1 | /* Determine the length of a string. For Intel 80x86, x>=3. |
2 | Copyright (C) 1991-2024 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 | |
21 | size_t |
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 | |