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 "replace.h"
21 #include <talloc.h>
22 #include "lib/util/bitmap.h"
23 #include "lib/util/debug.h"
24 #include "lib/util/fault.h"
25
26 struct bitmap {
27 unsigned int n;
28 uint32_t b[1]; /* We allocate more */
29 };
30
31 /* these functions provide a simple way to allocate integers from a
32 pool without repetition */
33
34 /****************************************************************************
35 talloc a bitmap
36 ****************************************************************************/
bitmap_talloc(TALLOC_CTX * mem_ctx,int n)37 struct bitmap *bitmap_talloc(TALLOC_CTX *mem_ctx, int n)
38 {
39 struct bitmap *bm;
40
41 bm = (struct bitmap *)talloc_zero_size(
42 mem_ctx,
43 offsetof(struct bitmap, b) + sizeof(uint32_t)*((n+31)/32));
44
45 if (!bm) return NULL;
46
47 talloc_set_name_const(bm, "struct bitmap");
48
49 bm->n = n;
50 return bm;
51 }
52
53 /****************************************************************************
54 copy as much of the source bitmap as will fit in the destination bitmap.
55 ****************************************************************************/
56
bitmap_copy(struct bitmap * const dst,const struct bitmap * const src)57 int bitmap_copy(struct bitmap * const dst, const struct bitmap * const src)
58 {
59 int count = MIN(dst->n, src->n);
60
61 SMB_ASSERT(dst->b != src->b);
62 memcpy(dst->b, src->b, sizeof(uint32_t)*((count+31)/32));
63
64 return count;
65 }
66
67 /****************************************************************************
68 set a bit in a bitmap
69 ****************************************************************************/
bitmap_set(struct bitmap * bm,unsigned i)70 bool bitmap_set(struct bitmap *bm, unsigned i)
71 {
72 if (i >= bm->n) {
73 DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
74 i, bm->n));
75 return false;
76 }
77 bm->b[i/32] |= (1U<<(i%32));
78 return true;
79 }
80
81 /****************************************************************************
82 clear a bit in a bitmap
83 ****************************************************************************/
bitmap_clear(struct bitmap * bm,unsigned i)84 bool bitmap_clear(struct bitmap *bm, unsigned i)
85 {
86 if (i >= bm->n) {
87 DEBUG(0,("clearing invalid bitmap entry %d (of %d)\n",
88 i, bm->n));
89 return false;
90 }
91 bm->b[i/32] &= ~(1U<<(i%32));
92 return true;
93 }
94
95 /****************************************************************************
96 query a bit in a bitmap
97 ****************************************************************************/
bitmap_query(struct bitmap * bm,unsigned i)98 bool bitmap_query(struct bitmap *bm, unsigned i)
99 {
100 if (i >= bm->n) return false;
101 if (bm->b[i/32] & (1U<<(i%32))) {
102 return true;
103 }
104 return false;
105 }
106
107 /****************************************************************************
108 find a zero bit in a bitmap starting at the specified offset, with
109 wraparound
110 ****************************************************************************/
bitmap_find(struct bitmap * bm,unsigned ofs)111 int bitmap_find(struct bitmap *bm, unsigned ofs)
112 {
113 unsigned int i, j;
114
115 if (ofs > bm->n) ofs = 0;
116
117 i = ofs;
118 while (i < bm->n) {
119 if (~(bm->b[i/32])) {
120 j = i;
121 do {
122 if (!bitmap_query(bm, j)) return j;
123 j++;
124 } while (j & 31 && j < bm->n);
125 }
126 i += 32;
127 i &= ~31;
128 }
129
130 i = 0;
131 while (i < ofs) {
132 if (~(bm->b[i/32])) {
133 j = i;
134 do {
135 if (!bitmap_query(bm, j)) return j;
136 j++;
137 } while (j & 31 && j < bm->n);
138 }
139 i += 32;
140 i &= ~31;
141 }
142
143 return -1;
144 }
145