.\"	$OpenBSD: ffs.9,v 1.2 2022/09/10 08:18:06 jsg Exp $
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.Dd $Mdocdate: September 10 2022 $
.Dt FFS 9
.Os
.Sh NAME
.Nm ffs ,
.Nm fls ,
.Nm flsl
.Nd kernel library find bit routines
.Sh SYNOPSIS
.In lib/libkern/libkern.h
.Ft int
.Fn ffs "int value"
.Ft int
.Fn fls "int value"
.Ft int
.Fn flsl "long value"
.Sh DESCRIPTION
The
.Fn ffs
function finds the first bit set in
.Fa value .
It has the same semantics as its libc counterpart
.Xr ffs 3 .
.Pp
The
.Fn fls
and
.Fn flsl
functions find the last bit set in
.Fa value
and return the index of that bit.
.Sh SEE ALSO
.Xr ffs 3
.Sh STANDARDS
The
.Fn ffs
function conforms to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn ffs
function is based on a vax instruction of the same name.