bitmap.c revision 20302 
1/*-
2 * Copyright (C) 1996
3 *	David L. Nugent.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY DAVID L. NUGENT AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL DAVID L. NUGENT OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 *	$Id: bitmap.c,v 1.1.1.1 1996/12/09 14:05:35 joerg Exp $
27 */
28
29#include <stdlib.h>
30#include <string.h>
31
32#include "bitmap.h"
33
34struct bitmap
35bm_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
47void
48bm_dealloc(struct bitmap * bm)
49{
50	if (bm->map)
51		free(bm->map);
52}
53
54static void
55bm_getmask(int *pos, unsigned char *bmask)
56{
57	*bmask = (unsigned char) (1 << (*pos % 8));
58	*pos /= 8;
59}
60
61void
62bm_setbit(struct bitmap * bm, int pos)
63{
64	unsigned char   bmask;
65
66	bm_getmask(&pos, &bmask);
67	bm->map[pos] |= bmask;
68}
69
70void
71bm_clrbit(struct bitmap * bm, int pos)
72{
73	unsigned char   bmask;
74
75	bm_getmask(&pos, &bmask);
76	bm->map[pos] &= ~bmask;
77}
78
79int
80bm_isset(struct bitmap * bm, int pos)
81{
82	unsigned char   bmask;
83
84	bm_getmask(&pos, &bmask);
85	return !!(bm->map[pos] & bmask);
86}
87
88int
89bm_firstunset(struct bitmap * bm)
90{
91	int             szmap = (bm->size / 8) + !!(bm->size % 8);
92	int             at = 0;
93	int             pos = 0;
94
95	while (pos < szmap) {
96		unsigned char   bmv = bm->map[pos++];
97		unsigned char   bmask = 1;
98
99		while (bmask & 0xff) {
100			if ((bmv & bmask) == 0)
101				return at;
102			bmask <<= 1;
103			++at;
104		}
105	}
106	return at;
107}
108
109int
110bm_lastset(struct bitmap * bm)
111{
112	int             szmap = (bm->size / 8) + !!(bm->size % 8);
113	int             at = 0;
114	int             pos = 0;
115	int             ofs = 0;
116
117	while (pos < szmap) {
118		unsigned char   bmv = bm->map[pos++];
119		unsigned char   bmask = 1;
120
121		while (bmask & 0xff) {
122			if ((bmv & bmask) != 0)
123				ofs = at;
124			bmask <<= 1;
125			++at;
126		}
127	}
128	return ofs;
129}
130