1.\" Copyright (c) 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Paul Vixie. 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)bitstring.3 8.1 (Berkeley) 7/19/93 35.\" $FreeBSD$ 36.\" 37.Dd July 19, 1993 38.Dt BITSTRING 3 39.Os 40.Sh NAME 41.Nm bit_alloc , 42.Nm bit_clear , 43.Nm bit_decl , 44.Nm bit_ffs , 45.Nm bit_nclear , 46.Nm bit_nset , 47.Nm bit_set , 48.Nm bitstr_size , 49.Nm bit_test 50.Nd bit-string manipulation macros 51.Sh SYNOPSIS 52.In bitstring.h 53.Ft bitstr_t * 54.Fn bit_alloc "int nbits" 55.Ft void 56.Fn bit_decl "bitstr_t *name" "int nbits" 57.Ft void 58.Fn bit_clear "bitstr_t *name" "int bit" 59.Ft void 60.Fn bit_ffc "bitstr_t *name" "int nbits" "int *value" 61.Ft void 62.Fn bit_ffs "bitstr_t *name" "int nbits" "int *value" 63.Ft void 64.Fn bit_nclear "bitstr_t *name" "int start" "int stop" 65.Ft void 66.Fn bit_nset "bitstr_t *name" "int start" "int stop" 67.Ft void 68.Fn bit_set "bitstr_t *name" "int bit" 69.Ft int 70.Fn bitstr_size "int nbits" 71.Ft int 72.Fn bit_test "bitstr_t *name" "int bit" 73.Sh DESCRIPTION 74These macros operate on strings of bits. 75.Pp 76The macro 77.Fn bit_alloc 78returns a pointer of type 79.Dq Fa "bitstr_t *" 80to sufficient space to store 81.Fa nbits 82bits, or 83.Dv NULL 84if no space is available. 85.Pp 86The macro 87.Fn bit_decl 88allocates sufficient space to store 89.Fa nbits 90bits on the stack. 91.Pp 92The macro 93.Fn bitstr_size 94returns the number of elements of type 95.Fa bitstr_t 96necessary to store 97.Fa nbits 98bits. 99This is useful for copying bit strings. 100.Pp 101The macros 102.Fn bit_clear 103and 104.Fn bit_set 105clear or set the zero-based numbered bit 106.Fa bit , 107in the bit string 108.Ar name . 109.Pp 110The 111.Fn bit_nset 112and 113.Fn bit_nclear 114macros 115set or clear the zero-based numbered bits from 116.Fa start 117through 118.Fa stop 119in the bit string 120.Ar name . 121.Pp 122The 123.Fn bit_test 124macro 125evaluates to non-zero if the zero-based numbered bit 126.Fa bit 127of bit string 128.Fa name 129is set, and zero otherwise. 130.Pp 131The 132.Fn bit_ffs 133macro 134stores in the location referenced by 135.Fa value 136the zero-based number of the first bit set in the array of 137.Fa nbits 138bits referenced by 139.Fa name . 140If no bits are set, the location referenced by 141.Fa value 142is set to \-1. 143.Pp 144The macro 145.Fn bit_ffc 146stores in the location referenced by 147.Fa value 148the zero-based number of the first bit not set in the array of 149.Fa nbits 150bits referenced by 151.Fa name . 152If all bits are set, the location referenced by 153.Fa value 154is set to \-1. 155.Pp 156The arguments to these macros are evaluated only once and may safely 157have side effects. 158.Sh EXAMPLES 159.Bd -literal -offset indent 160#include <limits.h> 161#include <bitstring.h> 162 163\&... 164#define LPR_BUSY_BIT 0 165#define LPR_FORMAT_BIT 1 166#define LPR_DOWNLOAD_BIT 2 167\&... 168#define LPR_AVAILABLE_BIT 9 169#define LPR_MAX_BITS 10 170 171make_lpr_available() 172{ 173 bitstr_t bit_decl(bitlist, LPR_MAX_BITS); 174 ... 175 bit_nclear(bitlist, 0, LPR_MAX_BITS - 1); 176 ... 177 if (!bit_test(bitlist, LPR_BUSY_BIT)) { 178 bit_clear(bitlist, LPR_FORMAT_BIT); 179 bit_clear(bitlist, LPR_DOWNLOAD_BIT); 180 bit_set(bitlist, LPR_AVAILABLE_BIT); 181 } 182} 183.Ed 184.Sh SEE ALSO 185.Xr malloc 3 186.Sh HISTORY 187The 188.Nm bitstring 189functions first appeared in 190.Bx 4.4 . 191