1.\" $NetBSD: bitstring.3,v 1.16 2015/11/20 20:41:58 christos 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 November 20, 2015 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_decl "bitstr_t *name" "size_t nbits" 53.Ft bitstr_t * 54.Fn bit_alloc "size_t nbits" 55.Fn bit_clear "bitstr_t *name" "size_t bit" 56.Fn bit_ffc "const bitstr_t *name" "size_t nbits" "int *value" 57.Fn bit_ffs "const bitstr_t *name" "size_t nbits" "int *value" 58.Fn bit_nclear "bitstr_t *name" "size_t start" "size_t stop" 59.Fn bit_nset "bitstr_t *name" "size_t start" "size_t stop" 60.Fn bit_set "bitstr_t *name" "size_t bit" 61.Fn bitstr_size "size_t nbits" 62.Fn bit_test "const bitstr_t *name" "size_t bit" 63.Sh DESCRIPTION 64These macros operate on strings of bits. 65.Pp 66The macro 67.Fn bit_alloc 68returns a pointer of type 69.Dq Fa "bitstr_t" 70to sufficient space to store 71.Fa nbits 72bits, or 73.Dv NULL 74if no space is available. 75.Pp 76The macro 77.Fn bit_decl 78allocates sufficient space to store 79.Fa nbits 80bits on the stack. 81.Pp 82The macro 83.Fn bitstr_size 84returns the number of elements of type 85.Fa bitstr_t 86necessary to store 87.Fa nbits 88bits. 89This is useful for copying bit strings. 90.Pp 91The macros 92.Fn bit_clear 93and 94.Fn bit_set 95clear or set the zero-based numbered bit 96.Fa bit , 97in the bit string 98.Ar name . 99.Pp 100The 101.Fn bit_nset 102and 103.Fn bit_nclear 104macros 105set or clear the zero-based numbered bits from 106.Fa start 107to 108.Fa stop 109in the bit string 110.Ar name . 111.Pp 112The 113.Fn bit_test 114macro 115evaluates to non-zero if the zero-based numbered bit 116.Fa bit 117of bit string 118.Fa name 119is set, and zero otherwise. 120.Pp 121The 122.Fn bit_ffs 123macro 124stores in the location referenced by 125.Fa value 126the zero-based number of the first bit set in the array of 127.Fa nbits 128bits referenced by 129.Fa name . 130If no bits are set, the location referenced by 131.Fa value 132is set to \-1. 133.Pp 134The macro 135.Fn bit_ffc 136stores in the location referenced by 137.Fa value 138the zero-based number of the first bit not set in the array of 139.Fa nbits 140bits referenced by 141.Fa name . 142If all bits are set, the location referenced by 143.Fa value 144is set to \-1. 145.Pp 146The arguments to these macros are evaluated only once and may safely 147have side effects. 148.Sh EXAMPLES 149.Bd -literal -offset indent 150#include \*[Lt]limits.h\*[Gt] 151#include \*[Lt]bitstring.h\*[Gt] 152 153\&... 154#define LPR_BUSY_BIT 0 155#define LPR_FORMAT_BIT 1 156#define LPR_DOWNLOAD_BIT 2 157\&... 158#define LPR_AVAILABLE_BIT 9 159#define LPR_MAX_BITS 10 160 161void 162make_lpr_available(void) 163{ 164 bitstr_t bit_decl(bitlist, LPR_MAX_BITS); 165 ... 166 bit_nclear(bitlist, 0, LPR_MAX_BITS - 1); 167 ... 168 if (!bit_test(bitlist, LPR_BUSY_BIT)) { 169 bit_clear(bitlist, LPR_FORMAT_BIT); 170 bit_clear(bitlist, LPR_DOWNLOAD_BIT); 171 bit_set(bitlist, LPR_AVAILABLE_BIT); 172 } 173} 174.Ed 175.Sh SEE ALSO 176.Xr bitmap 3 , 177.Xr calloc 3 , 178.Xr setbit 9 179.Sh HISTORY 180The 181.Nm bitstring 182functions first appeared in 183.Bx 4.4 . 184