84 lines
2.4 KiB
Groff
84 lines
2.4 KiB
Groff
.\" $NetBSD: setbit.9,v 1.3 2012/12/04 18:03:37 christos Exp $
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.\"
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.\" Copyright (c) 2010 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jukka Ruohonen.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd December 4, 2012
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.Dt SETBIT 9
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.Os
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.Sh NAME
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.Nm setbit
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.Nd macros related to bitmaps
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.Sh SYNOPSIS
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.In sys/param.h
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.Ft void
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.Fn setbit "array" "x"
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.Ft void
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.Fn clrbit "array" "x"
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.Ft int
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.Fn isset "array" "x"
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.Ft int
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.Fn isclr "array" "x"
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.Sh DESCRIPTION
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The
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.Nm
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family of macros operate with bitmaps, also known as bit arrays.
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.Pp
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In a nutshell,
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.Fn setbit
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sets the bit
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.Fa x
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in
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.Fa array ,
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.Fn clrbit
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clears it,
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.Fn isset
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tests whether
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.Fa x
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is set, and
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.Fn isclr
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returns 1 if
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.Fa x
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is not set.
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.Sh EXAMPLES
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The following example declares a buffer of 10 chars,
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treating it as an array of 80 bits:
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.Bd -literal -offset indent
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char buf[10];
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\&...
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setbit(buf, 12); /* set the fifth bit in the second byte */
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.Ed
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.Sh SEE ALSO
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.Xr bitmap 3 ,
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.Xr bitstring 3
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.Sh CAVEATS
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The number of valid bits in a given array is assumed to be multiple of
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.Dv CHAR_BIT ,
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the number of bits for smallest object that is not a bit-field.
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