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7b78baae DD |
1 | /* ffs -- Find the first bit set in the parameter |
2 | ||
ba19b94f | 3 | @deftypefn Supplemental int ffs (int @var{valu}) |
7b78baae | 4 | |
5d852400 | 5 | Find the first (least significant) bit set in @var{valu}. Bits are |
ba19b94f DD |
6 | numbered from right to left, starting with bit 1 (corresponding to the |
7 | value 1). If @var{valu} is zero, zero is returned. | |
7b78baae | 8 | |
ba19b94f | 9 | @end deftypefn |
7b78baae DD |
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 |