1 files changed, 38 insertions, 0 deletions
diff --git a/sysdeps/x86_64/ffs.c b/sysdeps/x86_64/ffs.c
new file mode 100644
index 0000000000..791e6ead70
--- /dev/null
+++ b/sysdeps/x86_64/ffs.c
@@ -0,0 +1,38 @@
+/* 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) 1991,92,93,94,97,98,2001 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.  */
+
+#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)