1.\" $NetBSD: bitstring.3,v 1.11 2003/08/07 10:31:00 agc 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_ffs , 42.Nm bit_nclear , 43.Nm bit_nset , 44.Nm bit_set , 45.Nm bitstr_size , 46.Nm bit_test 47.Nd bit-string manipulation macros 48.Sh SYNOPSIS 49.In bitstring.h 50.Ft bitstr_t * 51.Fn bit_alloc "int nbits" 52.Fn bit_decl "bit_str name" "int nbits" 53.Fn bit_clear "bit_str name" "int bit" 54.Fn bit_ffc "bit_str name" "int nbits" "int *value" 55.Fn bit_ffs "bit_str name" "int nbits" "int *value" 56.Fn bit_nclear "bit_str name" "int start" "int stop" 57.Fn bit_nset "bit_str name" "int start" "int stop" 58.Fn bit_set "bit_str name" "int bit" 59.Fn bitstr_size "int nbits" 60.Fn bit_test "bit_str name" "int bit" 61.Sh DESCRIPTION 62These macros operate on strings of bits. 63.Pp 64The macro 65.Fn bit_alloc 66returns a pointer of type 67.Dq Fa "bitstr_t *" 68to sufficient space to store 69.Fa nbits 70bits, or 71.Dv NULL 72if no space is available. 73.Pp 74The macro 75.Fn bit_decl 76allocates sufficient space to store 77.Fa nbits 78bits on the stack. 79.Pp 80The macro 81.Fn bitstr_size 82returns the number of elements of type 83.Fa bitstr_t 84necessary to store 85.Fa nbits 86bits. 87This is useful for copying bit strings. 88.Pp 89The macros 90.Fn bit_clear 91and 92.Fn bit_set 93clear or set the zero-based numbered bit 94.Fa bit , 95in the bit string 96.Ar name . 97.Pp 98The 99.Fn bit_nset 100and 101.Fn bit_nclear 102macros 103set or clear the zero-based numbered bits from 104.Fa start 105to 106.Fa stop 107in the bit string 108.Ar name . 109.Pp 110The 111.Fn bit_test 112macro 113evaluates to non-zero if the zero-based numbered bit 114.Fa bit 115of bit string 116.Fa name 117is set, and zero otherwise. 118.Pp 119The 120.Fn bit_ffs 121macro 122stores in the location referenced by 123.Fa value 124the zero-based number of the first bit set in the array of 125.Fa nbits 126bits referenced by 127.Fa name . 128If no bits are set, the location referenced by 129.Fa value 130is set to \-1. 131.Pp 132The macro 133.Fn bit_ffc 134stores in the location referenced by 135.Fa value 136the zero-based number of the first bit not set in the array of 137.Fa nbits 138bits referenced by 139.Fa name . 140If all bits are set, the location referenced by 141.Fa value 142is set to \-1. 143.Pp 144The arguments to these macros are evaluated only once and may safely 145have side effects. 146.Sh EXAMPLES 147.Bd -literal -offset indent 148#include \*[Lt]limits.h\*[Gt] 149#include \*[Lt]bitstring.h\*[Gt] 150 151... 152#define LPR_BUSY_BIT 0 153#define LPR_FORMAT_BIT 1 154#define LPR_DOWNLOAD_BIT 2 155... 156#define LPR_AVAILABLE_BIT 9 157#define LPR_MAX_BITS 10 158 159make_lpr_available() 160{ 161 bitstr_t bit_decl(bitlist, LPR_MAX_BITS); 162 ... 163 bit_nclear(bitlist, 0, LPR_MAX_BITS - 1); 164 ... 165 if (!bit_test(bitlist, LPR_BUSY_BIT)) { 166 bit_clear(bitlist, LPR_FORMAT_BIT); 167 bit_clear(bitlist, LPR_DOWNLOAD_BIT); 168 bit_set(bitlist, LPR_AVAILABLE_BIT); 169 } 170} 171.Ed 172.Sh SEE ALSO 173.Xr malloc 3 174.Sh HISTORY 175The 176.Nm bitstring 177functions first appeared in 178.Bx 4.4 . 179