libc/src/string/memccpy.cpp

   1 //===-- Implementation of memccpy ----------------------------------------===//
   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 "src/string/memccpy.h"
  10
  11 #include "src/__support/common.h"
  12 #include "src/__support/macros/config.h"
  13 #include <stddef.h> // For size_t.
  14
  15 namespace LIBC_NAMESPACE_DECL {
  16
  17 LLVM_LIBC_FUNCTION(void *, memccpy,
  18                    (void *__restrict dest, const void *__restrict src, int c,
  19                     size_t count)) {
  20   unsigned char end = static_cast<unsigned char>(c);
  21   const unsigned char *uc_src = static_cast<const unsigned char *>(src);
  22   unsigned char *uc_dest = static_cast<unsigned char *>(dest);
  23   size_t i = 0;
  24   // Copy up until end is found.
  25   for (; i < count && uc_src[i] != end; ++i)
  26     uc_dest[i] = uc_src[i];
  27   // if i < count, then end must have been found, so copy end into dest and
  28   // return the byte after.
  29   if (i < count) {
  30     uc_dest[i] = uc_src[i];
  31     return uc_dest + i + 1;
  32   }
  33   return nullptr;
  34 }
  35
  36 } // namespace LIBC_NAMESPACE_DECL