[llvm-branch-commits] [libc] [libc] Modular printf option (float only) (PR #147426)

[Alexey Samsonov via llvm-branch-commits]

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@@ -0,0 +1,55 @@
+//===-- Implementation of printf_modular for baremetal ----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/OSUtil/io.h"
+#include "src/__support/arg_list.h"
+#include "src/__support/macros/config.h"
+#include "src/stdio/printf.h"
+#include "src/stdio/printf_core/core_structs.h"
+#include "src/stdio/printf_core/printf_main.h"
+#include "src/stdio/printf_core/writer.h"
+
+#include <stdarg.h>
+#include <stddef.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace {
+
+LIBC_INLINE int stdout_write_hook(cpp::string_view new_str, void *) {
+  write_to_stdout(new_str);
+  return printf_core::WRITE_OK;
+}
+
+} // namespace
+
+LLVM_LIBC_FUNCTION(int, __printf_modular,
+                   (const char *__restrict format, ...)) {
+  va_list vlist;
+  va_start(vlist, format);
+  internal::ArgList args(vlist); // This holder class allows for easier copying
+                                 // and pointer semantics, as well as handling
+                                 // destruction automatically.
+  va_end(vlist);
+  static constexpr size_t BUFF_SIZE = 1024;
+  char buffer[BUFF_SIZE];
+
+  printf_core::WriteBuffer<printf_core::WriteMode::FLUSH_TO_STREAM> wb(
----------------
vonosmas wrote:

I will just add as a drive-by comment, that it's a tricky bug lurking here - this should be 
`printf_core::Mode<printf_core::WriteMode:: FLUSH_TO_STREAM >::value`. Needless to say, it's
easy to miss and is confusing. PR #169089 should fix it, if it can go in first.

https://github.com/llvm/llvm-project/pull/147426