FFS(3) Library Functions Manual FFS(3) NAME ffs, ffsl, ffsll, fls, flsl, flsll -- find first or last bit set in a bit string LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <strings.h> int ffs(int value); int ffsl(long value); int int ffsll(long long value); fls(int value); int flsl(long value); int flsll(long long value); DESCRIPTION The ffs(), ffsl() and ffsll() functions find the first bit set (beginning with the least significant bit) in value and return the index of that bit. The fls(), flsl() and flsll() functions find the last bit set in value and return the index of that bit. Bits are numbered starting at 1 (the least significant bit). A return value of zero from any of these functions means that the argument was zero. SEE ALSO bitstring(3) HISTORY The ffs() function appeared in 4.3BSD. Its prototype existed previously in <string.h> before it was moved to <strings.h> for IEEE Std 1003.1-2001 ("POSIX.1") compliance. The ffsl(), fls() and flsl() functions appeared in FreeBSD 5.3. The ff- sll() and flsll() functions appeared in FreeBSD 7.1. FreeBSD 8.0 October 26, 2008 FFS(3)
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