src/stdio/baremetal/printf.cpp

//===-- Implementation of printf 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/stdio/printf.h"
#include "src/__support/CPP/limits.h"
#include "src/__support/OSUtil/io.h"
#include "src/__support/arg_list.h"
#include "src/__support/libc_errno.h"
#include "src/__support/macros/config.h"
#include "src/stdio/printf_core/core_structs.h"
#include "src/stdio/printf_core/error_mapper.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, (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::FlushingBuffer wb(buffer, BUFF_SIZE, &stdout_write_hook,
                                 nullptr);
  printf_core::Writer writer(wb);

  auto retval = printf_core::printf_main(&writer, format, args);
  if (!retval.has_value()) {
    libc_errno = printf_core::internal_error_to_errno(retval.error());
    return -1;
  }

  int flushval = wb.flush_to_stream();
  if (flushval != printf_core::WRITE_OK) {
    libc_errno = printf_core::internal_error_to_errno(-flushval);
    return -1;
  }

  if (retval.value() > static_cast<size_t>(cpp::numeric_limits<int>::max())) {
    libc_errno =
        printf_core::internal_error_to_errno(-printf_core::OVERFLOW_ERROR);
    return -1;
  }

  return static_cast<int>(retval.value());
}

} // namespace LIBC_NAMESPACE_DECL