1/* Miscellaneous functions used in string implementations. Generic C version.
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 <http://www.gnu.org/licenses/>. */
18
19#ifndef _STRING_MISC_H
20#define _STRING_MISC_H 1
21
22#include <limits.h>
23#include <endian.h>
24#include <string-optype.h>
25
26/* Extract the byte at index IDX from word X, with index 0 being the
27 least significant byte. */
28static __always_inline unsigned char
29extractbyte (op_t x, unsigned int idx)
30{
31 if (__BYTE_ORDER == __LITTLE_ENDIAN)
32 return x >> (idx * CHAR_BIT);
33 else
34 return x >> (sizeof (x) - 1 - idx) * CHAR_BIT;
35}
36
37/* Setup an word with each byte being c_in. For instance, on a 64 bits
38 machine with input as 0xce the functions returns 0xcececececececece. */
39static __always_inline op_t
40repeat_bytes (unsigned char c_in)
41{
42 return ((op_t)-1 / 0xff) * c_in;
43}
44
45#endif /* _STRING_MISC_H */
46

source code of glibc/sysdeps/generic/string-misc.h