Originální popis anglicky:
ffs - find first bit set in a word
Návod, kniha: Linux Programmer's Manual
#include <strings.h>
int ffs(int i);
#define _GNU_SOURCE
#include <string.h>
int ffsl(long int i);
int ffsll(long long int i);
The
ffs() function returns the position of the first (least significant)
bit set in the word
i. The least significant bit is position 1 and the
most significant position e.g. 32 or 64. The functions
ffsll() and
ffsl() do the same but take arguments of possibly different size.
These functions return the position of the first bit set, or 0 if no bits are
set.
BSD 4.3, POSIX 1003.1-2001.
BSD systems have a prototype in
<string.h>.
