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+.\" Copyright (c) 1990, 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek.
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     @(#)ffs.3	8.2 (Berkeley) 4/19/94
+.\" $FreeBSD$
+.\"
+.Dd May 3, 2011
+.Dt FFS 3
+.Os
+.Sh NAME
+.Nm ffs ,
+.Nm ffsl ,
+.Nm ffsll ,
+.Nm fls ,
+.Nm flsl ,
+.Nm flsll
+.Nd find first or last bit set in a bit string
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In strings.h
+.Ft int
+.Fn ffs "int value"
+.Ft int
+.Fn ffsl "long value"
+.Ft int
+.Fn ffsll "long long value"
+.Ft int
+.Fn fls "int value"
+.Ft int
+.Fn flsl "long value"
+.Ft int
+.Fn flsll "long long value"
+.Sh DESCRIPTION
+The
+.Fn ffs ,
+.Fn ffsl
+and
+.Fn ffsll
+functions find the first bit set
+(beginning with the least significant bit)
+in
+.Fa value
+and return the index of that bit.
+.Pp
+The
+.Fn fls ,
+.Fn flsl
+and
+.Fn flsll
+functions find the last bit set in
+.Fa value
+and return the index of that bit.
+.Pp
+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.
+.Sh SEE ALSO
+.Xr bitstring 3
+.Sh HISTORY
+The
+.Fn ffs
+function appeared in
+.Bx 4.3 .
+Its prototype existed previously in
+.In string.h
+before it was moved to
+.In strings.h
+for
+.St -p1003.1-2001
+compliance.
+.Pp
+The
+.Fn ffsl ,
+.Fn fls
+and
+.Fn flsl
+functions appeared in
+.Fx 5.3 .
+The
+.Fn ffsll
+and
+.Fn flsll
+functions appeared in
+.Fx 7.1 .