newlib/libc/misc/ffs.c

   1 /*
   2 FUNCTION
   3         <<ffs>>---find first bit set in a word
   4
   5 INDEX
   6         ffs
   7
   8 SYNOPSIS
   9         #include <strings.h>
  10         int ffs(int <[word]>);
  11
  12 DESCRIPTION
  13
  14 <<ffs>> returns the first bit set in a word.
  15
  16 RETURNS
  17 <<ffs>> returns 0 if <[c]> is 0, 1 if <[c]> is odd, 2 if <[c]> is a multiple of
  18 2, etc.
  19
  20 PORTABILITY
  21 <<ffs>> is not ANSI C.
  22
  23 No supporting OS subroutines are required.  */
  24
  25 #include <strings.h>
  26
  27 int
  28 ffs(int i)
  29 {
  30
  31         return (__builtin_ffs(i));
  32 }