xref: /llvm-project/libc/src/string/memccpy.cpp (revision db8a88fef87e921c331c71503f73a76337c121c9)
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 <stddef.h> // For size_t.
13 
14 namespace __llvm_libc {
15 
16 LLVM_LIBC_FUNCTION(void *, memccpy,
17                    (void *__restrict dest, const void *__restrict src, int c,
18                     size_t count)) {
19   unsigned char end = static_cast<unsigned char>(c);
20   const unsigned char *ucSrc = static_cast<const unsigned char *>(src);
21   unsigned char *ucDest = static_cast<unsigned char *>(dest);
22   size_t i = 0;
23   // Copy up until end is found.
24   for (; i < count && ucSrc[i] != end; ++i)
25     ucDest[i] = ucSrc[i];
26   // if i < count, then end must have been found, so copy end into dest and
27   // return the byte after.
28   if (i < count) {
29     ucDest[i] = ucSrc[i];
30     return ucDest + i + 1;
31   }
32   return nullptr;
33 }
34 
35 } // namespace __llvm_libc
36