1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
/*
* Ouroboros - Copyright (C) 2016
*
* Bitmap implementation - taken partly from Linux kernel
*
* Sander Vrijders <sander.vrijders@intec.ugent.be>
* Francesco Salvestrini <f.salvestrini@nextworks.it>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#define OUROBOROS_PREFIX "bitmap"
#include <ouroboros/bitmap.h>
#include <ouroboros/logs.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#define BITS_PER_BYTE 8
#define BITS_PER_LONG (sizeof(long) * BITS_PER_BYTE)
#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
#define BITS_TO_LONGS(nr) \
DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
static unsigned long find_next_zero_bit(const unsigned long * addr,
unsigned long nbits)
{
unsigned long tmp;
unsigned long start = 0;
unsigned long pos = 0;
unsigned long mask;
/* First find correct word */
tmp = ~addr[start];
while (!tmp) {
start++;
if (start >= (nbits / BITS_PER_LONG))
return nbits;
tmp = ~addr[start];
}
/* Find the free bit in the word */
mask = 1UL;
while (!(tmp & mask)) {
pos++;
mask = 1UL << pos;
}
return (start * BITS_PER_LONG) + pos;
}
static void bitmap_zero(unsigned long * dst,
unsigned int nbits)
{
unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
memset(dst, 0, len);
}
static void bitmap_clear(unsigned long * map,
unsigned int start)
{
unsigned long * p = map + BIT_WORD(start);
unsigned long mask = ~(1UL << (start % (BITS_PER_LONG)));
*p &= mask;
}
static void bitmap_set(unsigned long * map,
unsigned int start)
{
unsigned long * p = map + BIT_WORD(start);
unsigned long mask = 1UL << (start % (BITS_PER_LONG));
*p |= mask;
}
struct bmp {
ssize_t offset;
size_t size;
unsigned long * bitmap;
};
struct bmp * bmp_create(size_t bits, ssize_t offset)
{
struct bmp * tmp;
if (bits == 0)
return NULL;
tmp = malloc(sizeof(*tmp));
if (tmp == NULL)
return NULL;
tmp->bitmap = malloc(BITS_TO_LONGS(bits) * sizeof(unsigned long));
if (tmp->bitmap == NULL) {
free(tmp);
return NULL;
}
tmp->size = bits;
tmp->offset = offset;
bitmap_zero(tmp->bitmap, bits);
return tmp;
}
int bmp_destroy(struct bmp * b)
{
if (b == NULL)
return -1;
if (b->bitmap == NULL) {
free(b);
return -1;
}
free(b->bitmap);
free(b);
return 0;
}
static ssize_t bad_id(struct bmp * b)
{
if (b == NULL)
return -1;
return b->offset - 1;
}
ssize_t bmp_allocate(struct bmp * b)
{
ssize_t id;
if (b == NULL)
return -1;
id = (ssize_t) find_next_zero_bit(b->bitmap,
b->size);
if (id >= (ssize_t) b->size)
return bad_id(b);
bitmap_set(b->bitmap, id);
return id + b->offset;
}
static bool is_id_valid(struct bmp * b,
ssize_t id)
{
assert(b);
if ((id < b->offset) || (id > (ssize_t) (b->offset + b->size)))
return false;
return true;
}
bool bmp_is_id_valid(struct bmp * b,
ssize_t id)
{
if (b == NULL)
return false;
return is_id_valid(b, id);
}
int bmp_release(struct bmp * b,
ssize_t id)
{
ssize_t rid;
if (b == NULL)
return -1;
if (!is_id_valid(b, id))
return -1;
rid = id - b->offset;
bitmap_clear(b->bitmap, rid);
return 0;
}
|
