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
23dm_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
45void dm_bitset_destroy(dm_bitset_t bs)
46{
47 dm_free(bs);
48}
49
50void 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 */
60static 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
71int 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
96int dm_bit_get_first(dm_bitset_t bs)
97{
98 return dm_bit_get_next(bs, -1);
99}
100