1/* $NetBSD: bitstring.h,v 1.15 2024/05/12 10:41:23 rillig Exp $ */
2
3/*
4 * Copyright (c) 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Paul Vixie.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. 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.h 8.1 (Berkeley) 7/19/93
35 */
36
37#ifndef _BITSTRING_H_
38#define _BITSTRING_H_
39
40/* modified for SV/AT and bitstring bugfix by M.R.Murphy, 11oct91
41 * bitstr_size changed gratuitously, but shorter
42 * bit_alloc spelling error fixed
43 * the following were efficient, but didn't work, they've been made to
44 * work, but are no longer as efficient :-)
45 * bit_nclear, bit_nset, bit_ffc, bit_ffs
46 */
47/*
48 * The comment above may or may not bear any resemblance to reality.
49 * This code has been maintained in a confusing way, with little
50 * information available on the provenance of much of it. "At least it
51 * works."
52 * /s/ Perry E. Metzger, 2 Feb 98
53 */
54typedef unsigned char bitstr_t;
55
56/* internal macros */
57 /* byte of the bitstring bit is in */
58#define _bit_byte(bit) \
59 (uint32_t)((bit) >> 3)
60
61 /* mask for the bit within its byte */
62#define _bit_mask(bit) \
63 (uint32_t)((1 << (uint32_t)((bit)&0x7)))
64
65/* external macros */
66 /* bytes in a bitstring of nbits bits */
67#define bitstr_size(nbits) \
68 (size_t)((uint32_t)((nbits) + 7) >> 3)
69
70 /* allocate a bitstring */
71#define bit_alloc(nbits) \
72 calloc(bitstr_size(nbits), sizeof(bitstr_t))
73
74 /* allocate a bitstring on the stack */
75#define bit_decl(name, nbits) \
76 ((name)[bitstr_size(nbits)])
77
78 /* is bit N of bitstring name set? */
79#define bit_test(name, bit) \
80 /*LINTED bitwise on signed*/((name)[_bit_byte(bit)] & _bit_mask(bit))
81
82 /* set bit N of bitstring name */
83#define bit_set(name, bit) \
84 /*LINTED bitwise on signed*/ \
85 ((name)[_bit_byte(bit)] = \
86 (unsigned char)(_bit_mask(bit) | (name)[_bit_byte(bit)]))
87
88 /* clear bit N of bitstring name */
89#define bit_clear(name, bit) \
90 /*LINTED bitwise on signed*/ \
91 ((name)[_bit_byte(bit)] &= (unsigned char)~_bit_mask(bit))
92
93 /* clear bits start ... stop in bitstring */
94#define bit_nclear(name, start, stop) do { \
95 bitstr_t *_name = name; \
96 size_t _start = start, _stop = stop; \
97 while (_start <= _stop) { \
98 bit_clear(_name, _start); \
99 _start++; \
100 } \
101} while (0)
102
103 /* set bits start ... stop in bitstring */
104#define bit_nset(name, start, stop) do { \
105 bitstr_t *_name = name; \
106 size_t _start = start, _stop = stop; \
107 while (_start <= _stop) { \
108 bit_set(_name, _start); \
109 _start++; \
110 } \
111} while (0)
112
113 /* find first bit clear in name */
114#define bit_ffc(name, nbits, value) do { \
115 const bitstr_t *_name = name; \
116 size_t _bit, _nbits = nbits; \
117 int _value = -1; \
118 for (_bit = 0; _bit < _nbits; ++_bit) \
119 if (!bit_test(_name, _bit)) { \
120 _value = _bit; \
121 break; \
122 } \
123 *(value) = _value; \
124} while (0)
125
126 /* find first bit set in name */
127#define bit_ffs(name, nbits, value) do { \
128 const bitstr_t *_name = name; \
129 size_t _bit, _nbits = nbits; \
130 int _value = -1; \
131 for (_bit = 0; _bit < _nbits; ++_bit) \
132 if (bit_test(_name, _bit)) { \
133 _value = _bit; \
134 break; \
135 } \
136 *(value) = _value; \
137} while (0)
138
139#endif /* !_BITSTRING_H_ */