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/* ffs -- find first set bit in a word, counted from least significant end.
For AMD x86-64.
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/>. */
#include <string.h>
#undef ffs
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)
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