libc/src/stdio/printf_core/writer.cpp

   1 //===-- Writer definition for printf ----------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "writer.h"
  10 #include "src/__support/CPP/string_view.h"
  11 #include "src/__support/macros/optimization.h"
  12 #include "src/stdio/printf_core/core_structs.h"
  13 #include "src/string/memory_utils/inline_memcpy.h"
  14 #include "src/string/memory_utils/inline_memset.h"
  15 #include <stddef.h>
  16
  17 namespace __llvm_libc {
  18 namespace printf_core {
  19
  20 int Writer::pad(char new_char, size_t length) {
  21   // First, fill as much of the buffer as possible with the padding char.
  22   size_t written = 0;
  23   const size_t buff_space = wb->buff_len - wb->buff_cur;
  24   // ASSERT: length > buff_space
  25   if (buff_space > 0) {
  26     inline_memset(wb->buff + wb->buff_cur, new_char, buff_space);
  27     wb->buff_cur += buff_space;
  28     written = buff_space;
  29   }
  30
  31   // Next, overflow write the rest of length using the mini_buff.
  32   constexpr size_t MINI_BUFF_SIZE = 64;
  33   char mini_buff[MINI_BUFF_SIZE];
  34   inline_memset(mini_buff, new_char, MINI_BUFF_SIZE);
  35   cpp::string_view mb_string_view(mini_buff, MINI_BUFF_SIZE);
  36   while (written + MINI_BUFF_SIZE < length) {
  37     int result = wb->overflow_write(mb_string_view);
  38     if (result != WRITE_OK)
  39       return result;
  40     written += MINI_BUFF_SIZE;
  41   }
  42   cpp::string_view mb_substr = mb_string_view.substr(0, length - written);
  43   return wb->overflow_write(mb_substr);
  44 }
  45
  46 } // namespace printf_core
  47 } // namespace __llvm_libc