diff options
Diffstat (limited to 'REORG.TODO/sysdeps/x86_64/ffs.c')
-rw-r--r-- | REORG.TODO/sysdeps/x86_64/ffs.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/x86_64/ffs.c b/REORG.TODO/sysdeps/x86_64/ffs.c new file mode 100644 index 0000000000..132812c488 --- /dev/null +++ b/REORG.TODO/sysdeps/x86_64/ffs.c @@ -0,0 +1,39 @@ +/* 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) 1991-2017 Free Software Foundation, Inc. + Contributed by Ulrich Drepper <drepper@cygnus.com>. + + 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/>. */ + +#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) |