newlib/libc/machine/riscv/ffs.c

   1 /* Copyright (c) 2017  SiFive Inc. All rights reserved.
   2
   3    This copyrighted material is made available to anyone wishing to use,
   4    modify, copy, or redistribute it subject to the terms and conditions
   5    of the FreeBSD License.   This program is distributed in the hope that
   6    it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
   7    including the implied warranties of MERCHANTABILITY or FITNESS FOR
   8    A PARTICULAR PURPOSE.  A copy of this license is available at
   9    http://www.opensource.org/licenses.
  10 */
  11 #include <strings.h>
  12
  13 int
  14 ffs (int word)
  15 {
  16 #if __riscv_xlen == 32
  17   return (__builtin_ffs (word));
  18 #else
  19   int i;
  20
  21   if (!word)
  22     return 0;
  23
  24   i = 0;
  25   for (;;)
  26     {
  27       if (((1 << i++) & word) != 0)
  28        return i;
  29     }
  30   return 0;
  31 #endif
  32 }