source: vendor/3.6.23/source3/lib/bitmap.c

Last change on this file was 740, checked in by Silvan Scherrer, 13 years ago

Samba Server: update vendor to 3.6.0
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
22/* these functions provide a simple way to allocate integers from a
23 pool without repetition */
24
25/****************************************************************************
26talloc a bitmap
27****************************************************************************/
28struct bitmap *bitmap_talloc(TALLOC_CTX *mem_ctx, int n)
29{
30 struct bitmap *bm;
31
32 bm = TALLOC_P(mem_ctx, struct bitmap);
33
34 if (!bm) return NULL;
35
36 bm->n = n;
37 bm->b = TALLOC_ZERO_ARRAY(bm, uint32, (n+31)/32);
38 if (!bm->b) {
39 TALLOC_FREE(bm);
40 return NULL;
41 }
42 return bm;
43}
44
45/****************************************************************************
46copy as much of the source bitmap as will fit in the destination bitmap.
47****************************************************************************/
48
49int bitmap_copy(struct bitmap * const dst, const struct bitmap * const src)
50{
51 int count = MIN(dst->n, src->n);
52
53 SMB_ASSERT(dst->b != src->b);
54 memcpy(dst->b, src->b, sizeof(uint32)*((count+31)/32));
55
56 return count;
57}
58
59/****************************************************************************
60set a bit in a bitmap
61****************************************************************************/
62bool bitmap_set(struct bitmap *bm, unsigned i)
63{
64 if (i >= bm->n) {
65 DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
66 i, bm->n));
67 return False;
68 }
69 bm->b[i/32] |= (1<<(i%32));
70 return True;
71}
72
73/****************************************************************************
74clear a bit in a bitmap
75****************************************************************************/
76bool bitmap_clear(struct bitmap *bm, unsigned i)
77{
78 if (i >= bm->n) {
79 DEBUG(0,("clearing invalid bitmap entry %d (of %d)\n",
80 i, bm->n));
81 return False;
82 }
83 bm->b[i/32] &= ~(1<<(i%32));
84 return True;
85}
86
87/****************************************************************************
88query a bit in a bitmap
89****************************************************************************/
90bool bitmap_query(struct bitmap *bm, unsigned i)
91{
92 if (i >= bm->n) return False;
93 if (bm->b[i/32] & (1<<(i%32))) {
94 return True;
95 }
96 return False;
97}
98
99/****************************************************************************
100find a zero bit in a bitmap starting at the specified offset, with
101wraparound
102****************************************************************************/
103int bitmap_find(struct bitmap *bm, unsigned ofs)
104{
105 unsigned int i, j;
106
107 if (ofs > bm->n) ofs = 0;
108
109 i = ofs;
110 while (i < bm->n) {
111 if (~(bm->b[i/32])) {
112 j = i;
113 do {
114 if (!bitmap_query(bm, j)) return j;
115 j++;
116 } while (j & 31 && j < bm->n);
117 }
118 i += 32;
119 i &= ~31;
120 }
121
122 i = 0;
123 while (i < ofs) {
124 if (~(bm->b[i/32])) {
125 j = i;
126 do {
127 if (!bitmap_query(bm, j)) return j;
128 j++;
129 } while (j & 31 && j < bm->n);
130 }
131 i += 32;
132 i &= ~31;
133 }
134
135 return -1;
136}
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