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Diffstat (limited to 'sysdeps/x86_64/ffsll.c')
-rw-r--r-- | sysdeps/x86_64/ffsll.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/sysdeps/x86_64/ffsll.c b/sysdeps/x86_64/ffsll.c new file mode 100644 index 0000000..7213c03 --- /dev/null +++ b/sysdeps/x86_64/ffsll.c @@ -0,0 +1,41 @@ +/* ffsll -- 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) 1991,92,93,94,97,98,2001 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#define ffsl __something_else +#include <string.h> + +#undef ffsll + +int +ffsll (long long int x) +{ + long long int cnt; + long long int tmp; + + asm ("bsfq %2,%0\n" /* Count low bits in X and store in %1. */ + "cmoveq %1,%0\n" /* If number was zero, use -1 as result. */ + : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1)); + + return cnt + 1; +} + +#undef ffsl +weak_alias (ffsll, ffsl) |