ffs—find first bit set in a word #include <strings.h>
int ffs(int word);
Description
ffs returns the first bit set in a word.
Returns
ffs returns 0 if c is 0, 1 if c is odd, 2 if c is a multiple of
2, etc.
Portability
ffs is not ANSI C.
No supporting OS subroutines are required.