sysdeps/m68k/ffs.c

   1 /* ffs -- find first set bit in a word, counted from least significant end.
   2    For mc68020, mc68030, mc68040.
   3    This file is part of the GNU C Library.
   4    Copyright (C) 1991-2023 Free Software Foundation, Inc.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library.  If not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #define ffsl __something_else
  21 #include <string.h>
  22
  23 #undef  ffs
  24
  25 #if     defined (__GNUC__) && defined (__mc68020__)
  26
  27 int
  28 __ffs (int x)
  29 {
  30   int cnt;
  31
  32   asm ("bfffo %1{#0:#0},%0" : "=d" (cnt) : "dm" (x & -x));
  33
  34   return 32 - cnt;
  35 }
  36 weak_alias (__ffs, ffs)
  37 libc_hidden_def (__ffs)
  38 libc_hidden_builtin_def (ffs)
  39 #undef ffsl
  40 weak_alias (__ffs, ffsl)
  41
  42 #else
  43
  44 #include <string/ffs.c>
  45
  46 #endif