1 /* Determine the length of a string. For Intel 80x86, x>=3.
2 Copyright (C) 1991-2022 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
21 size_t
strlen(const char * str)22 strlen (const char *str)
23 {
24 int cnt;
25
26 asm("cld\n" /* Search forward. */
27 /* Some old versions of gas need `repne' instead of `repnz'. */
28 "repnz\n" /* Look for a zero byte. */
29 "scasb" /* %0, %1, %3 */ :
30 "=c" (cnt) : "D" (str), "0" (-1), "a" (0));
31
32 return -2 - cnt;
33 }
34 libc_hidden_builtin_def (strlen)
35