bf2cc57012
haven't existed for years, if they ever existed. The "prototypes" are actually for macros, so they are difficult to check automatically.
191 lines
4.8 KiB
Groff
191 lines
4.8 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Paul Vixie.
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)bitstring.3 8.1 (Berkeley) 7/19/93
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.\" $Id: bitstring.3,v 1.3 1997/03/07 03:27:52 jmg Exp $
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.\"
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.Dd July 19, 1993
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.Dt BITSTRING 3
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.Os BSD 4
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.Sh NAME
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.Nm bit_alloc ,
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.Nm bit_clear ,
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.Nm bit_decl ,
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.Nm bit_ffs ,
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.Nm bit_nclear ,
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.Nm bit_nset,
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.Nm bit_set ,
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.Nm bitstr_size ,
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.Nm bit_test
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.Nd bit-string manipulation macros
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.Sh SYNOPSIS
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.Fd #include <bitstring.h>
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.Ft bitstr_t *
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.Fn bit_alloc "int nbits"
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.Ft void
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.Fn bit_decl "bitstr_t *name" "int nbits"
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.Ft void
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.Fn bit_clear "bitstr_t *name" "int bit"
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.Ft void
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.Fn bit_ffc "bitstr_t *name" "int nbits" "int *value"
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.Ft void
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.Fn bit_ffs "bitstr_t *name" "int nbits" "int *value"
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.Ft void
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.Fn bit_nclear "bitstr_t *name" "int start" "int stop"
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.Ft void
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.Fn bit_nset "bitstr_t *name" "int start" "int stop"
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.Ft void
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.Fn bit_set "bitstr_t *name" "int bit"
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.Ft int
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.Fn bitstr_size "int nbits"
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.Ft int
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.Fn bit_test "bitstr_t *name" "int bit"
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.Sh DESCRIPTION
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These macros operate on strings of bits.
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.Pp
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The macro
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.Fn bit_alloc
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returns a pointer of type
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.Dq Fa "bitstr_t *"
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to sufficient space to store
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.Fa nbits
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bits, or
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.Dv NULL
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if no space is available.
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.Pp
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The macro
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.Fn bit_decl
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allocates sufficient space to store
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.Fa nbits
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bits on the stack.
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.Pp
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The macro
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.Fn bitstr_size
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returns the number of elements of type
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.Fa bitstr_t
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necessary to store
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.Fa nbits
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bits.
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This is useful for copying bit strings.
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.Pp
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The macros
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.Fn bit_clear
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and
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.Fn bit_set
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clear or set the zero-based numbered bit
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.Fa bit ,
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in the bit string
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.Ar name .
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.Pp
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The
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.Fn bit_nset
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and
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.Fn bit_nclear
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macros
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set or clear the zero-based numbered bits from
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.Fa start
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to
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.Fa stop
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in the bit string
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.Ar name .
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.Pp
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The
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.Fn bit_test
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macro
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evaluates to non-zero if the zero-based numbered bit
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.Fa bit
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of bit string
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.Fa name
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is set, and zero otherwise.
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.Pp
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The
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.Fn bit_ffs
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macro
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stores in the location referenced by
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.Fa value
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the zero-based number of the first bit set in the array of
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.Fa nbits
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bits referenced by
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.Fa name .
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If no bits are set, the location referenced by
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.Fa value
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is set to \-1.
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.Pp
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The macro
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.Fn bit_ffc
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stores in the location referenced by
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.Fa value
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the zero-based number of the first bit not set in the array of
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.Fa nbits
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bits referenced by
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.Fa name .
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If all bits are set, the location referenced by
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.Fa value
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is set to \-1.
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.Pp
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The arguments to these macros are evaluated only once and may safely
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have side effects.
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.Sh EXAMPLE
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.Bd -literal -offset indent
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#include <limits.h>
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#include <bitstring.h>
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...
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#define LPR_BUSY_BIT 0
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#define LPR_FORMAT_BIT 1
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#define LPR_DOWNLOAD_BIT 2
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...
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#define LPR_AVAILABLE_BIT 9
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#define LPR_MAX_BITS 10
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make_lpr_available()
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{
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bitstr_t bit_decl(bitlist, LPR_MAX_BITS);
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...
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bit_nclear(bitlist, 0, LPR_MAX_BITS - 1);
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...
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if (!bit_test(bitlist, LPR_BUSY_BIT)) {
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bit_clear(bitlist, LPR_FORMAT_BIT);
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bit_clear(bitlist, LPR_DOWNLOAD_BIT);
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bit_set(bitlist, LPR_AVAILABLE_BIT);
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}
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}
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.Ed
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.Sh SEE ALSO
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.Xr malloc 3
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.Sh HISTORY
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The
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.Nm bitstring
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functions first appeared in
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.Bx 4.4 .
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