source: vendor/current/lib/util/bitmap.c

Last change on this file was 988, checked in by Silvan Scherrer, 9 years ago

Samba Server: update vendor to version 4.4.3
File size: 3.7 KB
Line 
1/*
2 Unix SMB/CIFS implementation.
3 simple bitmap functions
4 Copyright (C) Andrew Tridgell 1992-1998
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
18*/
19
20#include "includes.h"
21#include "lib/util/bitmap.h"
22
23struct bitmap {
24 unsigned int n;
25 uint32_t b[1]; /* We allocate more */
26};
27
28/* these functions provide a simple way to allocate integers from a
29 pool without repetition */
30
31/****************************************************************************
32talloc a bitmap
33****************************************************************************/
34struct bitmap *bitmap_talloc(TALLOC_CTX *mem_ctx, int n)
35{
36 struct bitmap *bm;
37
38 bm = (struct bitmap *)talloc_zero_size(
39 mem_ctx,
40 offsetof(struct bitmap, b) + sizeof(uint32_t)*((n+31)/32));
41
42 if (!bm) return NULL;
43
44 talloc_set_name_const(bm, "struct bitmap");
45
46 bm->n = n;
47 return bm;
48}
49
50/****************************************************************************
51copy as much of the source bitmap as will fit in the destination bitmap.
52****************************************************************************/
53
54int bitmap_copy(struct bitmap * const dst, const struct bitmap * const src)
55{
56 int count = MIN(dst->n, src->n);
57
58 SMB_ASSERT(dst->b != src->b);
59 memcpy(dst->b, src->b, sizeof(uint32_t)*((count+31)/32));
60
61 return count;
62}
63
64/****************************************************************************
65set a bit in a bitmap
66****************************************************************************/
67bool bitmap_set(struct bitmap *bm, unsigned i)
68{
69 if (i >= bm->n) {
70 DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
71 i, bm->n));
72 return false;
73 }
74 bm->b[i/32] |= (1<<(i%32));
75 return true;
76}
77
78/****************************************************************************
79clear a bit in a bitmap
80****************************************************************************/
81bool bitmap_clear(struct bitmap *bm, unsigned i)
82{
83 if (i >= bm->n) {
84 DEBUG(0,("clearing invalid bitmap entry %d (of %d)\n",
85 i, bm->n));
86 return false;
87 }
88 bm->b[i/32] &= ~(1<<(i%32));
89 return true;
90}
91
92/****************************************************************************
93query a bit in a bitmap
94****************************************************************************/
95bool bitmap_query(struct bitmap *bm, unsigned i)
96{
97 if (i >= bm->n) return false;
98 if (bm->b[i/32] & (1<<(i%32))) {
99 return true;
100 }
101 return false;
102}
103
104/****************************************************************************
105find a zero bit in a bitmap starting at the specified offset, with
106wraparound
107****************************************************************************/
108int bitmap_find(struct bitmap *bm, unsigned ofs)
109{
110 unsigned int i, j;
111
112 if (ofs > bm->n) ofs = 0;
113
114 i = ofs;
115 while (i < bm->n) {
116 if (~(bm->b[i/32])) {
117 j = i;
118 do {
119 if (!bitmap_query(bm, j)) return j;
120 j++;
121 } while (j & 31 && j < bm->n);
122 }
123 i += 32;
124 i &= ~31;
125 }
126
127 i = 0;
128 while (i < ofs) {
129 if (~(bm->b[i/32])) {
130 j = i;
131 do {
132 if (!bitmap_query(bm, j)) return j;
133 j++;
134 } while (j & 31 && j < bm->n);
135 }
136 i += 32;
137 i &= ~31;
138 }
139
140 return -1;
141}
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