1.\" $NetBSD: bitstring.3,v 1.13 2005/03/08 10:53:34 wiz 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. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)bitstring.3 8.1 (Berkeley) 7/19/93 33.\" 34.Dd July 19, 1993 35.Dt BITSTRING 3 36.Os 37.Sh NAME 38.Nm bit_alloc , 39.Nm bit_clear , 40.Nm bit_decl , 41.Nm bit_ffc , 42.Nm bit_ffs , 43.Nm bit_nclear , 44.Nm bit_nset , 45.Nm bit_set , 46.Nm bitstr_size , 47.Nm bit_test 48.Nd bit-string manipulation macros 49.Sh SYNOPSIS 50.In bitstring.h 51.Ft bitstr_t * 52.Fn bit_alloc "int nbits" 53.Fn bit_clear "bit_str name" "int bit" 54.Fn bit_decl "bit_str name" "int nbits" 55.Fn bit_ffc "bit_str name" "int nbits" "int *value" 56.Fn bit_ffs "bit_str name" "int nbits" "int *value" 57.Fn bit_nclear "bit_str name" "int start" "int stop" 58.Fn bit_nset "bit_str name" "int start" "int stop" 59.Fn bit_set "bit_str name" "int bit" 60.Fn bitstr_size "int nbits" 61.Fn bit_test "bit_str name" "int bit" 62.Sh DESCRIPTION 63These macros operate on strings of bits. 64.Pp 65The macro 66.Fn bit_alloc 67returns a pointer of type 68.Dq Fa "bitstr_t *" 69to sufficient space to store 70.Fa nbits 71bits, or 72.Dv NULL 73if no space is available. 74.Pp 75The macro 76.Fn bit_decl 77allocates sufficient space to store 78.Fa nbits 79bits on the stack. 80.Pp 81The macro 82.Fn bitstr_size 83returns the number of elements of type 84.Fa bitstr_t 85necessary to store 86.Fa nbits 87bits. 88This is useful for copying bit strings. 89.Pp 90The macros 91.Fn bit_clear 92and 93.Fn bit_set 94clear or set the zero-based numbered bit 95.Fa bit , 96in the bit string 97.Ar name . 98.Pp 99The 100.Fn bit_nset 101and 102.Fn bit_nclear 103macros 104set or clear the zero-based numbered bits from 105.Fa start 106to 107.Fa stop 108in the bit string 109.Ar name . 110.Pp 111The 112.Fn bit_test 113macro 114evaluates to non-zero if the zero-based numbered bit 115.Fa bit 116of bit string 117.Fa name 118is set, and zero otherwise. 119.Pp 120The 121.Fn bit_ffs 122macro 123stores in the location referenced by 124.Fa value 125the zero-based number of the first bit set in the array of 126.Fa nbits 127bits referenced by 128.Fa name . 129If no bits are set, the location referenced by 130.Fa value 131is set to \-1. 132.Pp 133The macro 134.Fn bit_ffc 135stores in the location referenced by 136.Fa value 137the zero-based number of the first bit not set in the array of 138.Fa nbits 139bits referenced by 140.Fa name . 141If all bits are set, the location referenced by 142.Fa value 143is set to \-1. 144.Pp 145The arguments to these macros are evaluated only once and may safely 146have side effects. 147.Sh EXAMPLES 148.Bd -literal -offset indent 149#include \*[Lt]limits.h\*[Gt] 150#include \*[Lt]bitstring.h\*[Gt] 151 152\&... 153#define LPR_BUSY_BIT 0 154#define LPR_FORMAT_BIT 1 155#define LPR_DOWNLOAD_BIT 2 156\&... 157#define LPR_AVAILABLE_BIT 9 158#define LPR_MAX_BITS 10 159 160make_lpr_available() 161{ 162 bitstr_t bit_decl(bitlist, LPR_MAX_BITS); 163 ... 164 bit_nclear(bitlist, 0, LPR_MAX_BITS - 1); 165 ... 166 if (!bit_test(bitlist, LPR_BUSY_BIT)) { 167 bit_clear(bitlist, LPR_FORMAT_BIT); 168 bit_clear(bitlist, LPR_DOWNLOAD_BIT); 169 bit_set(bitlist, LPR_AVAILABLE_BIT); 170 } 171} 172.Ed 173.Sh SEE ALSO 174.Xr malloc 3 175.Sh HISTORY 176The 177.Nm bitstring 178functions first appeared in 179.Bx 4.4 . 180