1.\" $NetBSD: bitstring.3,v 1.9 2002/02/13 08:17:28 ross Exp $ 2.\" 3.\" Copyright (c) 1989, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Paul Vixie. 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)bitstring.3 8.1 (Berkeley) 7/19/93 37.\" 38.Dd July 19, 1993 39.Dt BITSTRING 3 40.Os 41.Sh NAME 42.Nm bit_alloc , 43.Nm bit_clear , 44.Nm bit_decl , 45.Nm bit_ffs , 46.Nm bit_nclear , 47.Nm bit_nset , 48.Nm bit_set , 49.Nm bitstr_size , 50.Nm bit_test 51.Nd bit-string manipulation macros 52.Sh SYNOPSIS 53.Fd #include \*[Lt]bitstring.h\*[Gt] 54.Ft bitstr_t * 55.Fn bit_alloc "int nbits" 56.Fn bit_decl "bit_str name" "int nbits" 57.Fn bit_clear "bit_str name" "int bit" 58.Fn bit_ffc "bit_str name" "int nbits" "int *value" 59.Fn bit_ffs "bit_str name" "int nbits" "int *value" 60.Fn bit_nclear "bit_str name" "int start" "int stop" 61.Fn bit_nset "bit_str name" "int start" "int stop" 62.Fn bit_set "bit_str name" "int bit" 63.Fn bitstr_size "int nbits" 64.Fn bit_test "bit_str name" "int bit" 65.Sh DESCRIPTION 66These macros operate on strings of bits. 67.Pp 68The macro 69.Fn bit_alloc 70returns a pointer of type 71.Dq Fa "bitstr_t *" 72to sufficient space to store 73.Fa nbits 74bits, or 75.Dv NULL 76if no space is available. 77.Pp 78The macro 79.Fn bit_decl 80allocates sufficient space to store 81.Fa nbits 82bits on the stack. 83.Pp 84The macro 85.Fn bitstr_size 86returns the number of elements of type 87.Fa bitstr_t 88necessary to store 89.Fa nbits 90bits. 91This is useful for copying bit strings. 92.Pp 93The macros 94.Fn bit_clear 95and 96.Fn bit_set 97clear or set the zero-based numbered bit 98.Fa bit , 99in the bit string 100.Ar name . 101.Pp 102The 103.Fn bit_nset 104and 105.Fn bit_nclear 106macros 107set or clear the zero-based numbered bits from 108.Fa start 109to 110.Fa stop 111in the bit string 112.Ar name . 113.Pp 114The 115.Fn bit_test 116macro 117evaluates to non-zero if the zero-based numbered bit 118.Fa bit 119of bit string 120.Fa name 121is set, and zero otherwise. 122.Pp 123The 124.Fn bit_ffs 125macro 126stores in the location referenced by 127.Fa value 128the zero-based number of the first bit set in the array of 129.Fa nbits 130bits referenced by 131.Fa name . 132If no bits are set, the location referenced by 133.Fa value 134is set to \-1. 135.Pp 136The macro 137.Fn bit_ffc 138stores in the location referenced by 139.Fa value 140the zero-based number of the first bit not set in the array of 141.Fa nbits 142bits referenced by 143.Fa name . 144If all bits are set, the location referenced by 145.Fa value 146is set to \-1. 147.Pp 148The arguments to these macros are evaluated only once and may safely 149have side effects. 150.Sh EXAMPLES 151.Bd -literal -offset indent 152#include \*[Lt]limits.h\*[Gt] 153#include \*[Lt]bitstring.h\*[Gt] 154 155... 156#define LPR_BUSY_BIT 0 157#define LPR_FORMAT_BIT 1 158#define LPR_DOWNLOAD_BIT 2 159... 160#define LPR_AVAILABLE_BIT 9 161#define LPR_MAX_BITS 10 162 163make_lpr_available() 164{ 165 bitstr_t bit_decl(bitlist, LPR_MAX_BITS); 166 ... 167 bit_nclear(bitlist, 0, LPR_MAX_BITS - 1); 168 ... 169 if (!bit_test(bitlist, LPR_BUSY_BIT)) { 170 bit_clear(bitlist, LPR_FORMAT_BIT); 171 bit_clear(bitlist, LPR_DOWNLOAD_BIT); 172 bit_set(bitlist, LPR_AVAILABLE_BIT); 173 } 174} 175.Ed 176.Sh SEE ALSO 177.Xr malloc 3 178.Sh HISTORY 179The 180.Nm bitstring 181functions first appeared in 182.Bx 4.4 . 183