[Libclc-dev] [PATCH v3 1/1] Implement log10

[Jan Vesely]

v2: Use constant and multiplication instead of division
v3: Use hex constants

Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
---

So I understand the idea is to use only representable values as constants,
and not rely on the compiler to do the rounding, correct?

jan

 generic/include/clc/clc.h        |  1 +
 generic/include/clc/math/log10.h |  9 +++++++++
 generic/lib/SOURCES              |  1 +
 generic/lib/math/log10.cl        |  8 ++++++++
 generic/lib/math/log10.inc       | 13 +++++++++++++
 5 files changed, 32 insertions(+)
 create mode 100644 generic/include/clc/math/log10.h
 create mode 100644 generic/lib/math/log10.cl
 create mode 100644 generic/lib/math/log10.inc

diff --git a/generic/include/clc/clc.h b/generic/include/clc/clc.h
index bd92fdb..29c1855 100644
--- a/generic/include/clc/clc.h
+++ b/generic/include/clc/clc.h
@@ -50,6 +50,7 @@
 #include <clc/math/fmod.h>
 #include <clc/math/hypot.h>
 #include <clc/math/log.h>
+#include <clc/math/log10.h>
 #include <clc/math/log1p.h>
 #include <clc/math/log2.h>
 #include <clc/math/mad.h>
diff --git a/generic/include/clc/math/log10.h b/generic/include/clc/math/log10.h
new file mode 100644
index 0000000..ec4e4ae
--- /dev/null
+++ b/generic/include/clc/math/log10.h
@@ -0,0 +1,9 @@
+#undef log10
+
+#define __CLC_BODY <clc/math/unary_decl.inc>
+#define __CLC_FUNCTION log10
+
+#include <clc/math/gentype.inc>
+
+#undef __CLC_BODY
+#undef __CLC_FUNCTION
diff --git a/generic/lib/SOURCES b/generic/lib/SOURCES
index b76fec9..1032606 100644
--- a/generic/lib/SOURCES
+++ b/generic/lib/SOURCES
@@ -63,6 +63,7 @@ math/fmax.cl
 math/fmin.cl
 math/fmod.cl
 math/hypot.cl
+math/log10.cl
 math/log1p.cl
 math/mad.cl
 math/mix.cl
diff --git a/generic/lib/math/log10.cl b/generic/lib/math/log10.cl
new file mode 100644
index 0000000..d65764a
--- /dev/null
+++ b/generic/lib/math/log10.cl
@@ -0,0 +1,8 @@
+#include <clc/clc.h>
+
+#ifdef cl_khr_fp64
+#pragma OPENCL EXTENSION cl_khr_fp64 : enable
+#endif
+
+#define __CLC_BODY <log10.inc>
+#include <clc/math/gentype.inc>
diff --git a/generic/lib/math/log10.inc b/generic/lib/math/log10.inc
new file mode 100644
index 0000000..423308a
--- /dev/null
+++ b/generic/lib/math/log10.inc
@@ -0,0 +1,13 @@
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE log10(__CLC_GENTYPE val) {
+  // log10(x) = log2(x) / log2(10)
+  // 1 / log2(10) = 0.30102999566 = log10(2)
+  // SP representation is 0.30103 (0x1.344136p-2)
+  // DP representation is 0.301029995659999993762312442414(0x1.34413509E61D8p-2)
+#if __CLC_FPSIZE == 32
+  return log2(val) * 0x1.344136p-2f;
+#elif __CLC_FPSIZE == 64
+  return log2(val) * 0x1.34413509E61D8p-2;
+#else
+#error unknown _CLC_FPSIZE
+#endif
+}
-- 
2.1.0