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Diffstat (limited to 'lib/libc/string/ffs.3')
-rw-r--r-- | lib/libc/string/ffs.3 | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/lib/libc/string/ffs.3 b/lib/libc/string/ffs.3 new file mode 100644 index 0000000..bf6f5f5 --- /dev/null +++ b/lib/libc/string/ffs.3 @@ -0,0 +1,111 @@ +.\" 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 . |