[apple/libc.git] / string / ffs.3

.\" 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.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 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: src/lib/libc/string/ffs.3,v 1.5 2001/10/01 16:09:00 ru Exp $
.\"
.Dd April 19, 1994
.Dt FFS 3
.Os
.Sh NAME
.Nm ffs
.Nd find first bit set in a bit string
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In string.h
.Ft int
.Fn ffs "int value"
.Sh DESCRIPTION
The
.Fn ffs
function finds the first bit set in
.Fa value
and returns the index of that bit.
Bits are numbered starting from 1, starting at the right-most
bit.
A return value of 0 means that the argument was zero.
.Sh SEE ALSO
.Xr bitstring 3
.Sh HISTORY
The
.Fn ffs
function appeared in
.Bx 4.3 .
Commit	Line	Data
5b2abdfb	1	.\" Copyright (c) 1990, 1991, 1993
e9ce8d39 A	2	.\" The Regents of the University of California. All rights reserved.
e9ce8d39 A	3	.\"
5b2abdfb A	4	.\" This code is derived from software contributed to Berkeley by
5b2abdfb A	5	.\" Chris Torek.
e9ce8d39 A	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
5b2abdfb A	34	.\" @(#)ffs.3 8.2 (Berkeley) 4/19/94
5b2abdfb A	35	.\" $FreeBSD: src/lib/libc/string/ffs.3,v 1.5 2001/10/01 16:09:00 ru Exp $
e9ce8d39	36	.\"
5b2abdfb A	37	.Dd April 19, 1994
5b2abdfb A	38	.Dt FFS 3
e9ce8d39 A	39	.Os
e9ce8d39 A	40	.Sh NAME
5b2abdfb A	41	.Nm ffs
5b2abdfb A	42	.Nd find first bit set in a bit string
e9ce8d39 A	43	.Sh LIBRARY
	44	.Lb libc
	45	.Sh SYNOPSIS
5b2abdfb	46	.In string.h
e9ce8d39	47	.Ft int
5b2abdfb	48	.Fn ffs "int value"
e9ce8d39 A	49	.Sh DESCRIPTION
e9ce8d39 A	50	The
5b2abdfb A	51	.Fn ffs
	52	function finds the first bit set in
	53	.Fa value
	54	and returns the index of that bit.
	55	Bits are numbered starting from 1, starting at the right-most
	56	bit.
	57	A return value of 0 means that the argument was zero.
e9ce8d39	58	.Sh SEE ALSO
5b2abdfb	59	.Xr bitstring 3
e9ce8d39 A	60	.Sh HISTORY
e9ce8d39 A	61	The
5b2abdfb A	62	.Fn ffs
	63	function appeared in
	64	.Bx 4.3 .