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Diffstat (limited to 'sysdeps/i386/i686/ffs.c')
-rw-r--r-- | sysdeps/i386/i686/ffs.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/sysdeps/i386/i686/ffs.c b/sysdeps/i386/i686/ffs.c new file mode 100644 index 0000000000..c858b31a78 --- /dev/null +++ b/sysdeps/i386/i686/ffs.c @@ -0,0 +1,45 @@ +/* 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, 92, 93, 94, 97, 98 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 Library General Public License as + published by the Free Software Foundation; either version 2 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <string.h> + +#undef ffs + +#ifdef __GNUC__ + +int +__ffs (x) + 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) + +#else +#include <sysdeps/generic/ffs.c> +#endif |