sysdeps/rs6000/ffs.c

   1 /* ffs -- find first set bit in a word, counted from least significant end.
   2    For IBM rs6000.
   3    Copyright (C) 1991, 1992 Free Software Foundation, Inc.
   4    Contributed by Torbjorn Granlund (tege@sics.se).
   5
   6 The GNU C Library is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public License as
   8 published by the Free Software Foundation; either version 2 of the
   9 License, or (at your option) any later version.
  10
  11 The GNU C Library is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with the GNU C Library; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  19 Cambridge, MA 02139, USA.  */
  20
  21 #include <ansidecl.h>
  22 #include <bstring.h>
  23
  24 #undef  ffs
  25
  26 #ifdef  __GNUC__
  27
  28 int
  29 DEFUN(ffs, (x), int x)
  30 {
  31   int cnt;
  32
  33   asm ("cntlz %0,%1" : "=r" (cnt) : "r" (x & -x));
  34   return 32 - cnt;
  35 }
  36
  37 #else
  38 #include <sysdeps/generic/ffs.c>
  39 #endif