blob: 9ad58607439acd1abbba12f613b29430b12795e9 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
/* ffs -- find first set bit in a word, counted from least significant end.
For Intel 80x86, x>=3.
This file is part of the GNU C Library.
Copyright (C) 1991-2019 Free Software Foundation, Inc.
Contributed by Torbjorn Granlund (tege@sics.se).
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#define ffsl __something_else
#include <string.h>
#undef ffs
#ifdef __GNUC__
int
__ffs (int x)
{
int cnt;
int tmp;
asm ("xorl %0,%0\n" /* Set CNT to zero. */
"bsfl %2,%1\n" /* Count low bits in X and store in %1. */
"jz 1f\n" /* Jump if OK, i.e. X was non-zero. */
"leal 1(%1),%0\n" /* Return bsfl-result plus one on %0. */
"1:" : "=&a" (cnt), "=r" (tmp) : "rm" (x));
return cnt;
}
weak_alias (__ffs, ffs)
libc_hidden_def (__ffs)
libc_hidden_builtin_def (ffs)
#undef ffsl
weak_alias (__ffs, ffsl)
#else
#include <string/ffs.c>
#endif
|
