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fed8f7f7 UD |
1 | /* ffs -- find first set bit in a word, counted from least significant end. |
2 | For Intel 80x86, x>=6. | |
3 | This file is part of the GNU C Library. | |
04277e02 | 4 | Copyright (C) 1991-2019 Free Software Foundation, Inc. |
fed8f7f7 UD |
5 | Contributed by Ulrich Drepper <drepper@cygnus.com>. |
6 | ||
7 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
8 | modify it under the terms of the GNU Lesser General Public |
9 | License as published by the Free Software Foundation; either | |
10 | version 2.1 of the License, or (at your option) any later version. | |
fed8f7f7 UD |
11 | |
12 | The GNU C Library is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 15 | Lesser General Public License for more details. |
fed8f7f7 | 16 | |
41bdb6e2 | 17 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 18 | License along with the GNU C Library; if not, see |
5a82c748 | 19 | <https://www.gnu.org/licenses/>. */ |
fed8f7f7 | 20 | |
bdd421cc | 21 | #define ffsl __something_else |
fed8f7f7 UD |
22 | #include <string.h> |
23 | ||
24 | #undef ffs | |
25 | ||
26 | #ifdef __GNUC__ | |
27 | ||
28 | int | |
bd2260a2 | 29 | __ffs (int x) |
fed8f7f7 UD |
30 | { |
31 | int cnt; | |
32 | int tmp; | |
33 | ||
34 | asm ("bsfl %2,%0\n" /* Count low bits in X and store in %1. */ | |
35 | "cmovel %1,%0\n" /* If number was zero, use -1 as result. */ | |
36 | : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1)); | |
37 | ||
38 | return cnt + 1; | |
39 | } | |
40 | weak_alias (__ffs, ffs) | |
5bb43a43 | 41 | libc_hidden_def (__ffs) |
2dd18ce2 | 42 | libc_hidden_builtin_def (ffs) |
bdd421cc UD |
43 | #undef ffsl |
44 | weak_alias (__ffs, ffsl) | |
fed8f7f7 UD |
45 | |
46 | #else | |
2826ac7e | 47 | #include <string/ffs.c> |
fed8f7f7 | 48 | #endif |