FFS(3) Linux Programmers Manual FFS(3)
ffs, ffsl, ffsll - find first bit set in a word
int ffs(int i);
int ffsl(long int i);
int ffsll(long long int i);
The ffs() function returns the position of the first (least signifi
cant) bit set in the word i. The least significant bit is position 1
and the most significant position is, for example, 32 or 64. The func
tions ffsll() and ffsl() do the same but take arguments of possibly
These functions return the position of the first bit set, or 0 if no
bits are set in i.
BSD systems have a prototype in .
This page is part of release 3.05 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2003-08-05 FFS(3)