mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-22 13:00:06 +00:00
48 lines
1.3 KiB
C
48 lines
1.3 KiB
C
/* ffs -- find first set bit in a word, counted from least significant end.
|
|
For Intel 80x86, x>=6.
|
|
This file is part of the GNU C Library.
|
|
Copyright (C) 1991-2023 Free Software Foundation, Inc.
|
|
|
|
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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#define ffsl __something_else
|
|
#include <string.h>
|
|
|
|
#undef ffs
|
|
|
|
#ifdef __GNUC__
|
|
|
|
int
|
|
__ffs (int x)
|
|
{
|
|
int cnt;
|
|
int tmp;
|
|
|
|
asm ("bsfl %2,%0\n" /* Count low bits in X and store in %1. */
|
|
"cmovel %1,%0\n" /* If number was zero, use -1 as result. */
|
|
: "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1));
|
|
|
|
return cnt + 1;
|
|
}
|
|
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
|