1 /*	$NetBSD: bitset.c,v 1.1.1.1 2008/12/22 00:18:36 haad Exp $	*/
2 
3 /*
4  * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
5  * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
6  *
7  * This file is part of the device-mapper userspace tools.
8  *
9  * This copyrighted material is made available to anyone wishing to use,
10  * modify, copy, or redistribute it subject to the terms and conditions
11  * of the GNU Lesser General Public License v.2.1.
12  *
13  * You should have received a copy of the GNU Lesser General Public License
14  * along with this program; if not, write to the Free Software Foundation,
15  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
16  */
17 
18 #include "dmlib.h"
19 
20 /* FIXME: calculate this. */
21 #define INT_SHIFT 5
22 
23 dm_bitset_t dm_bitset_create(struct dm_pool *mem, unsigned num_bits)
24 {
25 	unsigned n = (num_bits / DM_BITS_PER_INT) + 2;
26 	size_t size = sizeof(int) * n;
27 	dm_bitset_t bs;
28 
29 	if (mem)
30 		bs = dm_pool_zalloc(mem, size);
31 	else
32 		bs = dm_malloc(size);
33 
34 	if (!bs)
35 		return NULL;
36 
37 	*bs = num_bits;
38 
39 	if (!mem)
40 		dm_bit_clear_all(bs);
41 
42 	return bs;
43 }
44 
45 void dm_bitset_destroy(dm_bitset_t bs)
46 {
47 	dm_free(bs);
48 }
49 
50 void dm_bit_union(dm_bitset_t out, dm_bitset_t in1, dm_bitset_t in2)
51 {
52 	int i;
53 	for (i = (in1[0] / DM_BITS_PER_INT) + 1; i; i--)
54 		out[i] = in1[i] | in2[i];
55 }
56 
57 /*
58  * FIXME: slow
59  */
60 static inline int _test_word(uint32_t test, int bit)
61 {
62 	while (bit < (int) DM_BITS_PER_INT) {
63 		if (test & (0x1 << bit))
64 			return bit;
65 		bit++;
66 	}
67 
68 	return -1;
69 }
70 
71 int dm_bit_get_next(dm_bitset_t bs, int last_bit)
72 {
73 	int bit, word;
74 	uint32_t test;
75 
76 	last_bit++;		/* otherwise we'll return the same bit again */
77 
78 	/*
79 	 * bs[0] holds number of bits
80 	 */
81 	while (last_bit < (int) bs[0]) {
82 		word = last_bit >> INT_SHIFT;
83 		test = bs[word + 1];
84 		bit = last_bit & (DM_BITS_PER_INT - 1);
85 
86 		if ((bit = _test_word(test, bit)) >= 0)
87 			return (word * DM_BITS_PER_INT) + bit;
88 
89 		last_bit = last_bit - (last_bit & (DM_BITS_PER_INT - 1)) +
90 		    DM_BITS_PER_INT;
91 	}
92 
93 	return -1;
94 }
95 
96 int dm_bit_get_first(dm_bitset_t bs)
97 {
98 	return dm_bit_get_next(bs, -1);
99 }
100