0 systems */
+ /* some testing */
+ /*
+ #ifdef PNG_READ_SUPPORTED
+ #  ifndef PNG_PNG_READ_BIG_ENDIAN_SUPPORTED
+ #    define PNG_READ_BIG_ENDIAN_SUPPORTED
+ #  endif
+ #endif
+ */
+ 
+ /* Buggy compilers (e.g., gcc 2.7.2.2) need this */
+ /*
+ #define PNG_NO_POINTER_INDEXING
+ */
+ 
+ /* These functions are turned off by default, as they will be phased out. */
+ /*
+ #define  PNG_USELESS_TESTS_SUPPORTED
+ #define  PNG_CORRECT_PALETTE_SUPPORTED
+ */
+ 
+ /* Any chunks you are not interested in, you can undef here.  The
+  * ones that allocate memory may be expecially important (hIST,
+  * tEXt, zTXt, tRNS, pCAL).  Others will just save time and make png_info
+  * a bit smaller.
+  */
+ 
+ #if defined(PNG_READ_SUPPORTED) && \
+     !defined(PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED) && \
+     !defined(PNG_NO_READ_ANCILLARY_CHUNKS)
+ #  define PNG_READ_ANCILLARY_CHUNKS_SUPPORTED
+ #endif
+ 
+ #if defined(PNG_WRITE_SUPPORTED) && \
+     !defined(PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED) && \
+     !defined(PNG_NO_WRITE_ANCILLARY_CHUNKS)
+ #  define PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED
+ #endif
+ 
+ #ifdef PNG_READ_ANCILLARY_CHUNKS_SUPPORTED
+ 
+ #ifdef PNG_NO_READ_TEXT
+ #  define PNG_NO_READ_iTXt
+ #  define PNG_NO_READ_tEXt
+ #  define PNG_NO_READ_zTXt
+ #endif
+ #ifndef PNG_NO_READ_bKGD
+ #  define PNG_READ_bKGD_SUPPORTED
+ #  define PNG_bKGD_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_cHRM
+ #  define PNG_READ_cHRM_SUPPORTED
+ #  define PNG_cHRM_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_gAMA
+ #  define PNG_READ_gAMA_SUPPORTED
+ #  define PNG_gAMA_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_hIST
+ #  define PNG_READ_hIST_SUPPORTED
+ #  define PNG_hIST_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_iCCP
+ #  define PNG_READ_iCCP_SUPPORTED
+ #  define PNG_iCCP_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_iTXt
+ #  ifndef PNG_READ_iTXt_SUPPORTED
+ #    define PNG_READ_iTXt_SUPPORTED
+ #  endif
+ #  ifndef PNG_iTXt_SUPPORTED
+ #    define PNG_iTXt_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_READ_oFFs
+ #  define PNG_READ_oFFs_SUPPORTED
+ #  define PNG_oFFs_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_pCAL
+ #  define PNG_READ_pCAL_SUPPORTED
+ #  define PNG_pCAL_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_sCAL
+ #  define PNG_READ_sCAL_SUPPORTED
+ #  define PNG_sCAL_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_pHYs
+ #  define PNG_READ_pHYs_SUPPORTED
+ #  define PNG_pHYs_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_sBIT
+ #  define PNG_READ_sBIT_SUPPORTED
+ #  define PNG_sBIT_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_sPLT
+ #  define PNG_READ_sPLT_SUPPORTED
+ #  define PNG_sPLT_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_sRGB
+ #  define PNG_READ_sRGB_SUPPORTED
+ #  define PNG_sRGB_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_tEXt
+ #  define PNG_READ_tEXt_SUPPORTED
+ #  define PNG_tEXt_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_tIME
+ #  define PNG_READ_tIME_SUPPORTED
+ #  define PNG_tIME_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_tRNS
+ #  define PNG_READ_tRNS_SUPPORTED
+ #  define PNG_tRNS_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_zTXt
+ #  define PNG_READ_zTXt_SUPPORTED
+ #  define PNG_zTXt_SUPPORTED
+ #endif
+ #ifndef PNG_NO_READ_UNKNOWN_CHUNKS
+ #  define PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+ #  ifndef PNG_UNKNOWN_CHUNKS_SUPPORTED
+ #    define PNG_UNKNOWN_CHUNKS_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_HANDLE_AS_UNKNOWN
+ #    define PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+ #  endif
+ #endif
+ #if !defined(PNG_NO_READ_USER_CHUNKS) && \
+      defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
+ #  define PNG_READ_USER_CHUNKS_SUPPORTED
+ #  define PNG_USER_CHUNKS_SUPPORTED
+ #  ifdef PNG_NO_READ_UNKNOWN_CHUNKS
+ #    undef PNG_NO_READ_UNKNOWN_CHUNKS
+ #  endif
+ #  ifdef PNG_NO_HANDLE_AS_UNKNOWN
+ #    undef PNG_NO_HANDLE_AS_UNKNOWN
+ #  endif
+ #endif
+ #ifndef PNG_NO_READ_OPT_PLTE
+ #  define PNG_READ_OPT_PLTE_SUPPORTED /* only affects support of the */
+ #endif                      /* optional PLTE chunk in RGB and RGBA images */
+ #if defined(PNG_READ_iTXt_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) || \
+     defined(PNG_READ_zTXt_SUPPORTED)
+ #  define PNG_READ_TEXT_SUPPORTED
+ #  define PNG_TEXT_SUPPORTED
+ #endif
+ 
+ #endif /* PNG_READ_ANCILLARY_CHUNKS_SUPPORTED */
+ 
+ #ifdef PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED
+ 
+ #ifdef PNG_NO_WRITE_TEXT
+ #  define PNG_NO_WRITE_iTXt
+ #  define PNG_NO_WRITE_tEXt
+ #  define PNG_NO_WRITE_zTXt
+ #endif
+ #ifndef PNG_NO_WRITE_bKGD
+ #  define PNG_WRITE_bKGD_SUPPORTED
+ #  ifndef PNG_bKGD_SUPPORTED
+ #    define PNG_bKGD_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_cHRM
+ #  define PNG_WRITE_cHRM_SUPPORTED
+ #  ifndef PNG_cHRM_SUPPORTED
+ #    define PNG_cHRM_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_gAMA
+ #  define PNG_WRITE_gAMA_SUPPORTED
+ #  ifndef PNG_gAMA_SUPPORTED
+ #    define PNG_gAMA_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_hIST
+ #  define PNG_WRITE_hIST_SUPPORTED
+ #  ifndef PNG_hIST_SUPPORTED
+ #    define PNG_hIST_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_iCCP
+ #  define PNG_WRITE_iCCP_SUPPORTED
+ #  ifndef PNG_iCCP_SUPPORTED
+ #    define PNG_iCCP_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_iTXt
+ #  ifndef PNG_WRITE_iTXt_SUPPORTED
+ #    define PNG_WRITE_iTXt_SUPPORTED
+ #  endif
+ #  ifndef PNG_iTXt_SUPPORTED
+ #    define PNG_iTXt_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_oFFs
+ #  define PNG_WRITE_oFFs_SUPPORTED
+ #  ifndef PNG_oFFs_SUPPORTED
+ #    define PNG_oFFs_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_pCAL
+ #  define PNG_WRITE_pCAL_SUPPORTED
+ #  ifndef PNG_pCAL_SUPPORTED
+ #    define PNG_pCAL_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_sCAL
+ #  define PNG_WRITE_sCAL_SUPPORTED
+ #  ifndef PNG_sCAL_SUPPORTED
+ #    define PNG_sCAL_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_pHYs
+ #  define PNG_WRITE_pHYs_SUPPORTED
+ #  ifndef PNG_pHYs_SUPPORTED
+ #    define PNG_pHYs_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_sBIT
+ #  define PNG_WRITE_sBIT_SUPPORTED
+ #  ifndef PNG_sBIT_SUPPORTED
+ #    define PNG_sBIT_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_sPLT
+ #  define PNG_WRITE_sPLT_SUPPORTED
+ #  ifndef PNG_sPLT_SUPPORTED
+ #    define PNG_sPLT_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_sRGB
+ #  define PNG_WRITE_sRGB_SUPPORTED
+ #  ifndef PNG_sRGB_SUPPORTED
+ #    define PNG_sRGB_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_tEXt
+ #  define PNG_WRITE_tEXt_SUPPORTED
+ #  ifndef PNG_tEXt_SUPPORTED
+ #    define PNG_tEXt_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_tIME
+ #  define PNG_WRITE_tIME_SUPPORTED
+ #  ifndef PNG_tIME_SUPPORTED
+ #    define PNG_tIME_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_tRNS
+ #  define PNG_WRITE_tRNS_SUPPORTED
+ #  ifndef PNG_tRNS_SUPPORTED
+ #    define PNG_tRNS_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_zTXt
+ #  define PNG_WRITE_zTXt_SUPPORTED
+ #  ifndef PNG_zTXt_SUPPORTED
+ #    define PNG_zTXt_SUPPORTED
+ #  endif
+ #endif
+ #ifndef PNG_NO_WRITE_UNKNOWN_CHUNKS
+ #  define PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
+ #  ifndef PNG_UNKNOWN_CHUNKS_SUPPORTED
+ #    define PNG_UNKNOWN_CHUNKS_SUPPORTED
+ #  endif
+ #  ifndef PNG_NO_HANDLE_AS_UNKNOWN
+ #     ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+ #       define PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+ #     endif
+ #  endif
+ #endif
+ #if defined(PNG_WRITE_iTXt_SUPPORTED) || defined(PNG_WRITE_tEXt_SUPPORTED) || \
+     defined(PNG_WRITE_zTXt_SUPPORTED)
+ #  define PNG_WRITE_TEXT_SUPPORTED
+ #  ifndef PNG_TEXT_SUPPORTED
+ #    define PNG_TEXT_SUPPORTED
+ #  endif
+ #endif
+ 
+ #endif /* PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED */
+ 
+ /* Turn this off to disable png_read_png() and
+  * png_write_png() and leave the row_pointers member
+  * out of the info structure.
+  */
+ #ifndef PNG_NO_INFO_IMAGE
+ #  define PNG_INFO_IMAGE_SUPPORTED
+ #endif
+ 
+ /* need the time information for reading tIME chunks */
+ #if defined(PNG_tIME_SUPPORTED)
+ #  if !defined(_WIN32_WCE)
+      /* "time.h" functions are not supported on WindowsCE */
+ #    include <time.h>
+ #  endif
+ #endif
+ 
+ /* Some typedefs to get us started.  These should be safe on most of the
+  * common platforms.  The typedefs should be at least as large as the
+  * numbers suggest (a png_uint_32 must be at least 32 bits long), but they
+  * don't have to be exactly that size.  Some compilers dislike passing
+  * unsigned shorts as function parameters, so you may be better off using
+  * unsigned int for png_uint_16.  Likewise, for 64-bit systems, you may
+  * want to have unsigned int for png_uint_32 instead of unsigned long.
+  */
+ 
+ typedef unsigned long png_uint_32;
+ typedef long png_int_32;
+ typedef unsigned short png_uint_16;
+ typedef short png_int_16;
+ typedef unsigned char png_byte;
+ 
+ /* This is usually size_t.  It is typedef'ed just in case you need it to
+    change (I'm not sure if you will or not, so I thought I'd be safe) */
+ typedef size_t png_size_t;
+ 
+ /* The following is needed for medium model support.  It cannot be in the
+  * PNG_INTERNAL section.  Needs modification for other compilers besides
+  * MSC.  Model independent support declares all arrays and pointers to be
+  * large using the far keyword.  The zlib version used must also support
+  * model independent data.  As of version zlib 1.0.4, the necessary changes
+  * have been made in zlib.  The USE_FAR_KEYWORD define triggers other
+  * changes that are needed. (Tim Wegner)
+  */
+ 
+ /* Separate compiler dependencies (problem here is that zlib.h always
+    defines FAR. (SJT) */
+ #ifdef __BORLANDC__
+ #  if defined(__LARGE__) || defined(__HUGE__) || defined(__COMPACT__)
+ #    define LDATA 1
+ #  else
+ #    define LDATA 0
+ #  endif
+    /* GRR:  why is Cygwin in here?  Cygwin is not Borland C... */
+ #  if !defined(__WIN32__) && !defined(__FLAT__) && !defined(__CYGWIN__)
+ #    define PNG_MAX_MALLOC_64K
+ #    if (LDATA != 1)
+ #      ifndef FAR
+ #        define FAR __far
+ #      endif
+ #      define USE_FAR_KEYWORD
+ #    endif   /* LDATA != 1 */
+      /* Possibly useful for moving data out of default segment.
+       * Uncomment it if you want. Could also define FARDATA as
+       * const if your compiler supports it. (SJT)
+ #    define FARDATA FAR
+       */
+ #  endif  /* __WIN32__, __FLAT__, __CYGWIN__ */
+ #endif   /* __BORLANDC__ */
+ 
+ 
+ /* Suggest testing for specific compiler first before testing for
+  * FAR.  The Watcom compiler defines both __MEDIUM__ and M_I86MM,
+  * making reliance oncertain keywords suspect. (SJT)
+  */
+ 
+ /* MSC Medium model */
+ #if defined(FAR)
+ #  if defined(M_I86MM)
+ #    define USE_FAR_KEYWORD
+ #    define FARDATA FAR
+ #    include <dos.h>
+ #  endif
+ #endif
+ 
+ /* SJT: default case */
+ #ifndef FAR
+ #  define FAR
+ #endif
+ 
+ /* At this point FAR is always defined */
+ #ifndef FARDATA
+ #  define FARDATA
+ #endif
+ 
+ /* Typedef for floating-point numbers that are converted
+    to fixed-point with a multiple of 100,000, e.g., int_gamma */
+ typedef png_int_32 png_fixed_point;
+ 
+ /* Add typedefs for pointers */
+ typedef void            FAR * png_voidp;
+ typedef png_byte        FAR * png_bytep;
+ typedef png_uint_32     FAR * png_uint_32p;
+ typedef png_int_32      FAR * png_int_32p;
+ typedef png_uint_16     FAR * png_uint_16p;
+ typedef png_int_16      FAR * png_int_16p;
+ typedef PNG_CONST char  FAR * png_const_charp;
+ typedef char            FAR * png_charp;
+ typedef png_fixed_point FAR * png_fixed_point_p;
+ 
+ #ifndef PNG_NO_STDIO
+ #if defined(_WIN32_WCE)
+ typedef HANDLE                png_FILE_p;
+ #else
+ typedef FILE                * png_FILE_p;
+ #endif
+ #endif
+ 
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ typedef double          FAR * png_doublep;
+ #endif
+ 
+ /* Pointers to pointers; i.e. arrays */
+ typedef png_byte        FAR * FAR * png_bytepp;
+ typedef png_uint_32     FAR * FAR * png_uint_32pp;
+ typedef png_int_32      FAR * FAR * png_int_32pp;
+ typedef png_uint_16     FAR * FAR * png_uint_16pp;
+ typedef png_int_16      FAR * FAR * png_int_16pp;
+ typedef PNG_CONST char  FAR * FAR * png_const_charpp;
+ typedef char            FAR * FAR * png_charpp;
+ typedef png_fixed_point FAR * FAR * png_fixed_point_pp;
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ typedef double          FAR * FAR * png_doublepp;
+ #endif
+ 
+ /* Pointers to pointers to pointers; i.e., pointer to array */
+ typedef char            FAR * FAR * FAR * png_charppp;
+ 
+ /* libpng typedefs for types in zlib. If zlib changes
+  * or another compression library is used, then change these.
+  * Eliminates need to change all the source files.
+  */
+ typedef charf *         png_zcharp;
+ typedef charf * FAR *   png_zcharpp;
+ typedef z_stream FAR *  png_zstreamp;
+ 
+ /*
+  * Define PNG_BUILD_DLL if the module being built is a Windows
+  * LIBPNG DLL.
+  *
+  * Define PNG_USE_DLL if you want to *link* to the Windows LIBPNG DLL.
+  * It is equivalent to Microsoft predefined macro _DLL that is
+  * automatically defined when you compile using the share
+  * version of the CRT (C Run-Time library)
+  *
+  * The cygwin mods make this behavior a little different:
+  * Define PNG_BUILD_DLL if you are building a dll for use with cygwin
+  * Define PNG_STATIC if you are building a static library for use with cygwin,
+  *   -or- if you are building an application that you want to link to the
+  *   static library.
+  * PNG_USE_DLL is defined by default (no user action needed) unless one of
+  *   the other flags is defined.
+  */
+ 
+ #if !defined(PNG_DLL) && (defined(PNG_BUILD_DLL) || defined(PNG_USE_DLL))
+ #  define PNG_DLL
+ #endif
+ /* If CYGWIN, then disallow GLOBAL ARRAYS unless building a static lib.
+  * When building a static lib, default to no GLOBAL ARRAYS, but allow
+  * command-line override
+  */
+ #if defined(__CYGWIN__)
+ #  if !defined(PNG_STATIC)
+ #    if defined(PNG_USE_GLOBAL_ARRAYS)
+ #      undef PNG_USE_GLOBAL_ARRAYS
+ #    endif
+ #    if !defined(PNG_USE_LOCAL_ARRAYS)
+ #      define PNG_USE_LOCAL_ARRAYS
+ #    endif
+ #  else
+ #    if defined(PNG_USE_LOCAL_ARRAYS) || defined(PNG_NO_GLOBAL_ARRAYS)
+ #      if defined(PNG_USE_GLOBAL_ARRAYS)
+ #        undef PNG_USE_GLOBAL_ARRAYS
+ #      endif
+ #    endif
+ #  endif
+ #  if !defined(PNG_USE_LOCAL_ARRAYS) && !defined(PNG_USE_GLOBAL_ARRAYS)
+ #    define PNG_USE_LOCAL_ARRAYS
+ #  endif
+ #endif
+ 
+ /* Do not use global arrays (helps with building DLL's)
+  * They are no longer used in libpng itself, since version 1.0.5c,
+  * but might be required for some pre-1.0.5c applications.
+  */
+ #if !defined(PNG_USE_LOCAL_ARRAYS) && !defined(PNG_USE_GLOBAL_ARRAYS)
+ #  if defined(PNG_NO_GLOBAL_ARRAYS) || (defined(__GNUC__) && defined(PNG_DLL))
+ #    define PNG_USE_LOCAL_ARRAYS
+ #  else
+ #    define PNG_USE_GLOBAL_ARRAYS
+ #  endif
+ #endif
+ 
+ #if defined(__CYGWIN__)
+ #  undef PNGAPI
+ #  define PNGAPI __cdecl
+ #  undef PNG_IMPEXP
+ #  define PNG_IMPEXP
+ #endif  
+ 
+ /* If you define PNGAPI, e.g., with compiler option "-DPNGAPI=__stdcall",
+  * you may get warnings regarding the linkage of png_zalloc and png_zfree.
+  * Don't ignore those warnings; you must also reset the default calling
+  * convention in your compiler to match your PNGAPI, and you must build
+  * zlib and your applications the same way you build libpng.
+  */
+ 
+ #ifndef PNGAPI
+ 
+ #if defined(__MINGW32__) && !defined(PNG_MODULEDEF)
+ #  ifndef PNG_NO_MODULEDEF
+ #    define PNG_NO_MODULEDEF
+ #  endif
+ #endif
+ 
+ #if !defined(PNG_IMPEXP) && defined(PNG_BUILD_DLL) && !defined(PNG_NO_MODULEDEF)
+ #  define PNG_IMPEXP
+ #endif
+ 
+ #if defined(PNG_DLL) || defined(_DLL) || defined(__DLL__ ) || \
+     (( defined(_Windows) || defined(_WINDOWS) || \
+        defined(WIN32) || defined(_WIN32) || defined(__WIN32__) ))
+ 
+ #  if defined(__GNUC__) || (defined (_MSC_VER) && (_MSC_VER >= 800))
+ #    define PNGAPI __cdecl
+ #  else
+ #    define PNGAPI _cdecl
+ #  endif
+ 
+ #  if !defined(PNG_IMPEXP) && (!defined(PNG_DLL) || \
+        0 /* WINCOMPILER_WITH_NO_SUPPORT_FOR_DECLIMPEXP */)
+ #     define PNG_IMPEXP
+ #  endif
+ 
+ #  if !defined(PNG_IMPEXP)
+ 
+ #     define PNG_EXPORT_TYPE1(type,symbol)  PNG_IMPEXP type PNGAPI symbol
+ #     define PNG_EXPORT_TYPE2(type,symbol)  type PNG_IMPEXP PNGAPI symbol
+ 
+       /* Borland/Microsoft */
+ #     if defined(_MSC_VER) || defined(__BORLANDC__)
+ #        if (_MSC_VER >= 800) || (__BORLANDC__ >= 0x500)
+ #           define PNG_EXPORT PNG_EXPORT_TYPE1
+ #        else
+ #           define PNG_EXPORT PNG_EXPORT_TYPE2
+ #           if defined(PNG_BUILD_DLL)
+ #              define PNG_IMPEXP __export
+ #           else
+ #              define PNG_IMPEXP /*__import */ /* doesn't exist AFAIK in
+                                                  VC++ */
+ #           endif                             /* Exists in Borland C++ for
+                                                  C++ classes (== huge) */
+ #        endif
+ #     endif
+ 
+ #     if !defined(PNG_IMPEXP)
+ #        if defined(PNG_BUILD_DLL)
+ #           define PNG_IMPEXP __declspec(dllexport)
+ #        else
+ #           define PNG_IMPEXP __declspec(dllimport)
+ #        endif
+ #     endif
+ #  endif  /* PNG_IMPEXP */
+ #else /* !(DLL || non-cygwin WINDOWS) */
+ #    if (defined(__IBMC__) || defined(IBMCPP__)) && defined(__OS2__)
+ #      define PNGAPI _System
+ #      define PNG_IMPEXP
+ #    else
+ #      if 0 /* ... other platforms, with other meanings */
+ #      else
+ #        define PNGAPI
+ #        define PNG_IMPEXP
+ #      endif
+ #    endif
+ #endif
+ #endif
+ 
+ #ifndef PNGAPI
+ #  define PNGAPI
+ #endif
+ #ifndef PNG_IMPEXP
+ #  define PNG_IMPEXP
+ #endif
+ 
+ #ifndef PNG_EXPORT
+ #  define PNG_EXPORT(type,symbol) PNG_IMPEXP type PNGAPI symbol
+ #endif
+ 
+ #ifdef PNG_USE_GLOBAL_ARRAYS
+ #  ifndef PNG_EXPORT_VAR
+ #    define PNG_EXPORT_VAR(type) extern PNG_IMPEXP type
+ #  endif
+ #endif
+ 
+ /* User may want to use these so they are not in PNG_INTERNAL. Any library
+  * functions that are passed far data must be model independent.
+  */
+ 
+ #ifndef PNG_ABORT
+ #  define PNG_ABORT() abort()
+ #endif
+ 
+ #ifdef PNG_SETJMP_SUPPORTED
+ #  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+ #else
+ #  define png_jmpbuf(png_ptr) \
+    (LIBPNG_WAS_COMPILED_WITH__PNG_SETJMP_NOT_SUPPORTED)
+ #endif
+ 
+ #if defined(USE_FAR_KEYWORD)  /* memory model independent fns */
+ /* use this to make far-to-near assignments */
+ #  define CHECK   1
+ #  define NOCHECK 0
+ #  define CVT_PTR(ptr) (png_far_to_near(png_ptr,ptr,CHECK))
+ #  define CVT_PTR_NOCHECK(ptr) (png_far_to_near(png_ptr,ptr,NOCHECK))
+ #  define png_strcpy _fstrcpy
+ #  define png_strlen _fstrlen
+ #  define png_memcmp _fmemcmp      /* SJT: added */
+ #  define png_memcpy _fmemcpy
+ #  define png_memset _fmemset
+ #else /* use the usual functions */
+ #  define CVT_PTR(ptr)         (ptr)
+ #  define CVT_PTR_NOCHECK(ptr) (ptr)
+ #  define png_strcpy strcpy
+ #  define png_strlen strlen
+ #  define png_memcmp memcmp     /* SJT: added */
+ #  define png_memcpy memcpy
+ #  define png_memset memset
+ #endif
+ /* End of memory model independent support */
+ 
+ /* Just a little check that someone hasn't tried to define something
+  * contradictory.
+  */
+ #if (PNG_ZBUF_SIZE > 65536) && defined(PNG_MAX_MALLOC_64K)
+ #  undef PNG_ZBUF_SIZE
+ #  define PNG_ZBUF_SIZE 65536
+ #endif
+ 
+ #ifdef PNG_READ_SUPPORTED
+ /* Prior to libpng-1.0.9, this block was in pngasmrd.h */
+ #if defined(PNG_INTERNAL)
+ 
+ /* These are the default thresholds before the MMX code kicks in; if either
+  * rowbytes or bitdepth is below the threshold, plain C code is used.  These
+  * can be overridden at runtime via the png_set_mmx_thresholds() call in
+  * libpng 1.2.0 and later.  The values below were chosen by Intel.
+  */
+ 
+ #ifndef PNG_MMX_ROWBYTES_THRESHOLD_DEFAULT
+ #  define PNG_MMX_ROWBYTES_THRESHOLD_DEFAULT  128  /*  >=  */
+ #endif
+ #ifndef PNG_MMX_BITDEPTH_THRESHOLD_DEFAULT
+ #  define PNG_MMX_BITDEPTH_THRESHOLD_DEFAULT  9    /*  >=  */   
+ #endif
+ 
+ /* Set this in the makefile for VC++ on Pentium, not here. */
+ /* Platform must be Pentium.  Makefile must assemble and load pngvcrd.c .
+  * MMX will be detected at run time and used if present.
+  */
+ #ifdef PNG_USE_PNGVCRD
+ #  define PNG_HAVE_ASSEMBLER_COMBINE_ROW
+ #  define PNG_HAVE_ASSEMBLER_READ_INTERLACE
+ #  define PNG_HAVE_ASSEMBLER_READ_FILTER_ROW
+ #endif
+ 
+ /* Set this in the makefile for gcc/as on Pentium, not here. */
+ /* Platform must be Pentium.  Makefile must assemble and load pnggccrd.c .
+  * MMX will be detected at run time and used if present.
+  */
+ #ifdef PNG_USE_PNGGCCRD
+ #  define PNG_HAVE_ASSEMBLER_COMBINE_ROW
+ #  define PNG_HAVE_ASSEMBLER_READ_INTERLACE
+ #  define PNG_HAVE_ASSEMBLER_READ_FILTER_ROW
+ #endif
+ /* - see pnggccrd.c for info about what is currently enabled */
+ 
+ #endif /* PNG_INTERNAL */
+ #endif /* PNG_READ_SUPPORTED */
+ 
+ #endif /* PNGCONF_H */
+ 


Index: llvm/runtime/libpng/pngerror.c
diff -c /dev/null llvm/runtime/libpng/pngerror.c:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/pngerror.c	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,291 ----
+ 
+ /* pngerror.c - stub functions for i/o and memory allocation
+  *
+  * libpng 1.2.5 - October 3, 2002
+  * For conditions of distribution and use, see copyright notice in png.h
+  * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+  *
+  * This file provides a location for all error handling.  Users who
+  * need special error handling are expected to write replacement functions
+  * and use png_set_error_fn() to use those functions.  See the instructions
+  * at each function.
+  */
+ 
+ #define PNG_INTERNAL
+ #include "png.h"
+ 
+ static void /* PRIVATE */
+ png_default_error PNGARG((png_structp png_ptr,
+   png_const_charp error_message));
+ static void /* PRIVATE */
+ png_default_warning PNGARG((png_structp png_ptr,
+   png_const_charp warning_message));
+ 
+ /* This function is called whenever there is a fatal error.  This function
+  * should not be changed.  If there is a need to handle errors differently,
+  * you should supply a replacement error function and use png_set_error_fn()
+  * to replace the error function at run-time.
+  */
+ void PNGAPI
+ png_error(png_structp png_ptr, png_const_charp error_message)
+ {
+ #ifdef PNG_ERROR_NUMBERS_SUPPORTED
+    char msg[16];
+    if (png_ptr->flags&(PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
+    {
+      int offset = 0;
+      if (*error_message == '#')
+      {
+          for (offset=1; offset<15; offset++)
+             if (*(error_message+offset) == ' ')
+                 break;
+          if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+          {
+             int i;
+             for (i=0; i<offset-1; i++)
+                msg[i]=error_message[i+1];
+             msg[i]='\0';
+             error_message=msg;
+          }
+          else
+             error_message+=offset;
+      }
+      else
+      {
+          if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+          {
+             msg[0]='0';        
+             msg[1]='\0';
+             error_message=msg;
+          }
+      }
+    }
+ #endif
+    if (png_ptr->error_fn != NULL)
+       (*(png_ptr->error_fn))(png_ptr, error_message);
+ 
+    /* if the following returns or doesn't exist, use the default function,
+       which will not return */
+    png_default_error(png_ptr, error_message);
+ }
+ 
+ /* This function is called whenever there is a non-fatal error.  This function
+  * should not be changed.  If there is a need to handle warnings differently,
+  * you should supply a replacement warning function and use
+  * png_set_error_fn() to replace the warning function at run-time.
+  */
+ void PNGAPI
+ png_warning(png_structp png_ptr, png_const_charp warning_message)
+ {
+      int offset = 0;
+ #ifdef PNG_ERROR_NUMBERS_SUPPORTED
+    if (png_ptr->flags&(PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
+ #endif
+    {
+      if (*warning_message == '#')
+      {
+          for (offset=1; offset<15; offset++)
+             if (*(warning_message+offset) == ' ')
+                 break;
+      }
+    }
+    if (png_ptr->warning_fn != NULL)
+       (*(png_ptr->warning_fn))(png_ptr,
+          (png_const_charp)(warning_message+offset));
+    else
+       png_default_warning(png_ptr, (png_const_charp)(warning_message+offset));
+ }
+ 
+ /* These utilities are used internally to build an error message that relates
+  * to the current chunk.  The chunk name comes from png_ptr->chunk_name,
+  * this is used to prefix the message.  The message is limited in length
+  * to 63 bytes, the name characters are output as hex digits wrapped in []
+  * if the character is invalid.
+  */
+ #define isnonalpha(c) ((c) < 41 || (c) > 122 || ((c) > 90 && (c) < 97))
+ static PNG_CONST char png_digit[16] = {
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E',
+    'F' };
+ 
+ static void /* PRIVATE */
+ png_format_buffer(png_structp png_ptr, png_charp buffer, png_const_charp
+    error_message)
+ {
+    int iout = 0, iin = 0;
+ 
+    while (iin < 4)
+    {
+       int c = png_ptr->chunk_name[iin++];
+       if (isnonalpha(c))
+       {
+          buffer[iout++] = '[';
+          buffer[iout++] = png_digit[(c & 0xf0) >> 4];
+          buffer[iout++] = png_digit[c & 0x0f];
+          buffer[iout++] = ']';
+       }
+       else
+       {
+          buffer[iout++] = (png_byte)c;
+       }
+    }
+ 
+    if (error_message == NULL)
+       buffer[iout] = 0;
+    else
+    {
+       buffer[iout++] = ':';
+       buffer[iout++] = ' ';
+       png_memcpy(buffer+iout, error_message, 64);
+       buffer[iout+63] = 0;
+    }
+ }
+ 
+ void PNGAPI
+ png_chunk_error(png_structp png_ptr, png_const_charp error_message)
+ {
+    char msg[18+64];
+    png_format_buffer(png_ptr, msg, error_message);
+    png_error(png_ptr, msg);
+ }
+ 
+ void PNGAPI
+ png_chunk_warning(png_structp png_ptr, png_const_charp warning_message)
+ {
+    char msg[18+64];
+    png_format_buffer(png_ptr, msg, warning_message);
+    png_warning(png_ptr, msg);
+ }
+ 
+ /* This is the default error handling function.  Note that replacements for
+  * this function MUST NOT RETURN, or the program will likely crash.  This
+  * function is used by default, or if the program supplies NULL for the
+  * error function pointer in png_set_error_fn().
+  */
+ static void /* PRIVATE */
+ png_default_error(png_structp png_ptr, png_const_charp error_message)
+ {
+ #ifndef PNG_NO_CONSOLE_IO
+ #ifdef PNG_ERROR_NUMBERS_SUPPORTED
+    if (*error_message == '#')
+    {
+      int offset;
+      char error_number[16];
+      for (offset=0; offset<15; offset++)
+      {
+          error_number[offset] = *(error_message+offset+1);
+          if (*(error_message+offset) == ' ')
+              break;
+      }
+      if((offset > 1) && (offset < 15))
+      {
+        error_number[offset-1]='\0';
+        fprintf(stderr, "libpng error no. %s: %s\n", error_number,
+           error_message+offset);
+      }
+      else
+        fprintf(stderr, "libpng error: %s, offset=%d\n", error_message,offset);
+    }
+    else
+ #endif
+    fprintf(stderr, "libpng error: %s\n", error_message);
+ #else
+    if (error_message)
+      /* make compiler happy */ ;
+ #endif
+ 
+ #ifdef PNG_SETJMP_SUPPORTED
+ #  ifdef USE_FAR_KEYWORD
+    {
+       jmp_buf jmpbuf;
+       png_memcpy(jmpbuf,png_ptr->jmpbuf,sizeof(jmp_buf));
+       longjmp(jmpbuf, 1);
+    }
+ #  else
+    longjmp(png_ptr->jmpbuf, 1);
+ # endif
+ #else
+    if (png_ptr)
+      /* make compiler happy */ ;
+    PNG_ABORT();
+ #endif
+ }
+ 
+ /* This function is called when there is a warning, but the library thinks
+  * it can continue anyway.  Replacement functions don't have to do anything
+  * here if you don't want them to.  In the default configuration, png_ptr is
+  * not used, but it is passed in case it may be useful.
+  */
+ static void /* PRIVATE */
+ png_default_warning(png_structp png_ptr, png_const_charp warning_message)
+ {
+ #ifndef PNG_NO_CONSOLE_IO
+ #  ifdef PNG_ERROR_NUMBERS_SUPPORTED
+    if (*warning_message == '#')
+    {
+      int offset;
+      char warning_number[16];
+      for (offset=0; offset<15; offset++)
+      {
+         warning_number[offset]=*(warning_message+offset+1);
+         if (*(warning_message+offset) == ' ')
+             break;
+      }
+      if((offset > 1) && (offset < 15))
+      {
+        warning_number[offset-1]='\0';
+        fprintf(stderr, "libpng warning no. %s: %s\n", warning_number,
+           warning_message+offset);
+      }
+      else
+        fprintf(stderr, "libpng warning: %s\n", warning_message);
+    }
+    else
+ #  endif
+      fprintf(stderr, "libpng warning: %s\n", warning_message);
+ #else
+    if (warning_message)
+      /* appease compiler */ ;
+ #endif
+    if (png_ptr)
+       return;
+ }
+ 
+ /* This function is called when the application wants to use another method
+  * of handling errors and warnings.  Note that the error function MUST NOT
+  * return to the calling routine or serious problems will occur.  The return
+  * method used in the default routine calls longjmp(png_ptr->jmpbuf, 1)
+  */
+ void PNGAPI
+ png_set_error_fn(png_structp png_ptr, png_voidp error_ptr,
+    png_error_ptr error_fn, png_error_ptr warning_fn)
+ {
+    png_ptr->error_ptr = error_ptr;
+    png_ptr->error_fn = error_fn;
+    png_ptr->warning_fn = warning_fn;
+ }
+ 
+ 
+ /* This function returns a pointer to the error_ptr associated with the user
+  * functions.  The application should free any memory associated with this
+  * pointer before png_write_destroy and png_read_destroy are called.
+  */
+ png_voidp PNGAPI
+ png_get_error_ptr(png_structp png_ptr)
+ {
+    return ((png_voidp)png_ptr->error_ptr);
+ }
+ 
+ 
+ #ifdef PNG_ERROR_NUMBERS_SUPPORTED
+ void PNGAPI
+ png_set_strip_error_numbers(png_structp png_ptr, png_uint_32 strip_mode)
+ {
+    if(png_ptr != NULL)
+    {
+      png_ptr->flags &=
+        ((~(PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
+    }
+ }
+ #endif


Index: llvm/runtime/libpng/pnggccrd.c
diff -c /dev/null llvm/runtime/libpng/pnggccrd.c:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/pnggccrd.c	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,5397 ----
+ /* pnggccrd.c - mixed C/assembler version of utilities to read a PNG file
+  *
+  * For Intel x86 CPU (Pentium-MMX or later) and GNU C compiler.
+  *
+  *     See http://www.intel.com/drg/pentiumII/appnotes/916/916.htm
+  *     and http://www.intel.com/drg/pentiumII/appnotes/923/923.htm
+  *     for Intel's performance analysis of the MMX vs. non-MMX code.
+  *
+  * libpng version 1.2.5 - October 3, 2002
+  * For conditions of distribution and use, see copyright notice in png.h
+  * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  * Copyright (c) 1998, Intel Corporation
+  *
+  * Based on MSVC code contributed by Nirav Chhatrapati, Intel Corp., 1998.
+  * Interface to libpng contributed by Gilles Vollant, 1999.
+  * GNU C port by Greg Roelofs, 1999-2001.
+  *
+  * Lines 2350-4300 converted in place with intel2gas 1.3.1:
+  *
+  *   intel2gas -mdI pnggccrd.c.partially-msvc -o pnggccrd.c
+  *
+  * and then cleaned up by hand.  See http://hermes.terminal.at/intel2gas/ .
+  *
+  * NOTE:  A sufficiently recent version of GNU as (or as.exe under DOS/Windows)
+  *        is required to assemble the newer MMX instructions such as movq.
+  *        For djgpp, see
+  *
+  *           ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bnu281b.zip
+  *
+  *        (or a later version in the same directory).  For Linux, check your
+  *        distribution's web site(s) or try these links:
+  *
+  *           http://rufus.w3.org/linux/RPM/binutils.html
+  *           http://www.debian.org/Packages/stable/devel/binutils.html
+  *           ftp://ftp.slackware.com/pub/linux/slackware/slackware/slakware/d1/
+  *             binutils.tgz
+  *
+  *        For other platforms, see the main GNU site:
+  *
+  *           ftp://ftp.gnu.org/pub/gnu/binutils/
+  *
+  *        Version 2.5.2l.15 is definitely too old...
+  */
+ 
+ /*
+  * TEMPORARY PORTING NOTES AND CHANGELOG (mostly by Greg Roelofs)
+  * =====================================
+  *
+  * 19991006:
+  *  - fixed sign error in post-MMX cleanup code (16- & 32-bit cases)
+  *
+  * 19991007:
+  *  - additional optimizations (possible or definite):
+  *     x [DONE] write MMX code for 64-bit case (pixel_bytes == 8) [not tested]
+  *     - write MMX code for 48-bit case (pixel_bytes == 6)
+  *     - figure out what's up with 24-bit case (pixel_bytes == 3):
+  *        why subtract 8 from width_mmx in the pass 4/5 case?
+  *        (only width_mmx case) (near line 1606)
+  *     x [DONE] replace pixel_bytes within each block with the true
+  *        constant value (or are compilers smart enough to do that?)
+  *     - rewrite all MMX interlacing code so it's aligned with
+  *        the *beginning* of the row buffer, not the end.  This
+  *        would not only allow one to eliminate half of the memory
+  *        writes for odd passes (that is, pass == odd), it may also
+  *        eliminate some unaligned-data-access exceptions (assuming
+  *        there's a penalty for not aligning 64-bit accesses on
+  *        64-bit boundaries).  The only catch is that the "leftover"
+  *        pixel(s) at the end of the row would have to be saved,
+  *        but there are enough unused MMX registers in every case,
+  *        so this is not a problem.  A further benefit is that the
+  *        post-MMX cleanup code (C code) in at least some of the
+  *        cases could be done within the assembler block.
+  *  x [DONE] the "v3 v2 v1 v0 v7 v6 v5 v4" comments are confusing,
+  *     inconsistent, and don't match the MMX Programmer's Reference
+  *     Manual conventions anyway.  They should be changed to
+  *     "b7 b6 b5 b4 b3 b2 b1 b0," where b0 indicates the byte that
+  *     was lowest in memory (e.g., corresponding to a left pixel)
+  *     and b7 is the byte that was highest (e.g., a right pixel).
+  *
+  * 19991016:
+  *  - Brennan's Guide notwithstanding, gcc under Linux does *not*
+  *     want globals prefixed by underscores when referencing them--
+  *     i.e., if the variable is const4, then refer to it as const4,
+  *     not _const4.  This seems to be a djgpp-specific requirement.
+  *     Also, such variables apparently *must* be declared outside
+  *     of functions; neither static nor automatic variables work if
+  *     defined within the scope of a single function, but both
+  *     static and truly global (multi-module) variables work fine.
+  *
+  * 19991023:
+  *  - fixed png_combine_row() non-MMX replication bug (odd passes only?)
+  *  - switched from string-concatenation-with-macros to cleaner method of
+  *     renaming global variables for djgpp--i.e., always use prefixes in
+  *     inlined assembler code (== strings) and conditionally rename the
+  *     variables, not the other way around.  Hence _const4, _mask8_0, etc.
+  *
+  * 19991024:
+  *  - fixed mmxsupport()/png_do_read_interlace() first-row bug
+  *     This one was severely weird:  even though mmxsupport() doesn't touch
+  *     ebx (where "row" pointer was stored), it nevertheless managed to zero
+  *     the register (even in static/non-fPIC code--see below), which in turn
+  *     caused png_do_read_interlace() to return prematurely on the first row of
+  *     interlaced images (i.e., without expanding the interlaced pixels).
+  *     Inspection of the generated assembly code didn't turn up any clues,
+  *     although it did point at a minor optimization (i.e., get rid of
+  *     mmx_supported_local variable and just use eax).  Possibly the CPUID
+  *     instruction is more destructive than it looks?  (Not yet checked.)
+  *  - "info gcc" was next to useless, so compared fPIC and non-fPIC assembly
+  *     listings...  Apparently register spillage has to do with ebx, since
+  *     it's used to index the global offset table.  Commenting it out of the
+  *     input-reg lists in png_combine_row() eliminated compiler barfage, so
+  *     ifdef'd with __PIC__ macro:  if defined, use a global for unmask
+  *
+  * 19991107:
+  *  - verified CPUID clobberage:  12-char string constant ("GenuineIntel",
+  *     "AuthenticAMD", etc.) placed in ebx:ecx:edx.  Still need to polish.
+  *
+  * 19991120:
+  *  - made "diff" variable (now "_dif") global to simplify conversion of
+  *     filtering routines (running out of regs, sigh).  "diff" is still used
+  *     in interlacing routines, however.
+  *  - fixed up both versions of mmxsupport() (ORIG_THAT_USED_TO_CLOBBER_EBX
+  *     macro determines which is used); original not yet tested.
+  *
+  * 20000213:
+  *  - when compiling with gcc, be sure to use  -fomit-frame-pointer
+  *
+  * 20000319:
+  *  - fixed a register-name typo in png_do_read_interlace(), default (MMX) case,
+  *     pass == 4 or 5, that caused visible corruption of interlaced images
+  *
+  * 20000623:
+  *  - Various problems were reported with gcc 2.95.2 in the Cygwin environment,
+  *     many of the form "forbidden register 0 (ax) was spilled for class AREG."
+  *     This is explained at http://gcc.gnu.org/fom_serv/cache/23.html, and
+  *     Chuck Wilson supplied a patch involving dummy output registers.  See
+  *     http://sourceforge.net/bugs/?func=detailbug&bug_id=108741&group_id=5624
+  *     for the original (anonymous) SourceForge bug report.
+  *
+  * 20000706:
+  *  - Chuck Wilson passed along these remaining gcc 2.95.2 errors:
+  *       pnggccrd.c: In function `png_combine_row':
+  *       pnggccrd.c:525: more than 10 operands in `asm'
+  *       pnggccrd.c:669: more than 10 operands in `asm'
+  *       pnggccrd.c:828: more than 10 operands in `asm'
+  *       pnggccrd.c:994: more than 10 operands in `asm'
+  *       pnggccrd.c:1177: more than 10 operands in `asm'
+  *     They are all the same problem and can be worked around by using the
+  *     global _unmask variable unconditionally, not just in the -fPIC case.
+  *     Reportedly earlier versions of gcc also have the problem with more than
+  *     10 operands; they just don't report it.  Much strangeness ensues, etc.
+  *
+  * 20000729:
+  *  - enabled png_read_filter_row_mmx_up() (shortest remaining unconverted
+  *     MMX routine); began converting png_read_filter_row_mmx_sub()
+  *  - to finish remaining sections:
+  *     - clean up indentation and comments
+  *     - preload local variables
+  *     - add output and input regs (order of former determines numerical
+  *        mapping of latter)
+  *     - avoid all usage of ebx (including bx, bh, bl) register [20000823]
+  *     - remove "$" from addressing of Shift and Mask variables [20000823]
+  *
+  * 20000731:
+  *  - global union vars causing segfaults in png_read_filter_row_mmx_sub()?
+  *
+  * 20000822:
+  *  - ARGH, stupid png_read_filter_row_mmx_sub() segfault only happens with
+  *     shared-library (-fPIC) version!  Code works just fine as part of static
+  *     library.  Damn damn damn damn damn, should have tested that sooner.
+  *     ebx is getting clobbered again (explicitly this time); need to save it
+  *     on stack or rewrite asm code to avoid using it altogether.  Blargh!
+  *
+  * 20000823:
+  *  - first section was trickiest; all remaining sections have ebx -> edx now.
+  *     (-fPIC works again.)  Also added missing underscores to various Shift*
+  *     and *Mask* globals and got rid of leading "$" signs.
+  *
+  * 20000826:
+  *  - added visual separators to help navigate microscopic printed copies
+  *     (http://pobox.com/~newt/code/gpr-latest.zip, mode 10); started working
+  *     on png_read_filter_row_mmx_avg()
+  *
+  * 20000828:
+  *  - finished png_read_filter_row_mmx_avg():  only Paeth left! (930 lines...)
+  *     What the hell, did png_read_filter_row_mmx_paeth(), too.  Comments not
+  *     cleaned up/shortened in either routine, but functionality is complete
+  *     and seems to be working fine.
+  *
+  * 20000829:
+  *  - ahhh, figured out last(?) bit of gcc/gas asm-fu:  if register is listed
+  *     as an input reg (with dummy output variables, etc.), then it *cannot*
+  *     also appear in the clobber list or gcc 2.95.2 will barf.  The solution
+  *     is simple enough...
+  *
+  * 20000914:
+  *  - bug in png_read_filter_row_mmx_avg():  16-bit grayscale not handled
+  *     correctly (but 48-bit RGB just fine)
+  *
+  * 20000916:
+  *  - fixed bug in png_read_filter_row_mmx_avg(), bpp == 2 case; three errors:
+  *     - "_ShiftBpp.use = 24;"      should have been   "_ShiftBpp.use = 16;"
+  *     - "_ShiftRem.use = 40;"      should have been   "_ShiftRem.use = 48;"
+  *     - "psllq _ShiftRem, %%mm2"   should have been   "psrlq _ShiftRem, %%mm2"
+  *
+  * 20010101:
+  *  - added new png_init_mmx_flags() function (here only because it needs to
+  *     call mmxsupport(), which should probably become global png_mmxsupport());
+  *     modified other MMX routines to run conditionally (png_ptr->asm_flags)
+  *
+  * 20010103:
+  *  - renamed mmxsupport() to png_mmx_support(), with auto-set of mmx_supported,
+  *     and made it public; moved png_init_mmx_flags() to png.c as internal func
+  *
+  * 20010104:
+  *  - removed dependency on png_read_filter_row_c() (C code already duplicated
+  *     within MMX version of png_read_filter_row()) so no longer necessary to
+  *     compile it into pngrutil.o
+  *
+  * 20010310:
+  *  - fixed buffer-overrun bug in png_combine_row() C code (non-MMX)
+  *
+  * 20020304:
+  *  - eliminated incorrect use of width_mmx in pixel_bytes == 8 case
+  *
+  * STILL TO DO:
+  *     - test png_do_read_interlace() 64-bit case (pixel_bytes == 8)
+  *     - write MMX code for 48-bit case (pixel_bytes == 6)
+  *     - figure out what's up with 24-bit case (pixel_bytes == 3):
+  *        why subtract 8 from width_mmx in the pass 4/5 case?
+  *        (only width_mmx case) (near line 1606)
+  *     - rewrite all MMX interlacing code so it's aligned with beginning
+  *        of the row buffer, not the end (see 19991007 for details)
+  *     x pick one version of mmxsupport() and get rid of the other
+  *     - add error messages to any remaining bogus default cases
+  *     - enable pixel_depth == 8 cases in png_read_filter_row()? (test speed)
+  *     x add support for runtime enable/disable/query of various MMX routines
+  */
+ 
+ #define PNG_INTERNAL
+ #include "png.h"
+ 
+ #if defined(PNG_USE_PNGGCCRD)
+ 
+ int PNGAPI png_mmx_support(void);
+ 
+ #ifdef PNG_USE_LOCAL_ARRAYS
+ static const int FARDATA png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+ static const int FARDATA png_pass_inc[7]   = {8, 8, 4, 4, 2, 2, 1};
+ static const int FARDATA png_pass_width[7] = {8, 4, 4, 2, 2, 1, 1};
+ #endif
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+ /* djgpp, Win32, and Cygwin add their own underscores to global variables,
+  * so define them without: */
+ #if defined(__DJGPP__) || defined(WIN32) || defined(__CYGWIN__)
+ #  define _mmx_supported  mmx_supported
+ #  define _const4         const4
+ #  define _const6         const6
+ #  define _mask8_0        mask8_0
+ #  define _mask16_1       mask16_1
+ #  define _mask16_0       mask16_0
+ #  define _mask24_2       mask24_2
+ #  define _mask24_1       mask24_1
+ #  define _mask24_0       mask24_0
+ #  define _mask32_3       mask32_3
+ #  define _mask32_2       mask32_2
+ #  define _mask32_1       mask32_1
+ #  define _mask32_0       mask32_0
+ #  define _mask48_5       mask48_5
+ #  define _mask48_4       mask48_4
+ #  define _mask48_3       mask48_3
+ #  define _mask48_2       mask48_2
+ #  define _mask48_1       mask48_1
+ #  define _mask48_0       mask48_0
+ #  define _LBCarryMask    LBCarryMask
+ #  define _HBClearMask    HBClearMask
+ #  define _ActiveMask     ActiveMask
+ #  define _ActiveMask2    ActiveMask2
+ #  define _ActiveMaskEnd  ActiveMaskEnd
+ #  define _ShiftBpp       ShiftBpp
+ #  define _ShiftRem       ShiftRem
+ #ifdef PNG_THREAD_UNSAFE_OK
+ #  define _unmask         unmask
+ #  define _FullLength     FullLength
+ #  define _MMXLength      MMXLength
+ #  define _dif            dif
+ #  define _patemp         patemp
+ #  define _pbtemp         pbtemp
+ #  define _pctemp         pctemp
+ #endif
+ #endif
+ 
+ 
+ /* These constants are used in the inlined MMX assembly code.
+    Ignore gcc's "At top level: defined but not used" warnings. */
+ 
+ /* GRR 20000706:  originally _unmask was needed only when compiling with -fPIC,
+  *  since that case uses the %ebx register for indexing the Global Offset Table
+  *  and there were no other registers available.  But gcc 2.95 and later emit
+  *  "more than 10 operands in `asm'" errors when %ebx is used to preload unmask
+  *  in the non-PIC case, so we'll just use the global unconditionally now.
+  */
+ #ifdef PNG_THREAD_UNSAFE_OK
+ static int _unmask;
+ #endif
+ 
+ static unsigned long long _mask8_0  = 0x0102040810204080LL;
+ 
+ static unsigned long long _mask16_1 = 0x0101020204040808LL;
+ static unsigned long long _mask16_0 = 0x1010202040408080LL;
+ 
+ static unsigned long long _mask24_2 = 0x0101010202020404LL;
+ static unsigned long long _mask24_1 = 0x0408080810101020LL;
+ static unsigned long long _mask24_0 = 0x2020404040808080LL;
+ 
+ static unsigned long long _mask32_3 = 0x0101010102020202LL;
+ static unsigned long long _mask32_2 = 0x0404040408080808LL;
+ static unsigned long long _mask32_1 = 0x1010101020202020LL;
+ static unsigned long long _mask32_0 = 0x4040404080808080LL;
+ 
+ static unsigned long long _mask48_5 = 0x0101010101010202LL;
+ static unsigned long long _mask48_4 = 0x0202020204040404LL;
+ static unsigned long long _mask48_3 = 0x0404080808080808LL;
+ static unsigned long long _mask48_2 = 0x1010101010102020LL;
+ static unsigned long long _mask48_1 = 0x2020202040404040LL;
+ static unsigned long long _mask48_0 = 0x4040808080808080LL;
+ 
+ static unsigned long long _const4   = 0x0000000000FFFFFFLL;
+ //static unsigned long long _const5 = 0x000000FFFFFF0000LL;     // NOT USED
+ static unsigned long long _const6   = 0x00000000000000FFLL;
+ 
+ // These are used in the row-filter routines and should/would be local
+ //  variables if not for gcc addressing limitations.
+ // WARNING: Their presence probably defeats the thread safety of libpng.
+ 
+ #ifdef PNG_THREAD_UNSAFE_OK
+ static png_uint_32  _FullLength;
+ static png_uint_32  _MMXLength;
+ static int          _dif;
+ static int          _patemp; // temp variables for Paeth routine
+ static int          _pbtemp;
+ static int          _pctemp;
+ #endif
+ 
+ void /* PRIVATE */
+ png_squelch_warnings(void)
+ {
+ #ifdef PNG_THREAD_UNSAFE_OK
+    _dif = _dif;
+    _patemp = _patemp;
+    _pbtemp = _pbtemp;
+    _pctemp = _pctemp;
+    _MMXLength = _MMXLength;
+ #endif
+    _const4  = _const4;
+    _const6  = _const6;
+    _mask8_0  = _mask8_0;
+    _mask16_1 = _mask16_1;
+    _mask16_0 = _mask16_0;
+    _mask24_2 = _mask24_2;
+    _mask24_1 = _mask24_1;
+    _mask24_0 = _mask24_0;
+    _mask32_3 = _mask32_3;
+    _mask32_2 = _mask32_2;
+    _mask32_1 = _mask32_1;
+    _mask32_0 = _mask32_0;
+    _mask48_5 = _mask48_5;
+    _mask48_4 = _mask48_4;
+    _mask48_3 = _mask48_3;
+    _mask48_2 = _mask48_2;
+    _mask48_1 = _mask48_1;
+    _mask48_0 = _mask48_0;
+ }
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+ 
+ 
+ static int _mmx_supported = 2;
+ 
+ /*===========================================================================*/
+ /*                                                                           */
+ /*                       P N G _ C O M B I N E _ R O W                       */
+ /*                                                                           */
+ /*===========================================================================*/
+ 
+ #if defined(PNG_HAVE_ASSEMBLER_COMBINE_ROW)
+ 
+ #define BPP2  2
+ #define BPP3  3 /* bytes per pixel (a.k.a. pixel_bytes) */
+ #define BPP4  4
+ #define BPP6  6 /* (defined only to help avoid cut-and-paste errors) */
+ #define BPP8  8
+ 
+ /* Combines the row recently read in with the previous row.
+    This routine takes care of alpha and transparency if requested.
+    This routine also handles the two methods of progressive display
+    of interlaced images, depending on the mask value.
+    The mask value describes which pixels are to be combined with
+    the row.  The pattern always repeats every 8 pixels, so just 8
+    bits are needed.  A one indicates the pixel is to be combined; a
+    zero indicates the pixel is to be skipped.  This is in addition
+    to any alpha or transparency value associated with the pixel.
+    If you want all pixels to be combined, pass 0xff (255) in mask. */
+ 
+ /* Use this routine for the x86 platform - it uses a faster MMX routine
+    if the machine supports MMX. */
+ 
+ void /* PRIVATE */
+ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
+ {
+    png_debug(1, "in png_combine_row (pnggccrd.c)\n");
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+    if (_mmx_supported == 2) {
+        /* this should have happened in png_init_mmx_flags() already */
+        png_warning(png_ptr, "asm_flags may not have been initialized");
+        png_mmx_support();
+    }
+ #endif
+ 
+    if (mask == 0xff)
+    {
+       png_debug(2,"mask == 0xff:  doing single png_memcpy()\n");
+       png_memcpy(row, png_ptr->row_buf + 1,
+        (png_size_t)((png_ptr->width * png_ptr->row_info.pixel_depth + 7) >> 3));
+    }
+    else   /* (png_combine_row() is never called with mask == 0) */
+    {
+       switch (png_ptr->row_info.pixel_depth)
+       {
+          case 1:        /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep sp;
+             png_bytep dp;
+             int s_inc, s_start, s_end;
+             int m;
+             int shift;
+             png_uint_32 i;
+ 
+             sp = png_ptr->row_buf + 1;
+             dp = row;
+             m = 0x80;
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED)
+             if (png_ptr->transformations & PNG_PACKSWAP)
+             {
+                 s_start = 0;
+                 s_end = 7;
+                 s_inc = 1;
+             }
+             else
+ #endif
+             {
+                 s_start = 7;
+                 s_end = 0;
+                 s_inc = -1;
+             }
+ 
+             shift = s_start;
+ 
+             for (i = 0; i < png_ptr->width; i++)
+             {
+                if (m & mask)
+                {
+                   int value;
+ 
+                   value = (*sp >> shift) & 0x1;
+                   *dp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
+                   *dp |= (png_byte)(value << shift);
+                }
+ 
+                if (shift == s_end)
+                {
+                   shift = s_start;
+                   sp++;
+                   dp++;
+                }
+                else
+                   shift += s_inc;
+ 
+                if (m == 1)
+                   m = 0x80;
+                else
+                   m >>= 1;
+             }
+             break;
+          }
+ 
+          case 2:        /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep sp;
+             png_bytep dp;
+             int s_start, s_end, s_inc;
+             int m;
+             int shift;
+             png_uint_32 i;
+             int value;
+ 
+             sp = png_ptr->row_buf + 1;
+             dp = row;
+             m = 0x80;
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED)
+             if (png_ptr->transformations & PNG_PACKSWAP)
+             {
+                s_start = 0;
+                s_end = 6;
+                s_inc = 2;
+             }
+             else
+ #endif
+             {
+                s_start = 6;
+                s_end = 0;
+                s_inc = -2;
+             }
+ 
+             shift = s_start;
+ 
+             for (i = 0; i < png_ptr->width; i++)
+             {
+                if (m & mask)
+                {
+                   value = (*sp >> shift) & 0x3;
+                   *dp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
+                   *dp |= (png_byte)(value << shift);
+                }
+ 
+                if (shift == s_end)
+                {
+                   shift = s_start;
+                   sp++;
+                   dp++;
+                }
+                else
+                   shift += s_inc;
+                if (m == 1)
+                   m = 0x80;
+                else
+                   m >>= 1;
+             }
+             break;
+          }
+ 
+          case 4:        /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep sp;
+             png_bytep dp;
+             int s_start, s_end, s_inc;
+             int m;
+             int shift;
+             png_uint_32 i;
+             int value;
+ 
+             sp = png_ptr->row_buf + 1;
+             dp = row;
+             m = 0x80;
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED)
+             if (png_ptr->transformations & PNG_PACKSWAP)
+             {
+                s_start = 0;
+                s_end = 4;
+                s_inc = 4;
+             }
+             else
+ #endif
+             {
+                s_start = 4;
+                s_end = 0;
+                s_inc = -4;
+             }
+             shift = s_start;
+ 
+             for (i = 0; i < png_ptr->width; i++)
+             {
+                if (m & mask)
+                {
+                   value = (*sp >> shift) & 0xf;
+                   *dp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
+                   *dp |= (png_byte)(value << shift);
+                }
+ 
+                if (shift == s_end)
+                {
+                   shift = s_start;
+                   sp++;
+                   dp++;
+                }
+                else
+                   shift += s_inc;
+                if (m == 1)
+                   m = 0x80;
+                else
+                   m >>= 1;
+             }
+             break;
+          }
+ 
+          case 8:        /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep srcptr;
+             png_bytep dstptr;
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+             if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_COMBINE_ROW)
+                 /* && _mmx_supported */ )
+ #else
+             if (_mmx_supported)
+ #endif
+             {
+                png_uint_32 len;
+                int diff;
+                int dummy_value_a;   // fix 'forbidden register spilled' error
+                int dummy_value_d;
+                int dummy_value_c;
+                int dummy_value_S;
+                int dummy_value_D;
+                _unmask = ~mask;            // global variable for -fPIC version
+                srcptr = png_ptr->row_buf + 1;
+                dstptr = row;
+                len  = png_ptr->width &~7;  // reduce to multiple of 8
+                diff = (int) (png_ptr->width & 7);  // amount lost
+ 
+                __asm__ __volatile__ (
+                   "movd      _unmask, %%mm7  \n\t" // load bit pattern
+                   "psubb     %%mm6, %%mm6    \n\t" // zero mm6
+                   "punpcklbw %%mm7, %%mm7    \n\t"
+                   "punpcklwd %%mm7, %%mm7    \n\t"
+                   "punpckldq %%mm7, %%mm7    \n\t" // fill reg with 8 masks
+ 
+                   "movq      _mask8_0, %%mm0 \n\t"
+                   "pand      %%mm7, %%mm0    \n\t" // nonzero if keep byte
+                   "pcmpeqb   %%mm6, %%mm0    \n\t" // zeros->1s, v versa
+ 
+ // preload        "movl      len, %%ecx      \n\t" // load length of line
+ // preload        "movl      srcptr, %%esi   \n\t" // load source
+ // preload        "movl      dstptr, %%edi   \n\t" // load dest
+ 
+                   "cmpl      $0, %%ecx       \n\t" // len == 0 ?
+                   "je        mainloop8end    \n\t"
+ 
+                 "mainloop8:                  \n\t"
+                   "movq      (%%esi), %%mm4  \n\t" // *srcptr
+                   "pand      %%mm0, %%mm4    \n\t"
+                   "movq      %%mm0, %%mm6    \n\t"
+                   "pandn     (%%edi), %%mm6  \n\t" // *dstptr
+                   "por       %%mm6, %%mm4    \n\t"
+                   "movq      %%mm4, (%%edi)  \n\t"
+                   "addl      $8, %%esi       \n\t" // inc by 8 bytes processed
+                   "addl      $8, %%edi       \n\t"
+                   "subl      $8, %%ecx       \n\t" // dec by 8 pixels processed
+                   "ja        mainloop8       \n\t"
+ 
+                 "mainloop8end:               \n\t"
+ // preload        "movl      diff, %%ecx     \n\t" // (diff is in eax)
+                   "movl      %%eax, %%ecx    \n\t"
+                   "cmpl      $0, %%ecx       \n\t"
+                   "jz        end8            \n\t"
+ // preload        "movl      mask, %%edx     \n\t"
+                   "sall      $24, %%edx      \n\t" // make low byte, high byte
+ 
+                 "secondloop8:                \n\t"
+                   "sall      %%edx           \n\t" // move high bit to CF
+                   "jnc       skip8           \n\t" // if CF = 0
+                   "movb      (%%esi), %%al   \n\t"
+                   "movb      %%al, (%%edi)   \n\t"
+ 
+                 "skip8:                      \n\t"
+                   "incl      %%esi           \n\t"
+                   "incl      %%edi           \n\t"
+                   "decl      %%ecx           \n\t"
+                   "jnz       secondloop8     \n\t"
+ 
+                 "end8:                       \n\t"
+                   "EMMS                      \n\t"  // DONE
+ 
+                   : "=a" (dummy_value_a),           // output regs (dummy)
+                     "=d" (dummy_value_d),
+                     "=c" (dummy_value_c),
+                     "=S" (dummy_value_S),
+                     "=D" (dummy_value_D)
+ 
+                   : "3" (srcptr),      // esi       // input regs
+                     "4" (dstptr),      // edi
+                     "0" (diff),        // eax
+ // was (unmask)     "b"    RESERVED    // ebx       // Global Offset Table idx
+                     "2" (len),         // ecx
+                     "1" (mask)         // edx
+ 
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+                   : "%mm0", "%mm4", "%mm6", "%mm7"  // clobber list
+ #endif
+                );
+             }
+             else /* mmx _not supported - Use modified C routine */
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+             {
+                register png_uint_32 i;
+                png_uint_32 initial_val = png_pass_start[png_ptr->pass];
+                  /* png.c:  png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; */
+                register int stride = png_pass_inc[png_ptr->pass];
+                  /* png.c:  png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; */
+                register int rep_bytes = png_pass_width[png_ptr->pass];
+                  /* png.c:  png_pass_width[] = {8, 4, 4, 2, 2, 1, 1}; */
+                png_uint_32 len = png_ptr->width &~7;  /* reduce to mult. of 8 */
+                int diff = (int) (png_ptr->width & 7); /* amount lost */
+                register png_uint_32 final_val = len;  /* GRR bugfix */
+ 
+                srcptr = png_ptr->row_buf + 1 + initial_val;
+                dstptr = row + initial_val;
+ 
+                for (i = initial_val; i < final_val; i += stride)
+                {
+                   png_memcpy(dstptr, srcptr, rep_bytes);
+                   srcptr += stride;
+                   dstptr += stride;
+                }
+                if (diff)  /* number of leftover pixels:  3 for pngtest */
+                {
+                   final_val+=diff /* *BPP1 */ ;
+                   for (; i < final_val; i += stride)
+                   {
+                      if (rep_bytes > (int)(final_val-i))
+                         rep_bytes = (int)(final_val-i);
+                      png_memcpy(dstptr, srcptr, rep_bytes);
+                      srcptr += stride;
+                      dstptr += stride;
+                   }
+                }
+ 
+             } /* end of else (_mmx_supported) */
+ 
+             break;
+          }       /* end 8 bpp */
+ 
+          case 16:       /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep srcptr;
+             png_bytep dstptr;
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+             if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_COMBINE_ROW)
+                 /* && _mmx_supported */ )
+ #else
+             if (_mmx_supported)
+ #endif
+             {
+                png_uint_32 len;
+                int diff;
+                int dummy_value_a;   // fix 'forbidden register spilled' error
+                int dummy_value_d;
+                int dummy_value_c;
+                int dummy_value_S;
+                int dummy_value_D;
+                _unmask = ~mask;            // global variable for -fPIC version
+                srcptr = png_ptr->row_buf + 1;
+                dstptr = row;
+                len  = png_ptr->width &~7;  // reduce to multiple of 8
+                diff = (int) (png_ptr->width & 7); // amount lost //
+ 
+                __asm__ __volatile__ (
+                   "movd      _unmask, %%mm7   \n\t" // load bit pattern
+                   "psubb     %%mm6, %%mm6     \n\t" // zero mm6
+                   "punpcklbw %%mm7, %%mm7     \n\t"
+                   "punpcklwd %%mm7, %%mm7     \n\t"
+                   "punpckldq %%mm7, %%mm7     \n\t" // fill reg with 8 masks
+ 
+                   "movq      _mask16_0, %%mm0 \n\t"
+                   "movq      _mask16_1, %%mm1 \n\t"
+ 
+                   "pand      %%mm7, %%mm0     \n\t"
+                   "pand      %%mm7, %%mm1     \n\t"
+ 
+                   "pcmpeqb   %%mm6, %%mm0     \n\t"
+                   "pcmpeqb   %%mm6, %%mm1     \n\t"
+ 
+ // preload        "movl      len, %%ecx       \n\t" // load length of line
+ // preload        "movl      srcptr, %%esi    \n\t" // load source
+ // preload        "movl      dstptr, %%edi    \n\t" // load dest
+ 
+                   "cmpl      $0, %%ecx        \n\t"
+                   "jz        mainloop16end    \n\t"
+ 
+                 "mainloop16:                  \n\t"
+                   "movq      (%%esi), %%mm4   \n\t"
+                   "pand      %%mm0, %%mm4     \n\t"
+                   "movq      %%mm0, %%mm6     \n\t"
+                   "movq      (%%edi), %%mm7   \n\t"
+                   "pandn     %%mm7, %%mm6     \n\t"
+                   "por       %%mm6, %%mm4     \n\t"
+                   "movq      %%mm4, (%%edi)   \n\t"
+ 
+                   "movq      8(%%esi), %%mm5  \n\t"
+                   "pand      %%mm1, %%mm5     \n\t"
+                   "movq      %%mm1, %%mm7     \n\t"
+                   "movq      8(%%edi), %%mm6  \n\t"
+                   "pandn     %%mm6, %%mm7     \n\t"
+                   "por       %%mm7, %%mm5     \n\t"
+                   "movq      %%mm5, 8(%%edi)  \n\t"
+ 
+                   "addl      $16, %%esi       \n\t" // inc by 16 bytes processed
+                   "addl      $16, %%edi       \n\t"
+                   "subl      $8, %%ecx        \n\t" // dec by 8 pixels processed
+                   "ja        mainloop16       \n\t"
+ 
+                 "mainloop16end:               \n\t"
+ // preload        "movl      diff, %%ecx      \n\t" // (diff is in eax)
+                   "movl      %%eax, %%ecx     \n\t"
+                   "cmpl      $0, %%ecx        \n\t"
+                   "jz        end16            \n\t"
+ // preload        "movl      mask, %%edx      \n\t"
+                   "sall      $24, %%edx       \n\t" // make low byte, high byte
+ 
+                 "secondloop16:                \n\t"
+                   "sall      %%edx            \n\t" // move high bit to CF
+                   "jnc       skip16           \n\t" // if CF = 0
+                   "movw      (%%esi), %%ax    \n\t"
+                   "movw      %%ax, (%%edi)    \n\t"
+ 
+                 "skip16:                      \n\t"
+                   "addl      $2, %%esi        \n\t"
+                   "addl      $2, %%edi        \n\t"
+                   "decl      %%ecx            \n\t"
+                   "jnz       secondloop16     \n\t"
+ 
+                 "end16:                       \n\t"
+                   "EMMS                       \n\t" // DONE
+ 
+                   : "=a" (dummy_value_a),           // output regs (dummy)
+                     "=c" (dummy_value_c),
+                     "=d" (dummy_value_d),
+                     "=S" (dummy_value_S),
+                     "=D" (dummy_value_D)
+ 
+                   : "0" (diff),        // eax       // input regs
+ // was (unmask)     " "    RESERVED    // ebx       // Global Offset Table idx
+                     "1" (len),         // ecx
+                     "2" (mask),        // edx
+                     "3" (srcptr),      // esi
+                     "4" (dstptr)       // edi
+ 
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+                   : "%mm0", "%mm1", "%mm4"          // clobber list
+                   , "%mm5", "%mm6", "%mm7"
+ #endif
+                );
+             }
+             else /* mmx _not supported - Use modified C routine */
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+             {
+                register png_uint_32 i;
+                png_uint_32 initial_val = BPP2 * png_pass_start[png_ptr->pass];
+                  /* png.c:  png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; */
+                register int stride = BPP2 * png_pass_inc[png_ptr->pass];
+                  /* png.c:  png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; */
+                register int rep_bytes = BPP2 * png_pass_width[png_ptr->pass];
+                  /* png.c:  png_pass_width[] = {8, 4, 4, 2, 2, 1, 1}; */
+                png_uint_32 len = png_ptr->width &~7;  /* reduce to mult. of 8 */
+                int diff = (int) (png_ptr->width & 7); /* amount lost */
+                register png_uint_32 final_val = BPP2 * len;   /* GRR bugfix */
+ 
+                srcptr = png_ptr->row_buf + 1 + initial_val;
+                dstptr = row + initial_val;
+ 
+                for (i = initial_val; i < final_val; i += stride)
+                {
+                   png_memcpy(dstptr, srcptr, rep_bytes);
+                   srcptr += stride;
+                   dstptr += stride;
+                }
+                if (diff)  /* number of leftover pixels:  3 for pngtest */
+                {
+                   final_val+=diff*BPP2;
+                   for (; i < final_val; i += stride)
+                   {
+                      if (rep_bytes > (int)(final_val-i))
+                         rep_bytes = (int)(final_val-i);
+                      png_memcpy(dstptr, srcptr, rep_bytes);
+                      srcptr += stride;
+                      dstptr += stride;
+                   }
+                }
+             } /* end of else (_mmx_supported) */
+ 
+             break;
+          }       /* end 16 bpp */
+ 
+          case 24:       /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep srcptr;
+             png_bytep dstptr;
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+             if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_COMBINE_ROW)
+                 /* && _mmx_supported */ )
+ #else
+             if (_mmx_supported)
+ #endif
+             {
+                png_uint_32 len;
+                int diff;
+                int dummy_value_a;   // fix 'forbidden register spilled' error
+                int dummy_value_d;
+                int dummy_value_c;
+                int dummy_value_S;
+                int dummy_value_D;
+                _unmask = ~mask;            // global variable for -fPIC version
+                srcptr = png_ptr->row_buf + 1;
+                dstptr = row;
+                len  = png_ptr->width &~7;  // reduce to multiple of 8
+                diff = (int) (png_ptr->width & 7); // amount lost //
+ 
+                __asm__ __volatile__ (
+                   "movd      _unmask, %%mm7   \n\t" // load bit pattern
+                   "psubb     %%mm6, %%mm6     \n\t" // zero mm6
+                   "punpcklbw %%mm7, %%mm7     \n\t"
+                   "punpcklwd %%mm7, %%mm7     \n\t"
+                   "punpckldq %%mm7, %%mm7     \n\t" // fill reg with 8 masks
+ 
+                   "movq      _mask24_0, %%mm0 \n\t"
+                   "movq      _mask24_1, %%mm1 \n\t"
+                   "movq      _mask24_2, %%mm2 \n\t"
+ 
+                   "pand      %%mm7, %%mm0     \n\t"
+                   "pand      %%mm7, %%mm1     \n\t"
+                   "pand      %%mm7, %%mm2     \n\t"
+ 
+                   "pcmpeqb   %%mm6, %%mm0     \n\t"
+                   "pcmpeqb   %%mm6, %%mm1     \n\t"
+                   "pcmpeqb   %%mm6, %%mm2     \n\t"
+ 
+ // preload        "movl      len, %%ecx       \n\t" // load length of line
+ // preload        "movl      srcptr, %%esi    \n\t" // load source
+ // preload        "movl      dstptr, %%edi    \n\t" // load dest
+ 
+                   "cmpl      $0, %%ecx        \n\t"
+                   "jz        mainloop24end    \n\t"
+ 
+                 "mainloop24:                  \n\t"
+                   "movq      (%%esi), %%mm4   \n\t"
+                   "pand      %%mm0, %%mm4     \n\t"
+                   "movq      %%mm0, %%mm6     \n\t"
+                   "movq      (%%edi), %%mm7   \n\t"
+                   "pandn     %%mm7, %%mm6     \n\t"
+                   "por       %%mm6, %%mm4     \n\t"
+                   "movq      %%mm4, (%%edi)   \n\t"
+ 
+                   "movq      8(%%esi), %%mm5  \n\t"
+                   "pand      %%mm1, %%mm5     \n\t"
+                   "movq      %%mm1, %%mm7     \n\t"
+                   "movq      8(%%edi), %%mm6  \n\t"
+                   "pandn     %%mm6, %%mm7     \n\t"
+                   "por       %%mm7, %%mm5     \n\t"
+                   "movq      %%mm5, 8(%%edi)  \n\t"
+ 
+                   "movq      16(%%esi), %%mm6 \n\t"
+                   "pand      %%mm2, %%mm6     \n\t"
+                   "movq      %%mm2, %%mm4     \n\t"
+                   "movq      16(%%edi), %%mm7 \n\t"
+                   "pandn     %%mm7, %%mm4     \n\t"
+                   "por       %%mm4, %%mm6     \n\t"
+                   "movq      %%mm6, 16(%%edi) \n\t"
+ 
+                   "addl      $24, %%esi       \n\t" // inc by 24 bytes processed
+                   "addl      $24, %%edi       \n\t"
+                   "subl      $8, %%ecx        \n\t" // dec by 8 pixels processed
+ 
+                   "ja        mainloop24       \n\t"
+ 
+                 "mainloop24end:               \n\t"
+ // preload        "movl      diff, %%ecx      \n\t" // (diff is in eax)
+                   "movl      %%eax, %%ecx     \n\t"
+                   "cmpl      $0, %%ecx        \n\t"
+                   "jz        end24            \n\t"
+ // preload        "movl      mask, %%edx      \n\t"
+                   "sall      $24, %%edx       \n\t" // make low byte, high byte
+ 
+                 "secondloop24:                \n\t"
+                   "sall      %%edx            \n\t" // move high bit to CF
+                   "jnc       skip24           \n\t" // if CF = 0
+                   "movw      (%%esi), %%ax    \n\t"
+                   "movw      %%ax, (%%edi)    \n\t"
+                   "xorl      %%eax, %%eax     \n\t"
+                   "movb      2(%%esi), %%al   \n\t"
+                   "movb      %%al, 2(%%edi)   \n\t"
+ 
+                 "skip24:                      \n\t"
+                   "addl      $3, %%esi        \n\t"
+                   "addl      $3, %%edi        \n\t"
+                   "decl      %%ecx            \n\t"
+                   "jnz       secondloop24     \n\t"
+ 
+                 "end24:                       \n\t"
+                   "EMMS                       \n\t" // DONE
+ 
+                   : "=a" (dummy_value_a),           // output regs (dummy)
+                     "=d" (dummy_value_d),
+                     "=c" (dummy_value_c),
+                     "=S" (dummy_value_S),
+                     "=D" (dummy_value_D)
+ 
+                   : "3" (srcptr),      // esi       // input regs
+                     "4" (dstptr),      // edi
+                     "0" (diff),        // eax
+ // was (unmask)     "b"    RESERVED    // ebx       // Global Offset Table idx
+                     "2" (len),         // ecx
+                     "1" (mask)         // edx
+ 
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+                   : "%mm0", "%mm1", "%mm2"          // clobber list
+                   , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+                );
+             }
+             else /* mmx _not supported - Use modified C routine */
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+             {
+                register png_uint_32 i;
+                png_uint_32 initial_val = BPP3 * png_pass_start[png_ptr->pass];
+                  /* png.c:  png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; */
+                register int stride = BPP3 * png_pass_inc[png_ptr->pass];
+                  /* png.c:  png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; */
+                register int rep_bytes = BPP3 * png_pass_width[png_ptr->pass];
+                  /* png.c:  png_pass_width[] = {8, 4, 4, 2, 2, 1, 1}; */
+                png_uint_32 len = png_ptr->width &~7;  /* reduce to mult. of 8 */
+                int diff = (int) (png_ptr->width & 7); /* amount lost */
+                register png_uint_32 final_val = BPP3 * len;   /* GRR bugfix */
+ 
+                srcptr = png_ptr->row_buf + 1 + initial_val;
+                dstptr = row + initial_val;
+ 
+                for (i = initial_val; i < final_val; i += stride)
+                {
+                   png_memcpy(dstptr, srcptr, rep_bytes);
+                   srcptr += stride;
+                   dstptr += stride;
+                }
+                if (diff)  /* number of leftover pixels:  3 for pngtest */
+                {
+                   final_val+=diff*BPP3;
+                   for (; i < final_val; i += stride)
+                   {
+                      if (rep_bytes > (int)(final_val-i))
+                         rep_bytes = (int)(final_val-i);
+                      png_memcpy(dstptr, srcptr, rep_bytes);
+                      srcptr += stride;
+                      dstptr += stride;
+                   }
+                }
+             } /* end of else (_mmx_supported) */
+ 
+             break;
+          }       /* end 24 bpp */
+ 
+          case 32:       /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep srcptr;
+             png_bytep dstptr;
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+             if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_COMBINE_ROW)
+                 /* && _mmx_supported */ )
+ #else
+             if (_mmx_supported)
+ #endif
+             {
+                png_uint_32 len;
+                int diff;
+                int dummy_value_a;   // fix 'forbidden register spilled' error
+                int dummy_value_d;
+                int dummy_value_c;
+                int dummy_value_S;
+                int dummy_value_D;
+                _unmask = ~mask;            // global variable for -fPIC version
+                srcptr = png_ptr->row_buf + 1;
+                dstptr = row;
+                len  = png_ptr->width &~7;  // reduce to multiple of 8
+                diff = (int) (png_ptr->width & 7); // amount lost //
+ 
+                __asm__ __volatile__ (
+                   "movd      _unmask, %%mm7   \n\t" // load bit pattern
+                   "psubb     %%mm6, %%mm6     \n\t" // zero mm6
+                   "punpcklbw %%mm7, %%mm7     \n\t"
+                   "punpcklwd %%mm7, %%mm7     \n\t"
+                   "punpckldq %%mm7, %%mm7     \n\t" // fill reg with 8 masks
+ 
+                   "movq      _mask32_0, %%mm0 \n\t"
+                   "movq      _mask32_1, %%mm1 \n\t"
+                   "movq      _mask32_2, %%mm2 \n\t"
+                   "movq      _mask32_3, %%mm3 \n\t"
+ 
+                   "pand      %%mm7, %%mm0     \n\t"
+                   "pand      %%mm7, %%mm1     \n\t"
+                   "pand      %%mm7, %%mm2     \n\t"
+                   "pand      %%mm7, %%mm3     \n\t"
+ 
+                   "pcmpeqb   %%mm6, %%mm0     \n\t"
+                   "pcmpeqb   %%mm6, %%mm1     \n\t"
+                   "pcmpeqb   %%mm6, %%mm2     \n\t"
+                   "pcmpeqb   %%mm6, %%mm3     \n\t"
+ 
+ // preload        "movl      len, %%ecx       \n\t" // load length of line
+ // preload        "movl      srcptr, %%esi    \n\t" // load source
+ // preload        "movl      dstptr, %%edi    \n\t" // load dest
+ 
+                   "cmpl      $0, %%ecx        \n\t" // lcr
+                   "jz        mainloop32end    \n\t"
+ 
+                 "mainloop32:                  \n\t"
+                   "movq      (%%esi), %%mm4   \n\t"
+                   "pand      %%mm0, %%mm4     \n\t"
+                   "movq      %%mm0, %%mm6     \n\t"
+                   "movq      (%%edi), %%mm7   \n\t"
+                   "pandn     %%mm7, %%mm6     \n\t"
+                   "por       %%mm6, %%mm4     \n\t"
+                   "movq      %%mm4, (%%edi)   \n\t"
+ 
+                   "movq      8(%%esi), %%mm5  \n\t"
+                   "pand      %%mm1, %%mm5     \n\t"
+                   "movq      %%mm1, %%mm7     \n\t"
+                   "movq      8(%%edi), %%mm6  \n\t"
+                   "pandn     %%mm6, %%mm7     \n\t"
+                   "por       %%mm7, %%mm5     \n\t"
+                   "movq      %%mm5, 8(%%edi)  \n\t"
+ 
+                   "movq      16(%%esi), %%mm6 \n\t"
+                   "pand      %%mm2, %%mm6     \n\t"
+                   "movq      %%mm2, %%mm4     \n\t"
+                   "movq      16(%%edi), %%mm7 \n\t"
+                   "pandn     %%mm7, %%mm4     \n\t"
+                   "por       %%mm4, %%mm6     \n\t"
+                   "movq      %%mm6, 16(%%edi) \n\t"
+ 
+                   "movq      24(%%esi), %%mm7 \n\t"
+                   "pand      %%mm3, %%mm7     \n\t"
+                   "movq      %%mm3, %%mm5     \n\t"
+                   "movq      24(%%edi), %%mm4 \n\t"
+                   "pandn     %%mm4, %%mm5     \n\t"
+                   "por       %%mm5, %%mm7     \n\t"
+                   "movq      %%mm7, 24(%%edi) \n\t"
+ 
+                   "addl      $32, %%esi       \n\t" // inc by 32 bytes processed
+                   "addl      $32, %%edi       \n\t"
+                   "subl      $8, %%ecx        \n\t" // dec by 8 pixels processed
+                   "ja        mainloop32       \n\t"
+ 
+                 "mainloop32end:               \n\t"
+ // preload        "movl      diff, %%ecx      \n\t" // (diff is in eax)
+                   "movl      %%eax, %%ecx     \n\t"
+                   "cmpl      $0, %%ecx        \n\t"
+                   "jz        end32            \n\t"
+ // preload        "movl      mask, %%edx      \n\t"
+                   "sall      $24, %%edx       \n\t" // low byte => high byte
+ 
+                 "secondloop32:                \n\t"
+                   "sall      %%edx            \n\t" // move high bit to CF
+                   "jnc       skip32           \n\t" // if CF = 0
+                   "movl      (%%esi), %%eax   \n\t"
+                   "movl      %%eax, (%%edi)   \n\t"
+ 
+                 "skip32:                      \n\t"
+                   "addl      $4, %%esi        \n\t"
+                   "addl      $4, %%edi        \n\t"
+                   "decl      %%ecx            \n\t"
+                   "jnz       secondloop32     \n\t"
+ 
+                 "end32:                       \n\t"
+                   "EMMS                       \n\t" // DONE
+ 
+                   : "=a" (dummy_value_a),           // output regs (dummy)
+                     "=d" (dummy_value_d),
+                     "=c" (dummy_value_c),
+                     "=S" (dummy_value_S),
+                     "=D" (dummy_value_D)
+ 
+                   : "3" (srcptr),      // esi       // input regs
+                     "4" (dstptr),      // edi
+                     "0" (diff),        // eax
+ // was (unmask)     "b"    RESERVED    // ebx       // Global Offset Table idx
+                     "2" (len),         // ecx
+                     "1" (mask)         // edx
+ 
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+                   : "%mm0", "%mm1", "%mm2", "%mm3"  // clobber list
+                   , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+                );
+             }
+             else /* mmx _not supported - Use modified C routine */
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+             {
+                register png_uint_32 i;
+                png_uint_32 initial_val = BPP4 * png_pass_start[png_ptr->pass];
+                  /* png.c:  png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; */
+                register int stride = BPP4 * png_pass_inc[png_ptr->pass];
+                  /* png.c:  png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; */
+                register int rep_bytes = BPP4 * png_pass_width[png_ptr->pass];
+                  /* png.c:  png_pass_width[] = {8, 4, 4, 2, 2, 1, 1}; */
+                png_uint_32 len = png_ptr->width &~7;  /* reduce to mult. of 8 */
+                int diff = (int) (png_ptr->width & 7); /* amount lost */
+                register png_uint_32 final_val = BPP4 * len;   /* GRR bugfix */
+ 
+                srcptr = png_ptr->row_buf + 1 + initial_val;
+                dstptr = row + initial_val;
+ 
+                for (i = initial_val; i < final_val; i += stride)
+                {
+                   png_memcpy(dstptr, srcptr, rep_bytes);
+                   srcptr += stride;
+                   dstptr += stride;
+                }
+                if (diff)  /* number of leftover pixels:  3 for pngtest */
+                {
+                   final_val+=diff*BPP4;
+                   for (; i < final_val; i += stride)
+                   {
+                      if (rep_bytes > (int)(final_val-i))
+                         rep_bytes = (int)(final_val-i);
+                      png_memcpy(dstptr, srcptr, rep_bytes);
+                      srcptr += stride;
+                      dstptr += stride;
+                   }
+                }
+             } /* end of else (_mmx_supported) */
+ 
+             break;
+          }       /* end 32 bpp */
+ 
+          case 48:       /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep srcptr;
+             png_bytep dstptr;
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+             if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_COMBINE_ROW)
+                 /* && _mmx_supported */ )
+ #else
+             if (_mmx_supported)
+ #endif
+             {
+                png_uint_32 len;
+                int diff;
+                int dummy_value_a;   // fix 'forbidden register spilled' error
+                int dummy_value_d;
+                int dummy_value_c;
+                int dummy_value_S;
+                int dummy_value_D;
+                _unmask = ~mask;            // global variable for -fPIC version
+                srcptr = png_ptr->row_buf + 1;
+                dstptr = row;
+                len  = png_ptr->width &~7;  // reduce to multiple of 8
+                diff = (int) (png_ptr->width & 7); // amount lost //
+ 
+                __asm__ __volatile__ (
+                   "movd      _unmask, %%mm7   \n\t" // load bit pattern
+                   "psubb     %%mm6, %%mm6     \n\t" // zero mm6
+                   "punpcklbw %%mm7, %%mm7     \n\t"
+                   "punpcklwd %%mm7, %%mm7     \n\t"
+                   "punpckldq %%mm7, %%mm7     \n\t" // fill reg with 8 masks
+ 
+                   "movq      _mask48_0, %%mm0 \n\t"
+                   "movq      _mask48_1, %%mm1 \n\t"
+                   "movq      _mask48_2, %%mm2 \n\t"
+                   "movq      _mask48_3, %%mm3 \n\t"
+                   "movq      _mask48_4, %%mm4 \n\t"
+                   "movq      _mask48_5, %%mm5 \n\t"
+ 
+                   "pand      %%mm7, %%mm0     \n\t"
+                   "pand      %%mm7, %%mm1     \n\t"
+                   "pand      %%mm7, %%mm2     \n\t"
+                   "pand      %%mm7, %%mm3     \n\t"
+                   "pand      %%mm7, %%mm4     \n\t"
+                   "pand      %%mm7, %%mm5     \n\t"
+ 
+                   "pcmpeqb   %%mm6, %%mm0     \n\t"
+                   "pcmpeqb   %%mm6, %%mm1     \n\t"
+                   "pcmpeqb   %%mm6, %%mm2     \n\t"
+                   "pcmpeqb   %%mm6, %%mm3     \n\t"
+                   "pcmpeqb   %%mm6, %%mm4     \n\t"
+                   "pcmpeqb   %%mm6, %%mm5     \n\t"
+ 
+ // preload        "movl      len, %%ecx       \n\t" // load length of line
+ // preload        "movl      srcptr, %%esi    \n\t" // load source
+ // preload        "movl      dstptr, %%edi    \n\t" // load dest
+ 
+                   "cmpl      $0, %%ecx        \n\t"
+                   "jz        mainloop48end    \n\t"
+ 
+                 "mainloop48:                  \n\t"
+                   "movq      (%%esi), %%mm7   \n\t"
+                   "pand      %%mm0, %%mm7     \n\t"
+                   "movq      %%mm0, %%mm6     \n\t"
+                   "pandn     (%%edi), %%mm6   \n\t"
+                   "por       %%mm6, %%mm7     \n\t"
+                   "movq      %%mm7, (%%edi)   \n\t"
+ 
+                   "movq      8(%%esi), %%mm6  \n\t"
+                   "pand      %%mm1, %%mm6     \n\t"
+                   "movq      %%mm1, %%mm7     \n\t"
+                   "pandn     8(%%edi), %%mm7  \n\t"
+                   "por       %%mm7, %%mm6     \n\t"
+                   "movq      %%mm6, 8(%%edi)  \n\t"
+ 
+                   "movq      16(%%esi), %%mm6 \n\t"
+                   "pand      %%mm2, %%mm6     \n\t"
+                   "movq      %%mm2, %%mm7     \n\t"
+                   "pandn     16(%%edi), %%mm7 \n\t"
+                   "por       %%mm7, %%mm6     \n\t"
+                   "movq      %%mm6, 16(%%edi) \n\t"
+ 
+                   "movq      24(%%esi), %%mm7 \n\t"
+                   "pand      %%mm3, %%mm7     \n\t"
+                   "movq      %%mm3, %%mm6     \n\t"
+                   "pandn     24(%%edi), %%mm6 \n\t"
+                   "por       %%mm6, %%mm7     \n\t"
+                   "movq      %%mm7, 24(%%edi) \n\t"
+ 
+                   "movq      32(%%esi), %%mm6 \n\t"
+                   "pand      %%mm4, %%mm6     \n\t"
+                   "movq      %%mm4, %%mm7     \n\t"
+                   "pandn     32(%%edi), %%mm7 \n\t"
+                   "por       %%mm7, %%mm6     \n\t"
+                   "movq      %%mm6, 32(%%edi) \n\t"
+ 
+                   "movq      40(%%esi), %%mm7 \n\t"
+                   "pand      %%mm5, %%mm7     \n\t"
+                   "movq      %%mm5, %%mm6     \n\t"
+                   "pandn     40(%%edi), %%mm6 \n\t"
+                   "por       %%mm6, %%mm7     \n\t"
+                   "movq      %%mm7, 40(%%edi) \n\t"
+ 
+                   "addl      $48, %%esi       \n\t" // inc by 48 bytes processed
+                   "addl      $48, %%edi       \n\t"
+                   "subl      $8, %%ecx        \n\t" // dec by 8 pixels processed
+ 
+                   "ja        mainloop48       \n\t"
+ 
+                 "mainloop48end:               \n\t"
+ // preload        "movl      diff, %%ecx      \n\t" // (diff is in eax)
+                   "movl      %%eax, %%ecx     \n\t"
+                   "cmpl      $0, %%ecx        \n\t"
+                   "jz        end48            \n\t"
+ // preload        "movl      mask, %%edx      \n\t"
+                   "sall      $24, %%edx       \n\t" // make low byte, high byte
+ 
+                 "secondloop48:                \n\t"
+                   "sall      %%edx            \n\t" // move high bit to CF
+                   "jnc       skip48           \n\t" // if CF = 0
+                   "movl      (%%esi), %%eax   \n\t"
+                   "movl      %%eax, (%%edi)   \n\t"
+ 
+                 "skip48:                      \n\t"
+                   "addl      $4, %%esi        \n\t"
+                   "addl      $4, %%edi        \n\t"
+                   "decl      %%ecx            \n\t"
+                   "jnz       secondloop48     \n\t"
+ 
+                 "end48:                       \n\t"
+                   "EMMS                       \n\t" // DONE
+ 
+                   : "=a" (dummy_value_a),           // output regs (dummy)
+                     "=d" (dummy_value_d),
+                     "=c" (dummy_value_c),
+                     "=S" (dummy_value_S),
+                     "=D" (dummy_value_D)
+ 
+                   : "3" (srcptr),      // esi       // input regs
+                     "4" (dstptr),      // edi
+                     "0" (diff),        // eax
+ // was (unmask)     "b"    RESERVED    // ebx       // Global Offset Table idx
+                     "2" (len),         // ecx
+                     "1" (mask)         // edx
+ 
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+                   : "%mm0", "%mm1", "%mm2", "%mm3"  // clobber list
+                   , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+                );
+             }
+             else /* mmx _not supported - Use modified C routine */
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+             {
+                register png_uint_32 i;
+                png_uint_32 initial_val = BPP6 * png_pass_start[png_ptr->pass];
+                  /* png.c:  png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; */
+                register int stride = BPP6 * png_pass_inc[png_ptr->pass];
+                  /* png.c:  png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; */
+                register int rep_bytes = BPP6 * png_pass_width[png_ptr->pass];
+                  /* png.c:  png_pass_width[] = {8, 4, 4, 2, 2, 1, 1}; */
+                png_uint_32 len = png_ptr->width &~7;  /* reduce to mult. of 8 */
+                int diff = (int) (png_ptr->width & 7); /* amount lost */
+                register png_uint_32 final_val = BPP6 * len;   /* GRR bugfix */
+ 
+                srcptr = png_ptr->row_buf + 1 + initial_val;
+                dstptr = row + initial_val;
+ 
+                for (i = initial_val; i < final_val; i += stride)
+                {
+                   png_memcpy(dstptr, srcptr, rep_bytes);
+                   srcptr += stride;
+                   dstptr += stride;
+                }
+                if (diff)  /* number of leftover pixels:  3 for pngtest */
+                {
+                   final_val+=diff*BPP6;
+                   for (; i < final_val; i += stride)
+                   {
+                      if (rep_bytes > (int)(final_val-i))
+                         rep_bytes = (int)(final_val-i);
+                      png_memcpy(dstptr, srcptr, rep_bytes);
+                      srcptr += stride;
+                      dstptr += stride;
+                   }
+                }
+             } /* end of else (_mmx_supported) */
+ 
+             break;
+          }       /* end 48 bpp */
+ 
+          case 64:       /* png_ptr->row_info.pixel_depth */
+          {
+             png_bytep srcptr;
+             png_bytep dstptr;
+             register png_uint_32 i;
+             png_uint_32 initial_val = BPP8 * png_pass_start[png_ptr->pass];
+               /* png.c:  png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; */
+             register int stride = BPP8 * png_pass_inc[png_ptr->pass];
+               /* png.c:  png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; */
+             register int rep_bytes = BPP8 * png_pass_width[png_ptr->pass];
+               /* png.c:  png_pass_width[] = {8, 4, 4, 2, 2, 1, 1}; */
+             png_uint_32 len = png_ptr->width &~7;  /* reduce to mult. of 8 */
+             int diff = (int) (png_ptr->width & 7); /* amount lost */
+             register png_uint_32 final_val = BPP8 * len;   /* GRR bugfix */
+ 
+             srcptr = png_ptr->row_buf + 1 + initial_val;
+             dstptr = row + initial_val;
+ 
+             for (i = initial_val; i < final_val; i += stride)
+             {
+                png_memcpy(dstptr, srcptr, rep_bytes);
+                srcptr += stride;
+                dstptr += stride;
+             }
+             if (diff)  /* number of leftover pixels:  3 for pngtest */
+             {
+                final_val+=diff*BPP8;
+                for (; i < final_val; i += stride)
+                {
+                   if (rep_bytes > (int)(final_val-i))
+                      rep_bytes = (int)(final_val-i);
+                   png_memcpy(dstptr, srcptr, rep_bytes);
+                   srcptr += stride;
+                   dstptr += stride;
+                }
+             }
+ 
+             break;
+          }       /* end 64 bpp */
+ 
+          default: /* png_ptr->row_info.pixel_depth != 1,2,4,8,16,24,32,48,64 */
+          {
+             /* this should never happen */
+             png_warning(png_ptr, "Invalid row_info.pixel_depth in pnggccrd");
+             break;
+          }
+       } /* end switch (png_ptr->row_info.pixel_depth) */
+ 
+    } /* end if (non-trivial mask) */
+ 
+ } /* end png_combine_row() */
+ 
+ #endif /* PNG_HAVE_ASSEMBLER_COMBINE_ROW */
+ 
+ 
+ 
+ 
+ /*===========================================================================*/
+ /*                                                                           */
+ /*                 P N G _ D O _ R E A D _ I N T E R L A C E                 */
+ /*                                                                           */
+ /*===========================================================================*/
+ 
+ #if defined(PNG_READ_INTERLACING_SUPPORTED)
+ #if defined(PNG_HAVE_ASSEMBLER_READ_INTERLACE)
+ 
+ /* png_do_read_interlace() is called after any 16-bit to 8-bit conversion
+  * has taken place.  [GRR: what other steps come before and/or after?]
+  */
+ 
+ void /* PRIVATE */
+ png_do_read_interlace(png_structp png_ptr)
+ {
+    png_row_infop row_info = &(png_ptr->row_info);
+    png_bytep row = png_ptr->row_buf + 1;
+    int pass = png_ptr->pass;
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED)
+    png_uint_32 transformations = png_ptr->transformations;
+ #endif
+ 
+    png_debug(1, "in png_do_read_interlace (pnggccrd.c)\n");
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+    if (_mmx_supported == 2) {
+ #if !defined(PNG_1_0_X)
+        /* this should have happened in png_init_mmx_flags() already */
+        png_warning(png_ptr, "asm_flags may not have been initialized");
+ #endif
+        png_mmx_support();
+    }
+ #endif
+ 
+    if (row != NULL && row_info != NULL)
+    {
+       png_uint_32 final_width;
+ 
+       final_width = row_info->width * png_pass_inc[pass];
+ 
+       switch (row_info->pixel_depth)
+       {
+          case 1:
+          {
+             png_bytep sp, dp;
+             int sshift, dshift;
+             int s_start, s_end, s_inc;
+             png_byte v;
+             png_uint_32 i;
+             int j;
+ 
+             sp = row + (png_size_t)((row_info->width - 1) >> 3);
+             dp = row + (png_size_t)((final_width - 1) >> 3);
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED)
+             if (transformations & PNG_PACKSWAP)
+             {
+                sshift = (int)((row_info->width + 7) & 7);
+                dshift = (int)((final_width + 7) & 7);
+                s_start = 7;
+                s_end = 0;
+                s_inc = -1;
+             }
+             else
+ #endif
+             {
+                sshift = 7 - (int)((row_info->width + 7) & 7);
+                dshift = 7 - (int)((final_width + 7) & 7);
+                s_start = 0;
+                s_end = 7;
+                s_inc = 1;
+             }
+ 
+             for (i = row_info->width; i; i--)
+             {
+                v = (png_byte)((*sp >> sshift) & 0x1);
+                for (j = 0; j < png_pass_inc[pass]; j++)
+                {
+                   *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);
+                   *dp |= (png_byte)(v << dshift);
+                   if (dshift == s_end)
+                   {
+                      dshift = s_start;
+                      dp--;
+                   }
+                   else
+                      dshift += s_inc;
+                }
+                if (sshift == s_end)
+                {
+                   sshift = s_start;
+                   sp--;
+                }
+                else
+                   sshift += s_inc;
+             }
+             break;
+          }
+ 
+          case 2:
+          {
+             png_bytep sp, dp;
+             int sshift, dshift;
+             int s_start, s_end, s_inc;
+             png_uint_32 i;
+ 
+             sp = row + (png_size_t)((row_info->width - 1) >> 2);
+             dp = row + (png_size_t)((final_width - 1) >> 2);
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED)
+             if (transformations & PNG_PACKSWAP)
+             {
+                sshift = (png_size_t)(((row_info->width + 3) & 3) << 1);
+                dshift = (png_size_t)(((final_width + 3) & 3) << 1);
+                s_start = 6;
+                s_end = 0;
+                s_inc = -2;
+             }
+             else
+ #endif
+             {
+                sshift = (png_size_t)((3 - ((row_info->width + 3) & 3)) << 1);
+                dshift = (png_size_t)((3 - ((final_width + 3) & 3)) << 1);
+                s_start = 0;
+                s_end = 6;
+                s_inc = 2;
+             }
+ 
+             for (i = row_info->width; i; i--)
+             {
+                png_byte v;
+                int j;
+ 
+                v = (png_byte)((*sp >> sshift) & 0x3);
+                for (j = 0; j < png_pass_inc[pass]; j++)
+                {
+                   *dp &= (png_byte)((0x3f3f >> (6 - dshift)) & 0xff);
+                   *dp |= (png_byte)(v << dshift);
+                   if (dshift == s_end)
+                   {
+                      dshift = s_start;
+                      dp--;
+                   }
+                   else
+                      dshift += s_inc;
+                }
+                if (sshift == s_end)
+                {
+                   sshift = s_start;
+                   sp--;
+                }
+                else
+                   sshift += s_inc;
+             }
+             break;
+          }
+ 
+          case 4:
+          {
+             png_bytep sp, dp;
+             int sshift, dshift;
+             int s_start, s_end, s_inc;
+             png_uint_32 i;
+ 
+             sp = row + (png_size_t)((row_info->width - 1) >> 1);
+             dp = row + (png_size_t)((final_width - 1) >> 1);
+ #if defined(PNG_READ_PACKSWAP_SUPPORTED)
+             if (transformations & PNG_PACKSWAP)
+             {
+                sshift = (png_size_t)(((row_info->width + 1) & 1) << 2);
+                dshift = (png_size_t)(((final_width + 1) & 1) << 2);
+                s_start = 4;
+                s_end = 0;
+                s_inc = -4;
+             }
+             else
+ #endif
+             {
+                sshift = (png_size_t)((1 - ((row_info->width + 1) & 1)) << 2);
+                dshift = (png_size_t)((1 - ((final_width + 1) & 1)) << 2);
+                s_start = 0;
+                s_end = 4;
+                s_inc = 4;
+             }
+ 
+             for (i = row_info->width; i; i--)
+             {
+                png_byte v;
+                int j;
+ 
+                v = (png_byte)((*sp >> sshift) & 0xf);
+                for (j = 0; j < png_pass_inc[pass]; j++)
+                {
+                   *dp &= (png_byte)((0xf0f >> (4 - dshift)) & 0xff);
+                   *dp |= (png_byte)(v << dshift);
+                   if (dshift == s_end)
+                   {
+                      dshift = s_start;
+                      dp--;
+                   }
+                   else
+                      dshift += s_inc;
+                }
+                if (sshift == s_end)
+                {
+                   sshift = s_start;
+                   sp--;
+                }
+                else
+                   sshift += s_inc;
+             }
+             break;
+          }
+ 
+        /*====================================================================*/
+ 
+          default: /* 8-bit or larger (this is where the routine is modified) */
+          {
+ #if 0
+ //          static unsigned long long _const4 = 0x0000000000FFFFFFLL;  no good
+ //          static unsigned long long const4 = 0x0000000000FFFFFFLL;   no good
+ //          unsigned long long _const4 = 0x0000000000FFFFFFLL;         no good
+ //          unsigned long long const4 = 0x0000000000FFFFFFLL;          no good
+ #endif
+             png_bytep sptr, dp;
+             png_uint_32 i;
+             png_size_t pixel_bytes;
+             int width = (int)row_info->width;
+ 
+             pixel_bytes = (row_info->pixel_depth >> 3);
+ 
+             /* point sptr at the last pixel in the pre-expanded row: */
+             sptr = row + (width - 1) * pixel_bytes;
+ 
+             /* point dp at the last pixel position in the expanded row: */
+             dp = row + (final_width - 1) * pixel_bytes;
+ 
+             /* New code by Nirav Chhatrapati - Intel Corporation */
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+ #if !defined(PNG_1_0_X)
+             if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_INTERLACE)
+                 /* && _mmx_supported */ )
+ #else
+             if (_mmx_supported)
+ #endif
+             {
+                //--------------------------------------------------------------
+                if (pixel_bytes == 3)
+                {
+                   if (((pass == 0) || (pass == 1)) && width)
+                   {
+                      int dummy_value_c;   // fix 'forbidden register spilled'
+                      int dummy_value_S;
+                      int dummy_value_D;
+ 
+                      __asm__ __volatile__ (
+                         "subl $21, %%edi         \n\t"
+                                      // (png_pass_inc[pass] - 1)*pixel_bytes
+ 
+                      ".loop3_pass0:              \n\t"
+                         "movd (%%esi), %%mm0     \n\t" // x x x x x 2 1 0
+                         "pand _const4, %%mm0     \n\t" // z z z z z 2 1 0
+                         "movq %%mm0, %%mm1       \n\t" // z z z z z 2 1 0
+                         "psllq $16, %%mm0        \n\t" // z z z 2 1 0 z z
+                         "movq %%mm0, %%mm2       \n\t" // z z z 2 1 0 z z
+                         "psllq $24, %%mm0        \n\t" // 2 1 0 z z z z z
+                         "psrlq $8, %%mm1         \n\t" // z z z z z z 2 1
+                         "por %%mm2, %%mm0        \n\t" // 2 1 0 2 1 0 z z
+                         "por %%mm1, %%mm0        \n\t" // 2 1 0 2 1 0 2 1
+                         "movq %%mm0, %%mm3       \n\t" // 2 1 0 2 1 0 2 1
+                         "psllq $16, %%mm0        \n\t" // 0 2 1 0 2 1 z z
+                         "movq %%mm3, %%mm4       \n\t" // 2 1 0 2 1 0 2 1
+                         "punpckhdq %%mm0, %%mm3  \n\t" // 0 2 1 0 2 1 0 2
+                         "movq %%mm4, 16(%%edi)   \n\t"
+                         "psrlq $32, %%mm0        \n\t" // z z z z 0 2 1 0
+                         "movq %%mm3, 8(%%edi)    \n\t"
+                         "punpckldq %%mm4, %%mm0  \n\t" // 1 0 2 1 0 2 1 0
+                         "subl $3, %%esi          \n\t"
+                         "movq %%mm0, (%%edi)     \n\t"
+                         "subl $24, %%edi         \n\t"
+                         "decl %%ecx              \n\t"
+                         "jnz .loop3_pass0        \n\t"
+                         "EMMS                    \n\t" // DONE
+ 
+                         : "=c" (dummy_value_c),        // output regs (dummy)
+                           "=S" (dummy_value_S),
+                           "=D" (dummy_value_D)
+ 
+                         : "1" (sptr),      // esi      // input regs
+                           "2" (dp),        // edi
+                           "0" (width)      // ecx
+ // doesn't work           "i" (0x0000000000FFFFFFLL)   // %1 (a.k.a. _const4)
+ 
+ #if 0  /* %mm0, ..., %mm4 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                         : "%mm0", "%mm1", "%mm2"       // clobber list
+                         , "%mm3", "%mm4"
+ #endif
+                      );
+                   }
+                   else if (((pass == 2) || (pass == 3)) && width)
+                   {
+                      int dummy_value_c;   // fix 'forbidden register spilled'
+                      int dummy_value_S;
+                      int dummy_value_D;
+ 
+                      __asm__ __volatile__ (
+                         "subl $9, %%edi          \n\t"
+                                      // (png_pass_inc[pass] - 1)*pixel_bytes
+ 
+                      ".loop3_pass2:              \n\t"
+                         "movd (%%esi), %%mm0     \n\t" // x x x x x 2 1 0
+                         "pand _const4, %%mm0     \n\t" // z z z z z 2 1 0
+                         "movq %%mm0, %%mm1       \n\t" // z z z z z 2 1 0
+                         "psllq $16, %%mm0        \n\t" // z z z 2 1 0 z z
+                         "movq %%mm0, %%mm2       \n\t" // z z z 2 1 0 z z
+                         "psllq $24, %%mm0        \n\t" // 2 1 0 z z z z z
+                         "psrlq $8, %%mm1         \n\t" // z z z z z z 2 1
+                         "por %%mm2, %%mm0        \n\t" // 2 1 0 2 1 0 z z
+                         "por %%mm1, %%mm0        \n\t" // 2 1 0 2 1 0 2 1
+                         "movq %%mm0, 4(%%edi)    \n\t"
+                         "psrlq $16, %%mm0        \n\t" // z z 2 1 0 2 1 0
+                         "subl $3, %%esi          \n\t"
+                         "movd %%mm0, (%%edi)     \n\t"
+                         "subl $12, %%edi         \n\t"
+                         "decl %%ecx              \n\t"
+                         "jnz .loop3_pass2        \n\t"
+                         "EMMS                    \n\t" // DONE
+ 
+                         : "=c" (dummy_value_c),        // output regs (dummy)
+                           "=S" (dummy_value_S),
+                           "=D" (dummy_value_D)
+ 
+                         : "1" (sptr),      // esi      // input regs
+                           "2" (dp),        // edi
+                           "0" (width)      // ecx
+ 
+ #if 0  /* %mm0, ..., %mm2 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                         : "%mm0", "%mm1", "%mm2"       // clobber list
+ #endif
+                      );
+                   }
+                   else if (width) /* && ((pass == 4) || (pass == 5)) */
+                   {
+                      int width_mmx = ((width >> 1) << 1) - 8;   // GRR:  huh?
+                      if (width_mmx < 0)
+                          width_mmx = 0;
+                      width -= width_mmx;        // 8 or 9 pix, 24 or 27 bytes
+                      if (width_mmx)
+                      {
+                         // png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
+                         // sptr points at last pixel in pre-expanded row
+                         // dp points at last pixel position in expanded row
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $3, %%esi          \n\t"
+                            "subl $9, %%edi          \n\t"
+                                         // (png_pass_inc[pass] + 1)*pixel_bytes
+ 
+                         ".loop3_pass4:              \n\t"
+                            "movq (%%esi), %%mm0     \n\t" // x x 5 4 3 2 1 0
+                            "movq %%mm0, %%mm1       \n\t" // x x 5 4 3 2 1 0
+                            "movq %%mm0, %%mm2       \n\t" // x x 5 4 3 2 1 0
+                            "psllq $24, %%mm0        \n\t" // 4 3 2 1 0 z z z
+                            "pand _const4, %%mm1     \n\t" // z z z z z 2 1 0
+                            "psrlq $24, %%mm2        \n\t" // z z z x x 5 4 3
+                            "por %%mm1, %%mm0        \n\t" // 4 3 2 1 0 2 1 0
+                            "movq %%mm2, %%mm3       \n\t" // z z z x x 5 4 3
+                            "psllq $8, %%mm2         \n\t" // z z x x 5 4 3 z
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "psrlq $16, %%mm3        \n\t" // z z z z z x x 5
+                            "pand _const6, %%mm3     \n\t" // z z z z z z z 5
+                            "por %%mm3, %%mm2        \n\t" // z z x x 5 4 3 5
+                            "subl $6, %%esi          \n\t"
+                            "movd %%mm2, 8(%%edi)    \n\t"
+                            "subl $12, %%edi         \n\t"
+                            "subl $2, %%ecx          \n\t"
+                            "jnz .loop3_pass4        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, ..., %mm3 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1"               // clobber list
+                            , "%mm2", "%mm3"
+ #endif
+                         );
+                      }
+ 
+                      sptr -= width_mmx*3;
+                      dp -= width_mmx*6;
+                      for (i = width; i; i--)
+                      {
+                         png_byte v[8];
+                         int j;
+ 
+                         png_memcpy(v, sptr, 3);
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            png_memcpy(dp, v, 3);
+                            dp -= 3;
+                         }
+                         sptr -= 3;
+                      }
+                   }
+                } /* end of pixel_bytes == 3 */
+ 
+                //--------------------------------------------------------------
+                else if (pixel_bytes == 1)
+                {
+                   if (((pass == 0) || (pass == 1)) && width)
+                   {
+                      int width_mmx = ((width >> 2) << 2);
+                      width -= width_mmx;        // 0-3 pixels => 0-3 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $3, %%esi          \n\t"
+                            "subl $31, %%edi         \n\t"
+ 
+                         ".loop1_pass0:              \n\t"
+                            "movd (%%esi), %%mm0     \n\t" // x x x x 3 2 1 0
+                            "movq %%mm0, %%mm1       \n\t" // x x x x 3 2 1 0
+                            "punpcklbw %%mm0, %%mm0  \n\t" // 3 3 2 2 1 1 0 0
+                            "movq %%mm0, %%mm2       \n\t" // 3 3 2 2 1 1 0 0
+                            "punpcklwd %%mm0, %%mm0  \n\t" // 1 1 1 1 0 0 0 0
+                            "movq %%mm0, %%mm3       \n\t" // 1 1 1 1 0 0 0 0
+                            "punpckldq %%mm0, %%mm0  \n\t" // 0 0 0 0 0 0 0 0
+                            "punpckhdq %%mm3, %%mm3  \n\t" // 1 1 1 1 1 1 1 1
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "punpckhwd %%mm2, %%mm2  \n\t" // 3 3 3 3 2 2 2 2
+                            "movq %%mm3, 8(%%edi)    \n\t"
+                            "movq %%mm2, %%mm4       \n\t" // 3 3 3 3 2 2 2 2
+                            "punpckldq %%mm2, %%mm2  \n\t" // 2 2 2 2 2 2 2 2
+                            "punpckhdq %%mm4, %%mm4  \n\t" // 3 3 3 3 3 3 3 3
+                            "movq %%mm2, 16(%%edi)   \n\t"
+                            "subl $4, %%esi          \n\t"
+                            "movq %%mm4, 24(%%edi)   \n\t"
+                            "subl $32, %%edi         \n\t"
+                            "subl $4, %%ecx          \n\t"
+                            "jnz .loop1_pass0        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, ..., %mm4 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1", "%mm2"       // clobber list
+                            , "%mm3", "%mm4"
+ #endif
+                         );
+                      }
+ 
+                      sptr -= width_mmx;
+                      dp -= width_mmx*8;
+                      for (i = width; i; i--)
+                      {
+                         int j;
+ 
+                        /* I simplified this part in version 1.0.4e
+                         * here and in several other instances where
+                         * pixel_bytes == 1  -- GR-P
+                         *
+                         * Original code:
+                         *
+                         * png_byte v[8];
+                         * png_memcpy(v, sptr, pixel_bytes);
+                         * for (j = 0; j < png_pass_inc[pass]; j++)
+                         * {
+                         *    png_memcpy(dp, v, pixel_bytes);
+                         *    dp -= pixel_bytes;
+                         * }
+                         * sptr -= pixel_bytes;
+                         *
+                         * Replacement code is in the next three lines:
+                         */
+ 
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            *dp-- = *sptr;
+                         }
+                         --sptr;
+                      }
+                   }
+                   else if (((pass == 2) || (pass == 3)) && width)
+                   {
+                      int width_mmx = ((width >> 2) << 2);
+                      width -= width_mmx;        // 0-3 pixels => 0-3 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $3, %%esi          \n\t"
+                            "subl $15, %%edi         \n\t"
+ 
+                         ".loop1_pass2:              \n\t"
+                            "movd (%%esi), %%mm0     \n\t" // x x x x 3 2 1 0
+                            "punpcklbw %%mm0, %%mm0  \n\t" // 3 3 2 2 1 1 0 0
+                            "movq %%mm0, %%mm1       \n\t" // 3 3 2 2 1 1 0 0
+                            "punpcklwd %%mm0, %%mm0  \n\t" // 1 1 1 1 0 0 0 0
+                            "punpckhwd %%mm1, %%mm1  \n\t" // 3 3 3 3 2 2 2 2
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "subl $4, %%esi          \n\t"
+                            "movq %%mm1, 8(%%edi)    \n\t"
+                            "subl $16, %%edi         \n\t"
+                            "subl $4, %%ecx          \n\t"
+                            "jnz .loop1_pass2        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, %mm1 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1"               // clobber list
+ #endif
+                         );
+                      }
+ 
+                      sptr -= width_mmx;
+                      dp -= width_mmx*4;
+                      for (i = width; i; i--)
+                      {
+                         int j;
+ 
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            *dp-- = *sptr;
+                         }
+                         --sptr;
+                      }
+                   }
+                   else if (width)  /* && ((pass == 4) || (pass == 5)) */
+                   {
+                      int width_mmx = ((width >> 3) << 3);
+                      width -= width_mmx;        // 0-3 pixels => 0-3 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $7, %%esi          \n\t"
+                            "subl $15, %%edi         \n\t"
+ 
+                         ".loop1_pass4:              \n\t"
+                            "movq (%%esi), %%mm0     \n\t" // 7 6 5 4 3 2 1 0
+                            "movq %%mm0, %%mm1       \n\t" // 7 6 5 4 3 2 1 0
+                            "punpcklbw %%mm0, %%mm0  \n\t" // 3 3 2 2 1 1 0 0
+                            "punpckhbw %%mm1, %%mm1  \n\t" // 7 7 6 6 5 5 4 4
+                            "movq %%mm1, 8(%%edi)    \n\t"
+                            "subl $8, %%esi          \n\t"
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "subl $16, %%edi         \n\t"
+                            "subl $8, %%ecx          \n\t"
+                            "jnz .loop1_pass4        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (none)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, %mm1 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1"               // clobber list
+ #endif
+                         );
+                      }
+ 
+                      sptr -= width_mmx;
+                      dp -= width_mmx*2;
+                      for (i = width; i; i--)
+                      {
+                         int j;
+ 
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            *dp-- = *sptr;
+                         }
+                         --sptr;
+                      }
+                   }
+                } /* end of pixel_bytes == 1 */
+ 
+                //--------------------------------------------------------------
+                else if (pixel_bytes == 2)
+                {
+                   if (((pass == 0) || (pass == 1)) && width)
+                   {
+                      int width_mmx = ((width >> 1) << 1);
+                      width -= width_mmx;        // 0,1 pixels => 0,2 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $2, %%esi          \n\t"
+                            "subl $30, %%edi         \n\t"
+ 
+                         ".loop2_pass0:              \n\t"
+                            "movd (%%esi), %%mm0     \n\t" // x x x x 3 2 1 0
+                            "punpcklwd %%mm0, %%mm0  \n\t" // 3 2 3 2 1 0 1 0
+                            "movq %%mm0, %%mm1       \n\t" // 3 2 3 2 1 0 1 0
+                            "punpckldq %%mm0, %%mm0  \n\t" // 1 0 1 0 1 0 1 0
+                            "punpckhdq %%mm1, %%mm1  \n\t" // 3 2 3 2 3 2 3 2
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "movq %%mm0, 8(%%edi)    \n\t"
+                            "movq %%mm1, 16(%%edi)   \n\t"
+                            "subl $4, %%esi          \n\t"
+                            "movq %%mm1, 24(%%edi)   \n\t"
+                            "subl $32, %%edi         \n\t"
+                            "subl $2, %%ecx          \n\t"
+                            "jnz .loop2_pass0        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, %mm1 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1"               // clobber list
+ #endif
+                         );
+                      }
+ 
+                      sptr -= (width_mmx*2 - 2); // sign fixed
+                      dp -= (width_mmx*16 - 2);  // sign fixed
+                      for (i = width; i; i--)
+                      {
+                         png_byte v[8];
+                         int j;
+                         sptr -= 2;
+                         png_memcpy(v, sptr, 2);
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            dp -= 2;
+                            png_memcpy(dp, v, 2);
+                         }
+                      }
+                   }
+                   else if (((pass == 2) || (pass == 3)) && width)
+                   {
+                      int width_mmx = ((width >> 1) << 1) ;
+                      width -= width_mmx;        // 0,1 pixels => 0,2 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $2, %%esi          \n\t"
+                            "subl $14, %%edi         \n\t"
+ 
+                         ".loop2_pass2:              \n\t"
+                            "movd (%%esi), %%mm0     \n\t" // x x x x 3 2 1 0
+                            "punpcklwd %%mm0, %%mm0  \n\t" // 3 2 3 2 1 0 1 0
+                            "movq %%mm0, %%mm1       \n\t" // 3 2 3 2 1 0 1 0
+                            "punpckldq %%mm0, %%mm0  \n\t" // 1 0 1 0 1 0 1 0
+                            "punpckhdq %%mm1, %%mm1  \n\t" // 3 2 3 2 3 2 3 2
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "subl $4, %%esi          \n\t"
+                            "movq %%mm1, 8(%%edi)    \n\t"
+                            "subl $16, %%edi         \n\t"
+                            "subl $2, %%ecx          \n\t"
+                            "jnz .loop2_pass2        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, %mm1 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1"               // clobber list
+ #endif
+                         );
+                      }
+ 
+                      sptr -= (width_mmx*2 - 2); // sign fixed
+                      dp -= (width_mmx*8 - 2);   // sign fixed
+                      for (i = width; i; i--)
+                      {
+                         png_byte v[8];
+                         int j;
+                         sptr -= 2;
+                         png_memcpy(v, sptr, 2);
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            dp -= 2;
+                            png_memcpy(dp, v, 2);
+                         }
+                      }
+                   }
+                   else if (width)  // pass == 4 or 5
+                   {
+                      int width_mmx = ((width >> 1) << 1) ;
+                      width -= width_mmx;        // 0,1 pixels => 0,2 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $2, %%esi          \n\t"
+                            "subl $6, %%edi          \n\t"
+ 
+                         ".loop2_pass4:              \n\t"
+                            "movd (%%esi), %%mm0     \n\t" // x x x x 3 2 1 0
+                            "punpcklwd %%mm0, %%mm0  \n\t" // 3 2 3 2 1 0 1 0
+                            "subl $4, %%esi          \n\t"
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "subl $8, %%edi          \n\t"
+                            "subl $2, %%ecx          \n\t"
+                            "jnz .loop2_pass4        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0"                       // clobber list
+ #endif
+                         );
+                      }
+ 
+                      sptr -= (width_mmx*2 - 2); // sign fixed
+                      dp -= (width_mmx*4 - 2);   // sign fixed
+                      for (i = width; i; i--)
+                      {
+                         png_byte v[8];
+                         int j;
+                         sptr -= 2;
+                         png_memcpy(v, sptr, 2);
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            dp -= 2;
+                            png_memcpy(dp, v, 2);
+                         }
+                      }
+                   }
+                } /* end of pixel_bytes == 2 */
+ 
+                //--------------------------------------------------------------
+                else if (pixel_bytes == 4)
+                {
+                   if (((pass == 0) || (pass == 1)) && width)
+                   {
+                      int width_mmx = ((width >> 1) << 1);
+                      width -= width_mmx;        // 0,1 pixels => 0,4 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $4, %%esi          \n\t"
+                            "subl $60, %%edi         \n\t"
+ 
+                         ".loop4_pass0:              \n\t"
+                            "movq (%%esi), %%mm0     \n\t" // 7 6 5 4 3 2 1 0
+                            "movq %%mm0, %%mm1       \n\t" // 7 6 5 4 3 2 1 0
+                            "punpckldq %%mm0, %%mm0  \n\t" // 3 2 1 0 3 2 1 0
+                            "punpckhdq %%mm1, %%mm1  \n\t" // 7 6 5 4 7 6 5 4
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "movq %%mm0, 8(%%edi)    \n\t"
+                            "movq %%mm0, 16(%%edi)   \n\t"
+                            "movq %%mm0, 24(%%edi)   \n\t"
+                            "movq %%mm1, 32(%%edi)   \n\t"
+                            "movq %%mm1, 40(%%edi)   \n\t"
+                            "movq %%mm1, 48(%%edi)   \n\t"
+                            "subl $8, %%esi          \n\t"
+                            "movq %%mm1, 56(%%edi)   \n\t"
+                            "subl $64, %%edi         \n\t"
+                            "subl $2, %%ecx          \n\t"
+                            "jnz .loop4_pass0        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, %mm1 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1"               // clobber list
+ #endif
+                         );
+                      }
+ 
+                      sptr -= (width_mmx*4 - 4); // sign fixed
+                      dp -= (width_mmx*32 - 4);  // sign fixed
+                      for (i = width; i; i--)
+                      {
+                         png_byte v[8];
+                         int j;
+                         sptr -= 4;
+                         png_memcpy(v, sptr, 4);
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            dp -= 4;
+                            png_memcpy(dp, v, 4);
+                         }
+                      }
+                   }
+                   else if (((pass == 2) || (pass == 3)) && width)
+                   {
+                      int width_mmx = ((width >> 1) << 1);
+                      width -= width_mmx;        // 0,1 pixels => 0,4 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $4, %%esi          \n\t"
+                            "subl $28, %%edi         \n\t"
+ 
+                         ".loop4_pass2:              \n\t"
+                            "movq (%%esi), %%mm0     \n\t" // 7 6 5 4 3 2 1 0
+                            "movq %%mm0, %%mm1       \n\t" // 7 6 5 4 3 2 1 0
+                            "punpckldq %%mm0, %%mm0  \n\t" // 3 2 1 0 3 2 1 0
+                            "punpckhdq %%mm1, %%mm1  \n\t" // 7 6 5 4 7 6 5 4
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "movq %%mm0, 8(%%edi)    \n\t"
+                            "movq %%mm1, 16(%%edi)   \n\t"
+                            "movq %%mm1, 24(%%edi)   \n\t"
+                            "subl $8, %%esi          \n\t"
+                            "subl $32, %%edi         \n\t"
+                            "subl $2, %%ecx          \n\t"
+                            "jnz .loop4_pass2        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, %mm1 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1"               // clobber list
+ #endif
+                         );
+                      }
+ 
+                      sptr -= (width_mmx*4 - 4); // sign fixed
+                      dp -= (width_mmx*16 - 4);  // sign fixed
+                      for (i = width; i; i--)
+                      {
+                         png_byte v[8];
+                         int j;
+                         sptr -= 4;
+                         png_memcpy(v, sptr, 4);
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            dp -= 4;
+                            png_memcpy(dp, v, 4);
+                         }
+                      }
+                   }
+                   else if (width)  // pass == 4 or 5
+                   {
+                      int width_mmx = ((width >> 1) << 1) ;
+                      width -= width_mmx;        // 0,1 pixels => 0,4 bytes
+                      if (width_mmx)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $4, %%esi          \n\t"
+                            "subl $12, %%edi         \n\t"
+ 
+                         ".loop4_pass4:              \n\t"
+                            "movq (%%esi), %%mm0     \n\t" // 7 6 5 4 3 2 1 0
+                            "movq %%mm0, %%mm1       \n\t" // 7 6 5 4 3 2 1 0
+                            "punpckldq %%mm0, %%mm0  \n\t" // 3 2 1 0 3 2 1 0
+                            "punpckhdq %%mm1, %%mm1  \n\t" // 7 6 5 4 7 6 5 4
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "subl $8, %%esi          \n\t"
+                            "movq %%mm1, 8(%%edi)    \n\t"
+                            "subl $16, %%edi         \n\t"
+                            "subl $2, %%ecx          \n\t"
+                            "jnz .loop4_pass4        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width_mmx)  // ecx
+ 
+ #if 0  /* %mm0, %mm1 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0", "%mm1"               // clobber list
+ #endif
+                         );
+                      }
+ 
+                      sptr -= (width_mmx*4 - 4); // sign fixed
+                      dp -= (width_mmx*8 - 4);   // sign fixed
+                      for (i = width; i; i--)
+                      {
+                         png_byte v[8];
+                         int j;
+                         sptr -= 4;
+                         png_memcpy(v, sptr, 4);
+                         for (j = 0; j < png_pass_inc[pass]; j++)
+                         {
+                            dp -= 4;
+                            png_memcpy(dp, v, 4);
+                         }
+                      }
+                   }
+                } /* end of pixel_bytes == 4 */
+ 
+                //--------------------------------------------------------------
+                else if (pixel_bytes == 8)
+                {
+ // GRR TEST:  should work, but needs testing (special 64-bit version of rpng2?)
+                   // GRR NOTE:  no need to combine passes here!
+                   if (((pass == 0) || (pass == 1)) && width)
+                   {
+                      int dummy_value_c;  // fix 'forbidden register spilled'
+                      int dummy_value_S;
+                      int dummy_value_D;
+ 
+                      // source is 8-byte RRGGBBAA
+                      // dest is 64-byte RRGGBBAA RRGGBBAA RRGGBBAA RRGGBBAA ...
+                      __asm__ __volatile__ (
+                         "subl $56, %%edi         \n\t" // start of last block
+ 
+                      ".loop8_pass0:              \n\t"
+                         "movq (%%esi), %%mm0     \n\t" // 7 6 5 4 3 2 1 0
+                         "movq %%mm0, (%%edi)     \n\t"
+                         "movq %%mm0, 8(%%edi)    \n\t"
+                         "movq %%mm0, 16(%%edi)   \n\t"
+                         "movq %%mm0, 24(%%edi)   \n\t"
+                         "movq %%mm0, 32(%%edi)   \n\t"
+                         "movq %%mm0, 40(%%edi)   \n\t"
+                         "movq %%mm0, 48(%%edi)   \n\t"
+                         "subl $8, %%esi          \n\t"
+                         "movq %%mm0, 56(%%edi)   \n\t"
+                         "subl $64, %%edi         \n\t"
+                         "decl %%ecx              \n\t"
+                         "jnz .loop8_pass0        \n\t"
+                         "EMMS                    \n\t" // DONE
+ 
+                         : "=c" (dummy_value_c),        // output regs (dummy)
+                           "=S" (dummy_value_S),
+                           "=D" (dummy_value_D)
+ 
+                         : "1" (sptr),      // esi      // input regs
+                           "2" (dp),        // edi
+                           "0" (width)      // ecx
+ 
+ #if 0  /* %mm0 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                         : "%mm0"                       // clobber list
+ #endif
+                      );
+                   }
+                   else if (((pass == 2) || (pass == 3)) && width)
+                   {
+                      // source is 8-byte RRGGBBAA
+                      // dest is 32-byte RRGGBBAA RRGGBBAA RRGGBBAA RRGGBBAA
+                      // (recall that expansion is _in place_:  sptr and dp
+                      //  both point at locations within same row buffer)
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $24, %%edi         \n\t" // start of last block
+ 
+                         ".loop8_pass2:              \n\t"
+                            "movq (%%esi), %%mm0     \n\t" // 7 6 5 4 3 2 1 0
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "movq %%mm0, 8(%%edi)    \n\t"
+                            "movq %%mm0, 16(%%edi)   \n\t"
+                            "subl $8, %%esi          \n\t"
+                            "movq %%mm0, 24(%%edi)   \n\t"
+                            "subl $32, %%edi         \n\t"
+                            "decl %%ecx              \n\t"
+                            "jnz .loop8_pass2        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width)      // ecx
+ 
+ #if 0  /* %mm0 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0"                       // clobber list
+ #endif
+                         );
+                      }
+                   }
+                   else if (width)  // pass == 4 or 5
+                   {
+                      // source is 8-byte RRGGBBAA
+                      // dest is 16-byte RRGGBBAA RRGGBBAA
+                      {
+                         int dummy_value_c;  // fix 'forbidden register spilled'
+                         int dummy_value_S;
+                         int dummy_value_D;
+ 
+                         __asm__ __volatile__ (
+                            "subl $8, %%edi          \n\t" // start of last block
+ 
+                         ".loop8_pass4:              \n\t"
+                            "movq (%%esi), %%mm0     \n\t" // 7 6 5 4 3 2 1 0
+                            "movq %%mm0, (%%edi)     \n\t"
+                            "subl $8, %%esi          \n\t"
+                            "movq %%mm0, 8(%%edi)    \n\t"
+                            "subl $16, %%edi         \n\t"
+                            "decl %%ecx              \n\t"
+                            "jnz .loop8_pass4        \n\t"
+                            "EMMS                    \n\t" // DONE
+ 
+                            : "=c" (dummy_value_c),        // output regs (dummy)
+                              "=S" (dummy_value_S),
+                              "=D" (dummy_value_D)
+ 
+                            : "1" (sptr),      // esi      // input regs
+                              "2" (dp),        // edi
+                              "0" (width)      // ecx
+ 
+ #if 0  /* %mm0 not supported by gcc 2.7.2.3 or egcs 1.1 */
+                            : "%mm0"                       // clobber list
+ #endif
+                         );
+                      }
+                   }
+ 
+                } /* end of pixel_bytes == 8 */
+ 
+                //--------------------------------------------------------------
+                else if (pixel_bytes == 6)
+                {
+                   for (i = width; i; i--)
+                   {
+                      png_byte v[8];
+                      int j;
+                      png_memcpy(v, sptr, 6);
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+                         png_memcpy(dp, v, 6);
+                         dp -= 6;
+                      }
+                      sptr -= 6;
+                   }
+                } /* end of pixel_bytes == 6 */
+ 
+                //--------------------------------------------------------------
+                else
+                {
+                   for (i = width; i; i--)
+                   {
+                      png_byte v[8];
+                      int j;
+                      png_memcpy(v, sptr, pixel_bytes);
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+                         png_memcpy(dp, v, pixel_bytes);
+                         dp -= pixel_bytes;
+                      }
+                      sptr-= pixel_bytes;
+                   }
+                }
+             } // end of _mmx_supported ========================================
+ 
+             else /* MMX not supported:  use modified C code - takes advantage
+                   *   of inlining of png_memcpy for a constant */
+                  /* GRR 19991007:  does it?  or should pixel_bytes in each
+                   *   block be replaced with immediate value (e.g., 1)? */
+                  /* GRR 19991017:  replaced with constants in each case */
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+             {
+                if (pixel_bytes == 1)
+                {
+                   for (i = width; i; i--)
+                   {
+                      int j;
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+                         *dp-- = *sptr;
+                      }
+                      --sptr;
+                   }
+                }
+                else if (pixel_bytes == 3)
+                {
+                   for (i = width; i; i--)
+                   {
+                      png_byte v[8];
+                      int j;
+                      png_memcpy(v, sptr, 3);
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+                         png_memcpy(dp, v, 3);
+                         dp -= 3;
+                      }
+                      sptr -= 3;
+                   }
+                }
+                else if (pixel_bytes == 2)
+                {
+                   for (i = width; i; i--)
+                   {
+                      png_byte v[8];
+                      int j;
+                      png_memcpy(v, sptr, 2);
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+                         png_memcpy(dp, v, 2);
+                         dp -= 2;
+                      }
+                      sptr -= 2;
+                   }
+                }
+                else if (pixel_bytes == 4)
+                {
+                   for (i = width; i; i--)
+                   {
+                      png_byte v[8];
+                      int j;
+                      png_memcpy(v, sptr, 4);
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+ #ifdef PNG_DEBUG
+                         if (dp < row || dp+3 > row+png_ptr->row_buf_size)
+                         {
+                            printf("dp out of bounds: row=%d, dp=%d, rp=%d\n",
+                              row, dp, row+png_ptr->row_buf_size);
+                            printf("row_buf=%d\n",png_ptr->row_buf_size);
+                         }
+ #endif
+                         png_memcpy(dp, v, 4);
+                         dp -= 4;
+                      }
+                      sptr -= 4;
+                   }
+                }
+                else if (pixel_bytes == 6)
+                {
+                   for (i = width; i; i--)
+                   {
+                      png_byte v[8];
+                      int j;
+                      png_memcpy(v, sptr, 6);
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+                         png_memcpy(dp, v, 6);
+                         dp -= 6;
+                      }
+                      sptr -= 6;
+                   }
+                }
+                else if (pixel_bytes == 8)
+                {
+                   for (i = width; i; i--)
+                   {
+                      png_byte v[8];
+                      int j;
+                      png_memcpy(v, sptr, 8);
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+                         png_memcpy(dp, v, 8);
+                         dp -= 8;
+                      }
+                      sptr -= 8;
+                   }
+                }
+                else     /* GRR:  should never be reached */
+                {
+                   for (i = width; i; i--)
+                   {
+                      png_byte v[8];
+                      int j;
+                      png_memcpy(v, sptr, pixel_bytes);
+                      for (j = 0; j < png_pass_inc[pass]; j++)
+                      {
+                         png_memcpy(dp, v, pixel_bytes);
+                         dp -= pixel_bytes;
+                      }
+                      sptr -= pixel_bytes;
+                   }
+                }
+ 
+             } /* end if (MMX not supported) */
+             break;
+          }
+       } /* end switch (row_info->pixel_depth) */
+ 
+       row_info->width = final_width;
+       row_info->rowbytes = ((final_width *
+          (png_uint_32)row_info->pixel_depth + 7) >> 3);
+    }
+ 
+ } /* end png_do_read_interlace() */
+ 
+ #endif /* PNG_HAVE_ASSEMBLER_READ_INTERLACE */
+ #endif /* PNG_READ_INTERLACING_SUPPORTED */
+ 
+ 
+ 
+ #if defined(PNG_HAVE_ASSEMBLER_READ_FILTER_ROW)
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+ 
+ // These variables are utilized in the functions below.  They are declared
+ // globally here to ensure alignment on 8-byte boundaries.
+ 
+ union uAll {
+    long long use;
+    double  align;
+ } _LBCarryMask = {0x0101010101010101LL},
+   _HBClearMask = {0x7f7f7f7f7f7f7f7fLL},
+   _ActiveMask, _ActiveMask2, _ActiveMaskEnd, _ShiftBpp, _ShiftRem;
+ 
+ #ifdef PNG_THREAD_UNSAFE_OK
+ //===========================================================================//
+ //                                                                           //
+ //           P N G _ R E A D _ F I L T E R _ R O W _ M M X _ A V G           //
+ //                                                                           //
+ //===========================================================================//
+ 
+ // Optimized code for PNG Average filter decoder
+ 
+ static void /* PRIVATE */
+ png_read_filter_row_mmx_avg(png_row_infop row_info, png_bytep row,
+                             png_bytep prev_row)
+ {
+    int bpp;
+    int dummy_value_c;   // fix 'forbidden register 2 (cx) was spilled' error
+    int dummy_value_S;
+    int dummy_value_D;
+ 
+    bpp = (row_info->pixel_depth + 7) >> 3;  // get # bytes per pixel
+    _FullLength  = row_info->rowbytes;       // # of bytes to filter
+ 
+    __asm__ __volatile__ (
+       // initialize address pointers and offset
+ #ifdef __PIC__
+       "pushl %%ebx                 \n\t" // save index to Global Offset Table
+ #endif
+ //pre "movl row, %%edi             \n\t" // edi:  Avg(x)
+       "xorl %%ebx, %%ebx           \n\t" // ebx:  x
+       "movl %%edi, %%edx           \n\t"
+ //pre "movl prev_row, %%esi        \n\t" // esi:  Prior(x)
+ //pre "subl bpp, %%edx             \n\t" // (bpp is preloaded into ecx)
+       "subl %%ecx, %%edx           \n\t" // edx:  Raw(x-bpp)
+ 
+       "xorl %%eax,%%eax            \n\t"
+ 
+       // Compute the Raw value for the first bpp bytes
+       //    Raw(x) = Avg(x) + (Prior(x)/2)
+    "avg_rlp:                       \n\t"
+       "movb (%%esi,%%ebx,),%%al    \n\t" // load al with Prior(x)
+       "incl %%ebx                  \n\t"
+       "shrb %%al                   \n\t" // divide by 2
+       "addb -1(%%edi,%%ebx,),%%al  \n\t" // add Avg(x); -1 to offset inc ebx
+ //pre "cmpl bpp, %%ebx             \n\t" // (bpp is preloaded into ecx)
+       "cmpl %%ecx, %%ebx           \n\t"
+       "movb %%al,-1(%%edi,%%ebx,)  \n\t" // write Raw(x); -1 to offset inc ebx
+       "jb avg_rlp                  \n\t" // mov does not affect flags
+ 
+       // get # of bytes to alignment
+       "movl %%edi, _dif            \n\t" // take start of row
+       "addl %%ebx, _dif            \n\t" // add bpp
+       "addl $0xf, _dif             \n\t" // add 7+8 to incr past alignment bdry
+       "andl $0xfffffff8, _dif      \n\t" // mask to alignment boundary
+       "subl %%edi, _dif            \n\t" // subtract from start => value ebx at
+       "jz avg_go                   \n\t" //  alignment
+ 
+       // fix alignment
+       // Compute the Raw value for the bytes up to the alignment boundary
+       //    Raw(x) = Avg(x) + ((Raw(x-bpp) + Prior(x))/2)
+       "xorl %%ecx, %%ecx           \n\t"
+ 
+    "avg_lp1:                       \n\t"
+       "xorl %%eax, %%eax           \n\t"
+       "movb (%%esi,%%ebx,), %%cl   \n\t" // load cl with Prior(x)
+       "movb (%%edx,%%ebx,), %%al   \n\t" // load al with Raw(x-bpp)
+       "addw %%cx, %%ax             \n\t"
+       "incl %%ebx                  \n\t"
+       "shrw %%ax                   \n\t" // divide by 2
+       "addb -1(%%edi,%%ebx,), %%al \n\t" // add Avg(x); -1 to offset inc ebx
+       "cmpl _dif, %%ebx            \n\t" // check if at alignment boundary
+       "movb %%al, -1(%%edi,%%ebx,) \n\t" // write Raw(x); -1 to offset inc ebx
+       "jb avg_lp1                  \n\t" // repeat until at alignment boundary
+ 
+    "avg_go:                        \n\t"
+       "movl _FullLength, %%eax     \n\t"
+       "movl %%eax, %%ecx           \n\t"
+       "subl %%ebx, %%eax           \n\t" // subtract alignment fix
+       "andl $0x00000007, %%eax     \n\t" // calc bytes over mult of 8
+       "subl %%eax, %%ecx           \n\t" // drop over bytes from original length
+       "movl %%ecx, _MMXLength      \n\t"
+ #ifdef __PIC__
+       "popl %%ebx                  \n\t" // restore index to Global Offset Table
+ #endif
+ 
+       : "=c" (dummy_value_c),            // output regs (dummy)
+         "=S" (dummy_value_S),
+         "=D" (dummy_value_D)
+ 
+       : "0" (bpp),       // ecx          // input regs
+         "1" (prev_row),  // esi
+         "2" (row)        // edi
+ 
+       : "%eax", "%edx"                   // clobber list
+ #ifndef __PIC__
+       , "%ebx"
+ #endif
+       // GRR: INCLUDE "memory" as clobbered? (_dif, _MMXLength)
+       // (seems to work fine without...)
+    );
+ 
+    // now do the math for the rest of the row
+    switch (bpp)
+    {
+       case 3:
+       {
+          _ActiveMask.use  = 0x0000000000ffffffLL;
+          _ShiftBpp.use = 24;    // == 3 * 8
+          _ShiftRem.use = 40;    // == 64 - 24
+ 
+          __asm__ __volatile__ (
+             // re-init address pointers and offset
+             "movq _ActiveMask, %%mm7      \n\t"
+             "movl _dif, %%ecx             \n\t" // ecx:  x = offset to
+             "movq _LBCarryMask, %%mm5     \n\t" //  alignment boundary
+ // preload  "movl row, %%edi              \n\t" // edi:  Avg(x)
+             "movq _HBClearMask, %%mm4     \n\t"
+ // preload  "movl prev_row, %%esi         \n\t" // esi:  Prior(x)
+ 
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%ecx,), %%mm2 \n\t" // load previous aligned 8 bytes
+                                                 // (correct pos. in loop below)
+          "avg_3lp:                        \n\t"
+             "movq (%%edi,%%ecx,), %%mm0   \n\t" // load mm0 with Avg(x)
+             "movq %%mm5, %%mm3            \n\t"
+             "psrlq _ShiftRem, %%mm2       \n\t" // correct position Raw(x-bpp)
+                                                 // data
+             "movq (%%esi,%%ecx,), %%mm1   \n\t" // load mm1 with Prior(x)
+             "movq %%mm7, %%mm6            \n\t"
+             "pand %%mm1, %%mm3            \n\t" // get lsb for each prev_row byte
+             "psrlq $1, %%mm1              \n\t" // divide prev_row bytes by 2
+             "pand  %%mm4, %%mm1           \n\t" // clear invalid bit 7 of each
+                                                 // byte
+             "paddb %%mm1, %%mm0           \n\t" // add (Prev_row/2) to Avg for
+                                                 // each byte
+             // add 1st active group (Raw(x-bpp)/2) to average with LBCarry
+             "movq %%mm3, %%mm1            \n\t" // now use mm1 for getting
+                                                 // LBCarrys
+             "pand %%mm2, %%mm1            \n\t" // get LBCarrys for each byte
+                                                 // where both
+                                // lsb's were == 1 (only valid for active group)
+             "psrlq $1, %%mm2              \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2           \n\t" // clear invalid bit 7 of each
+                                                 // byte
+             "paddb %%mm1, %%mm2           \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                 // for each byte
+             "pand %%mm6, %%mm2            \n\t" // leave only Active Group 1
+                                                 // bytes to add to Avg
+             "paddb %%mm2, %%mm0           \n\t" // add (Raw/2) + LBCarrys to
+                                                 // Avg for each Active
+                                //  byte
+             // add 2nd active group (Raw(x-bpp)/2) to average with _LBCarry
+             "psllq _ShiftBpp, %%mm6       \n\t" // shift the mm6 mask to cover
+                                                 // bytes 3-5
+             "movq %%mm0, %%mm2            \n\t" // mov updated Raws to mm2
+             "psllq _ShiftBpp, %%mm2       \n\t" // shift data to pos. correctly
+             "movq %%mm3, %%mm1            \n\t" // now use mm1 for getting
+                                                 // LBCarrys
+             "pand %%mm2, %%mm1            \n\t" // get LBCarrys for each byte
+                                                 // where both
+                                // lsb's were == 1 (only valid for active group)
+             "psrlq $1, %%mm2              \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2           \n\t" // clear invalid bit 7 of each
+                                                 // byte
+             "paddb %%mm1, %%mm2           \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                 // for each byte
+             "pand %%mm6, %%mm2            \n\t" // leave only Active Group 2
+                                                 // bytes to add to Avg
+             "paddb %%mm2, %%mm0           \n\t" // add (Raw/2) + LBCarrys to
+                                                 // Avg for each Active
+                                //  byte
+ 
+             // add 3rd active group (Raw(x-bpp)/2) to average with _LBCarry
+             "psllq _ShiftBpp, %%mm6       \n\t" // shift mm6 mask to cover last
+                                                 // two
+                                  // bytes
+             "movq %%mm0, %%mm2            \n\t" // mov updated Raws to mm2
+             "psllq _ShiftBpp, %%mm2       \n\t" // shift data to pos. correctly
+                               // Data only needs to be shifted once here to
+                               // get the correct x-bpp offset.
+             "movq %%mm3, %%mm1            \n\t" // now use mm1 for getting
+                                                 // LBCarrys
+             "pand %%mm2, %%mm1            \n\t" // get LBCarrys for each byte
+                                                 // where both
+                               // lsb's were == 1 (only valid for active group)
+             "psrlq $1, %%mm2              \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2           \n\t" // clear invalid bit 7 of each
+                                                 // byte
+             "paddb %%mm1, %%mm2           \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                 // for each byte
+             "pand %%mm6, %%mm2            \n\t" // leave only Active Group 2
+                                                 // bytes to add to Avg
+             "addl $8, %%ecx               \n\t"
+             "paddb %%mm2, %%mm0           \n\t" // add (Raw/2) + LBCarrys to
+                                                 // Avg for each Active
+                                                 // byte
+             // now ready to write back to memory
+             "movq %%mm0, -8(%%edi,%%ecx,) \n\t"
+             // move updated Raw(x) to use as Raw(x-bpp) for next loop
+             "cmpl _MMXLength, %%ecx       \n\t"
+             "movq %%mm0, %%mm2            \n\t" // mov updated Raw(x) to mm2
+             "jb avg_3lp                   \n\t"
+ 
+             : "=S" (dummy_value_S),             // output regs (dummy)
+               "=D" (dummy_value_D)
+ 
+             : "0" (prev_row),  // esi           // input regs
+               "1" (row)        // edi
+ 
+             : "%ecx"                            // clobber list
+ #if 0  /* %mm0, ..., %mm7 not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2", "%mm3"
+             , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;  // end 3 bpp
+ 
+       case 6:
+       case 4:
+       //case 7:   // who wrote this?  PNG doesn't support 5 or 7 bytes/pixel
+       //case 5:   // GRR BOGUS
+       {
+          _ActiveMask.use  = 0xffffffffffffffffLL; // use shift below to clear
+                                                   // appropriate inactive bytes
+          _ShiftBpp.use = bpp << 3;
+          _ShiftRem.use = 64 - _ShiftBpp.use;
+ 
+          __asm__ __volatile__ (
+             "movq _HBClearMask, %%mm4    \n\t"
+ 
+             // re-init address pointers and offset
+             "movl _dif, %%ecx            \n\t" // ecx:  x = offset to
+                                                // alignment boundary
+ 
+             // load _ActiveMask and clear all bytes except for 1st active group
+             "movq _ActiveMask, %%mm7     \n\t"
+ // preload  "movl row, %%edi             \n\t" // edi:  Avg(x)
+             "psrlq _ShiftRem, %%mm7      \n\t"
+ // preload  "movl prev_row, %%esi        \n\t" // esi:  Prior(x)
+             "movq %%mm7, %%mm6           \n\t"
+             "movq _LBCarryMask, %%mm5    \n\t"
+             "psllq _ShiftBpp, %%mm6      \n\t" // create mask for 2nd active
+                                                // group
+ 
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%ecx,), %%mm2 \n\t" // load previous aligned 8 bytes
+                                           // (we correct pos. in loop below)
+          "avg_4lp:                       \n\t"
+             "movq (%%edi,%%ecx,), %%mm0  \n\t"
+             "psrlq _ShiftRem, %%mm2      \n\t" // shift data to pos. correctly
+             "movq (%%esi,%%ecx,), %%mm1  \n\t"
+             // add (Prev_row/2) to average
+             "movq %%mm5, %%mm3           \n\t"
+             "pand %%mm1, %%mm3           \n\t" // get lsb for each prev_row byte
+             "psrlq $1, %%mm1             \n\t" // divide prev_row bytes by 2
+             "pand  %%mm4, %%mm1          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm1, %%mm0          \n\t" // add (Prev_row/2) to Avg for
+                                                // each byte
+             // add 1st active group (Raw(x-bpp)/2) to average with _LBCarry
+             "movq %%mm3, %%mm1           \n\t" // now use mm1 for getting
+                                                // LBCarrys
+             "pand %%mm2, %%mm1           \n\t" // get LBCarrys for each byte
+                                                // where both
+                               // lsb's were == 1 (only valid for active group)
+             "psrlq $1, %%mm2             \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm1, %%mm2          \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                // for each byte
+             "pand %%mm7, %%mm2           \n\t" // leave only Active Group 1
+                                                // bytes to add to Avg
+             "paddb %%mm2, %%mm0          \n\t" // add (Raw/2) + LBCarrys to Avg
+                                                // for each Active
+                               // byte
+             // add 2nd active group (Raw(x-bpp)/2) to average with _LBCarry
+             "movq %%mm0, %%mm2           \n\t" // mov updated Raws to mm2
+             "psllq _ShiftBpp, %%mm2      \n\t" // shift data to pos. correctly
+             "addl $8, %%ecx              \n\t"
+             "movq %%mm3, %%mm1           \n\t" // now use mm1 for getting
+                                                // LBCarrys
+             "pand %%mm2, %%mm1           \n\t" // get LBCarrys for each byte
+                                                // where both
+                               // lsb's were == 1 (only valid for active group)
+             "psrlq $1, %%mm2             \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm1, %%mm2          \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                // for each byte
+             "pand %%mm6, %%mm2           \n\t" // leave only Active Group 2
+                                                // bytes to add to Avg
+             "paddb %%mm2, %%mm0          \n\t" // add (Raw/2) + LBCarrys to
+                                                // Avg for each Active
+                               // byte
+             "cmpl _MMXLength, %%ecx      \n\t"
+             // now ready to write back to memory
+             "movq %%mm0, -8(%%edi,%%ecx,) \n\t"
+             // prep Raw(x-bpp) for next loop
+             "movq %%mm0, %%mm2           \n\t" // mov updated Raws to mm2
+             "jb avg_4lp                  \n\t"
+ 
+             : "=S" (dummy_value_S),            // output regs (dummy)
+               "=D" (dummy_value_D)
+ 
+             : "0" (prev_row),  // esi          // input regs
+               "1" (row)        // edi
+ 
+             : "%ecx"                           // clobber list
+ #if 0  /* %mm0, ..., %mm7 not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2", "%mm3"
+             , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;  // end 4,6 bpp
+ 
+       case 2:
+       {
+          _ActiveMask.use  = 0x000000000000ffffLL;
+          _ShiftBpp.use = 16;   // == 2 * 8
+          _ShiftRem.use = 48;   // == 64 - 16
+ 
+          __asm__ __volatile__ (
+             // load _ActiveMask
+             "movq _ActiveMask, %%mm7     \n\t"
+             // re-init address pointers and offset
+             "movl _dif, %%ecx            \n\t" // ecx:  x = offset to alignment
+                                                // boundary
+             "movq _LBCarryMask, %%mm5    \n\t"
+ // preload  "movl row, %%edi             \n\t" // edi:  Avg(x)
+             "movq _HBClearMask, %%mm4    \n\t"
+ // preload  "movl prev_row, %%esi        \n\t" // esi:  Prior(x)
+ 
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%ecx,), %%mm2 \n\t" // load previous aligned 8 bytes
+                               // (we correct pos. in loop below)
+          "avg_2lp:                       \n\t"
+             "movq (%%edi,%%ecx,), %%mm0  \n\t"
+             "psrlq _ShiftRem, %%mm2      \n\t" // shift data to pos. correctly
+             "movq (%%esi,%%ecx,), %%mm1  \n\t" //  (GRR BUGFIX:  was psllq)
+             // add (Prev_row/2) to average
+             "movq %%mm5, %%mm3           \n\t"
+             "pand %%mm1, %%mm3           \n\t" // get lsb for each prev_row byte
+             "psrlq $1, %%mm1             \n\t" // divide prev_row bytes by 2
+             "pand  %%mm4, %%mm1          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "movq %%mm7, %%mm6           \n\t"
+             "paddb %%mm1, %%mm0          \n\t" // add (Prev_row/2) to Avg for
+                                                // each byte
+ 
+             // add 1st active group (Raw(x-bpp)/2) to average with _LBCarry
+             "movq %%mm3, %%mm1           \n\t" // now use mm1 for getting
+                                                // LBCarrys
+             "pand %%mm2, %%mm1           \n\t" // get LBCarrys for each byte
+                                                // where both
+                                                // lsb's were == 1 (only valid
+                                                // for active group)
+             "psrlq $1, %%mm2             \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm1, %%mm2          \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                // for each byte
+             "pand %%mm6, %%mm2           \n\t" // leave only Active Group 1
+                                                // bytes to add to Avg
+             "paddb %%mm2, %%mm0          \n\t" // add (Raw/2) + LBCarrys to Avg
+                                                // for each Active byte
+ 
+             // add 2nd active group (Raw(x-bpp)/2) to average with _LBCarry
+             "psllq _ShiftBpp, %%mm6      \n\t" // shift the mm6 mask to cover
+                                                // bytes 2 & 3
+             "movq %%mm0, %%mm2           \n\t" // mov updated Raws to mm2
+             "psllq _ShiftBpp, %%mm2      \n\t" // shift data to pos. correctly
+             "movq %%mm3, %%mm1           \n\t" // now use mm1 for getting
+                                                // LBCarrys
+             "pand %%mm2, %%mm1           \n\t" // get LBCarrys for each byte
+                                                // where both
+                                                // lsb's were == 1 (only valid
+                                                // for active group)
+             "psrlq $1, %%mm2             \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm1, %%mm2          \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                // for each byte
+             "pand %%mm6, %%mm2           \n\t" // leave only Active Group 2
+                                                // bytes to add to Avg
+             "paddb %%mm2, %%mm0          \n\t" // add (Raw/2) + LBCarrys to
+                                                // Avg for each Active byte
+ 
+             // add 3rd active group (Raw(x-bpp)/2) to average with _LBCarry
+             "psllq _ShiftBpp, %%mm6      \n\t" // shift the mm6 mask to cover
+                                                // bytes 4 & 5
+             "movq %%mm0, %%mm2           \n\t" // mov updated Raws to mm2
+             "psllq _ShiftBpp, %%mm2      \n\t" // shift data to pos. correctly
+             "movq %%mm3, %%mm1           \n\t" // now use mm1 for getting
+                                                // LBCarrys
+             "pand %%mm2, %%mm1           \n\t" // get LBCarrys for each byte
+                                                // where both lsb's were == 1
+                                                // (only valid for active group)
+             "psrlq $1, %%mm2             \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm1, %%mm2          \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                // for each byte
+             "pand %%mm6, %%mm2           \n\t" // leave only Active Group 2
+                                                // bytes to add to Avg
+             "paddb %%mm2, %%mm0          \n\t" // add (Raw/2) + LBCarrys to
+                                                // Avg for each Active byte
+ 
+             // add 4th active group (Raw(x-bpp)/2) to average with _LBCarry
+             "psllq _ShiftBpp, %%mm6      \n\t" // shift the mm6 mask to cover
+                                                // bytes 6 & 7
+             "movq %%mm0, %%mm2           \n\t" // mov updated Raws to mm2
+             "psllq _ShiftBpp, %%mm2      \n\t" // shift data to pos. correctly
+             "addl $8, %%ecx              \n\t"
+             "movq %%mm3, %%mm1           \n\t" // now use mm1 for getting
+                                                // LBCarrys
+             "pand %%mm2, %%mm1           \n\t" // get LBCarrys for each byte
+                                                // where both
+                                                // lsb's were == 1 (only valid
+                                                // for active group)
+             "psrlq $1, %%mm2             \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm2          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm1, %%mm2          \n\t" // add LBCarrys to (Raw(x-bpp)/2)
+                                                // for each byte
+             "pand %%mm6, %%mm2           \n\t" // leave only Active Group 2
+                                                // bytes to add to Avg
+             "paddb %%mm2, %%mm0          \n\t" // add (Raw/2) + LBCarrys to
+                                                // Avg for each Active byte
+ 
+             "cmpl _MMXLength, %%ecx      \n\t"
+             // now ready to write back to memory
+             "movq %%mm0, -8(%%edi,%%ecx,) \n\t"
+             // prep Raw(x-bpp) for next loop
+             "movq %%mm0, %%mm2           \n\t" // mov updated Raws to mm2
+             "jb avg_2lp                  \n\t"
+ 
+             : "=S" (dummy_value_S),            // output regs (dummy)
+               "=D" (dummy_value_D)
+ 
+             : "0" (prev_row),  // esi          // input regs
+               "1" (row)        // edi
+ 
+             : "%ecx"                           // clobber list
+ #if 0  /* %mm0, ..., %mm7 not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2", "%mm3"
+             , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;  // end 2 bpp
+ 
+       case 1:
+       {
+          __asm__ __volatile__ (
+             // re-init address pointers and offset
+ #ifdef __PIC__
+             "pushl %%ebx                 \n\t" // save Global Offset Table index
+ #endif
+             "movl _dif, %%ebx            \n\t" // ebx:  x = offset to alignment
+                                                // boundary
+ // preload  "movl row, %%edi             \n\t" // edi:  Avg(x)
+             "cmpl _FullLength, %%ebx     \n\t" // test if offset at end of array
+             "jnb avg_1end                \n\t"
+             // do Paeth decode for remaining bytes
+ // preload  "movl prev_row, %%esi        \n\t" // esi:  Prior(x)
+             "movl %%edi, %%edx           \n\t"
+ // preload  "subl bpp, %%edx             \n\t" // (bpp is preloaded into ecx)
+             "subl %%ecx, %%edx           \n\t" // edx:  Raw(x-bpp)
+             "xorl %%ecx, %%ecx           \n\t" // zero ecx before using cl & cx
+                                                //  in loop below
+          "avg_1lp:                       \n\t"
+             // Raw(x) = Avg(x) + ((Raw(x-bpp) + Prior(x))/2)
+             "xorl %%eax, %%eax           \n\t"
+             "movb (%%esi,%%ebx,), %%cl   \n\t" // load cl with Prior(x)
+             "movb (%%edx,%%ebx,), %%al   \n\t" // load al with Raw(x-bpp)
+             "addw %%cx, %%ax             \n\t"
+             "incl %%ebx                  \n\t"
+             "shrw %%ax                   \n\t" // divide by 2
+             "addb -1(%%edi,%%ebx,), %%al \n\t" // add Avg(x); -1 to offset
+                                                // inc ebx
+             "cmpl _FullLength, %%ebx     \n\t" // check if at end of array
+             "movb %%al, -1(%%edi,%%ebx,) \n\t" // write back Raw(x);
+                          // mov does not affect flags; -1 to offset inc ebx
+             "jb avg_1lp                  \n\t"
+ 
+          "avg_1end:                      \n\t"
+ #ifdef __PIC__
+             "popl %%ebx                  \n\t" // Global Offset Table index
+ #endif
+ 
+             : "=c" (dummy_value_c),            // output regs (dummy)
+               "=S" (dummy_value_S),
+               "=D" (dummy_value_D)
+ 
+             : "0" (bpp),       // ecx          // input regs
+               "1" (prev_row),  // esi
+               "2" (row)        // edi
+ 
+             : "%eax", "%edx"                   // clobber list
+ #ifndef __PIC__
+             , "%ebx"
+ #endif
+          );
+       }
+       return;  // end 1 bpp
+ 
+       case 8:
+       {
+          __asm__ __volatile__ (
+             // re-init address pointers and offset
+             "movl _dif, %%ecx            \n\t" // ecx:  x == offset to alignment
+             "movq _LBCarryMask, %%mm5    \n\t" //            boundary
+ // preload  "movl row, %%edi             \n\t" // edi:  Avg(x)
+             "movq _HBClearMask, %%mm4    \n\t"
+ // preload  "movl prev_row, %%esi        \n\t" // esi:  Prior(x)
+ 
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%ecx,), %%mm2 \n\t" // load previous aligned 8 bytes
+                                       // (NO NEED to correct pos. in loop below)
+ 
+          "avg_8lp:                       \n\t"
+             "movq (%%edi,%%ecx,), %%mm0  \n\t"
+             "movq %%mm5, %%mm3           \n\t"
+             "movq (%%esi,%%ecx,), %%mm1  \n\t"
+             "addl $8, %%ecx              \n\t"
+             "pand %%mm1, %%mm3           \n\t" // get lsb for each prev_row byte
+             "psrlq $1, %%mm1             \n\t" // divide prev_row bytes by 2
+             "pand %%mm2, %%mm3           \n\t" // get LBCarrys for each byte
+                                                //  where both lsb's were == 1
+             "psrlq $1, %%mm2             \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm1          \n\t" // clear invalid bit 7, each byte
+             "paddb %%mm3, %%mm0          \n\t" // add LBCarrys to Avg, each byte
+             "pand  %%mm4, %%mm2          \n\t" // clear invalid bit 7, each byte
+             "paddb %%mm1, %%mm0          \n\t" // add (Prev_row/2) to Avg, each
+             "paddb %%mm2, %%mm0          \n\t" // add (Raw/2) to Avg for each
+             "cmpl _MMXLength, %%ecx      \n\t"
+             "movq %%mm0, -8(%%edi,%%ecx,) \n\t"
+             "movq %%mm0, %%mm2           \n\t" // reuse as Raw(x-bpp)
+             "jb avg_8lp                  \n\t"
+ 
+             : "=S" (dummy_value_S),            // output regs (dummy)
+               "=D" (dummy_value_D)
+ 
+             : "0" (prev_row),  // esi          // input regs
+               "1" (row)        // edi
+ 
+             : "%ecx"                           // clobber list
+ #if 0  /* %mm0, ..., %mm5 not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2"
+             , "%mm3", "%mm4", "%mm5"
+ #endif
+          );
+       }
+       break;  // end 8 bpp
+ 
+       default:                  // bpp greater than 8 (!= 1,2,3,4,[5],6,[7],8)
+       {
+ 
+ #ifdef PNG_DEBUG
+          // GRR:  PRINT ERROR HERE:  SHOULD NEVER BE REACHED
+         png_debug(1,
+         "Internal logic error in pnggccrd (png_read_filter_row_mmx_avg())\n");
+ #endif
+ 
+ #if 0
+         __asm__ __volatile__ (
+             "movq _LBCarryMask, %%mm5    \n\t"
+             // re-init address pointers and offset
+             "movl _dif, %%ebx            \n\t" // ebx:  x = offset to
+                                                // alignment boundary
+             "movl row, %%edi             \n\t" // edi:  Avg(x)
+             "movq _HBClearMask, %%mm4    \n\t"
+             "movl %%edi, %%edx           \n\t"
+             "movl prev_row, %%esi        \n\t" // esi:  Prior(x)
+             "subl bpp, %%edx             \n\t" // edx:  Raw(x-bpp)
+          "avg_Alp:                       \n\t"
+             "movq (%%edi,%%ebx,), %%mm0  \n\t"
+             "movq %%mm5, %%mm3           \n\t"
+             "movq (%%esi,%%ebx,), %%mm1  \n\t"
+             "pand %%mm1, %%mm3           \n\t" // get lsb for each prev_row byte
+             "movq (%%edx,%%ebx,), %%mm2  \n\t"
+             "psrlq $1, %%mm1             \n\t" // divide prev_row bytes by 2
+             "pand %%mm2, %%mm3           \n\t" // get LBCarrys for each byte
+                                                // where both lsb's were == 1
+             "psrlq $1, %%mm2             \n\t" // divide raw bytes by 2
+             "pand  %%mm4, %%mm1          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm3, %%mm0          \n\t" // add LBCarrys to Avg for each
+                                                // byte
+             "pand  %%mm4, %%mm2          \n\t" // clear invalid bit 7 of each
+                                                // byte
+             "paddb %%mm1, %%mm0          \n\t" // add (Prev_row/2) to Avg for
+                                                // each byte
+             "addl $8, %%ebx              \n\t"
+             "paddb %%mm2, %%mm0          \n\t" // add (Raw/2) to Avg for each
+                                                // byte
+             "cmpl _MMXLength, %%ebx      \n\t"
+             "movq %%mm0, -8(%%edi,%%ebx,) \n\t"
+             "jb avg_Alp                  \n\t"
+ 
+             : // FIXASM: output regs/vars go here, e.g.:  "=m" (memory_var)
+ 
+             : // FIXASM: input regs, e.g.:  "c" (count), "S" (src), "D" (dest)
+ 
+             : "%ebx", "%edx", "%edi", "%esi" // CHECKASM: clobber list
+          );
+ #endif /* 0 - NEVER REACHED */
+       }
+       break;
+ 
+    } // end switch (bpp)
+ 
+    __asm__ __volatile__ (
+       // MMX acceleration complete; now do clean-up
+       // check if any remaining bytes left to decode
+ #ifdef __PIC__
+       "pushl %%ebx                 \n\t" // save index to Global Offset Table
+ #endif
+       "movl _MMXLength, %%ebx      \n\t" // ebx:  x == offset bytes after MMX
+ //pre "movl row, %%edi             \n\t" // edi:  Avg(x)
+       "cmpl _FullLength, %%ebx     \n\t" // test if offset at end of array
+       "jnb avg_end                 \n\t"
+ 
+       // do Avg decode for remaining bytes
+ //pre "movl prev_row, %%esi        \n\t" // esi:  Prior(x)
+       "movl %%edi, %%edx           \n\t"
+ //pre "subl bpp, %%edx             \n\t" // (bpp is preloaded into ecx)
+       "subl %%ecx, %%edx           \n\t" // edx:  Raw(x-bpp)
+       "xorl %%ecx, %%ecx           \n\t" // zero ecx before using cl & cx below
+ 
+    "avg_lp2:                       \n\t"
+       // Raw(x) = Avg(x) + ((Raw(x-bpp) + Prior(x))/2)
+       "xorl %%eax, %%eax           \n\t"
+       "movb (%%esi,%%ebx,), %%cl   \n\t" // load cl with Prior(x)
+       "movb (%%edx,%%ebx,), %%al   \n\t" // load al with Raw(x-bpp)
+       "addw %%cx, %%ax             \n\t"
+       "incl %%ebx                  \n\t"
+       "shrw %%ax                   \n\t" // divide by 2
+       "addb -1(%%edi,%%ebx,), %%al \n\t" // add Avg(x); -1 to offset inc ebx
+       "cmpl _FullLength, %%ebx     \n\t" // check if at end of array
+       "movb %%al, -1(%%edi,%%ebx,) \n\t" // write back Raw(x) [mov does not
+       "jb avg_lp2                  \n\t" //  affect flags; -1 to offset inc ebx]
+ 
+    "avg_end:                       \n\t"
+       "EMMS                        \n\t" // end MMX; prep for poss. FP instrs.
+ #ifdef __PIC__
+       "popl %%ebx                  \n\t" // restore index to Global Offset Table
+ #endif
+ 
+       : "=c" (dummy_value_c),            // output regs (dummy)
+         "=S" (dummy_value_S),
+         "=D" (dummy_value_D)
+ 
+       : "0" (bpp),       // ecx          // input regs
+         "1" (prev_row),  // esi
+         "2" (row)        // edi
+ 
+       : "%eax", "%edx"                   // clobber list
+ #ifndef __PIC__
+       , "%ebx"
+ #endif
+    );
+ 
+ } /* end png_read_filter_row_mmx_avg() */
+ #endif
+ 
+ 
+ 
+ #ifdef PNG_THREAD_UNSAFE_OK
+ //===========================================================================//
+ //                                                                           //
+ //         P N G _ R E A D _ F I L T E R _ R O W _ M M X _ P A E T H         //
+ //                                                                           //
+ //===========================================================================//
+ 
+ // Optimized code for PNG Paeth filter decoder
+ 
+ static void /* PRIVATE */
+ png_read_filter_row_mmx_paeth(png_row_infop row_info, png_bytep row,
+                               png_bytep prev_row)
+ {
+    int bpp;
+    int dummy_value_c;   // fix 'forbidden register 2 (cx) was spilled' error
+    int dummy_value_S;
+    int dummy_value_D;
+ 
+    bpp = (row_info->pixel_depth + 7) >> 3; // Get # bytes per pixel
+    _FullLength  = row_info->rowbytes; // # of bytes to filter
+ 
+    __asm__ __volatile__ (
+ #ifdef __PIC__
+       "pushl %%ebx                 \n\t" // save index to Global Offset Table
+ #endif
+       "xorl %%ebx, %%ebx           \n\t" // ebx:  x offset
+ //pre "movl row, %%edi             \n\t"
+       "xorl %%edx, %%edx           \n\t" // edx:  x-bpp offset
+ //pre "movl prev_row, %%esi        \n\t"
+       "xorl %%eax, %%eax           \n\t"
+ 
+       // Compute the Raw value for the first bpp bytes
+       // Note: the formula works out to be always
+       //   Paeth(x) = Raw(x) + Prior(x)      where x < bpp
+    "paeth_rlp:                     \n\t"
+       "movb (%%edi,%%ebx,), %%al   \n\t"
+       "addb (%%esi,%%ebx,), %%al   \n\t"
+       "incl %%ebx                  \n\t"
+ //pre "cmpl bpp, %%ebx             \n\t" (bpp is preloaded into ecx)
+       "cmpl %%ecx, %%ebx           \n\t"
+       "movb %%al, -1(%%edi,%%ebx,) \n\t"
+       "jb paeth_rlp                \n\t"
+       // get # of bytes to alignment
+       "movl %%edi, _dif            \n\t" // take start of row
+       "addl %%ebx, _dif            \n\t" // add bpp
+       "xorl %%ecx, %%ecx           \n\t"
+       "addl $0xf, _dif             \n\t" // add 7 + 8 to incr past alignment
+                                          // boundary
+       "andl $0xfffffff8, _dif      \n\t" // mask to alignment boundary
+       "subl %%edi, _dif            \n\t" // subtract from start ==> value ebx
+                                          // at alignment
+       "jz paeth_go                 \n\t"
+       // fix alignment
+ 
+    "paeth_lp1:                     \n\t"
+       "xorl %%eax, %%eax           \n\t"
+       // pav = p - a = (a + b - c) - a = b - c
+       "movb (%%esi,%%ebx,), %%al   \n\t" // load Prior(x) into al
+       "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+       "subl %%ecx, %%eax           \n\t" // subtract Prior(x-bpp)
+       "movl %%eax, _patemp         \n\t" // Save pav for later use
+       "xorl %%eax, %%eax           \n\t"
+       // pbv = p - b = (a + b - c) - b = a - c
+       "movb (%%edi,%%edx,), %%al   \n\t" // load Raw(x-bpp) into al
+       "subl %%ecx, %%eax           \n\t" // subtract Prior(x-bpp)
+       "movl %%eax, %%ecx           \n\t"
+       // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+       "addl _patemp, %%eax         \n\t" // pcv = pav + pbv
+       // pc = abs(pcv)
+       "testl $0x80000000, %%eax    \n\t"
+       "jz paeth_pca                \n\t"
+       "negl %%eax                  \n\t" // reverse sign of neg values
+ 
+    "paeth_pca:                     \n\t"
+       "movl %%eax, _pctemp         \n\t" // save pc for later use
+       // pb = abs(pbv)
+       "testl $0x80000000, %%ecx    \n\t"
+       "jz paeth_pba                \n\t"
+       "negl %%ecx                  \n\t" // reverse sign of neg values
+ 
+    "paeth_pba:                     \n\t"
+       "movl %%ecx, _pbtemp         \n\t" // save pb for later use
+       // pa = abs(pav)
+       "movl _patemp, %%eax         \n\t"
+       "testl $0x80000000, %%eax    \n\t"
+       "jz paeth_paa                \n\t"
+       "negl %%eax                  \n\t" // reverse sign of neg values
+ 
+    "paeth_paa:                     \n\t"
+       "movl %%eax, _patemp         \n\t" // save pa for later use
+       // test if pa <= pb
+       "cmpl %%ecx, %%eax           \n\t"
+       "jna paeth_abb               \n\t"
+       // pa > pb; now test if pb <= pc
+       "cmpl _pctemp, %%ecx         \n\t"
+       "jna paeth_bbc               \n\t"
+       // pb > pc; Raw(x) = Paeth(x) + Prior(x-bpp)
+       "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+       "jmp paeth_paeth             \n\t"
+ 
+    "paeth_bbc:                     \n\t"
+       // pb <= pc; Raw(x) = Paeth(x) + Prior(x)
+       "movb (%%esi,%%ebx,), %%cl   \n\t" // load Prior(x) into cl
+       "jmp paeth_paeth             \n\t"
+ 
+    "paeth_abb:                     \n\t"
+       // pa <= pb; now test if pa <= pc
+       "cmpl _pctemp, %%eax         \n\t"
+       "jna paeth_abc               \n\t"
+       // pa > pc; Raw(x) = Paeth(x) + Prior(x-bpp)
+       "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+       "jmp paeth_paeth             \n\t"
+ 
+    "paeth_abc:                     \n\t"
+       // pa <= pc; Raw(x) = Paeth(x) + Raw(x-bpp)
+       "movb (%%edi,%%edx,), %%cl   \n\t" // load Raw(x-bpp) into cl
+ 
+    "paeth_paeth:                   \n\t"
+       "incl %%ebx                  \n\t"
+       "incl %%edx                  \n\t"
+       // Raw(x) = (Paeth(x) + Paeth_Predictor( a, b, c )) mod 256
+       "addb %%cl, -1(%%edi,%%ebx,) \n\t"
+       "cmpl _dif, %%ebx            \n\t"
+       "jb paeth_lp1                \n\t"
+ 
+    "paeth_go:                      \n\t"
+       "movl _FullLength, %%ecx     \n\t"
+       "movl %%ecx, %%eax           \n\t"
+       "subl %%ebx, %%eax           \n\t" // subtract alignment fix
+       "andl $0x00000007, %%eax     \n\t" // calc bytes over mult of 8
+       "subl %%eax, %%ecx           \n\t" // drop over bytes from original length
+       "movl %%ecx, _MMXLength      \n\t"
+ #ifdef __PIC__
+       "popl %%ebx                  \n\t" // restore index to Global Offset Table
+ #endif
+ 
+       : "=c" (dummy_value_c),            // output regs (dummy)
+         "=S" (dummy_value_S),
+         "=D" (dummy_value_D)
+ 
+       : "0" (bpp),       // ecx          // input regs
+         "1" (prev_row),  // esi
+         "2" (row)        // edi
+ 
+       : "%eax", "%edx"                   // clobber list
+ #ifndef __PIC__
+       , "%ebx"
+ #endif
+    );
+ 
+    // now do the math for the rest of the row
+    switch (bpp)
+    {
+       case 3:
+       {
+          _ActiveMask.use = 0x0000000000ffffffLL;
+          _ActiveMaskEnd.use = 0xffff000000000000LL;
+          _ShiftBpp.use = 24;    // == bpp(3) * 8
+          _ShiftRem.use = 40;    // == 64 - 24
+ 
+          __asm__ __volatile__ (
+             "movl _dif, %%ecx            \n\t"
+ // preload  "movl row, %%edi             \n\t"
+ // preload  "movl prev_row, %%esi        \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%ecx,), %%mm1 \n\t"
+          "paeth_3lp:                     \n\t"
+             "psrlq _ShiftRem, %%mm1      \n\t" // shift last 3 bytes to 1st
+                                                // 3 bytes
+             "movq (%%esi,%%ecx,), %%mm2  \n\t" // load b=Prior(x)
+             "punpcklbw %%mm0, %%mm1      \n\t" // unpack High bytes of a
+             "movq -8(%%esi,%%ecx,), %%mm3 \n\t" // prep c=Prior(x-bpp) bytes
+             "punpcklbw %%mm0, %%mm2      \n\t" // unpack High bytes of b
+             "psrlq _ShiftRem, %%mm3      \n\t" // shift last 3 bytes to 1st
+                                                // 3 bytes
+             // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             "punpcklbw %%mm0, %%mm3      \n\t" // unpack High bytes of c
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             "psubw %%mm3, %%mm4          \n\t"
+             "pxor %%mm7, %%mm7           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "movq %%mm4, %%mm6           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+ 
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm4, %%mm0        \n\t" // create mask pav bytes < 0
+             "paddw %%mm5, %%mm6          \n\t"
+             "pand %%mm4, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "pcmpgtw %%mm5, %%mm7        \n\t" // create mask pbv bytes < 0
+             "psubw %%mm0, %%mm4          \n\t"
+             "pand %%mm5, %%mm7           \n\t" // only pbv bytes < 0 in mm0
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm7, %%mm5          \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "pxor %%mm1, %%mm1           \n\t"
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "packuswb %%mm1, %%mm7       \n\t"
+             "movq (%%esi,%%ecx,), %%mm3  \n\t" // load c=Prior(x-bpp)
+             "pand _ActiveMask, %%mm7     \n\t"
+             "movq %%mm3, %%mm2           \n\t" // load b=Prior(x) step 1
+             "paddb (%%edi,%%ecx,), %%mm7 \n\t" // add Paeth predictor with Raw(x)
+             "punpcklbw %%mm0, %%mm3      \n\t" // unpack High bytes of c
+             "movq %%mm7, (%%edi,%%ecx,)  \n\t" // write back updated value
+             "movq %%mm7, %%mm1           \n\t" // now mm1 will be used as
+                                                // Raw(x-bpp)
+             // now do Paeth for 2nd set of bytes (3-5)
+             "psrlq _ShiftBpp, %%mm2      \n\t" // load b=Prior(x) step 2
+             "punpcklbw %%mm0, %%mm1      \n\t" // unpack High bytes of a
+             "pxor %%mm7, %%mm7           \n\t"
+             "punpcklbw %%mm0, %%mm2      \n\t" // unpack High bytes of b
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+             "psubw %%mm3, %%mm4          \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) =
+             //       pav + pbv = pbv + pav
+             "movq %%mm5, %%mm6           \n\t"
+             "paddw %%mm4, %%mm6          \n\t"
+ 
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm5, %%mm0        \n\t" // create mask pbv bytes < 0
+             "pcmpgtw %%mm4, %%mm7        \n\t" // create mask pav bytes < 0
+             "pand %%mm5, %%mm0           \n\t" // only pbv bytes < 0 in mm0
+             "pand %%mm4, %%mm7           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm0, %%mm5          \n\t"
+             "psubw %%mm7, %%mm4          \n\t"
+             "psubw %%mm0, %%mm5          \n\t"
+             "psubw %%mm7, %%mm4          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "movq (%%esi,%%ecx,), %%mm2  \n\t" // load b=Prior(x)
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "pxor %%mm1, %%mm1           \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "packuswb %%mm1, %%mm7       \n\t"
+             "movq %%mm2, %%mm3           \n\t" // load c=Prior(x-bpp) step 1
+             "pand _ActiveMask, %%mm7     \n\t"
+             "punpckhbw %%mm0, %%mm2      \n\t" // unpack High bytes of b
+             "psllq _ShiftBpp, %%mm7      \n\t" // shift bytes to 2nd group of
+                                                // 3 bytes
+              // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             "paddb (%%edi,%%ecx,), %%mm7 \n\t" // add Paeth predictor with Raw(x)
+             "psllq _ShiftBpp, %%mm3      \n\t" // load c=Prior(x-bpp) step 2
+             "movq %%mm7, (%%edi,%%ecx,)  \n\t" // write back updated value
+             "movq %%mm7, %%mm1           \n\t"
+             "punpckhbw %%mm0, %%mm3      \n\t" // unpack High bytes of c
+             "psllq _ShiftBpp, %%mm1      \n\t" // shift bytes
+                                     // now mm1 will be used as Raw(x-bpp)
+             // now do Paeth for 3rd, and final, set of bytes (6-7)
+             "pxor %%mm7, %%mm7           \n\t"
+             "punpckhbw %%mm0, %%mm1      \n\t" // unpack High bytes of a
+             "psubw %%mm3, %%mm4          \n\t"
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "movq %%mm4, %%mm6           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "paddw %%mm5, %%mm6          \n\t"
+ 
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm4, %%mm0        \n\t" // create mask pav bytes < 0
+             "pcmpgtw %%mm5, %%mm7        \n\t" // create mask pbv bytes < 0
+             "pand %%mm4, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "pand %%mm5, %%mm7           \n\t" // only pbv bytes < 0 in mm0
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm1, %%mm1           \n\t"
+             "packuswb %%mm7, %%mm1       \n\t"
+             // step ecx to next set of 8 bytes and repeat loop til done
+             "addl $8, %%ecx              \n\t"
+             "pand _ActiveMaskEnd, %%mm1  \n\t"
+             "paddb -8(%%edi,%%ecx,), %%mm1 \n\t" // add Paeth predictor with
+                                                  // Raw(x)
+ 
+             "cmpl _MMXLength, %%ecx      \n\t"
+             "pxor %%mm0, %%mm0           \n\t" // pxor does not affect flags
+             "movq %%mm1, -8(%%edi,%%ecx,) \n\t" // write back updated value
+                                  // mm1 will be used as Raw(x-bpp) next loop
+                            // mm3 ready to be used as Prior(x-bpp) next loop
+             "jb paeth_3lp                \n\t"
+ 
+             : "=S" (dummy_value_S),             // output regs (dummy)
+               "=D" (dummy_value_D)
+ 
+             : "0" (prev_row),  // esi           // input regs
+               "1" (row)        // edi
+ 
+             : "%ecx"                            // clobber list
+ #if 0  /* %mm0, ..., %mm7 not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2", "%mm3"
+             , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;  // end 3 bpp
+ 
+       case 6:
+       //case 7:   // GRR BOGUS
+       //case 5:   // GRR BOGUS
+       {
+          _ActiveMask.use  = 0x00000000ffffffffLL;
+          _ActiveMask2.use = 0xffffffff00000000LL;
+          _ShiftBpp.use = bpp << 3;    // == bpp * 8
+          _ShiftRem.use = 64 - _ShiftBpp.use;
+ 
+          __asm__ __volatile__ (
+             "movl _dif, %%ecx            \n\t"
+ // preload  "movl row, %%edi             \n\t"
+ // preload  "movl prev_row, %%esi        \n\t"
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%ecx,), %%mm1 \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+ 
+          "paeth_6lp:                     \n\t"
+             // must shift to position Raw(x-bpp) data
+             "psrlq _ShiftRem, %%mm1      \n\t"
+             // do first set of 4 bytes
+             "movq -8(%%esi,%%ecx,), %%mm3 \n\t" // read c=Prior(x-bpp) bytes
+             "punpcklbw %%mm0, %%mm1      \n\t" // unpack Low bytes of a
+             "movq (%%esi,%%ecx,), %%mm2  \n\t" // load b=Prior(x)
+             "punpcklbw %%mm0, %%mm2      \n\t" // unpack Low bytes of b
+             // must shift to position Prior(x-bpp) data
+             "psrlq _ShiftRem, %%mm3      \n\t"
+             // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             "punpcklbw %%mm0, %%mm3      \n\t" // unpack Low bytes of c
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             "psubw %%mm3, %%mm4          \n\t"
+             "pxor %%mm7, %%mm7           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "movq %%mm4, %%mm6           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm4, %%mm0        \n\t" // create mask pav bytes < 0
+             "paddw %%mm5, %%mm6          \n\t"
+             "pand %%mm4, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "pcmpgtw %%mm5, %%mm7        \n\t" // create mask pbv bytes < 0
+             "psubw %%mm0, %%mm4          \n\t"
+             "pand %%mm5, %%mm7           \n\t" // only pbv bytes < 0 in mm0
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm7, %%mm5          \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "pxor %%mm1, %%mm1           \n\t"
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "packuswb %%mm1, %%mm7       \n\t"
+             "movq -8(%%esi,%%ecx,), %%mm3 \n\t" // load c=Prior(x-bpp)
+             "pand _ActiveMask, %%mm7     \n\t"
+             "psrlq _ShiftRem, %%mm3      \n\t"
+             "movq (%%esi,%%ecx,), %%mm2  \n\t" // load b=Prior(x) step 1
+             "paddb (%%edi,%%ecx,), %%mm7 \n\t" // add Paeth predictor and Raw(x)
+             "movq %%mm2, %%mm6           \n\t"
+             "movq %%mm7, (%%edi,%%ecx,)  \n\t" // write back updated value
+             "movq -8(%%edi,%%ecx,), %%mm1 \n\t"
+             "psllq _ShiftBpp, %%mm6      \n\t"
+             "movq %%mm7, %%mm5           \n\t"
+             "psrlq _ShiftRem, %%mm1      \n\t"
+             "por %%mm6, %%mm3            \n\t"
+             "psllq _ShiftBpp, %%mm5      \n\t"
+             "punpckhbw %%mm0, %%mm3      \n\t" // unpack High bytes of c
+             "por %%mm5, %%mm1            \n\t"
+             // do second set of 4 bytes
+             "punpckhbw %%mm0, %%mm2      \n\t" // unpack High bytes of b
+             "punpckhbw %%mm0, %%mm1      \n\t" // unpack High bytes of a
+             // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             "psubw %%mm3, %%mm4          \n\t"
+             "pxor %%mm7, %%mm7           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "movq %%mm4, %%mm6           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm4, %%mm0        \n\t" // create mask pav bytes < 0
+             "paddw %%mm5, %%mm6          \n\t"
+             "pand %%mm4, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "pcmpgtw %%mm5, %%mm7        \n\t" // create mask pbv bytes < 0
+             "psubw %%mm0, %%mm4          \n\t"
+             "pand %%mm5, %%mm7           \n\t" // only pbv bytes < 0 in mm0
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm7, %%mm5          \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "pxor %%mm1, %%mm1           \n\t"
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "pxor %%mm1, %%mm1           \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             // step ecx to next set of 8 bytes and repeat loop til done
+             "addl $8, %%ecx              \n\t"
+             "packuswb %%mm7, %%mm1       \n\t"
+             "paddb -8(%%edi,%%ecx,), %%mm1 \n\t" // add Paeth predictor with Raw(x)
+             "cmpl _MMXLength, %%ecx      \n\t"
+             "movq %%mm1, -8(%%edi,%%ecx,) \n\t" // write back updated value
+                                 // mm1 will be used as Raw(x-bpp) next loop
+             "jb paeth_6lp                \n\t"
+ 
+             : "=S" (dummy_value_S),             // output regs (dummy)
+               "=D" (dummy_value_D)
+ 
+             : "0" (prev_row),  // esi           // input regs
+               "1" (row)        // edi
+ 
+             : "%ecx"                            // clobber list
+ #if 0  /* %mm0, ..., %mm7 not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2", "%mm3"
+             , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;  // end 6 bpp
+ 
+       case 4:
+       {
+          _ActiveMask.use  = 0x00000000ffffffffLL;
+ 
+          __asm__ __volatile__ (
+             "movl _dif, %%ecx            \n\t"
+ // preload  "movl row, %%edi             \n\t"
+ // preload  "movl prev_row, %%esi        \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%ecx,), %%mm1 \n\t" // only time should need to read
+                                      //  a=Raw(x-bpp) bytes
+          "paeth_4lp:                     \n\t"
+             // do first set of 4 bytes
+             "movq -8(%%esi,%%ecx,), %%mm3 \n\t" // read c=Prior(x-bpp) bytes
+             "punpckhbw %%mm0, %%mm1      \n\t" // unpack Low bytes of a
+             "movq (%%esi,%%ecx,), %%mm2  \n\t" // load b=Prior(x)
+             "punpcklbw %%mm0, %%mm2      \n\t" // unpack High bytes of b
+             // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             "punpckhbw %%mm0, %%mm3      \n\t" // unpack High bytes of c
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             "psubw %%mm3, %%mm4          \n\t"
+             "pxor %%mm7, %%mm7           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "movq %%mm4, %%mm6           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm4, %%mm0        \n\t" // create mask pav bytes < 0
+             "paddw %%mm5, %%mm6          \n\t"
+             "pand %%mm4, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "pcmpgtw %%mm5, %%mm7        \n\t" // create mask pbv bytes < 0
+             "psubw %%mm0, %%mm4          \n\t"
+             "pand %%mm5, %%mm7           \n\t" // only pbv bytes < 0 in mm0
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm7, %%mm5          \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "pxor %%mm1, %%mm1           \n\t"
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "packuswb %%mm1, %%mm7       \n\t"
+             "movq (%%esi,%%ecx,), %%mm3  \n\t" // load c=Prior(x-bpp)
+             "pand _ActiveMask, %%mm7     \n\t"
+             "movq %%mm3, %%mm2           \n\t" // load b=Prior(x) step 1
+             "paddb (%%edi,%%ecx,), %%mm7 \n\t" // add Paeth predictor with Raw(x)
+             "punpcklbw %%mm0, %%mm3      \n\t" // unpack High bytes of c
+             "movq %%mm7, (%%edi,%%ecx,)  \n\t" // write back updated value
+             "movq %%mm7, %%mm1           \n\t" // now mm1 will be used as Raw(x-bpp)
+             // do second set of 4 bytes
+             "punpckhbw %%mm0, %%mm2      \n\t" // unpack Low bytes of b
+             "punpcklbw %%mm0, %%mm1      \n\t" // unpack Low bytes of a
+             // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             "psubw %%mm3, %%mm4          \n\t"
+             "pxor %%mm7, %%mm7           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "movq %%mm4, %%mm6           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm4, %%mm0        \n\t" // create mask pav bytes < 0
+             "paddw %%mm5, %%mm6          \n\t"
+             "pand %%mm4, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "pcmpgtw %%mm5, %%mm7        \n\t" // create mask pbv bytes < 0
+             "psubw %%mm0, %%mm4          \n\t"
+             "pand %%mm5, %%mm7           \n\t" // only pbv bytes < 0 in mm0
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm7, %%mm5          \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "pxor %%mm1, %%mm1           \n\t"
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "pxor %%mm1, %%mm1           \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             // step ecx to next set of 8 bytes and repeat loop til done
+             "addl $8, %%ecx              \n\t"
+             "packuswb %%mm7, %%mm1       \n\t"
+             "paddb -8(%%edi,%%ecx,), %%mm1 \n\t" // add predictor with Raw(x)
+             "cmpl _MMXLength, %%ecx      \n\t"
+             "movq %%mm1, -8(%%edi,%%ecx,) \n\t" // write back updated value
+                                 // mm1 will be used as Raw(x-bpp) next loop
+             "jb paeth_4lp                \n\t"
+ 
+             : "=S" (dummy_value_S),             // output regs (dummy)
+               "=D" (dummy_value_D)
+ 
+             : "0" (prev_row),  // esi           // input regs
+               "1" (row)        // edi
+ 
+             : "%ecx"                            // clobber list
+ #if 0  /* %mm0, ..., %mm7 not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2", "%mm3"
+             , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;  // end 4 bpp
+ 
+       case 8:                          // bpp == 8
+       {
+          _ActiveMask.use  = 0x00000000ffffffffLL;
+ 
+          __asm__ __volatile__ (
+             "movl _dif, %%ecx            \n\t"
+ // preload  "movl row, %%edi             \n\t"
+ // preload  "movl prev_row, %%esi        \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%ecx,), %%mm1 \n\t" // only time should need to read
+                                        //  a=Raw(x-bpp) bytes
+          "paeth_8lp:                     \n\t"
+             // do first set of 4 bytes
+             "movq -8(%%esi,%%ecx,), %%mm3 \n\t" // read c=Prior(x-bpp) bytes
+             "punpcklbw %%mm0, %%mm1      \n\t" // unpack Low bytes of a
+             "movq (%%esi,%%ecx,), %%mm2  \n\t" // load b=Prior(x)
+             "punpcklbw %%mm0, %%mm2      \n\t" // unpack Low bytes of b
+             // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             "punpcklbw %%mm0, %%mm3      \n\t" // unpack Low bytes of c
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             "psubw %%mm3, %%mm4          \n\t"
+             "pxor %%mm7, %%mm7           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "movq %%mm4, %%mm6           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm4, %%mm0        \n\t" // create mask pav bytes < 0
+             "paddw %%mm5, %%mm6          \n\t"
+             "pand %%mm4, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "pcmpgtw %%mm5, %%mm7        \n\t" // create mask pbv bytes < 0
+             "psubw %%mm0, %%mm4          \n\t"
+             "pand %%mm5, %%mm7           \n\t" // only pbv bytes < 0 in mm0
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm7, %%mm5          \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "pxor %%mm1, %%mm1           \n\t"
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "packuswb %%mm1, %%mm7       \n\t"
+             "movq -8(%%esi,%%ecx,), %%mm3 \n\t" // read c=Prior(x-bpp) bytes
+             "pand _ActiveMask, %%mm7     \n\t"
+             "movq (%%esi,%%ecx,), %%mm2  \n\t" // load b=Prior(x)
+             "paddb (%%edi,%%ecx,), %%mm7 \n\t" // add Paeth predictor with Raw(x)
+             "punpckhbw %%mm0, %%mm3      \n\t" // unpack High bytes of c
+             "movq %%mm7, (%%edi,%%ecx,)  \n\t" // write back updated value
+             "movq -8(%%edi,%%ecx,), %%mm1 \n\t" // read a=Raw(x-bpp) bytes
+ 
+             // do second set of 4 bytes
+             "punpckhbw %%mm0, %%mm2      \n\t" // unpack High bytes of b
+             "punpckhbw %%mm0, %%mm1      \n\t" // unpack High bytes of a
+             // pav = p - a = (a + b - c) - a = b - c
+             "movq %%mm2, %%mm4           \n\t"
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movq %%mm1, %%mm5           \n\t"
+             "psubw %%mm3, %%mm4          \n\t"
+             "pxor %%mm7, %%mm7           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "movq %%mm4, %%mm6           \n\t"
+             "psubw %%mm3, %%mm5          \n\t"
+             // pa = abs(p-a) = abs(pav)
+             // pb = abs(p-b) = abs(pbv)
+             // pc = abs(p-c) = abs(pcv)
+             "pcmpgtw %%mm4, %%mm0        \n\t" // create mask pav bytes < 0
+             "paddw %%mm5, %%mm6          \n\t"
+             "pand %%mm4, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "pcmpgtw %%mm5, %%mm7        \n\t" // create mask pbv bytes < 0
+             "psubw %%mm0, %%mm4          \n\t"
+             "pand %%mm5, %%mm7           \n\t" // only pbv bytes < 0 in mm0
+             "psubw %%mm0, %%mm4          \n\t"
+             "psubw %%mm7, %%mm5          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             "pcmpgtw %%mm6, %%mm0        \n\t" // create mask pcv bytes < 0
+             "pand %%mm6, %%mm0           \n\t" // only pav bytes < 0 in mm7
+             "psubw %%mm7, %%mm5          \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             //  test pa <= pb
+             "movq %%mm4, %%mm7           \n\t"
+             "psubw %%mm0, %%mm6          \n\t"
+             "pcmpgtw %%mm5, %%mm7        \n\t" // pa > pb?
+             "movq %%mm7, %%mm0           \n\t"
+             // use mm7 mask to merge pa & pb
+             "pand %%mm7, %%mm5           \n\t"
+             // use mm0 mask copy to merge a & b
+             "pand %%mm0, %%mm2           \n\t"
+             "pandn %%mm4, %%mm7          \n\t"
+             "pandn %%mm1, %%mm0          \n\t"
+             "paddw %%mm5, %%mm7          \n\t"
+             "paddw %%mm2, %%mm0          \n\t"
+             //  test  ((pa <= pb)? pa:pb) <= pc
+             "pcmpgtw %%mm6, %%mm7        \n\t" // pab > pc?
+             "pxor %%mm1, %%mm1           \n\t"
+             "pand %%mm7, %%mm3           \n\t"
+             "pandn %%mm0, %%mm7          \n\t"
+             "pxor %%mm1, %%mm1           \n\t"
+             "paddw %%mm3, %%mm7          \n\t"
+             "pxor %%mm0, %%mm0           \n\t"
+             // step ecx to next set of 8 bytes and repeat loop til done
+             "addl $8, %%ecx              \n\t"
+             "packuswb %%mm7, %%mm1       \n\t"
+             "paddb -8(%%edi,%%ecx,), %%mm1 \n\t" // add Paeth predictor with Raw(x)
+             "cmpl _MMXLength, %%ecx      \n\t"
+             "movq %%mm1, -8(%%edi,%%ecx,) \n\t" // write back updated value
+                             // mm1 will be used as Raw(x-bpp) next loop
+             "jb paeth_8lp                \n\t"
+ 
+             : "=S" (dummy_value_S),             // output regs (dummy)
+               "=D" (dummy_value_D)
+ 
+             : "0" (prev_row),  // esi           // input regs
+               "1" (row)        // edi
+ 
+             : "%ecx"                            // clobber list
+ #if 0  /* %mm0, ..., %mm7 not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2", "%mm3"
+             , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;  // end 8 bpp
+ 
+       case 1:                // bpp = 1
+       case 2:                // bpp = 2
+       default:               // bpp > 8
+       {
+          __asm__ __volatile__ (
+ #ifdef __PIC__
+             "pushl %%ebx                 \n\t" // save Global Offset Table index
+ #endif
+             "movl _dif, %%ebx            \n\t"
+             "cmpl _FullLength, %%ebx     \n\t"
+             "jnb paeth_dend              \n\t"
+ 
+ // preload  "movl row, %%edi             \n\t"
+ // preload  "movl prev_row, %%esi        \n\t"
+             // do Paeth decode for remaining bytes
+             "movl %%ebx, %%edx           \n\t"
+ // preload  "subl bpp, %%edx             \n\t" // (bpp is preloaded into ecx)
+             "subl %%ecx, %%edx           \n\t" // edx = ebx - bpp
+             "xorl %%ecx, %%ecx           \n\t" // zero ecx before using cl & cx
+ 
+          "paeth_dlp:                     \n\t"
+             "xorl %%eax, %%eax           \n\t"
+             // pav = p - a = (a + b - c) - a = b - c
+             "movb (%%esi,%%ebx,), %%al   \n\t" // load Prior(x) into al
+             "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+             "subl %%ecx, %%eax           \n\t" // subtract Prior(x-bpp)
+             "movl %%eax, _patemp         \n\t" // Save pav for later use
+             "xorl %%eax, %%eax           \n\t"
+             // pbv = p - b = (a + b - c) - b = a - c
+             "movb (%%edi,%%edx,), %%al   \n\t" // load Raw(x-bpp) into al
+             "subl %%ecx, %%eax           \n\t" // subtract Prior(x-bpp)
+             "movl %%eax, %%ecx           \n\t"
+             // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+             "addl _patemp, %%eax         \n\t" // pcv = pav + pbv
+             // pc = abs(pcv)
+             "testl $0x80000000, %%eax    \n\t"
+             "jz paeth_dpca               \n\t"
+             "negl %%eax                  \n\t" // reverse sign of neg values
+ 
+          "paeth_dpca:                    \n\t"
+             "movl %%eax, _pctemp         \n\t" // save pc for later use
+             // pb = abs(pbv)
+             "testl $0x80000000, %%ecx    \n\t"
+             "jz paeth_dpba               \n\t"
+             "negl %%ecx                  \n\t" // reverse sign of neg values
+ 
+          "paeth_dpba:                    \n\t"
+             "movl %%ecx, _pbtemp         \n\t" // save pb for later use
+             // pa = abs(pav)
+             "movl _patemp, %%eax         \n\t"
+             "testl $0x80000000, %%eax    \n\t"
+             "jz paeth_dpaa               \n\t"
+             "negl %%eax                  \n\t" // reverse sign of neg values
+ 
+          "paeth_dpaa:                    \n\t"
+             "movl %%eax, _patemp         \n\t" // save pa for later use
+             // test if pa <= pb
+             "cmpl %%ecx, %%eax           \n\t"
+             "jna paeth_dabb              \n\t"
+             // pa > pb; now test if pb <= pc
+             "cmpl _pctemp, %%ecx         \n\t"
+             "jna paeth_dbbc              \n\t"
+             // pb > pc; Raw(x) = Paeth(x) + Prior(x-bpp)
+             "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+             "jmp paeth_dpaeth            \n\t"
+ 
+          "paeth_dbbc:                    \n\t"
+             // pb <= pc; Raw(x) = Paeth(x) + Prior(x)
+             "movb (%%esi,%%ebx,), %%cl   \n\t" // load Prior(x) into cl
+             "jmp paeth_dpaeth            \n\t"
+ 
+          "paeth_dabb:                    \n\t"
+             // pa <= pb; now test if pa <= pc
+             "cmpl _pctemp, %%eax         \n\t"
+             "jna paeth_dabc              \n\t"
+             // pa > pc; Raw(x) = Paeth(x) + Prior(x-bpp)
+             "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+             "jmp paeth_dpaeth            \n\t"
+ 
+          "paeth_dabc:                    \n\t"
+             // pa <= pc; Raw(x) = Paeth(x) + Raw(x-bpp)
+             "movb (%%edi,%%edx,), %%cl   \n\t" // load Raw(x-bpp) into cl
+ 
+          "paeth_dpaeth:                  \n\t"
+             "incl %%ebx                  \n\t"
+             "incl %%edx                  \n\t"
+             // Raw(x) = (Paeth(x) + Paeth_Predictor( a, b, c )) mod 256
+             "addb %%cl, -1(%%edi,%%ebx,) \n\t"
+             "cmpl _FullLength, %%ebx     \n\t"
+             "jb paeth_dlp                \n\t"
+ 
+          "paeth_dend:                    \n\t"
+ #ifdef __PIC__
+             "popl %%ebx                  \n\t" // index to Global Offset Table
+ #endif
+ 
+             : "=c" (dummy_value_c),            // output regs (dummy)
+               "=S" (dummy_value_S),
+               "=D" (dummy_value_D)
+ 
+             : "0" (bpp),       // ecx          // input regs
+               "1" (prev_row),  // esi
+               "2" (row)        // edi
+ 
+             : "%eax", "%edx"                   // clobber list
+ #ifndef __PIC__
+             , "%ebx"
+ #endif
+          );
+       }
+       return;                   // No need to go further with this one
+ 
+    } // end switch (bpp)
+ 
+    __asm__ __volatile__ (
+       // MMX acceleration complete; now do clean-up
+       // check if any remaining bytes left to decode
+ #ifdef __PIC__
+       "pushl %%ebx                 \n\t" // save index to Global Offset Table
+ #endif
+       "movl _MMXLength, %%ebx      \n\t"
+       "cmpl _FullLength, %%ebx     \n\t"
+       "jnb paeth_end               \n\t"
+ //pre "movl row, %%edi             \n\t"
+ //pre "movl prev_row, %%esi        \n\t"
+       // do Paeth decode for remaining bytes
+       "movl %%ebx, %%edx           \n\t"
+ //pre "subl bpp, %%edx             \n\t" // (bpp is preloaded into ecx)
+       "subl %%ecx, %%edx           \n\t" // edx = ebx - bpp
+       "xorl %%ecx, %%ecx           \n\t" // zero ecx before using cl & cx below
+ 
+    "paeth_lp2:                     \n\t"
+       "xorl %%eax, %%eax           \n\t"
+       // pav = p - a = (a + b - c) - a = b - c
+       "movb (%%esi,%%ebx,), %%al   \n\t" // load Prior(x) into al
+       "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+       "subl %%ecx, %%eax           \n\t" // subtract Prior(x-bpp)
+       "movl %%eax, _patemp         \n\t" // Save pav for later use
+       "xorl %%eax, %%eax           \n\t"
+       // pbv = p - b = (a + b - c) - b = a - c
+       "movb (%%edi,%%edx,), %%al   \n\t" // load Raw(x-bpp) into al
+       "subl %%ecx, %%eax           \n\t" // subtract Prior(x-bpp)
+       "movl %%eax, %%ecx           \n\t"
+       // pcv = p - c = (a + b - c) -c = (a - c) + (b - c) = pav + pbv
+       "addl _patemp, %%eax         \n\t" // pcv = pav + pbv
+       // pc = abs(pcv)
+       "testl $0x80000000, %%eax    \n\t"
+       "jz paeth_pca2               \n\t"
+       "negl %%eax                  \n\t" // reverse sign of neg values
+ 
+    "paeth_pca2:                    \n\t"
+       "movl %%eax, _pctemp         \n\t" // save pc for later use
+       // pb = abs(pbv)
+       "testl $0x80000000, %%ecx    \n\t"
+       "jz paeth_pba2               \n\t"
+       "negl %%ecx                  \n\t" // reverse sign of neg values
+ 
+    "paeth_pba2:                    \n\t"
+       "movl %%ecx, _pbtemp         \n\t" // save pb for later use
+       // pa = abs(pav)
+       "movl _patemp, %%eax         \n\t"
+       "testl $0x80000000, %%eax    \n\t"
+       "jz paeth_paa2               \n\t"
+       "negl %%eax                  \n\t" // reverse sign of neg values
+ 
+    "paeth_paa2:                    \n\t"
+       "movl %%eax, _patemp         \n\t" // save pa for later use
+       // test if pa <= pb
+       "cmpl %%ecx, %%eax           \n\t"
+       "jna paeth_abb2              \n\t"
+       // pa > pb; now test if pb <= pc
+       "cmpl _pctemp, %%ecx         \n\t"
+       "jna paeth_bbc2              \n\t"
+       // pb > pc; Raw(x) = Paeth(x) + Prior(x-bpp)
+       "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+       "jmp paeth_paeth2            \n\t"
+ 
+    "paeth_bbc2:                    \n\t"
+       // pb <= pc; Raw(x) = Paeth(x) + Prior(x)
+       "movb (%%esi,%%ebx,), %%cl   \n\t" // load Prior(x) into cl
+       "jmp paeth_paeth2            \n\t"
+ 
+    "paeth_abb2:                    \n\t"
+       // pa <= pb; now test if pa <= pc
+       "cmpl _pctemp, %%eax         \n\t"
+       "jna paeth_abc2              \n\t"
+       // pa > pc; Raw(x) = Paeth(x) + Prior(x-bpp)
+       "movb (%%esi,%%edx,), %%cl   \n\t" // load Prior(x-bpp) into cl
+       "jmp paeth_paeth2            \n\t"
+ 
+    "paeth_abc2:                    \n\t"
+       // pa <= pc; Raw(x) = Paeth(x) + Raw(x-bpp)
+       "movb (%%edi,%%edx,), %%cl   \n\t" // load Raw(x-bpp) into cl
+ 
+    "paeth_paeth2:                  \n\t"
+       "incl %%ebx                  \n\t"
+       "incl %%edx                  \n\t"
+       // Raw(x) = (Paeth(x) + Paeth_Predictor( a, b, c )) mod 256
+       "addb %%cl, -1(%%edi,%%ebx,) \n\t"
+       "cmpl _FullLength, %%ebx     \n\t"
+       "jb paeth_lp2                \n\t"
+ 
+    "paeth_end:                     \n\t"
+       "EMMS                        \n\t" // end MMX; prep for poss. FP instrs.
+ #ifdef __PIC__
+       "popl %%ebx                  \n\t" // restore index to Global Offset Table
+ #endif
+ 
+       : "=c" (dummy_value_c),            // output regs (dummy)
+         "=S" (dummy_value_S),
+         "=D" (dummy_value_D)
+ 
+       : "0" (bpp),       // ecx          // input regs
+         "1" (prev_row),  // esi
+         "2" (row)        // edi
+ 
+       : "%eax", "%edx"                   // clobber list (no input regs!)
+ #ifndef __PIC__
+       , "%ebx"
+ #endif
+    );
+ 
+ } /* end png_read_filter_row_mmx_paeth() */
+ #endif
+ 
+ 
+ 
+ 
+ #ifdef PNG_THREAD_UNSAFE_OK
+ //===========================================================================//
+ //                                                                           //
+ //           P N G _ R E A D _ F I L T E R _ R O W _ M M X _ S U B           //
+ //                                                                           //
+ //===========================================================================//
+ 
+ // Optimized code for PNG Sub filter decoder
+ 
+ static void /* PRIVATE */
+ png_read_filter_row_mmx_sub(png_row_infop row_info, png_bytep row)
+ {
+    int bpp;
+    int dummy_value_a;
+    int dummy_value_D;
+ 
+    bpp = (row_info->pixel_depth + 7) >> 3;   // calc number of bytes per pixel
+    _FullLength = row_info->rowbytes - bpp;   // number of bytes to filter
+ 
+    __asm__ __volatile__ (
+ //pre "movl row, %%edi             \n\t"
+       "movl %%edi, %%esi           \n\t" // lp = row
+ //pre "movl bpp, %%eax             \n\t"
+       "addl %%eax, %%edi           \n\t" // rp = row + bpp
+ //irr "xorl %%eax, %%eax           \n\t"
+       // get # of bytes to alignment
+       "movl %%edi, _dif            \n\t" // take start of row
+       "addl $0xf, _dif             \n\t" // add 7 + 8 to incr past
+                                          //  alignment boundary
+       "xorl %%ecx, %%ecx           \n\t"
+       "andl $0xfffffff8, _dif      \n\t" // mask to alignment boundary
+       "subl %%edi, _dif            \n\t" // subtract from start ==> value
+       "jz sub_go                   \n\t" //  ecx at alignment
+ 
+    "sub_lp1:                       \n\t" // fix alignment
+       "movb (%%esi,%%ecx,), %%al   \n\t"
+       "addb %%al, (%%edi,%%ecx,)   \n\t"
+       "incl %%ecx                  \n\t"
+       "cmpl _dif, %%ecx            \n\t"
+       "jb sub_lp1                  \n\t"
+ 
+    "sub_go:                        \n\t"
+       "movl _FullLength, %%eax     \n\t"
+       "movl %%eax, %%edx           \n\t"
+       "subl %%ecx, %%edx           \n\t" // subtract alignment fix
+       "andl $0x00000007, %%edx     \n\t" // calc bytes over mult of 8
+       "subl %%edx, %%eax           \n\t" // drop over bytes from length
+       "movl %%eax, _MMXLength      \n\t"
+ 
+       : "=a" (dummy_value_a),   // 0      // output regs (dummy)
+         "=D" (dummy_value_D)    // 1
+ 
+       : "0" (bpp),              // eax    // input regs
+         "1" (row)               // edi
+ 
+       : "%ebx", "%ecx", "%edx"            // clobber list
+       , "%esi"
+ 
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+       , "%mm0", "%mm1", "%mm2", "%mm3"
+       , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+    );
+ 
+    // now do the math for the rest of the row
+    switch (bpp)
+    {
+       case 3:
+       {
+          _ActiveMask.use  = 0x0000ffffff000000LL;
+          _ShiftBpp.use = 24;       // == 3 * 8
+          _ShiftRem.use  = 40;      // == 64 - 24
+ 
+          __asm__ __volatile__ (
+ // preload  "movl row, %%edi              \n\t"
+             "movq _ActiveMask, %%mm7       \n\t" // load _ActiveMask for 2nd
+                                                 //  active byte group
+             "movl %%edi, %%esi            \n\t" // lp = row
+ // preload  "movl bpp, %%eax              \n\t"
+             "addl %%eax, %%edi            \n\t" // rp = row + bpp
+             "movq %%mm7, %%mm6            \n\t"
+             "movl _dif, %%edx             \n\t"
+             "psllq _ShiftBpp, %%mm6       \n\t" // move mask in mm6 to cover
+                                                 //  3rd active byte group
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%edx,), %%mm1 \n\t"
+ 
+          "sub_3lp:                        \n\t" // shift data for adding first
+             "psrlq _ShiftRem, %%mm1       \n\t" //  bpp bytes (no need for mask;
+                                                 //  shift clears inactive bytes)
+             // add 1st active group
+             "movq (%%edi,%%edx,), %%mm0   \n\t"
+             "paddb %%mm1, %%mm0           \n\t"
+ 
+             // add 2nd active group
+             "movq %%mm0, %%mm1            \n\t" // mov updated Raws to mm1
+             "psllq _ShiftBpp, %%mm1       \n\t" // shift data to pos. correctly
+             "pand %%mm7, %%mm1            \n\t" // mask to use 2nd active group
+             "paddb %%mm1, %%mm0           \n\t"
+ 
+             // add 3rd active group
+             "movq %%mm0, %%mm1            \n\t" // mov updated Raws to mm1
+             "psllq _ShiftBpp, %%mm1       \n\t" // shift data to pos. correctly
+             "pand %%mm6, %%mm1            \n\t" // mask to use 3rd active group
+             "addl $8, %%edx               \n\t"
+             "paddb %%mm1, %%mm0           \n\t"
+ 
+             "cmpl _MMXLength, %%edx       \n\t"
+             "movq %%mm0, -8(%%edi,%%edx,) \n\t" // write updated Raws to array
+             "movq %%mm0, %%mm1            \n\t" // prep 1st add at top of loop
+             "jb sub_3lp                   \n\t"
+ 
+             : "=a" (dummy_value_a),   // 0      // output regs (dummy)
+               "=D" (dummy_value_D)    // 1
+ 
+             : "0" (bpp),              // eax    // input regs
+               "1" (row)               // edi
+ 
+             : "%edx", "%esi"                    // clobber list
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;
+ 
+       case 1:
+       {
+          __asm__ __volatile__ (
+             "movl _dif, %%edx            \n\t"
+ // preload  "movl row, %%edi             \n\t"
+             "cmpl _FullLength, %%edx     \n\t"
+             "jnb sub_1end                \n\t"
+             "movl %%edi, %%esi           \n\t" // lp = row
+             "xorl %%eax, %%eax           \n\t"
+ // preload  "movl bpp, %%eax             \n\t"
+             "addl %%eax, %%edi           \n\t" // rp = row + bpp
+ 
+          "sub_1lp:                       \n\t"
+             "movb (%%esi,%%edx,), %%al   \n\t"
+             "addb %%al, (%%edi,%%edx,)   \n\t"
+             "incl %%edx                  \n\t"
+             "cmpl _FullLength, %%edx     \n\t"
+             "jb sub_1lp                  \n\t"
+ 
+          "sub_1end:                      \n\t"
+ 
+             : "=a" (dummy_value_a),   // 0      // output regs (dummy)
+               "=D" (dummy_value_D)    // 1
+ 
+             : "0" (bpp),              // eax    // input regs
+               "1" (row)               // edi
+ 
+             : "%edx", "%esi"                    // clobber list
+          );
+       }
+       return;
+ 
+       case 6:
+       case 4:
+       //case 7:   // GRR BOGUS
+       //case 5:   // GRR BOGUS
+       {
+          _ShiftBpp.use = bpp << 3;
+          _ShiftRem.use = 64 - _ShiftBpp.use;
+ 
+          __asm__ __volatile__ (
+ // preload  "movl row, %%edi              \n\t"
+             "movl _dif, %%edx             \n\t"
+             "movl %%edi, %%esi            \n\t" // lp = row
+ // preload  "movl bpp, %%eax              \n\t"
+             "addl %%eax, %%edi            \n\t" // rp = row + bpp
+ 
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%edx,), %%mm1 \n\t"
+ 
+          "sub_4lp:                        \n\t" // shift data for adding first
+             "psrlq _ShiftRem, %%mm1       \n\t" //  bpp bytes (no need for mask;
+                                                 //  shift clears inactive bytes)
+             "movq (%%edi,%%edx,), %%mm0   \n\t"
+             "paddb %%mm1, %%mm0           \n\t"
+ 
+             // add 2nd active group
+             "movq %%mm0, %%mm1            \n\t" // mov updated Raws to mm1
+             "psllq _ShiftBpp, %%mm1       \n\t" // shift data to pos. correctly
+             "addl $8, %%edx               \n\t"
+             "paddb %%mm1, %%mm0           \n\t"
+ 
+             "cmpl _MMXLength, %%edx       \n\t"
+             "movq %%mm0, -8(%%edi,%%edx,) \n\t"
+             "movq %%mm0, %%mm1            \n\t" // prep 1st add at top of loop
+             "jb sub_4lp                   \n\t"
+ 
+             : "=a" (dummy_value_a),   // 0      // output regs (dummy)
+               "=D" (dummy_value_D)    // 1
+ 
+             : "0" (bpp),              // eax    // input regs
+               "1" (row)               // edi
+ 
+             : "%edx", "%esi"                    // clobber list
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1"
+ #endif
+          );
+       }
+       break;
+ 
+       case 2:
+       {
+          _ActiveMask.use = 0x00000000ffff0000LL;
+          _ShiftBpp.use = 16;       // == 2 * 8
+          _ShiftRem.use = 48;       // == 64 - 16
+ 
+          __asm__ __volatile__ (
+             "movq _ActiveMask, %%mm7      \n\t" // load _ActiveMask for 2nd
+                                                 //  active byte group
+             "movl _dif, %%edx             \n\t"
+             "movq %%mm7, %%mm6            \n\t"
+ // preload  "movl row, %%edi              \n\t"
+             "psllq _ShiftBpp, %%mm6       \n\t" // move mask in mm6 to cover
+                                                 //  3rd active byte group
+             "movl %%edi, %%esi            \n\t" // lp = row
+             "movq %%mm6, %%mm5            \n\t"
+ // preload  "movl bpp, %%eax              \n\t"
+             "addl %%eax, %%edi            \n\t" // rp = row + bpp
+             "psllq _ShiftBpp, %%mm5       \n\t" // move mask in mm5 to cover
+                                                 //  4th active byte group
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%edx,), %%mm1 \n\t"
+ 
+          "sub_2lp:                        \n\t" // shift data for adding first
+             "psrlq _ShiftRem, %%mm1       \n\t" //  bpp bytes (no need for mask;
+                                                 //  shift clears inactive bytes)
+             // add 1st active group
+             "movq (%%edi,%%edx,), %%mm0   \n\t"
+             "paddb %%mm1, %%mm0           \n\t"
+ 
+             // add 2nd active group
+             "movq %%mm0, %%mm1            \n\t" // mov updated Raws to mm1
+             "psllq _ShiftBpp, %%mm1       \n\t" // shift data to pos. correctly
+             "pand %%mm7, %%mm1            \n\t" // mask to use 2nd active group
+             "paddb %%mm1, %%mm0           \n\t"
+ 
+             // add 3rd active group
+             "movq %%mm0, %%mm1            \n\t" // mov updated Raws to mm1
+             "psllq _ShiftBpp, %%mm1       \n\t" // shift data to pos. correctly
+             "pand %%mm6, %%mm1            \n\t" // mask to use 3rd active group
+             "paddb %%mm1, %%mm0           \n\t"
+ 
+             // add 4th active group
+             "movq %%mm0, %%mm1            \n\t" // mov updated Raws to mm1
+             "psllq _ShiftBpp, %%mm1       \n\t" // shift data to pos. correctly
+             "pand %%mm5, %%mm1            \n\t" // mask to use 4th active group
+             "addl $8, %%edx               \n\t"
+             "paddb %%mm1, %%mm0           \n\t"
+             "cmpl _MMXLength, %%edx       \n\t"
+             "movq %%mm0, -8(%%edi,%%edx,) \n\t" // write updated Raws to array
+             "movq %%mm0, %%mm1            \n\t" // prep 1st add at top of loop
+             "jb sub_2lp                   \n\t"
+ 
+             : "=a" (dummy_value_a),   // 0      // output regs (dummy)
+               "=D" (dummy_value_D)    // 1
+ 
+             : "0" (bpp),              // eax    // input regs
+               "1" (row)               // edi
+ 
+             : "%edx", "%esi"                    // clobber list
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;
+ 
+       case 8:
+       {
+          __asm__ __volatile__ (
+ // preload  "movl row, %%edi              \n\t"
+             "movl _dif, %%edx             \n\t"
+             "movl %%edi, %%esi            \n\t" // lp = row
+ // preload  "movl bpp, %%eax              \n\t"
+             "addl %%eax, %%edi            \n\t" // rp = row + bpp
+             "movl _MMXLength, %%ecx       \n\t"
+ 
+             // prime the pump:  load the first Raw(x-bpp) data set
+             "movq -8(%%edi,%%edx,), %%mm7 \n\t"
+             "andl $0x0000003f, %%ecx      \n\t" // calc bytes over mult of 64
+ 
+          "sub_8lp:                        \n\t"
+             "movq (%%edi,%%edx,), %%mm0   \n\t" // load Sub(x) for 1st 8 bytes
+             "paddb %%mm7, %%mm0           \n\t"
+             "movq 8(%%edi,%%edx,), %%mm1  \n\t" // load Sub(x) for 2nd 8 bytes
+             "movq %%mm0, (%%edi,%%edx,)   \n\t" // write Raw(x) for 1st 8 bytes
+ 
+             // Now mm0 will be used as Raw(x-bpp) for the 2nd group of 8 bytes.
+             // This will be repeated for each group of 8 bytes with the 8th
+             // group being used as the Raw(x-bpp) for the 1st group of the
+             // next loop.
+ 
+             "paddb %%mm0, %%mm1           \n\t"
+             "movq 16(%%edi,%%edx,), %%mm2 \n\t" // load Sub(x) for 3rd 8 bytes
+             "movq %%mm1, 8(%%edi,%%edx,)  \n\t" // write Raw(x) for 2nd 8 bytes
+             "paddb %%mm1, %%mm2           \n\t"
+             "movq 24(%%edi,%%edx,), %%mm3 \n\t" // load Sub(x) for 4th 8 bytes
+             "movq %%mm2, 16(%%edi,%%edx,) \n\t" // write Raw(x) for 3rd 8 bytes
+             "paddb %%mm2, %%mm3           \n\t"
+             "movq 32(%%edi,%%edx,), %%mm4 \n\t" // load Sub(x) for 5th 8 bytes
+             "movq %%mm3, 24(%%edi,%%edx,) \n\t" // write Raw(x) for 4th 8 bytes
+             "paddb %%mm3, %%mm4           \n\t"
+             "movq 40(%%edi,%%edx,), %%mm5 \n\t" // load Sub(x) for 6th 8 bytes
+             "movq %%mm4, 32(%%edi,%%edx,) \n\t" // write Raw(x) for 5th 8 bytes
+             "paddb %%mm4, %%mm5           \n\t"
+             "movq 48(%%edi,%%edx,), %%mm6 \n\t" // load Sub(x) for 7th 8 bytes
+             "movq %%mm5, 40(%%edi,%%edx,) \n\t" // write Raw(x) for 6th 8 bytes
+             "paddb %%mm5, %%mm6           \n\t"
+             "movq 56(%%edi,%%edx,), %%mm7 \n\t" // load Sub(x) for 8th 8 bytes
+             "movq %%mm6, 48(%%edi,%%edx,) \n\t" // write Raw(x) for 7th 8 bytes
+             "addl $64, %%edx              \n\t"
+             "paddb %%mm6, %%mm7           \n\t"
+             "cmpl %%ecx, %%edx            \n\t"
+             "movq %%mm7, -8(%%edi,%%edx,) \n\t" // write Raw(x) for 8th 8 bytes
+             "jb sub_8lp                   \n\t"
+ 
+             "cmpl _MMXLength, %%edx       \n\t"
+             "jnb sub_8lt8                 \n\t"
+ 
+          "sub_8lpA:                       \n\t"
+             "movq (%%edi,%%edx,), %%mm0   \n\t"
+             "addl $8, %%edx               \n\t"
+             "paddb %%mm7, %%mm0           \n\t"
+             "cmpl _MMXLength, %%edx       \n\t"
+             "movq %%mm0, -8(%%edi,%%edx,) \n\t" // -8 to offset early addl edx
+             "movq %%mm0, %%mm7            \n\t" // move calculated Raw(x) data
+                                                 //  to mm1 to be new Raw(x-bpp)
+                                                 //  for next loop
+             "jb sub_8lpA                  \n\t"
+ 
+          "sub_8lt8:                       \n\t"
+ 
+             : "=a" (dummy_value_a),   // 0      // output regs (dummy)
+               "=D" (dummy_value_D)    // 1
+ 
+             : "0" (bpp),              // eax    // input regs
+               "1" (row)               // edi
+ 
+             : "%ecx", "%edx", "%esi"            // clobber list
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1", "%mm2", "%mm3", "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+          );
+       }
+       break;
+ 
+       default:                // bpp greater than 8 bytes   GRR BOGUS
+       {
+          __asm__ __volatile__ (
+             "movl _dif, %%edx             \n\t"
+ // preload  "movl row, %%edi              \n\t"
+             "movl %%edi, %%esi            \n\t" // lp = row
+ // preload  "movl bpp, %%eax              \n\t"
+             "addl %%eax, %%edi            \n\t" // rp = row + bpp
+ 
+          "sub_Alp:                        \n\t"
+             "movq (%%edi,%%edx,), %%mm0   \n\t"
+             "movq (%%esi,%%edx,), %%mm1   \n\t"
+             "addl $8, %%edx               \n\t"
+             "paddb %%mm1, %%mm0           \n\t"
+             "cmpl _MMXLength, %%edx       \n\t"
+             "movq %%mm0, -8(%%edi,%%edx,) \n\t" // mov does not affect flags;
+                                                 //  -8 to offset addl edx
+             "jb sub_Alp                   \n\t"
+ 
+             : "=a" (dummy_value_a),   // 0      // output regs (dummy)
+               "=D" (dummy_value_D)    // 1
+ 
+             : "0" (bpp),              // eax    // input regs
+               "1" (row)               // edi
+ 
+             : "%edx", "%esi"                    // clobber list
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+             , "%mm0", "%mm1"
+ #endif
+          );
+       }
+       break;
+ 
+    } // end switch (bpp)
+ 
+    __asm__ __volatile__ (
+       "movl _MMXLength, %%edx       \n\t"
+ //pre "movl row, %%edi              \n\t"
+       "cmpl _FullLength, %%edx      \n\t"
+       "jnb sub_end                  \n\t"
+ 
+       "movl %%edi, %%esi            \n\t" // lp = row
+ //pre "movl bpp, %%eax              \n\t"
+       "addl %%eax, %%edi            \n\t" // rp = row + bpp
+       "xorl %%eax, %%eax            \n\t"
+ 
+    "sub_lp2:                        \n\t"
+       "movb (%%esi,%%edx,), %%al    \n\t"
+       "addb %%al, (%%edi,%%edx,)    \n\t"
+       "incl %%edx                   \n\t"
+       "cmpl _FullLength, %%edx      \n\t"
+       "jb sub_lp2                   \n\t"
+ 
+    "sub_end:                        \n\t"
+       "EMMS                         \n\t" // end MMX instructions
+ 
+       : "=a" (dummy_value_a),   // 0      // output regs (dummy)
+         "=D" (dummy_value_D)    // 1
+ 
+       : "0" (bpp),              // eax    // input regs
+         "1" (row)               // edi
+ 
+       : "%edx", "%esi"                    // clobber list
+    );
+ 
+ } // end of png_read_filter_row_mmx_sub()
+ #endif
+ 
+ 
+ 
+ 
+ //===========================================================================//
+ //                                                                           //
+ //            P N G _ R E A D _ F I L T E R _ R O W _ M M X _ U P            //
+ //                                                                           //
+ //===========================================================================//
+ 
+ // Optimized code for PNG Up filter decoder
+ 
+ static void /* PRIVATE */
+ png_read_filter_row_mmx_up(png_row_infop row_info, png_bytep row,
+                            png_bytep prev_row)
+ {
+    png_uint_32 len;
+    int dummy_value_d;   // fix 'forbidden register 3 (dx) was spilled' error
+    int dummy_value_S;
+    int dummy_value_D;
+ 
+    len = row_info->rowbytes;              // number of bytes to filter
+ 
+    __asm__ __volatile__ (
+ //pre "movl row, %%edi              \n\t"
+       // get # of bytes to alignment
+ #ifdef __PIC__
+       "pushl %%ebx                  \n\t"
+ #endif
+       "movl %%edi, %%ecx            \n\t"
+       "xorl %%ebx, %%ebx            \n\t"
+       "addl $0x7, %%ecx             \n\t"
+       "xorl %%eax, %%eax            \n\t"
+       "andl $0xfffffff8, %%ecx      \n\t"
+ //pre "movl prev_row, %%esi         \n\t"
+       "subl %%edi, %%ecx            \n\t"
+       "jz up_go                     \n\t"
+ 
+    "up_lp1:                         \n\t" // fix alignment
+       "movb (%%edi,%%ebx,), %%al    \n\t"
+       "addb (%%esi,%%ebx,), %%al    \n\t"
+       "incl %%ebx                   \n\t"
+       "cmpl %%ecx, %%ebx            \n\t"
+       "movb %%al, -1(%%edi,%%ebx,)  \n\t" // mov does not affect flags; -1 to
+       "jb up_lp1                    \n\t" //  offset incl ebx
+ 
+    "up_go:                          \n\t"
+ //pre "movl len, %%edx              \n\t"
+       "movl %%edx, %%ecx            \n\t"
+       "subl %%ebx, %%edx            \n\t" // subtract alignment fix
+       "andl $0x0000003f, %%edx      \n\t" // calc bytes over mult of 64
+       "subl %%edx, %%ecx            \n\t" // drop over bytes from length
+ 
+       // unrolled loop - use all MMX registers and interleave to reduce
+       // number of branch instructions (loops) and reduce partial stalls
+    "up_loop:                        \n\t"
+       "movq (%%esi,%%ebx,), %%mm1   \n\t"
+       "movq (%%edi,%%ebx,), %%mm0   \n\t"
+       "movq 8(%%esi,%%ebx,), %%mm3  \n\t"
+       "paddb %%mm1, %%mm0           \n\t"
+       "movq 8(%%edi,%%ebx,), %%mm2  \n\t"
+       "movq %%mm0, (%%edi,%%ebx,)   \n\t"
+       "paddb %%mm3, %%mm2           \n\t"
+       "movq 16(%%esi,%%ebx,), %%mm5 \n\t"
+       "movq %%mm2, 8(%%edi,%%ebx,)  \n\t"
+       "movq 16(%%edi,%%ebx,), %%mm4 \n\t"
+       "movq 24(%%esi,%%ebx,), %%mm7 \n\t"
+       "paddb %%mm5, %%mm4           \n\t"
+       "movq 24(%%edi,%%ebx,), %%mm6 \n\t"
+       "movq %%mm4, 16(%%edi,%%ebx,) \n\t"
+       "paddb %%mm7, %%mm6           \n\t"
+       "movq 32(%%esi,%%ebx,), %%mm1 \n\t"
+       "movq %%mm6, 24(%%edi,%%ebx,) \n\t"
+       "movq 32(%%edi,%%ebx,), %%mm0 \n\t"
+       "movq 40(%%esi,%%ebx,), %%mm3 \n\t"
+       "paddb %%mm1, %%mm0           \n\t"
+       "movq 40(%%edi,%%ebx,), %%mm2 \n\t"
+       "movq %%mm0, 32(%%edi,%%ebx,) \n\t"
+       "paddb %%mm3, %%mm2           \n\t"
+       "movq 48(%%esi,%%ebx,), %%mm5 \n\t"
+       "movq %%mm2, 40(%%edi,%%ebx,) \n\t"
+       "movq 48(%%edi,%%ebx,), %%mm4 \n\t"
+       "movq 56(%%esi,%%ebx,), %%mm7 \n\t"
+       "paddb %%mm5, %%mm4           \n\t"
+       "movq 56(%%edi,%%ebx,), %%mm6 \n\t"
+       "movq %%mm4, 48(%%edi,%%ebx,) \n\t"
+       "addl $64, %%ebx              \n\t"
+       "paddb %%mm7, %%mm6           \n\t"
+       "cmpl %%ecx, %%ebx            \n\t"
+       "movq %%mm6, -8(%%edi,%%ebx,) \n\t" // (+56)movq does not affect flags;
+       "jb up_loop                   \n\t" //  -8 to offset addl ebx
+ 
+       "cmpl $0, %%edx               \n\t" // test for bytes over mult of 64
+       "jz up_end                    \n\t"
+ 
+       "cmpl $8, %%edx               \n\t" // test for less than 8 bytes
+       "jb up_lt8                    \n\t" //  [added by lcreeve at netins.net]
+ 
+       "addl %%edx, %%ecx            \n\t"
+       "andl $0x00000007, %%edx      \n\t" // calc bytes over mult of 8
+       "subl %%edx, %%ecx            \n\t" // drop over bytes from length
+       "jz up_lt8                    \n\t"
+ 
+    "up_lpA:                         \n\t" // use MMX regs to update 8 bytes sim.
+       "movq (%%esi,%%ebx,), %%mm1   \n\t"
+       "movq (%%edi,%%ebx,), %%mm0   \n\t"
+       "addl $8, %%ebx               \n\t"
+       "paddb %%mm1, %%mm0           \n\t"
+       "cmpl %%ecx, %%ebx            \n\t"
+       "movq %%mm0, -8(%%edi,%%ebx,) \n\t" // movq does not affect flags; -8 to
+       "jb up_lpA                    \n\t" //  offset add ebx
+       "cmpl $0, %%edx               \n\t" // test for bytes over mult of 8
+       "jz up_end                    \n\t"
+ 
+    "up_lt8:                         \n\t"
+       "xorl %%eax, %%eax            \n\t"
+       "addl %%edx, %%ecx            \n\t" // move over byte count into counter
+ 
+    "up_lp2:                         \n\t" // use x86 regs for remaining bytes
+       "movb (%%edi,%%ebx,), %%al    \n\t"
+       "addb (%%esi,%%ebx,), %%al    \n\t"
+       "incl %%ebx                   \n\t"
+       "cmpl %%ecx, %%ebx            \n\t"
+       "movb %%al, -1(%%edi,%%ebx,)  \n\t" // mov does not affect flags; -1 to
+       "jb up_lp2                    \n\t" //  offset inc ebx
+ 
+    "up_end:                         \n\t"
+       "EMMS                         \n\t" // conversion of filtered row complete
+ #ifdef __PIC__
+       "popl %%ebx                   \n\t"
+ #endif
+ 
+       : "=d" (dummy_value_d),   // 0      // output regs (dummy)
+         "=S" (dummy_value_S),   // 1
+         "=D" (dummy_value_D)    // 2
+ 
+       : "0" (len),              // edx    // input regs
+         "1" (prev_row),         // esi
+         "2" (row)               // edi
+ 
+       : "%eax", "%ebx", "%ecx"            // clobber list (no input regs!)
+ 
+ #if 0  /* MMX regs (%mm0, etc.) not supported by gcc 2.7.2.3 or egcs 1.1 */
+       , "%mm0", "%mm1", "%mm2", "%mm3"
+       , "%mm4", "%mm5", "%mm6", "%mm7"
+ #endif
+    );
+ 
+ } // end of png_read_filter_row_mmx_up()
+ 
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+ 
+ 
+ 
+ 
+ /*===========================================================================*/
+ /*                                                                           */
+ /*                   P N G _ R E A D _ F I L T E R _ R O W                   */
+ /*                                                                           */
+ /*===========================================================================*/
+ 
+ 
+ /* Optimized png_read_filter_row routines */
+ 
+ void /* PRIVATE */
+ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep
+    row, png_bytep prev_row, int filter)
+ {
+ #ifdef PNG_DEBUG
+    char filnm[10];
+ #endif
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+ /* GRR:  these are superseded by png_ptr->asm_flags: */
+ #define UseMMX_sub    1   // GRR:  converted 20000730
+ #define UseMMX_up     1   // GRR:  converted 20000729
+ #define UseMMX_avg    1   // GRR:  converted 20000828 (+ 16-bit bugfix 20000916)
+ #define UseMMX_paeth  1   // GRR:  converted 20000828
+ 
+    if (_mmx_supported == 2) {
+        /* this should have happened in png_init_mmx_flags() already */
+ #if !defined(PNG_1_0_X)
+        png_warning(png_ptr, "asm_flags may not have been initialized");
+ #endif
+        png_mmx_support();
+    }
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+ 
+ #ifdef PNG_DEBUG
+    png_debug(1, "in png_read_filter_row (pnggccrd.c)\n");
+    switch (filter)
+    {
+       case 0: sprintf(filnm, "none");
+          break;
+       case 1: sprintf(filnm, "sub-%s",
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+         (png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_FILTER_SUB)? "MMX" : 
+ #endif
+ #endif
+ "x86");
+          break;
+       case 2: sprintf(filnm, "up-%s",
+ #ifdef PNG_ASSEMBLER_CODE_SUPPORTED
+ #if !defined(PNG_1_0_X)
+         (png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_FILTER_UP)? "MMX" :
+ #endif
+ #endif
+  "x86");
+          break;
+       case 3: sprintf(filnm, "avg-%s",
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+         (png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_FILTER_AVG)? "MMX" :
+ #endif
+ #endif
+  "x86");
+          break;
+       case 4: sprintf(filnm, "Paeth-%s",
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+         (png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_FILTER_PAETH)? "MMX":
+ #endif
+ #endif
+ "x86");
+          break;
+       default: sprintf(filnm, "unknw");
+          break;
+    }
+    png_debug2(0, "row_number=%5ld, %5s, ", png_ptr->row_number, filnm);
+    png_debug1(0, "row=0x%08lx, ", (unsigned long)row);
+    png_debug2(0, "pixdepth=%2d, bytes=%d, ", (int)row_info->pixel_depth,
+       (int)((row_info->pixel_depth + 7) >> 3));
+    png_debug1(0,"rowbytes=%8ld\n", row_info->rowbytes);
+ #endif /* PNG_DEBUG */
+ 
+    switch (filter)
+    {
+       case PNG_FILTER_VALUE_NONE:
+          break;
+ 
+       case PNG_FILTER_VALUE_SUB:
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+          if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_FILTER_SUB) &&
+              (row_info->pixel_depth >= png_ptr->mmx_bitdepth_threshold) &&
+              (row_info->rowbytes >= png_ptr->mmx_rowbytes_threshold))
+ #else
+          if (_mmx_supported)
+ #endif
+          {
+             png_read_filter_row_mmx_sub(row_info, row);
+          }
+          else
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+          {
+             png_uint_32 i;
+             png_uint_32 istop = row_info->rowbytes;
+             png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
+             png_bytep rp = row + bpp;
+             png_bytep lp = row;
+ 
+             for (i = bpp; i < istop; i++)
+             {
+                *rp = (png_byte)(((int)(*rp) + (int)(*lp++)) & 0xff);
+                rp++;
+             }
+          }  /* end !UseMMX_sub */
+          break;
+ 
+       case PNG_FILTER_VALUE_UP:
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+ #if !defined(PNG_1_0_X)
+          if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_FILTER_UP) &&
+              (row_info->pixel_depth >= png_ptr->mmx_bitdepth_threshold) &&
+              (row_info->rowbytes >= png_ptr->mmx_rowbytes_threshold))
+ #else
+          if (_mmx_supported)
+ #endif
+          {
+             png_read_filter_row_mmx_up(row_info, row, prev_row);
+          }
+           else
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+          {
+             png_uint_32 i;
+             png_uint_32 istop = row_info->rowbytes;
+             png_bytep rp = row;
+             png_bytep pp = prev_row;
+ 
+             for (i = 0; i < istop; ++i)
+             {
+                *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+                rp++;
+             }
+          }  /* end !UseMMX_up */
+          break;
+ 
+       case PNG_FILTER_VALUE_AVG:
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+          if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_FILTER_AVG) &&
+              (row_info->pixel_depth >= png_ptr->mmx_bitdepth_threshold) &&
+              (row_info->rowbytes >= png_ptr->mmx_rowbytes_threshold))
+ #else
+          if (_mmx_supported)
+ #endif
+          {
+             png_read_filter_row_mmx_avg(row_info, row, prev_row);
+          }
+          else
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+          {
+             png_uint_32 i;
+             png_bytep rp = row;
+             png_bytep pp = prev_row;
+             png_bytep lp = row;
+             png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
+             png_uint_32 istop = row_info->rowbytes - bpp;
+ 
+             for (i = 0; i < bpp; i++)
+             {
+                *rp = (png_byte)(((int)(*rp) +
+                   ((int)(*pp++) >> 1)) & 0xff);
+                rp++;
+             }
+ 
+             for (i = 0; i < istop; i++)
+             {
+                *rp = (png_byte)(((int)(*rp) +
+                   ((int)(*pp++ + *lp++) >> 1)) & 0xff);
+                rp++;
+             }
+          }  /* end !UseMMX_avg */
+          break;
+ 
+       case PNG_FILTER_VALUE_PAETH:
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_THREAD_UNSAFE_OK)
+ #if !defined(PNG_1_0_X)
+          if ((png_ptr->asm_flags & PNG_ASM_FLAG_MMX_READ_FILTER_PAETH) &&
+              (row_info->pixel_depth >= png_ptr->mmx_bitdepth_threshold) &&
+              (row_info->rowbytes >= png_ptr->mmx_rowbytes_threshold))
+ #else
+          if (_mmx_supported)
+ #endif
+          {
+             png_read_filter_row_mmx_paeth(row_info, row, prev_row);
+          }
+          else
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+          {
+             png_uint_32 i;
+             png_bytep rp = row;
+             png_bytep pp = prev_row;
+             png_bytep lp = row;
+             png_bytep cp = prev_row;
+             png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
+             png_uint_32 istop = row_info->rowbytes - bpp;
+ 
+             for (i = 0; i < bpp; i++)
+             {
+                *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+                rp++;
+             }
+ 
+             for (i = 0; i < istop; i++)   /* use leftover rp,pp */
+             {
+                int a, b, c, pa, pb, pc, p;
+ 
+                a = *lp++;
+                b = *pp++;
+                c = *cp++;
+ 
+                p = b - c;
+                pc = a - c;
+ 
+ #ifdef PNG_USE_ABS
+                pa = abs(p);
+                pb = abs(pc);
+                pc = abs(p + pc);
+ #else
+                pa = p < 0 ? -p : p;
+                pb = pc < 0 ? -pc : pc;
+                pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+ #endif
+ 
+                /*
+                   if (pa <= pb && pa <= pc)
+                      p = a;
+                   else if (pb <= pc)
+                      p = b;
+                   else
+                      p = c;
+                 */
+ 
+                p = (pa <= pb && pa <= pc) ? a : (pb <= pc) ? b : c;
+ 
+                *rp = (png_byte)(((int)(*rp) + p) & 0xff);
+                rp++;
+             }
+          }  /* end !UseMMX_paeth */
+          break;
+ 
+       default:
+          png_warning(png_ptr, "Ignoring bad row-filter type");
+          *row=0;
+          break;
+    }
+ }
+ 
+ #endif /* PNG_HAVE_ASSEMBLER_READ_FILTER_ROW */
+ 
+ 
+ /*===========================================================================*/
+ /*                                                                           */
+ /*                      P N G _ M M X _ S U P P O R T                        */
+ /*                                                                           */
+ /*===========================================================================*/
+ 
+ /* GRR NOTES:  (1) the following code assumes 386 or better (pushfl/popfl)
+  *             (2) all instructions compile with gcc 2.7.2.3 and later
+  *             (3) the function is moved down here to prevent gcc from
+  *                  inlining it in multiple places and then barfing be-
+  *                  cause the ".NOT_SUPPORTED" label is multiply defined
+  *             [is there a way to signal that a *single* function should
+  *              not be inlined?  is there a way to modify the label for
+  *              each inlined instance, e.g., by appending _1, _2, etc.?
+  *              maybe if don't use leading "." in label name? (nope...sigh)]
+  */
+ 
+ int PNGAPI
+ png_mmx_support(void)
+ {
+ #if defined(PNG_MMX_CODE_SUPPORTED)
+     __asm__ __volatile__ (
+         "pushl %%ebx          \n\t"  // ebx gets clobbered by CPUID instruction
+         "pushl %%ecx          \n\t"  // so does ecx...
+         "pushl %%edx          \n\t"  // ...and edx (but ecx & edx safe on Linux)
+ //      ".byte  0x66          \n\t"  // convert 16-bit pushf to 32-bit pushfd
+ //      "pushf                \n\t"  // 16-bit pushf
+         "pushfl               \n\t"  // save Eflag to stack
+         "popl %%eax           \n\t"  // get Eflag from stack into eax
+         "movl %%eax, %%ecx    \n\t"  // make another copy of Eflag in ecx
+         "xorl $0x200000, %%eax \n\t" // toggle ID bit in Eflag (i.e., bit 21)
+         "pushl %%eax          \n\t"  // save modified Eflag back to stack
+ //      ".byte  0x66          \n\t"  // convert 16-bit popf to 32-bit popfd
+ //      "popf                 \n\t"  // 16-bit popf
+         "popfl                \n\t"  // restore modified value to Eflag reg
+         "pushfl               \n\t"  // save Eflag to stack
+         "popl %%eax           \n\t"  // get Eflag from stack
+         "pushl %%ecx          \n\t"  // save original Eflag to stack
+         "popfl                \n\t"  // restore original Eflag
+         "xorl %%ecx, %%eax    \n\t"  // compare new Eflag with original Eflag
+         "jz 0f                \n\t"  // if same, CPUID instr. is not supported
+ 
+         "xorl %%eax, %%eax    \n\t"  // set eax to zero
+ //      ".byte  0x0f, 0xa2    \n\t"  // CPUID instruction (two-byte opcode)
+         "cpuid                \n\t"  // get the CPU identification info
+         "cmpl $1, %%eax       \n\t"  // make sure eax return non-zero value
+         "jl 0f                \n\t"  // if eax is zero, MMX is not supported
+ 
+         "xorl %%eax, %%eax    \n\t"  // set eax to zero and...
+         "incl %%eax           \n\t"  // ...increment eax to 1.  This pair is
+                                      // faster than the instruction "mov eax, 1"
+         "cpuid                \n\t"  // get the CPU identification info again
+         "andl $0x800000, %%edx \n\t" // mask out all bits but MMX bit (23)
+         "cmpl $0, %%edx       \n\t"  // 0 = MMX not supported
+         "jz 0f                \n\t"  // non-zero = yes, MMX IS supported
+ 
+         "movl $1, %%eax       \n\t"  // set return value to 1
+         "jmp  1f              \n\t"  // DONE:  have MMX support
+ 
+     "0:                       \n\t"  // .NOT_SUPPORTED: target label for jump instructions
+         "movl $0, %%eax       \n\t"  // set return value to 0
+     "1:                       \n\t"  // .RETURN: target label for jump instructions
+         "movl %%eax, _mmx_supported \n\t" // save in global static variable, too
+         "popl %%edx           \n\t"  // restore edx
+         "popl %%ecx           \n\t"  // restore ecx
+         "popl %%ebx           \n\t"  // restore ebx
+ 
+ //      "ret                  \n\t"  // DONE:  no MMX support
+                                      // (fall through to standard C "ret")
+ 
+         :                            // output list (none)
+ 
+         :                            // any variables used on input (none)
+ 
+         : "%eax"                     // clobber list
+ //      , "%ebx", "%ecx", "%edx"     // GRR:  we handle these manually
+ //      , "memory"   // if write to a variable gcc thought was in a reg
+ //      , "cc"       // "condition codes" (flag bits)
+     );
+ #else     
+     _mmx_supported = 0;
+ #endif /* PNG_MMX_CODE_SUPPORTED */
+ 
+     return _mmx_supported;
+ }
+ 
+ 
+ #endif /* PNG_USE_PNGGCCRD */


Index: llvm/runtime/libpng/pngget.c
diff -c /dev/null llvm/runtime/libpng/pngget.c:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/pngget.c	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,927 ----
+ 
+ /* pngget.c - retrieval of values from info struct
+  *
+  * libpng 1.2.5 - October 3, 2002
+  * For conditions of distribution and use, see copyright notice in png.h
+  * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+  */
+ 
+ #define PNG_INTERNAL
+ #include "png.h"
+ 
+ png_uint_32 PNGAPI
+ png_get_valid(png_structp png_ptr, png_infop info_ptr, png_uint_32 flag)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+       return(info_ptr->valid & flag);
+    else
+       return(0);
+ }
+ 
+ png_uint_32 PNGAPI
+ png_get_rowbytes(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+       return(info_ptr->rowbytes);
+    else
+       return(0);
+ }
+ 
+ #if defined(PNG_INFO_IMAGE_SUPPORTED)
+ png_bytepp PNGAPI
+ png_get_rows(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+       return(info_ptr->row_pointers);
+    else
+       return(0);
+ }
+ #endif
+ 
+ #ifdef PNG_EASY_ACCESS_SUPPORTED
+ /* easy access to info, added in libpng-0.99 */
+ png_uint_32 PNGAPI
+ png_get_image_width(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+    {
+       return info_ptr->width;
+    }
+    return (0);
+ }
+ 
+ png_uint_32 PNGAPI
+ png_get_image_height(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+    {
+       return info_ptr->height;
+    }
+    return (0);
+ }
+ 
+ png_byte PNGAPI
+ png_get_bit_depth(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+    {
+       return info_ptr->bit_depth;
+    }
+    return (0);
+ }
+ 
+ png_byte PNGAPI
+ png_get_color_type(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+    {
+       return info_ptr->color_type;
+    }
+    return (0);
+ }
+ 
+ png_byte PNGAPI
+ png_get_filter_type(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+    {
+       return info_ptr->filter_type;
+    }
+    return (0);
+ }
+ 
+ png_byte PNGAPI
+ png_get_interlace_type(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+    {
+       return info_ptr->interlace_type;
+    }
+    return (0);
+ }
+ 
+ png_byte PNGAPI
+ png_get_compression_type(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+    {
+       return info_ptr->compression_type;
+    }
+    return (0);
+ }
+ 
+ png_uint_32 PNGAPI
+ png_get_x_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+ #if defined(PNG_pHYs_SUPPORTED)
+    if (info_ptr->valid & PNG_INFO_pHYs)
+    {
+       png_debug1(1, "in %s retrieval function\n", "png_get_x_pixels_per_meter");
+       if(info_ptr->phys_unit_type != PNG_RESOLUTION_METER)
+           return (0);
+       else return (info_ptr->x_pixels_per_unit);
+    }
+ #else
+    return (0);
+ #endif
+    return (0);
+ }
+ 
+ png_uint_32 PNGAPI
+ png_get_y_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+ #if defined(PNG_pHYs_SUPPORTED)
+    if (info_ptr->valid & PNG_INFO_pHYs)
+    {
+       png_debug1(1, "in %s retrieval function\n", "png_get_y_pixels_per_meter");
+       if(info_ptr->phys_unit_type != PNG_RESOLUTION_METER)
+           return (0);
+       else return (info_ptr->y_pixels_per_unit);
+    }
+ #else
+    return (0);
+ #endif
+    return (0);
+ }
+ 
+ png_uint_32 PNGAPI
+ png_get_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+ #if defined(PNG_pHYs_SUPPORTED)
+    if (info_ptr->valid & PNG_INFO_pHYs)
+    {
+       png_debug1(1, "in %s retrieval function\n", "png_get_pixels_per_meter");
+       if(info_ptr->phys_unit_type != PNG_RESOLUTION_METER ||
+          info_ptr->x_pixels_per_unit != info_ptr->y_pixels_per_unit)
+           return (0);
+       else return (info_ptr->x_pixels_per_unit);
+    }
+ #else
+    return (0);
+ #endif
+    return (0);
+ }
+ 
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ float PNGAPI
+ png_get_pixel_aspect_ratio(png_structp png_ptr, png_infop info_ptr)
+    {
+    if (png_ptr != NULL && info_ptr != NULL)
+ #if defined(PNG_pHYs_SUPPORTED)
+    if (info_ptr->valid & PNG_INFO_pHYs)
+    {
+       png_debug1(1, "in %s retrieval function\n", "png_get_aspect_ratio");
+       if (info_ptr->x_pixels_per_unit == 0)
+          return ((float)0.0);
+       else
+          return ((float)((float)info_ptr->y_pixels_per_unit
+             /(float)info_ptr->x_pixels_per_unit));
+    }
+ #else
+    return (0.0);
+ #endif
+    return ((float)0.0);
+ }
+ #endif
+ 
+ png_int_32 PNGAPI
+ png_get_x_offset_microns(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+ #if defined(PNG_oFFs_SUPPORTED)
+    if (info_ptr->valid & PNG_INFO_oFFs)
+    {
+       png_debug1(1, "in %s retrieval function\n", "png_get_x_offset_microns");
+       if(info_ptr->offset_unit_type != PNG_OFFSET_MICROMETER)
+           return (0);
+       else return (info_ptr->x_offset);
+    }
+ #else
+    return (0);
+ #endif
+    return (0);
+ }
+ 
+ png_int_32 PNGAPI
+ png_get_y_offset_microns(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+ #if defined(PNG_oFFs_SUPPORTED)
+    if (info_ptr->valid & PNG_INFO_oFFs)
+    {
+       png_debug1(1, "in %s retrieval function\n", "png_get_y_offset_microns");
+       if(info_ptr->offset_unit_type != PNG_OFFSET_MICROMETER)
+           return (0);
+       else return (info_ptr->y_offset);
+    }
+ #else
+    return (0);
+ #endif
+    return (0);
+ }
+ 
+ png_int_32 PNGAPI
+ png_get_x_offset_pixels(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+ #if defined(PNG_oFFs_SUPPORTED)
+    if (info_ptr->valid & PNG_INFO_oFFs)
+    {
+       png_debug1(1, "in %s retrieval function\n", "png_get_x_offset_microns");
+       if(info_ptr->offset_unit_type != PNG_OFFSET_PIXEL)
+           return (0);
+       else return (info_ptr->x_offset);
+    }
+ #else
+    return (0);
+ #endif
+    return (0);
+ }
+ 
+ png_int_32 PNGAPI
+ png_get_y_offset_pixels(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+ #if defined(PNG_oFFs_SUPPORTED)
+    if (info_ptr->valid & PNG_INFO_oFFs)
+    {
+       png_debug1(1, "in %s retrieval function\n", "png_get_y_offset_microns");
+       if(info_ptr->offset_unit_type != PNG_OFFSET_PIXEL)
+           return (0);
+       else return (info_ptr->y_offset);
+    }
+ #else
+    return (0);
+ #endif
+    return (0);
+ }
+ 
+ #if defined(PNG_INCH_CONVERSIONS) && defined(PNG_FLOATING_POINT_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_pixels_per_inch(png_structp png_ptr, png_infop info_ptr)
+ {
+    return ((png_uint_32)((float)png_get_pixels_per_meter(png_ptr, info_ptr)
+      *.0254 +.5));
+ }
+ 
+ png_uint_32 PNGAPI
+ png_get_x_pixels_per_inch(png_structp png_ptr, png_infop info_ptr)
+ {
+    return ((png_uint_32)((float)png_get_x_pixels_per_meter(png_ptr, info_ptr)
+      *.0254 +.5));
+ }
+ 
+ png_uint_32 PNGAPI
+ png_get_y_pixels_per_inch(png_structp png_ptr, png_infop info_ptr)
+ {
+    return ((png_uint_32)((float)png_get_y_pixels_per_meter(png_ptr, info_ptr)
+      *.0254 +.5));
+ }
+ 
+ float PNGAPI
+ png_get_x_offset_inches(png_structp png_ptr, png_infop info_ptr)
+ {
+    return ((float)png_get_x_offset_microns(png_ptr, info_ptr)
+      *.00003937);
+ }
+ 
+ float PNGAPI
+ png_get_y_offset_inches(png_structp png_ptr, png_infop info_ptr)
+ {
+    return ((float)png_get_y_offset_microns(png_ptr, info_ptr)
+      *.00003937);
+ }
+ 
+ #if defined(PNG_pHYs_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_pHYs_dpi(png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
+ {
+    png_uint_32 retval = 0;
+ 
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+    {
+       png_debug1(1, "in %s retrieval function\n", "pHYs");
+       if (res_x != NULL)
+       {
+          *res_x = info_ptr->x_pixels_per_unit;
+          retval |= PNG_INFO_pHYs;
+       }
+       if (res_y != NULL)
+       {
+          *res_y = info_ptr->y_pixels_per_unit;
+          retval |= PNG_INFO_pHYs;
+       }
+       if (unit_type != NULL)
+       {
+          *unit_type = (int)info_ptr->phys_unit_type;
+          retval |= PNG_INFO_pHYs;
+          if(*unit_type == 1)
+          {
+             if (res_x != NULL) *res_x = (png_uint_32)(*res_x * .0254 + .50);
+             if (res_y != NULL) *res_y = (png_uint_32)(*res_y * .0254 + .50);
+          }
+       }
+    }
+    return (retval);
+ }
+ #endif /* PNG_pHYs_SUPPORTED */
+ #endif  /* PNG_INCH_CONVERSIONS && PNG_FLOATING_POINT_SUPPORTED */
+ 
+ /* png_get_channels really belongs in here, too, but it's been around longer */
+ 
+ #endif  /* PNG_EASY_ACCESS_SUPPORTED */
+ 
+ png_byte PNGAPI
+ png_get_channels(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+       return(info_ptr->channels);
+    else
+       return (0);
+ }
+ 
+ png_bytep PNGAPI
+ png_get_signature(png_structp png_ptr, png_infop info_ptr)
+ {
+    if (png_ptr != NULL && info_ptr != NULL)
+       return(info_ptr->signature);
+    else
+       return (NULL);
+ }
+ 
+ #if defined(PNG_bKGD_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_bKGD(png_structp png_ptr, png_infop info_ptr,
+    png_color_16p *background)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD)
+       && background != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "bKGD");
+       *background = &(info_ptr->background);
+       return (PNG_INFO_bKGD);
+    }
+    return (0);
+ }
+ #endif
+ 
+ #if defined(PNG_cHRM_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_uint_32 PNGAPI
+ png_get_cHRM(png_structp png_ptr, png_infop info_ptr,
+    double *white_x, double *white_y, double *red_x, double *red_y,
+    double *green_x, double *green_y, double *blue_x, double *blue_y)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
+    {
+       png_debug1(1, "in %s retrieval function\n", "cHRM");
+       if (white_x != NULL)
+          *white_x = (double)info_ptr->x_white;
+       if (white_y != NULL)
+          *white_y = (double)info_ptr->y_white;
+       if (red_x != NULL)
+          *red_x = (double)info_ptr->x_red;
+       if (red_y != NULL)
+          *red_y = (double)info_ptr->y_red;
+       if (green_x != NULL)
+          *green_x = (double)info_ptr->x_green;
+       if (green_y != NULL)
+          *green_y = (double)info_ptr->y_green;
+       if (blue_x != NULL)
+          *blue_x = (double)info_ptr->x_blue;
+       if (blue_y != NULL)
+          *blue_y = (double)info_ptr->y_blue;
+       return (PNG_INFO_cHRM);
+    }
+    return (0);
+ }
+ #endif
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ png_uint_32 PNGAPI
+ png_get_cHRM_fixed(png_structp png_ptr, png_infop info_ptr,
+    png_fixed_point *white_x, png_fixed_point *white_y, png_fixed_point *red_x,
+    png_fixed_point *red_y, png_fixed_point *green_x, png_fixed_point *green_y,
+    png_fixed_point *blue_x, png_fixed_point *blue_y)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
+    {
+       png_debug1(1, "in %s retrieval function\n", "cHRM");
+       if (white_x != NULL)
+          *white_x = info_ptr->int_x_white;
+       if (white_y != NULL)
+          *white_y = info_ptr->int_y_white;
+       if (red_x != NULL)
+          *red_x = info_ptr->int_x_red;
+       if (red_y != NULL)
+          *red_y = info_ptr->int_y_red;
+       if (green_x != NULL)
+          *green_x = info_ptr->int_x_green;
+       if (green_y != NULL)
+          *green_y = info_ptr->int_y_green;
+       if (blue_x != NULL)
+          *blue_x = info_ptr->int_x_blue;
+       if (blue_y != NULL)
+          *blue_y = info_ptr->int_y_blue;
+       return (PNG_INFO_cHRM);
+    }
+    return (0);
+ }
+ #endif
+ #endif
+ 
+ #if defined(PNG_gAMA_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_uint_32 PNGAPI
+ png_get_gAMA(png_structp png_ptr, png_infop info_ptr, double *file_gamma)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
+       && file_gamma != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "gAMA");
+       *file_gamma = (double)info_ptr->gamma;
+       return (PNG_INFO_gAMA);
+    }
+    return (0);
+ }
+ #endif
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ png_uint_32 PNGAPI
+ png_get_gAMA_fixed(png_structp png_ptr, png_infop info_ptr,
+     png_fixed_point *int_file_gamma)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
+       && int_file_gamma != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "gAMA");
+       *int_file_gamma = info_ptr->int_gamma;
+       return (PNG_INFO_gAMA);
+    }
+    return (0);
+ }
+ #endif
+ #endif
+ 
+ #if defined(PNG_sRGB_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_sRGB(png_structp png_ptr, png_infop info_ptr, int *file_srgb_intent)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB)
+       && file_srgb_intent != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "sRGB");
+       *file_srgb_intent = (int)info_ptr->srgb_intent;
+       return (PNG_INFO_sRGB);
+    }
+    return (0);
+ }
+ #endif
+ 
+ #if defined(PNG_iCCP_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_iCCP(png_structp png_ptr, png_infop info_ptr,
+              png_charpp name, int *compression_type,
+              png_charpp profile, png_uint_32 *proflen)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP)
+       && name != NULL && profile != NULL && proflen != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "iCCP");
+       *name = info_ptr->iccp_name;
+       *profile = info_ptr->iccp_profile;
+       /* compression_type is a dummy so the API won't have to change
+          if we introduce multiple compression types later. */
+       *proflen = (int)info_ptr->iccp_proflen;
+       *compression_type = (int)info_ptr->iccp_compression;
+       return (PNG_INFO_iCCP);
+    }
+    return (0);
+ }
+ #endif
+ 
+ #if defined(PNG_sPLT_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_sPLT(png_structp png_ptr, png_infop info_ptr,
+              png_sPLT_tpp spalettes)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && spalettes != NULL)
+      *spalettes = info_ptr->splt_palettes;
+    return ((png_uint_32)info_ptr->splt_palettes_num);
+ }
+ #endif
+ 
+ #if defined(PNG_hIST_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_16p *hist)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST)
+       && hist != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "hIST");
+       *hist = info_ptr->hist;
+       return (PNG_INFO_hIST);
+    }
+    return (0);
+ }
+ #endif
+ 
+ png_uint_32 PNGAPI
+ png_get_IHDR(png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 *width, png_uint_32 *height, int *bit_depth,
+    int *color_type, int *interlace_type, int *compression_type,
+    int *filter_type)
+ 
+ {
+    if (png_ptr != NULL && info_ptr != NULL && width != NULL && height != NULL &&
+       bit_depth != NULL && color_type != NULL)
+    {
+       int pixel_depth, channels;
+       png_uint_32 rowbytes_per_pixel;
+ 
+       png_debug1(1, "in %s retrieval function\n", "IHDR");
+       *width = info_ptr->width;
+       *height = info_ptr->height;
+       *bit_depth = info_ptr->bit_depth;
+       if (info_ptr->bit_depth < 1 || info_ptr->bit_depth > 16)
+         png_error(png_ptr, "Invalid bit depth");
+       *color_type = info_ptr->color_type;
+       if (info_ptr->color_type > 6)
+         png_error(png_ptr, "Invalid color type");
+       if (compression_type != NULL)
+          *compression_type = info_ptr->compression_type;
+       if (filter_type != NULL)
+          *filter_type = info_ptr->filter_type;
+       if (interlace_type != NULL)
+          *interlace_type = info_ptr->interlace_type;
+ 
+       /* check for potential overflow of rowbytes */
+       if (*color_type == PNG_COLOR_TYPE_PALETTE)
+          channels = 1;
+       else if (*color_type & PNG_COLOR_MASK_COLOR)
+          channels = 3;
+       else
+          channels = 1;
+       if (*color_type & PNG_COLOR_MASK_ALPHA)
+          channels++;
+       pixel_depth = *bit_depth * channels;
+       rowbytes_per_pixel = (pixel_depth + 7) >> 3;
+       if (width == 0 || *width > PNG_MAX_UINT)
+         png_error(png_ptr, "Invalid image width");
+       if (height == 0 || *height > PNG_MAX_UINT)
+         png_error(png_ptr, "Invalid image height");
+       if (*width > PNG_MAX_UINT/rowbytes_per_pixel - 64)
+       {
+          png_error(png_ptr,
+             "Width too large for libpng to process image data.");
+       }
+       return (1);
+    }
+    return (0);
+ }
+ 
+ #if defined(PNG_oFFs_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_oFFs(png_structp png_ptr, png_infop info_ptr,
+    png_int_32 *offset_x, png_int_32 *offset_y, int *unit_type)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs)
+       && offset_x != NULL && offset_y != NULL && unit_type != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "oFFs");
+       *offset_x = info_ptr->x_offset;
+       *offset_y = info_ptr->y_offset;
+       *unit_type = (int)info_ptr->offset_unit_type;
+       return (PNG_INFO_oFFs);
+    }
+    return (0);
+ }
+ #endif
+ 
+ #if defined(PNG_pCAL_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_pCAL(png_structp png_ptr, png_infop info_ptr,
+    png_charp *purpose, png_int_32 *X0, png_int_32 *X1, int *type, int *nparams,
+    png_charp *units, png_charpp *params)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL)
+       && purpose != NULL && X0 != NULL && X1 != NULL && type != NULL &&
+       nparams != NULL && units != NULL && params != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "pCAL");
+       *purpose = info_ptr->pcal_purpose;
+       *X0 = info_ptr->pcal_X0;
+       *X1 = info_ptr->pcal_X1;
+       *type = (int)info_ptr->pcal_type;
+       *nparams = (int)info_ptr->pcal_nparams;
+       *units = info_ptr->pcal_units;
+       *params = info_ptr->pcal_params;
+       return (PNG_INFO_pCAL);
+    }
+    return (0);
+ }
+ #endif
+ 
+ #if defined(PNG_sCAL_SUPPORTED)
+ #ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_uint_32 PNGAPI
+ png_get_sCAL(png_structp png_ptr, png_infop info_ptr,
+              int *unit, double *width, double *height)
+ {
+     if (png_ptr != NULL && info_ptr != NULL &&
+        (info_ptr->valid & PNG_INFO_sCAL))
+     {
+         *unit = info_ptr->scal_unit;
+         *width = info_ptr->scal_pixel_width;
+         *height = info_ptr->scal_pixel_height;
+         return (PNG_INFO_sCAL);
+     }
+     return(0);
+ }
+ #else
+ #ifdef PNG_FIXED_POINT_SUPPORTED
+ png_uint_32 PNGAPI
+ png_get_sCAL_s(png_structp png_ptr, png_infop info_ptr,
+              int *unit, png_charpp width, png_charpp height)
+ {
+     if (png_ptr != NULL && info_ptr != NULL &&
+        (info_ptr->valid & PNG_INFO_sCAL))
+     {
+         *unit = info_ptr->scal_unit;
+         *width = info_ptr->scal_s_width;
+         *height = info_ptr->scal_s_height;
+         return (PNG_INFO_sCAL);
+     }
+     return(0);
+ }
+ #endif
+ #endif
+ #endif
+ 
+ #if defined(PNG_pHYs_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_pHYs(png_structp png_ptr, png_infop info_ptr,
+    png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
+ {
+    png_uint_32 retval = 0;
+ 
+    if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs))
+    {
+       png_debug1(1, "in %s retrieval function\n", "pHYs");
+       if (res_x != NULL)
+       {
+          *res_x = info_ptr->x_pixels_per_unit;
+          retval |= PNG_INFO_pHYs;
+       }
+       if (res_y != NULL)
+       {
+          *res_y = info_ptr->y_pixels_per_unit;
+          retval |= PNG_INFO_pHYs;
+       }
+       if (unit_type != NULL)
+       {
+          *unit_type = (int)info_ptr->phys_unit_type;
+          retval |= PNG_INFO_pHYs;
+       }
+    }
+    return (retval);
+ }
+ #endif
+ 
+ png_uint_32 PNGAPI
+ png_get_PLTE(png_structp png_ptr, png_infop info_ptr, png_colorp *palette,
+    int *num_palette)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_PLTE)
+        && palette != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "PLTE");
+       *palette = info_ptr->palette;
+       *num_palette = info_ptr->num_palette;
+       png_debug1(3, "num_palette = %d\n", *num_palette);
+       return (PNG_INFO_PLTE);
+    }
+    return (0);
+ }
+ 
+ #if defined(PNG_sBIT_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_sBIT(png_structp png_ptr, png_infop info_ptr, png_color_8p *sig_bit)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT)
+       && sig_bit != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "sBIT");
+       *sig_bit = &(info_ptr->sig_bit);
+       return (PNG_INFO_sBIT);
+    }
+    return (0);
+ }
+ #endif
+ 
+ #if defined(PNG_TEXT_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_text(png_structp png_ptr, png_infop info_ptr, png_textp *text_ptr,
+    int *num_text)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && info_ptr->num_text > 0)
+    {
+       png_debug1(1, "in %s retrieval function\n",
+          (png_ptr->chunk_name[0] == '\0' ? "text"
+              : (png_const_charp)png_ptr->chunk_name));
+       if (text_ptr != NULL)
+          *text_ptr = info_ptr->text;
+       if (num_text != NULL)
+          *num_text = info_ptr->num_text;
+       return ((png_uint_32)info_ptr->num_text);
+    }
+    if (num_text != NULL)
+      *num_text = 0;
+    return(0);
+ }
+ #endif
+ 
+ #if defined(PNG_tIME_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_tIME(png_structp png_ptr, png_infop info_ptr, png_timep *mod_time)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME)
+        && mod_time != NULL)
+    {
+       png_debug1(1, "in %s retrieval function\n", "tIME");
+       *mod_time = &(info_ptr->mod_time);
+       return (PNG_INFO_tIME);
+    }
+    return (0);
+ }
+ #endif
+ 
+ #if defined(PNG_tRNS_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_tRNS(png_structp png_ptr, png_infop info_ptr,
+    png_bytep *trans, int *num_trans, png_color_16p *trans_values)
+ {
+    png_uint_32 retval = 0;
+    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+    {
+       png_debug1(1, "in %s retrieval function\n", "tRNS");
+       if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+       {
+           if (trans != NULL)
+           {
+              *trans = info_ptr->trans;
+              retval |= PNG_INFO_tRNS;
+           }
+           if (trans_values != NULL)
+              *trans_values = &(info_ptr->trans_values);
+       }
+       else /* if (info_ptr->color_type != PNG_COLOR_TYPE_PALETTE) */
+       {
+           if (trans_values != NULL)
+           {
+              *trans_values = &(info_ptr->trans_values);
+              retval |= PNG_INFO_tRNS;
+           }
+           if(trans != NULL)
+              *trans = NULL;
+       }
+       if(num_trans != NULL)
+       {
+          *num_trans = info_ptr->num_trans;
+          retval |= PNG_INFO_tRNS;
+       }
+    }
+    return (retval);
+ }
+ #endif
+ 
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ png_uint_32 PNGAPI
+ png_get_unknown_chunks(png_structp png_ptr, png_infop info_ptr,
+              png_unknown_chunkpp unknowns)
+ {
+    if (png_ptr != NULL && info_ptr != NULL && unknowns != NULL)
+      *unknowns = info_ptr->unknown_chunks;
+    return ((png_uint_32)info_ptr->unknown_chunks_num);
+ }
+ #endif
+ 
+ #if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ png_byte PNGAPI
+ png_get_rgb_to_gray_status (png_structp png_ptr)
+ {
+    return (png_byte)(png_ptr? png_ptr->rgb_to_gray_status : 0);
+ }
+ #endif
+ 
+ #if defined(PNG_USER_CHUNKS_SUPPORTED)
+ png_voidp PNGAPI
+ png_get_user_chunk_ptr(png_structp png_ptr)
+ {
+    return (png_ptr? png_ptr->user_chunk_ptr : NULL);
+ }
+ #endif
+ 
+ 
+ png_uint_32 PNGAPI
+ png_get_compression_buffer_size(png_structp png_ptr)
+ {
+    return (png_uint_32)(png_ptr? png_ptr->zbuf_size : 0L);
+ }
+ 
+ 
+ #ifndef PNG_1_0_X
+ #ifdef PNG_ASSEMBLER_CODE_SUPPORTED
+ /* this function was added to libpng 1.2.0 and should exist by default */
+ png_uint_32 PNGAPI
+ png_get_asm_flags (png_structp png_ptr)
+ {
+     return (png_uint_32)(png_ptr? png_ptr->asm_flags : 0L);
+ }
+ 
+ /* this function was added to libpng 1.2.0 and should exist by default */
+ png_uint_32 PNGAPI
+ png_get_asm_flagmask (int flag_select)
+ {
+     png_uint_32 settable_asm_flags = 0;
+ 
+     if (flag_select & PNG_SELECT_READ)
+         settable_asm_flags |=
+           PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  |
+           PNG_ASM_FLAG_MMX_READ_INTERLACE    |
+           PNG_ASM_FLAG_MMX_READ_FILTER_SUB   |
+           PNG_ASM_FLAG_MMX_READ_FILTER_UP    |
+           PNG_ASM_FLAG_MMX_READ_FILTER_AVG   |
+           PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;
+           /* no non-MMX flags yet */
+ 
+ #if 0
+     /* GRR:  no write-flags yet, either, but someday... */
+     if (flag_select & PNG_SELECT_WRITE)
+         settable_asm_flags |=
+           PNG_ASM_FLAG_MMX_WRITE_ [whatever] ;
+ #endif /* 0 */
+ 
+     return settable_asm_flags;  /* _theoretically_ settable capabilities only */
+ }
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+ 
+ 
+ #if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
+     /* GRR:  could add this:   && defined(PNG_MMX_CODE_SUPPORTED) */
+ /* this function was added to libpng 1.2.0 */
+ png_uint_32 PNGAPI
+ png_get_mmx_flagmask (int flag_select, int *compilerID)
+ {
+     png_uint_32 settable_mmx_flags = 0;
+ 
+     if (flag_select & PNG_SELECT_READ)
+         settable_mmx_flags |=
+           PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  |
+           PNG_ASM_FLAG_MMX_READ_INTERLACE    |
+           PNG_ASM_FLAG_MMX_READ_FILTER_SUB   |
+           PNG_ASM_FLAG_MMX_READ_FILTER_UP    |
+           PNG_ASM_FLAG_MMX_READ_FILTER_AVG   |
+           PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;
+ #if 0
+     /* GRR:  no MMX write support yet, but someday... */
+     if (flag_select & PNG_SELECT_WRITE)
+         settable_mmx_flags |=
+           PNG_ASM_FLAG_MMX_WRITE_ [whatever] ;
+ #endif /* 0 */
+ 
+     if (compilerID != NULL) {
+ #ifdef PNG_USE_PNGVCRD
+         *compilerID = 1;    /* MSVC */
+ #else
+ #ifdef PNG_USE_PNGGCCRD
+         *compilerID = 2;    /* gcc/gas */
+ #else
+         *compilerID = -1;   /* unknown (i.e., no asm/MMX code compiled) */
+ #endif
+ #endif
+     }
+ 
+     return settable_mmx_flags;  /* _theoretically_ settable capabilities only */
+ }
+ 
+ /* this function was added to libpng 1.2.0 */
+ png_byte PNGAPI
+ png_get_mmx_bitdepth_threshold (png_structp png_ptr)
+ {
+     return (png_byte)(png_ptr? png_ptr->mmx_bitdepth_threshold : 0);
+ }
+ 
+ /* this function was added to libpng 1.2.0 */
+ png_uint_32 PNGAPI
+ png_get_mmx_rowbytes_threshold (png_structp png_ptr)
+ {
+     return (png_uint_32)(png_ptr? png_ptr->mmx_rowbytes_threshold : 0L);
+ }
+ #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
+ #endif /* PNG_1_0_X */


Index: llvm/runtime/libpng/pngmem.c
diff -c /dev/null llvm/runtime/libpng/pngmem.c:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/pngmem.c	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,566 ----
+ 
+ /* pngmem.c - stub functions for memory allocation
+  *
+  * libpng 1.2.5 - October 3, 2002
+  * For conditions of distribution and use, see copyright notice in png.h
+  * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+  *
+  * This file provides a location for all memory allocation.  Users who
+  * need special memory handling are expected to supply replacement
+  * functions for png_malloc() and png_free(), and to use
+  * png_create_read_struct_2() and png_create_write_struct_2() to
+  * identify the replacement functions.
+  */
+ 
+ #define PNG_INTERNAL
+ #include "png.h"
+ 
+ /* Borland DOS special memory handler */
+ #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
+ /* if you change this, be sure to change the one in png.h also */
+ 
+ /* Allocate memory for a png_struct.  The malloc and memset can be replaced
+    by a single call to calloc() if this is thought to improve performance. */
+ png_voidp /* PRIVATE */
+ png_create_struct(int type)
+ {
+ #ifdef PNG_USER_MEM_SUPPORTED
+    return (png_create_struct_2(type, png_malloc_ptr_NULL, png_voidp_NULL));
+ }
+ 
+ /* Alternate version of png_create_struct, for use with user-defined malloc. */
+ png_voidp /* PRIVATE */
+ png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
+ {
+ #endif /* PNG_USER_MEM_SUPPORTED */
+    png_size_t size;
+    png_voidp struct_ptr;
+ 
+    if (type == PNG_STRUCT_INFO)
+      size = sizeof(png_info);
+    else if (type == PNG_STRUCT_PNG)
+      size = sizeof(png_struct);
+    else
+      return (png_get_copyright());
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+    if(malloc_fn != NULL)
+    {
+       png_struct dummy_struct;
+       png_structp png_ptr = &dummy_struct;
+       png_ptr->mem_ptr=mem_ptr;
+       struct_ptr = (*(malloc_fn))(png_ptr, (png_uint_32)size);
+    }
+    else
+ #endif /* PNG_USER_MEM_SUPPORTED */
+       struct_ptr = (png_voidp)farmalloc(size));
+    if (struct_ptr != NULL)
+       png_memset(struct_ptr, 0, size);
+    return (struct_ptr);
+ }
+ 
+ /* Free memory allocated by a png_create_struct() call */
+ void /* PRIVATE */
+ png_destroy_struct(png_voidp struct_ptr)
+ {
+ #ifdef PNG_USER_MEM_SUPPORTED
+    png_destroy_struct_2(struct_ptr, png_free_ptr_NULL, png_voidp_NULL);
+ }
+ 
+ /* Free memory allocated by a png_create_struct() call */
+ void /* PRIVATE */
+ png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
+     png_voidp mem_ptr)
+ {
+ #endif
+    if (struct_ptr != NULL)
+    {
+ #ifdef PNG_USER_MEM_SUPPORTED
+       if(free_fn != NULL)
+       {
+          png_struct dummy_struct;
+          png_structp png_ptr = &dummy_struct;
+          png_ptr->mem_ptr=mem_ptr;
+          (*(free_fn))(png_ptr, struct_ptr);
+          return;
+       }
+ #endif /* PNG_USER_MEM_SUPPORTED */
+       farfree (struct_ptr);
+    }
+ }
+ 
+ /* Allocate memory.  For reasonable files, size should never exceed
+  * 64K.  However, zlib may allocate more then 64K if you don't tell
+  * it not to.  See zconf.h and png.h for more information. zlib does
+  * need to allocate exactly 64K, so whatever you call here must
+  * have the ability to do that.
+  *
+  * Borland seems to have a problem in DOS mode for exactly 64K.
+  * It gives you a segment with an offset of 8 (perhaps to store its
+  * memory stuff).  zlib doesn't like this at all, so we have to
+  * detect and deal with it.  This code should not be needed in
+  * Windows or OS/2 modes, and only in 16 bit mode.  This code has
+  * been updated by Alexander Lehmann for version 0.89 to waste less
+  * memory.
+  *
+  * Note that we can't use png_size_t for the "size" declaration,
+  * since on some systems a png_size_t is a 16-bit quantity, and as a
+  * result, we would be truncating potentially larger memory requests
+  * (which should cause a fatal error) and introducing major problems.
+  */
+ 
+ png_voidp PNGAPI
+ png_malloc(png_structp png_ptr, png_uint_32 size)
+ {
+    png_voidp ret;
+ 
+    if (png_ptr == NULL || size == 0)
+       return (NULL);
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+    if(png_ptr->malloc_fn != NULL)
+    {
+        ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
+        if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+           png_error(png_ptr, "Out of memory!");
+        return (ret);
+    }
+    else
+        return png_malloc_default(png_ptr, size);
+ }
+ 
+ png_voidp PNGAPI
+ png_malloc_default(png_structp png_ptr, png_uint_32 size)
+ {
+    png_voidp ret;
+ #endif /* PNG_USER_MEM_SUPPORTED */
+ 
+ #ifdef PNG_MAX_MALLOC_64K
+    if (size > (png_uint_32)65536L)
+       png_error(png_ptr, "Cannot Allocate > 64K");
+ #endif
+ 
+    if (size == (png_uint_32)65536L)
+    {
+       if (png_ptr->offset_table == NULL)
+       {
+          /* try to see if we need to do any of this fancy stuff */
+          ret = farmalloc(size);
+          if (ret == NULL || ((png_size_t)ret & 0xffff))
+          {
+             int num_blocks;
+             png_uint_32 total_size;
+             png_bytep table;
+             int i;
+             png_byte huge * hptr;
+ 
+             if (ret != NULL)
+             {
+                farfree(ret);
+                ret = NULL;
+             }
+ 
+             if(png_ptr->zlib_window_bits > 14)
+                num_blocks = (int)(1 << (png_ptr->zlib_window_bits - 14));
+             else
+                num_blocks = 1;
+             if (png_ptr->zlib_mem_level >= 7)
+                num_blocks += (int)(1 << (png_ptr->zlib_mem_level - 7));
+             else
+                num_blocks++;
+ 
+             total_size = ((png_uint_32)65536L) * (png_uint_32)num_blocks+16;
+ 
+             table = farmalloc(total_size);
+ 
+             if (table == NULL)
+             {
+                if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+                   png_error(png_ptr, "Out Of Memory."); /* Note "O" and "M" */
+                else
+                   png_warning(png_ptr, "Out Of Memory.");
+                return (NULL);
+             }
+ 
+             if ((png_size_t)table & 0xfff0)
+             {
+                if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+                   png_error(png_ptr,
+                     "Farmalloc didn't return normalized pointer");
+                else
+                   png_warning(png_ptr,
+                     "Farmalloc didn't return normalized pointer");
+                return (NULL);
+             }
+ 
+             png_ptr->offset_table = table;
+             png_ptr->offset_table_ptr = farmalloc(num_blocks *
+                sizeof (png_bytep));
+ 
+             if (png_ptr->offset_table_ptr == NULL)
+             {
+                if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+                   png_error(png_ptr, "Out Of memory."); /* Note "O" and "M" */
+                else
+                   png_warning(png_ptr, "Out Of memory.");
+                return (NULL);
+             }
+ 
+             hptr = (png_byte huge *)table;
+             if ((png_size_t)hptr & 0xf)
+             {
+                hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
+                hptr = hptr + 16L;  /* "hptr += 16L" fails on Turbo C++ 3.0 */
+             }
+             for (i = 0; i < num_blocks; i++)
+             {
+                png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
+                hptr = hptr + (png_uint_32)65536L;  /* "+=" fails on TC++3.0 */
+             }
+ 
+             png_ptr->offset_table_number = num_blocks;
+             png_ptr->offset_table_count = 0;
+             png_ptr->offset_table_count_free = 0;
+          }
+       }
+ 
+       if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
+       {
+          if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+             png_error(png_ptr, "Out of Memory."); /* Note "o" and "M" */
+          else
+             png_warning(png_ptr, "Out of Memory.");
+          return (NULL);
+       }
+ 
+       ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
+    }
+    else
+       ret = farmalloc(size);
+ 
+    if (ret == NULL)
+    {
+       if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+          png_error(png_ptr, "Out of memory."); /* Note "o" and "m" */
+       else
+          png_warning(png_ptr, "Out of memory."); /* Note "o" and "m" */
+    }
+ 
+    return (ret);
+ }
+ 
+ /* free a pointer allocated by png_malloc().  In the default
+    configuration, png_ptr is not used, but is passed in case it
+    is needed.  If ptr is NULL, return without taking any action. */
+ void PNGAPI
+ png_free(png_structp png_ptr, png_voidp ptr)
+ {
+    if (png_ptr == NULL || ptr == NULL)
+       return;
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+    if (png_ptr->free_fn != NULL)
+    {
+       (*(png_ptr->free_fn))(png_ptr, ptr);
+       return;
+    }
+    else png_free_default(png_ptr, ptr);
+ }
+ 
+ void PNGAPI
+ png_free_default(png_structp png_ptr, png_voidp ptr)
+ {
+ #endif /* PNG_USER_MEM_SUPPORTED */
+ 
+    if (png_ptr->offset_table != NULL)
+    {
+       int i;
+ 
+       for (i = 0; i < png_ptr->offset_table_count; i++)
+       {
+          if (ptr == png_ptr->offset_table_ptr[i])
+          {
+             ptr = NULL;
+             png_ptr->offset_table_count_free++;
+             break;
+          }
+       }
+       if (png_ptr->offset_table_count_free == png_ptr->offset_table_count)
+       {
+          farfree(png_ptr->offset_table);
+          farfree(png_ptr->offset_table_ptr);
+          png_ptr->offset_table = NULL;
+          png_ptr->offset_table_ptr = NULL;
+       }
+    }
+ 
+    if (ptr != NULL)
+    {
+       farfree(ptr);
+    }
+ }
+ 
+ #else /* Not the Borland DOS special memory handler */
+ 
+ /* Allocate memory for a png_struct or a png_info.  The malloc and
+    memset can be replaced by a single call to calloc() if this is thought
+    to improve performance noticably. */
+ png_voidp /* PRIVATE */
+ png_create_struct(int type)
+ {
+ #ifdef PNG_USER_MEM_SUPPORTED
+    return (png_create_struct_2(type, png_malloc_ptr_NULL, png_voidp_NULL));
+ }
+ 
+ /* Allocate memory for a png_struct or a png_info.  The malloc and
+    memset can be replaced by a single call to calloc() if this is thought
+    to improve performance noticably. */
+ png_voidp /* PRIVATE */
+ png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
+ {
+ #endif /* PNG_USER_MEM_SUPPORTED */
+    png_size_t size;
+    png_voidp struct_ptr;
+ 
+    if (type == PNG_STRUCT_INFO)
+       size = sizeof(png_info);
+    else if (type == PNG_STRUCT_PNG)
+       size = sizeof(png_struct);
+    else
+       return (NULL);
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+    if(malloc_fn != NULL)
+    {
+       png_struct dummy_struct;
+       png_structp png_ptr = &dummy_struct;
+       png_ptr->mem_ptr=mem_ptr;
+       struct_ptr = (*(malloc_fn))(png_ptr, size);
+       if (struct_ptr != NULL)
+          png_memset(struct_ptr, 0, size);
+       return (struct_ptr);
+    }
+ #endif /* PNG_USER_MEM_SUPPORTED */
+ 
+ #if defined(__TURBOC__) && !defined(__FLAT__)
+    if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
+ #else
+ # if defined(_MSC_VER) && defined(MAXSEG_64K)
+    if ((struct_ptr = (png_voidp)halloc(size,1)) != NULL)
+ # else
+    if ((struct_ptr = (png_voidp)malloc(size)) != NULL)
+ # endif
+ #endif
+    {
+       png_memset(struct_ptr, 0, size);
+    }
+ 
+    return (struct_ptr);
+ }
+ 
+ 
+ /* Free memory allocated by a png_create_struct() call */
+ void /* PRIVATE */
+ png_destroy_struct(png_voidp struct_ptr)
+ {
+ #ifdef PNG_USER_MEM_SUPPORTED
+    png_destroy_struct_2(struct_ptr, png_free_ptr_NULL, png_voidp_NULL);
+ }
+ 
+ /* Free memory allocated by a png_create_struct() call */
+ void /* PRIVATE */
+ png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
+     png_voidp mem_ptr)
+ {
+ #endif /* PNG_USER_MEM_SUPPORTED */
+    if (struct_ptr != NULL)
+    {
+ #ifdef PNG_USER_MEM_SUPPORTED
+       if(free_fn != NULL)
+       {
+          png_struct dummy_struct;
+          png_structp png_ptr = &dummy_struct;
+          png_ptr->mem_ptr=mem_ptr;
+          (*(free_fn))(png_ptr, struct_ptr);
+          return;
+       }
+ #endif /* PNG_USER_MEM_SUPPORTED */
+ #if defined(__TURBOC__) && !defined(__FLAT__)
+       farfree(struct_ptr);
+ #else
+ # if defined(_MSC_VER) && defined(MAXSEG_64K)
+       hfree(struct_ptr);
+ # else
+       free(struct_ptr);
+ # endif
+ #endif
+    }
+ }
+ 
+ /* Allocate memory.  For reasonable files, size should never exceed
+    64K.  However, zlib may allocate more then 64K if you don't tell
+    it not to.  See zconf.h and png.h for more information.  zlib does
+    need to allocate exactly 64K, so whatever you call here must
+    have the ability to do that. */
+ 
+ png_voidp PNGAPI
+ png_malloc(png_structp png_ptr, png_uint_32 size)
+ {
+    png_voidp ret;
+ 
+    if (png_ptr == NULL || size == 0)
+       return (NULL);
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+    if(png_ptr->malloc_fn != NULL)
+    {
+        ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
+        if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+           png_error(png_ptr, "Out of Memory!");
+        return (ret);
+    }
+    else
+        return (png_malloc_default(png_ptr, size));
+ }
+ 
+ png_voidp PNGAPI
+ png_malloc_default(png_structp png_ptr, png_uint_32 size)
+ {
+    png_voidp ret;
+ #endif /* PNG_USER_MEM_SUPPORTED */
+ 
+ #ifdef PNG_MAX_MALLOC_64K
+    if (size > (png_uint_32)65536L)
+    {
+       if(png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+          png_error(png_ptr, "Cannot Allocate > 64K");
+       else
+          return NULL;
+    }
+ #endif
+ 
+ #if defined(__TURBOC__) && !defined(__FLAT__)
+    ret = farmalloc(size);
+ #else
+ # if defined(_MSC_VER) && defined(MAXSEG_64K)
+    ret = halloc(size, 1);
+ # else
+    ret = malloc((size_t)size);
+ # endif
+ #endif
+ 
+    if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
+       png_error(png_ptr, "Out of Memory");
+ 
+    return (ret);
+ }
+ 
+ /* Free a pointer allocated by png_malloc().  If ptr is NULL, return
+    without taking any action. */
+ void PNGAPI
+ png_free(png_structp png_ptr, png_voidp ptr)
+ {
+    if (png_ptr == NULL || ptr == NULL)
+       return;
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+    if (png_ptr->free_fn != NULL)
+    {
+       (*(png_ptr->free_fn))(png_ptr, ptr);
+       return;
+    }
+    else png_free_default(png_ptr, ptr);
+ }
+ void PNGAPI
+ png_free_default(png_structp png_ptr, png_voidp ptr)
+ {
+    if (png_ptr == NULL || ptr == NULL)
+       return;
+ 
+ #endif /* PNG_USER_MEM_SUPPORTED */
+ 
+ #if defined(__TURBOC__) && !defined(__FLAT__)
+    farfree(ptr);
+ #else
+ # if defined(_MSC_VER) && defined(MAXSEG_64K)
+    hfree(ptr);
+ # else
+    free(ptr);
+ # endif
+ #endif
+ }
+ 
+ #endif /* Not Borland DOS special memory handler */
+ 
+ #if defined(PNG_1_0_X)
+ #  define png_malloc_warn png_malloc
+ #else
+ /* This function was added at libpng version 1.2.3.  The png_malloc_warn()
+  * function will issue a png_warning and return NULL instead of issuing a
+  * png_error, if it fails to allocate the requested memory.
+  */
+ png_voidp PNGAPI
+ png_malloc_warn(png_structp png_ptr, png_uint_32 size)
+ {
+    png_voidp ptr;
+    png_uint_32 save_flags=png_ptr->flags;
+ 
+    png_ptr->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
+    ptr = (png_voidp)png_malloc((png_structp)png_ptr, size);
+    png_ptr->flags=save_flags;
+    return(ptr);
+ }
+ #endif
+ 
+ png_voidp PNGAPI
+ png_memcpy_check (png_structp png_ptr, png_voidp s1, png_voidp s2,
+    png_uint_32 length)
+ {
+    png_size_t size;
+ 
+    size = (png_size_t)length;
+    if ((png_uint_32)size != length)
+       png_error(png_ptr,"Overflow in png_memcpy_check.");
+ 
+    return(png_memcpy (s1, s2, size));
+ }
+ 
+ png_voidp PNGAPI
+ png_memset_check (png_structp png_ptr, png_voidp s1, int value,
+    png_uint_32 length)
+ {
+    png_size_t size;
+ 
+    size = (png_size_t)length;
+    if ((png_uint_32)size != length)
+       png_error(png_ptr,"Overflow in png_memset_check.");
+ 
+    return (png_memset (s1, value, size));
+ 
+ }
+ 
+ #ifdef PNG_USER_MEM_SUPPORTED
+ /* This function is called when the application wants to use another method
+  * of allocating and freeing memory.
+  */
+ void PNGAPI
+ png_set_mem_fn(png_structp png_ptr, png_voidp mem_ptr, png_malloc_ptr
+   malloc_fn, png_free_ptr free_fn)
+ {
+    png_ptr->mem_ptr = mem_ptr;
+    png_ptr->malloc_fn = malloc_fn;
+    png_ptr->free_fn = free_fn;
+ }
+ 
+ /* This function returns a pointer to the mem_ptr associated with the user
+  * functions.  The application should free any memory associated with this
+  * pointer before png_write_destroy and png_read_destroy are called.
+  */
+ png_voidp PNGAPI
+ png_get_mem_ptr(png_structp png_ptr)
+ {
+    return ((png_voidp)png_ptr->mem_ptr);
+ }
+ #endif /* PNG_USER_MEM_SUPPORTED */


Index: llvm/runtime/libpng/pngnow.png


Index: llvm/runtime/libpng/pngpread.c
diff -c /dev/null llvm/runtime/libpng/pngpread.c:1.1.2.1
*** /dev/null	Mon Mar  1 17:58:56 2004
--- llvm/runtime/libpng/pngpread.c	Mon Mar  1 17:58:45 2004
***************
*** 0 ****
--- 1,1543 ----
+ 
+ /* pngpread.c - read a png file in push mode
+  *
+  * libpng 1.2.5 - October 3, 2002
+  * For conditions of distribution and use, see copyright notice in png.h
+  * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+  */
+ 
+ #define PNG_INTERNAL
+ #include "png.h"
+ 
+ #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+ 
+ /* push model modes */
+ #define PNG_READ_SIG_MODE   0
+ #define PNG_READ_CHUNK_MODE 1
+ #define PNG_READ_IDAT_MODE  2
+ #define PNG_SKIP_MODE       3
+ #define PNG_READ_tEXt_MODE  4
+ #define PNG_READ_zTXt_MODE  5
+ #define PNG_READ_DONE_MODE  6
+ #define PNG_READ_iTXt_MODE  7
+ #define PNG_ERROR_MODE      8
+ 
+ void PNGAPI
+ png_process_data(png_structp png_ptr, png_infop info_ptr,
+    png_bytep buffer, png_size_t buffer_size)
+ {
+    png_push_restore_buffer(png_ptr, buffer, buffer_size);
+ 
+    while (png_ptr->buffer_size)
+    {
+       png_process_some_data(png_ptr, info_ptr);
+    }
+ }
+ 
+ /* What we do with the incoming data depends on what we were previously
+  * doing before we ran out of data...
+  */
+ void /* PRIVATE */
+ png_process_some_data(png_structp png_ptr, png_infop info_ptr)
+ {
+    switch (png_ptr->process_mode)
+    {
+       case PNG_READ_SIG_MODE:
+       {
+          png_push_read_sig(png_ptr, info_ptr);
+          break;
+       }
+       case PNG_READ_CHUNK_MODE:
+       {
+          png_push_read_chunk(png_ptr, info_ptr);
+          break;
+       }
+       case PNG_READ_IDAT_MODE:
+       {
+          png_push_read_IDAT(png_ptr);
+          break;
+       }
+ #if defined(PNG_READ_tEXt_SUPPORTED)
+       case PNG_READ_tEXt_MODE:
+       {
+          png_push_read_tEXt(png_ptr, info_ptr);
+          break;
+       }
+ #endif
+ #if defined(PNG_READ_zTXt_SUPPORTED)
+       case PNG_READ_zTXt_MODE:
+       {
+          png_push_read_zTXt(png_ptr, info_ptr);
+          break;
+       }
+ #endif
+ #if defined(PNG_READ_iTXt_SUPPORTED)
+       case PNG_READ_iTXt_MODE:
+       {
+          png_push_read_iTXt(png_ptr, info_ptr);
+          break;
+       }
+ #endif
+       case PNG_SKIP_MODE:
+       {
+          png_push_crc_finish(png_ptr);
+          break;
+       }
+       default:
+       {
+          png_ptr->buffer_size = 0;
+          break;
+       }
+    }
+ }
+ 
+ /* Read any remaining signature bytes from the stream and compare them with
+  * the correct PNG signature.  It is possible that this routine is called
+  * with bytes already read from the signature, either because they have been
+  * checked by the calling application, or because of multiple calls to this
+  * routine.
+  */
+ void /* PRIVATE */
+ png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
+ {
+    png_size_t num_checked = png_ptr->sig_bytes,
+              num_to_check = 8 - num_checked;
+ 
+    if (png_ptr->buffer_size < num_to_check)
+    {
+       num_to_check = png_ptr->buffer_size;
+    }
+ 
+    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
+       num_to_check);
+    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes+num_to_check);
+ 
+    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
+    {
+       if (num_checked < 4 &&
+           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
+          png_error(png_ptr, "Not a PNG file");
+       else
+          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
+    }
+    else
+    {
+       if (png_ptr->sig_bytes >= 8)
+       {
+          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
+       }
+    }
+ }
+ 
+ void /* PRIVATE */
+ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
+ {
+ #ifdef PNG_USE_LOCAL_ARRAYS
+       PNG_IHDR;
+       PNG_IDAT;
+       PNG_IEND;
+       PNG_PLTE;
+ #if defined(PNG_READ_bKGD_SUPPORTED)
+       PNG_bKGD;
+ #endif
+ #if defined(PNG_READ_cHRM_SUPPORTED)
+       PNG_cHRM;
+ #endif
+ #if defined(PNG_READ_gAMA_SUPPORTED)
+       PNG_gAMA;
+ #endif
+ #if defined(PNG_READ_hIST_SUPPORTED)
+       PNG_hIST;
+ #endif
+ #if defined(PNG_READ_iCCP_SUPPORTED)
+       PNG_iCCP;
+ #endif
+ #if defined(PNG_READ_iTXt_SUPPORTED)
+       PNG_iTXt;
+ #endif
+ #if defined(PNG_READ_oFFs_SUPPORTED)
+       PNG_oFFs;
+ #endif
+ #if defined(PNG_READ_pCAL_SUPPORTED)
+       PNG_pCAL;
+ #endif
+ #if defined(PNG_READ_pHYs_SUPPORTED)
+       PNG_pHYs;
+ #endif
+ #if defined(PNG_READ_sBIT_SUPPORTED)
+       PNG_sBIT;
+ #endif
+ #if defined(PNG_READ_sCAL_SUPPORTED)
+       PNG_sCAL;
+ #endif
+ #if defined(PNG_READ_sRGB_SUPPORTED)
+       PNG_sRGB;
+ #endif
+ #if defined(PNG_READ_sPLT_SUPPORTED)
+       PNG_sPLT;
+ #endif
+ #if defined(PNG_READ_tEXt_SUPPORTED)
+       PNG_tEXt;
+ #endif
+ #if defined(PNG_READ_tIME_SUPPORTED)
+       PNG_tIME;
+ #endif
+ #if defined(PNG_READ_tRNS_SUPPORTED)
+       PNG_tRNS;
+ #endif
+ #if defined(PNG_READ_zTXt_SUPPORTED)
+       PNG_zTXt;
+ #endif
+ #endif /* PNG_USE_LOCAL_ARRAYS */
+    /* First we make sure we have enough data for the 4 byte chunk name
+     * and the 4 byte chunk length before proceeding with decoding the
+     * chunk data.  To fully decode each of these chunks, we also make
+     * sure we have enough data in the buffer for the 4 byte CRC at the
+     * end of every chunk (except IDAT, which is handled separately).
+     */
+    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
+    {
+       png_byte chunk_length[4];
+ 
+       if (png_ptr->buffer_size < 8)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+ 
+       png_push_fill_buffer(png_ptr, chunk_length, 4);
+       png_ptr->push_length = png_get_uint_32(chunk_length);
+       png_reset_crc(png_ptr);
+       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
+       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
+    }
+ 
+    if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
+    }
+    else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
+    }
+    else if (!png_memcmp(png_ptr->chunk_name, (png_bytep)png_IDAT, 4))
+    {
+       /* If we reach an IDAT chunk, this means we have read all of the
+        * header chunks, and we can start reading the image (or if this
+        * is called after the image has been read - we have an error).
+        */
+      if (!(png_ptr->mode & PNG_HAVE_IHDR))
+        png_error(png_ptr, "Missing IHDR before IDAT");
+      else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+          !(png_ptr->mode & PNG_HAVE_PLTE))
+        png_error(png_ptr, "Missing PLTE before IDAT");
+ 
+       if (png_ptr->mode & PNG_HAVE_IDAT)
+       {
+          if (png_ptr->push_length == 0)
+             return;
+ 
+          if (png_ptr->mode & PNG_AFTER_IDAT)
+             png_error(png_ptr, "Too many IDAT's found");
+       }
+ 
+       png_ptr->idat_size = png_ptr->push_length;
+       png_ptr->mode |= PNG_HAVE_IDAT;
+       png_ptr->process_mode = PNG_READ_IDAT_MODE;
+       png_push_have_info(png_ptr, info_ptr);
+       png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
+       png_ptr->zstream.next_out = png_ptr->row_buf;
+       return;
+    }
+    else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
+ 
+       png_ptr->process_mode = PNG_READ_DONE_MODE;
+       png_push_have_end(png_ptr, info_ptr);
+    }
+ #if defined(PNG_READ_gAMA_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_sBIT_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_cHRM_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_sRGB_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_iCCP_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_sPLT_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_tRNS_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_bKGD_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_hIST_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_pHYs_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_oFFs_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_pCAL_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_sCAL_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_tIME_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_tEXt_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_push_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_zTXt_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_push_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+ #if defined(PNG_READ_iTXt_SUPPORTED)
+    else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_push_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ #endif
+    else
+    {
+       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+       png_push_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
+    }
+ 
+    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
+ }
+ 
+ void /* PRIVATE */
+ png_push_crc_skip(png_structp png_ptr, png_uint_32 skip)
+ {
+    png_ptr->process_mode = PNG_SKIP_MODE;
+    png_ptr->skip_length = skip;
+ }
+ 
+ void /* PRIVATE */
+ png_push_crc_finish(png_structp png_ptr)
+ {
+    if (png_ptr->skip_length && png_ptr->save_buffer_size)
+    {
+       png_size_t save_size;
+ 
+       if (png_ptr->skip_length < (png_uint_32)png_ptr->save_buffer_size)
+          save_size = (png_size_t)png_ptr->skip_length;
+       else
+          save_size = png_ptr->save_buffer_size;
+ 
+       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
+ 
+       png_ptr->skip_length -= save_size;
+       png_ptr->buffer_size -= save_size;
+       png_ptr->save_buffer_size -= save_size;
+       png_ptr->save_buffer_ptr += save_size;
+    }
+    if (png_ptr->skip_length && png_ptr->current_buffer_size)
+    {
+       png_size_t save_size;
+ 
+       if (png_ptr->skip_length < (png_uint_32)png_ptr->current_buffer_size)
+          save_size = (png_size_t)png_ptr->skip_length;
+       else
+          save_size = png_ptr->current_buffer_size;
+ 
+       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
+ 
+       png_ptr->skip_length -= save_size;
+       png_ptr->buffer_size -= save_size;
+       png_ptr->current_buffer_size -= save_size;
+       png_ptr->current_buffer_ptr += save_size;
+    }
+    if (!png_ptr->skip_length)
+    {
+       if (png_ptr->buffer_size < 4)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+ 
+       png_crc_finish(png_ptr, 0);
+       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
+    }
+ }
+ 
+ void PNGAPI
+ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
+ {
+    png_bytep ptr;
+ 
+    ptr = buffer;
+    if (png_ptr->save_buffer_size)
+    {
+       png_size_t save_size;
+ 
+       if (length < png_ptr->save_buffer_size)
+          save_size = length;
+       else
+          save_size = png_ptr->save_buffer_size;
+ 
+       png_memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
+       length -= save_size;
+       ptr += save_size;
+       png_ptr->buffer_size -= save_size;
+       png_ptr->save_buffer_size -= save_size;
+       png_ptr->save_buffer_ptr += save_size;
+    }
+    if (length && png_ptr->current_buffer_size)
+    {
+       png_size_t save_size;
+ 
+       if (length < png_ptr->current_buffer_size)
+          save_size = length;
+       else
+          save_size = png_ptr->current_buffer_size;
+ 
+       png_memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
+       png_ptr->buffer_size -= save_size;
+       png_ptr->current_buffer_size -= save_size;
+       png_ptr->current_buffer_ptr += save_size;
+    }
+ }
+ 
+ void /* PRIVATE */
+ png_push_save_buffer(png_structp png_ptr)
+ {
+    if (png_ptr->save_buffer_size)
+    {
+       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
+       {
+          png_size_t i,istop;
+          png_bytep sp;
+          png_bytep dp;
+ 
+          istop = png_ptr->save_buffer_size;
+          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
+             i < istop; i++, sp++, dp++)
+          {
+             *dp = *sp;
+          }
+       }
+    }
+    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
+       png_ptr->save_buffer_max)
+    {
+       png_size_t new_max;
+       png_bytep old_buffer;
+ 
+       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
+       old_buffer = png_ptr->save_buffer;
+       png_ptr->save_buffer = (png_bytep)png_malloc(png_ptr,
+          (png_uint_32)new_max);
+       png_memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
+       png_free(png_ptr, old_buffer);
+       png_ptr->save_buffer_max = new_max;
+    }
+    if (png_ptr->current_buffer_size)
+    {
+       png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
+          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
+       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
+       png_ptr->current_buffer_size = 0;
+    }
+    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
+    png_ptr->buffer_size = 0;
+ }
+ 
+ void /* PRIVATE */
+ png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
+    png_size_t buffer_length)
+ {
+    png_ptr->current_buffer = buffer;
+    png_ptr->current_buffer_size = buffer_length;
+    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
+    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
+ }
+ 
+ void /* PRIVATE */
+ png_push_read_IDAT(png_structp png_ptr)
+ {
+ #ifdef PNG_USE_LOCAL_ARRAYS
+    PNG_IDAT;
+ #endif
+    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
+    {
+       png_byte chunk_length[4];
+ 
+       if (png_ptr->buffer_size < 8)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+ 
+       png_push_fill_buffer(png_ptr, chunk_length, 4);
+       png_ptr->push_length = png_get_uint_32(chunk_length);
+ 
+       png_reset_crc(png_ptr);
+       png_crc_read(png_ptr, png_ptr->chunk_name, 4);
+       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
+ 
+       if (png_memcmp(png_ptr->chunk_name, (png_bytep)png_IDAT, 4))
+       {
+          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
+          if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
+             png_error(png_ptr, "Not enough compressed data");
+          return;
+       }
+ 
+       png_ptr->idat_size = png_ptr->push_length;
+    }
+    if (png_ptr->idat_size && png_ptr->save_buffer_size)
+    {
+       png_size_t save_size;
+ 
+       if (png_ptr->idat_size < (png_uint_32)png_ptr->save_buffer_size)
+       {
+          save_size = (png_size_t)png_ptr->idat_size;
+          /* check for overflow */
+          if((png_uint_32)save_size != png_ptr->idat_size)
+             png_error(png_ptr, "save_size overflowed in pngpread");
+       }
+       else
+          save_size = png_ptr->save_buffer_size;
+ 
+       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
+       if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
+          png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
+       png_ptr->idat_size -= save_size;
+       png_ptr->buffer_size -= save_size;
+       png_ptr->save_buffer_size -= save_size;
+       png_ptr->save_buffer_ptr += save_size;
+    }
+    if (png_ptr->idat_size && png_ptr->current_buffer_size)
+    {
+       png_size_t save_size;
+ 
+       if (png_ptr->idat_size < (png_uint_32)png_ptr->current_buffer_size)
+       {
+          save_size = (png_size_t)png_ptr->idat_size;
+          /* check for overflow */
+          if((png_uint_32)save_size != png_ptr->idat_size)
+             png_error(png_ptr, "save_size overflowed in pngpread");
+       }
+       else
+          save_size = png_ptr->current_buffer_size;
+ 
+       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
+       if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
+         png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
+ 
+       png_ptr->idat_size -= save_size;
+       png_ptr->buffer_size -= save_size;
+       png_ptr->current_buffer_size -= save_size;
+       png_ptr->current_buffer_ptr += save_size;
+    }
+    if (!png_ptr->idat_size)
+    {
+       if (png_ptr->buffer_size < 4)
+       {
+          png_push_save_buffer(png_ptr);
+          return;
+       }
+ 
+       png_crc_finish(png_ptr, 0);
+       png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
+       png_ptr->mode |= PNG_AFTER_IDAT;
+    }
+ }
+ 
+ void /* PRIVATE */
+ png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
+    png_size_t buffer_length)
+ {
+    int ret;
+ 
+    if ((png_ptr->flags & PNG_FLAG_ZLIB_FINISHED) && buffer_length)
+       png_error(png_ptr, "Extra compression data");
+ 
+    png_ptr->zstream.next_in = buffer;
+    png_ptr->zstream.avail_in = (uInt)buffer_length;
+    for(;;)
+    {
+       ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
+       if (ret != Z_OK)
+       {
+          if (ret == Z_STREAM_END)
+          {
+             if (png_ptr->zstream.avail_in)
+                png_error(png_ptr, "Extra compressed data");
+             if (!(png_ptr->zstream.avail_out))
+             {
+                png_push_process_row(png_ptr);
+             }
+ 
+             png_ptr->mode |= PNG_AFTER_IDAT;
+             png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+             break;
+          }
+          else if (ret == Z_BUF_ERROR)
+             break;
+          else
+             png_error(png_ptr, "Decompression Error");
+       }
+       if (!(png_ptr->zstream.avail_out))
+       {
+          if ((
+ #if defined(PNG_READ_INTERLACING_SUPPORTED)
+              png_ptr->interlaced && png_ptr->pass > 6) ||
+              (!png_ptr->interlaced &&
+ #endif
+              png_ptr->row_number == png_ptr->num_rows-1))
+          {
+            if (png_ptr->zstream.avail_in)
+              png_warning(png_ptr, "Too much data in IDAT chunks");
+            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+            break;
+          }
+          png_push_process_row(png_ptr);
+          png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
+          png_ptr->zstream.next_out = png_ptr->row_buf;
+       }
+       else
+          break;
+    }
+ }
+ 
+ void /* PRIVATE */
+ png_push_process_row(png_structp png_ptr)
+ {
+    png_ptr->row_info.color_type = png_ptr->color_type;
+    png_ptr->row_info.width = png_ptr->iwidth;
+    png_ptr->row_info.channels = png_ptr->channels;
+    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
+    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
+ 
+    png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *
+       (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
+ 
+    png_read_filter_row(png_ptr, &(png_ptr->row_info),
+       png_ptr->row_buf + 1, png_ptr->prev_row + 1,
+       (int)(png_ptr->row_buf[0]));
+ 
+    png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
+       png_ptr->rowbytes + 1);
+ 
+    if (png_ptr->transformations)
+       png_do_read_transformations(png_ptr);
+ 
+ #if defined(PNG_READ_INTERLACING_SUPPORTED)
+    /* blow up interlaced rows to full size */
+    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
+    {
+       if (png_ptr->pass < 6)
+ /*       old interface (pre-1.0.9):
+          png_do_read_interlace(&(png_ptr->row_info),
+             png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
+  */
+          png_do_read_interlace(png_ptr);
+ 
+     switch (png_ptr->pass)
+     {
+          case 0:
+          {
+             int i;
+             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
+             {
+                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
+                png_read_push_finish_row(png_ptr); /* updates png_ptr->pass */
+             }
+             if (png_ptr->pass == 2) /* pass 1 might be empty */
+             {
+                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
+                {
+                   png_push_have_row(png_ptr, png_bytep_NULL);
+                   png_read_push_finish_row(png_ptr);
+                }
+             }
+             if (png_ptr->pass == 4 && png_ptr->height <= 4)
+             {
+                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
+                {
+                   png_push_have_row(png_ptr, png_bytep_NULL);
+                   png_read_push_finish_row(png_ptr);
+                }
+             }
+             if (png_ptr->pass == 6 && png_ptr->height <= 4)
+             {
+                 png_push_have_row(png_ptr, png_bytep_NULL);
+                 png_read_push_finish_row(png_ptr);
+             }
+             break;
+          }
+          case 1:
+          {
+             int i;
+             for (i = 0; i < 8 && png_ptr->pass == 1; i++)
+             {
+                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
+                png_read_push_finish_row(png_ptr);
+             }
+             if (png_ptr->pass == 2) /* skip top 4 generated rows */
+             {
+                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
+                {
+                   png_push_have_row(png_ptr, png_bytep_NULL);
+                   png_read_push_finish_row(png_ptr);
+                }
+             }
+             break;
+          }
+          case 2:
+          {
+             int i;
+             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
+             {
+                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
+                png_read_push_finish_row(png_ptr);
+             }
+             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
+             {
+                png_push_have_row(png_ptr, png_bytep_NULL);
+                png_read_push_finish_row(png_ptr);
+             }
+             if (png_ptr->pass == 4) /* pass 3 might be empty */
+             {
+                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
+                {
+                   png_push_have_row(png_ptr, png_bytep_NULL);
+                   png_read_push_finish_row(png_ptr);
+                }
+             }
+             break;
+          }
+          case 3:
+          {
+             int i;
+             for (i = 0; i < 4 && png_ptr->pass == 3; i++)
+             {
+                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
+                png_read_push_finish_row(png_ptr);
+             }
+             if (png_ptr->pass == 4) /* skip top two generated rows */
+             {
+                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
+                {
+                   png_push_have_row(png_ptr, png_bytep_NULL);
+                   png_read_push_finish_row(png_ptr);
+                }
+             }
+             break;
+          }
+          case 4:
+          {
+             int i;
+             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
+             {
+                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
+                png_read_push_finish_row(png_ptr);
+             }
+             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
+             {
+                png_push_have_row(png_ptr, png_bytep_NULL);
+                png_read_push_finish_row(png_ptr);
+             }
+             if (png_ptr->pass == 6) /* pass 5 might be empty */
+             {
+                png_push_have_row(png_ptr, png_bytep_NULL);
+                png_read_push_finish_row(png_ptr);
+             }
+             break;
+          }
+          case 5:
+          {
+             int i;
+             for (i = 0; i < 2 && png_ptr->pass == 5; i++)
+             {
+                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
+                png_read_push_finish_row(png_ptr);
+             }
+             if (png_ptr->pass == 6) /* skip top generated row */
+             {
+                png_push_have_row(png_ptr, png_bytep_NULL);
+                png_read_push_finish_row(png_ptr);
+             }
+             break;
+          }
+          case 6:
+          {
+             png_push_have_row(png_ptr, png_ptr->row_buf + 1);
+             png_read_push_finish_row(png_ptr);
+             if (png_ptr->pass != 6)
+                break