bitmap.c revision 50479 
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
27#ifndef lint
28static const char rcsid[] =
29  "$FreeBSD: head/usr.sbin/pw/bitmap.c 50479 1999-08-28 01:35:59Z peter $";
30#endif /* not lint */
31
32#include <stdlib.h>
33#include <string.h>
34
35#include "bitmap.h"
36
37struct bitmap
38bm_alloc(int size)
39{
40	struct bitmap   bm;
41	int             szmap = (size / 8) + !!(size % 8);
42
43	bm.size = size;
44	bm.map = malloc(szmap);
45	if (bm.map)
46		memset(bm.map, 0, szmap);
47	return bm;
48}
49
50void
51bm_dealloc(struct bitmap * bm)
52{
53	if (bm->map)
54		free(bm->map);
55}
56
57static void
58bm_getmask(int *pos, unsigned char *bmask)
59{
60	*bmask = (unsigned char) (1 << (*pos % 8));
61	*pos /= 8;
62}
63
64void
65bm_setbit(struct bitmap * bm, int pos)
66{
67	unsigned char   bmask;
68
69	bm_getmask(&pos, &bmask);
70	bm->map[pos] |= bmask;
71}
72
73void
74bm_clrbit(struct bitmap * bm, int pos)
75{
76	unsigned char   bmask;
77
78	bm_getmask(&pos, &bmask);
79	bm->map[pos] &= ~bmask;
80}
81
82int
83bm_isset(struct bitmap * bm, int pos)
84{
85	unsigned char   bmask;
86
87	bm_getmask(&pos, &bmask);
88	return !!(bm->map[pos] & bmask);
89}
90
91int
92bm_firstunset(struct bitmap * bm)
93{
94	int             szmap = (bm->size / 8) + !!(bm->size % 8);
95	int             at = 0;
96	int             pos = 0;
97
98	while (pos < szmap) {
99		unsigned char   bmv = bm->map[pos++];
100		unsigned char   bmask = 1;
101
102		while (bmask & 0xff) {
103			if ((bmv & bmask) == 0)
104				return at;
105			bmask <<= 1;
106			++at;
107		}
108	}
109	return at;
110}
111
112int
113bm_lastset(struct bitmap * bm)
114{
115	int             szmap = (bm->size / 8) + !!(bm->size % 8);
116	int             at = 0;
117	int             pos = 0;
118	int             ofs = 0;
119
120	while (pos < szmap) {
121		unsigned char   bmv = bm->map[pos++];
122		unsigned char   bmask = 1;
123
124		while (bmask & 0xff) {
125			if ((bmv & bmask) != 0)
126				ofs = at;
127			bmask <<= 1;
128			++at;
129		}
130	}
131	return ofs;
132}
133