1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (C) 1996
5 * David L. Nugent. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY DAVID L. NUGENT AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL DAVID L. NUGENT OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <stdlib.h>
30 #include <string.h>
31
32 #include "bitmap.h"
33
34 struct bitmap
bm_alloc(int size)35 bm_alloc(int size)
36 {
37 struct bitmap bm;
38 int szmap = (size / 8) + !!(size % 8);
39
40 bm.size = size;
41 bm.map = malloc(szmap);
42 if (bm.map)
43 memset(bm.map, 0, szmap);
44 return bm;
45 }
46
47 void
bm_dealloc(struct bitmap * bm)48 bm_dealloc(struct bitmap * bm)
49 {
50 free(bm->map);
51 }
52
53 static void
bm_getmask(int * pos,unsigned char * bmask)54 bm_getmask(int *pos, unsigned char *bmask)
55 {
56 *bmask = (unsigned char) (1 << (*pos % 8));
57 *pos /= 8;
58 }
59
60 void
bm_setbit(struct bitmap * bm,int pos)61 bm_setbit(struct bitmap * bm, int pos)
62 {
63 unsigned char bmask;
64
65 bm_getmask(&pos, &bmask);
66 bm->map[pos] |= bmask;
67 }
68
69 void
bm_clrbit(struct bitmap * bm,int pos)70 bm_clrbit(struct bitmap * bm, int pos)
71 {
72 unsigned char bmask;
73
74 bm_getmask(&pos, &bmask);
75 bm->map[pos] &= ~bmask;
76 }
77
78 int
bm_isset(struct bitmap * bm,int pos)79 bm_isset(struct bitmap * bm, int pos)
80 {
81 unsigned char bmask;
82
83 bm_getmask(&pos, &bmask);
84 return !!(bm->map[pos] & bmask);
85 }
86
87 int
bm_firstunset(struct bitmap * bm)88 bm_firstunset(struct bitmap * bm)
89 {
90 int szmap = (bm->size / 8) + !!(bm->size % 8);
91 int at = 0;
92 int pos = 0;
93
94 while (pos < szmap) {
95 unsigned char bmv = bm->map[pos++];
96 unsigned char bmask = 1;
97
98 while (bmask & 0xff) {
99 if ((bmv & bmask) == 0)
100 return at;
101 bmask <<= 1;
102 ++at;
103 }
104 }
105 return at;
106 }
107
108 int
bm_lastset(struct bitmap * bm)109 bm_lastset(struct bitmap * bm)
110 {
111 int szmap = (bm->size / 8) + !!(bm->size % 8);
112 int at = 0;
113 int pos = 0;
114 int ofs = 0;
115
116 while (pos < szmap) {
117 unsigned char bmv = bm->map[pos++];
118 unsigned char bmask = 1;
119
120 while (bmask & 0xff) {
121 if ((bmv & bmask) != 0)
122 ofs = at;
123 bmask <<= 1;
124 ++at;
125 }
126 }
127 return ofs;
128 }
129