ffs.3 revision 163274
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.
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This product includes software developed by the University of
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THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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@(#)ffs.3 8.2 (Berkeley) 4/19/94
$FreeBSD: head/lib/libc/string/ffs.3 163274 2006-10-12 15:08:41Z ru $
.Dd October 12, 2006 .Dt FFS 3 .Os .Sh NAME .Nm ffs , .Nm ffsl , .Nm fls , .Nm flsl .Nd find first or last bit set in a bit string .Sh LIBRARY .Lb libc .Sh SYNOPSIS n strings.h .Ft int .Fn ffs "int value" .Ft int .Fn ffsl "long value" .Ft int .Fn fls "int value" .Ft int .Fn flsl "long value" .Sh DESCRIPTION The .Fn ffs and .Fn ffsl functions find the first bit set (beginning with the least significant bit) in .Fa value and return the index of that bit.
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: head/lib/libc/string/ffs.3 163274 2006-10-12 15:08:41Z ru $
.Dd October 12, 2006 .Dt FFS 3 .Os .Sh NAME .Nm ffs , .Nm ffsl , .Nm fls , .Nm flsl .Nd find first or last bit set in a bit string .Sh LIBRARY .Lb libc .Sh SYNOPSIS n strings.h .Ft int .Fn ffs "int value" .Ft int .Fn ffsl "long value" .Ft int .Fn fls "int value" .Ft int .Fn flsl "long value" .Sh DESCRIPTION The .Fn ffs and .Fn ffsl functions find the first bit set (beginning with the least significant bit) in .Fa value and return the index of that bit.
p The .Fn fls and .Fn flsl functions find the last bit set in .Fa value and return the index of that bit.
p 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 x 4.3 . Its prototype existed previously in n string.h before it was moved to n strings.h for .St -p1003.1-2001 compliance.
p The .Fn ffsl , .Fn fls and .Fn flsl functions appeared in .Fx 5.3 .