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c9cf6dde AJ |
1 | /* ffs -- find first set bit in a word, counted from least significant end. |
2 | For AMD x86-64. | |
3 | This file is part of the GNU C Library. | |
688903eb | 4 | Copyright (C) 1991-2018 Free Software Foundation, Inc. |
c9cf6dde AJ |
5 | Contributed by Ulrich Drepper <drepper@cygnus.com>. |
6 | ||
7 | The GNU C Library is free software; you can redistribute it and/or | |
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. | |
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 | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 PE |
18 | License along with the GNU C Library; if not, see |
19 | <http://www.gnu.org/licenses/>. */ | |
c9cf6dde AJ |
20 | |
21 | #include <string.h> | |
22 | ||
23 | #undef ffs | |
24 | ||
25 | int | |
26 | __ffs (int x) | |
27 | { | |
28 | int cnt; | |
29 | int tmp; | |
30 | ||
31 | asm ("bsfl %2,%0\n" /* Count low bits in X and store in %1. */ | |
32 | "cmovel %1,%0\n" /* If number was zero, use -1 as result. */ | |
33 | : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1)); | |
34 | ||
35 | return cnt + 1; | |
36 | } | |
37 | weak_alias (__ffs, ffs) | |
5bb43a43 | 38 | libc_hidden_def (__ffs) |
2dd18ce2 | 39 | libc_hidden_builtin_def (ffs) |