| 1 | /* ffs -- Find the first bit set in the parameter |
| 2 | |
| 3 | @deftypefn Supplemental int ffs (int @var{valu}) |
| 4 | |
| 5 | Find the first (least significant) bit set in @var{valu}. Bits are |
| 6 | numbered from right to left, starting with bit 1 (corresponding to the |
| 7 | value 1). If @var{valu} is zero, zero is returned. |
| 8 | |
| 9 | @end deftypefn |
| 10 | |
| 11 | */ |
| 12 | |
| 13 | int |
| 14 | ffs (valu) |
| 15 | register int valu; |
| 16 | { |
| 17 | register int bit; |
| 18 | |
| 19 | if (valu == 0) |
| 20 | return 0; |
| 21 | |
| 22 | for (bit = 1; !(valu & 1); bit++) |
| 23 | valu >>= 1; |
| 24 | |
| 25 | return bit; |
| 26 | } |
| 27 | |