1/* Swap the content of two memory blocks, overlap is NOT handled.
2 Copyright (C) 2023-2024 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <string.h>
20
21static inline void
22__memswap (void *__restrict p1, void *__restrict p2, size_t n)
23{
24 /* Use multiple small memcpys with constant size to enable inlining on most
25 targets. */
26 enum { SWAP_GENERIC_SIZE = 32 };
27 unsigned char tmp[SWAP_GENERIC_SIZE];
28 while (n > SWAP_GENERIC_SIZE)
29 {
30 memcpy (tmp, p1, SWAP_GENERIC_SIZE);
31 p1 = __mempcpy (p1, p2, SWAP_GENERIC_SIZE);
32 p2 = __mempcpy (p2, tmp, SWAP_GENERIC_SIZE);
33 n -= SWAP_GENERIC_SIZE;
34 }
35 while (n > 0)
36 {
37 unsigned char t = ((unsigned char *)p1)[--n];
38 ((unsigned char *)p1)[n] = ((unsigned char *)p2)[n];
39 ((unsigned char *)p2)[n] = t;
40 }
41}
42

source code of glibc/sysdeps/generic/memswap.h