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, 1997 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Torbjorn Granlund (tege@sics.se).
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Library General Public License as
   9    published by the Free Software Foundation; either version 2 of the
  10    License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Library General Public License for more details.
  16
  17    You should have received a copy of the GNU Library General Public
  18    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  19    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include <string.h>
  23
  24 #undef  ffs
  25
  26 #ifdef  __GNUC__
  27
  28 int
  29 ffs (x)
  30      int x;
  31 {
  32   int cnt;
  33
  34   asm ("cntlz %0,%1" : "=r" (cnt) : "r" (x & -x));
  35   return 32 - cnt;
  36 }
  37
  38 #else
  39 #include <sysdeps/generic/ffs.c>
  40 #endif