1 /**************************************************************************
2 *
3 * Copyright 2009 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28 /**
29 * @file
30 * Generic bitmask implementation.
31 *
32 * @author Jose Fonseca <jfonseca@vmware.com>
33 */
34
35
36 #include "pipe/p_compiler.h"
37 #include "util/u_debug.h"
38
39 #include "util/u_memory.h"
40 #include "util/u_bitmask.h"
41
42
43 typedef uint32_t util_bitmask_word;
44
45
46 #define UTIL_BITMASK_INITIAL_WORDS 16
47 #define UTIL_BITMASK_BITS_PER_BYTE 8
48 #define UTIL_BITMASK_BITS_PER_WORD (sizeof(util_bitmask_word) * UTIL_BITMASK_BITS_PER_BYTE)
49
50
51 struct util_bitmask
52 {
53 util_bitmask_word *words;
54
55 /** Number of bits we can currently hold */
56 unsigned size;
57
58 /** Number of consecutive bits set at the start of the bitmask */
59 unsigned filled;
60 };
61
62
63 struct util_bitmask *
util_bitmask_create(void)64 util_bitmask_create(void)
65 {
66 struct util_bitmask *bm;
67
68 bm = MALLOC_STRUCT(util_bitmask);
69 if(!bm)
70 return NULL;
71
72 bm->words = (util_bitmask_word *)CALLOC(UTIL_BITMASK_INITIAL_WORDS, sizeof(util_bitmask_word));
73 if(!bm->words) {
74 FREE(bm);
75 return NULL;
76 }
77
78 bm->size = UTIL_BITMASK_INITIAL_WORDS * UTIL_BITMASK_BITS_PER_WORD;
79 bm->filled = 0;
80
81 return bm;
82 }
83
84
85 /**
86 * Resize the bitmask if necessary
87 */
88 static INLINE boolean
util_bitmask_resize(struct util_bitmask * bm,unsigned minimum_index)89 util_bitmask_resize(struct util_bitmask *bm,
90 unsigned minimum_index)
91 {
92 unsigned minimum_size = minimum_index + 1;
93 unsigned new_size;
94 util_bitmask_word *new_words;
95
96 /* Check integer overflow */
97 if(!minimum_size)
98 return FALSE;
99
100 if(bm->size >= minimum_size)
101 return TRUE;
102
103 assert(bm->size % UTIL_BITMASK_BITS_PER_WORD == 0);
104 new_size = bm->size;
105 while(new_size < minimum_size) {
106 new_size *= 2;
107 /* Check integer overflow */
108 if(new_size < bm->size)
109 return FALSE;
110 }
111 assert(new_size);
112 assert(new_size % UTIL_BITMASK_BITS_PER_WORD == 0);
113
114 new_words = (util_bitmask_word *)REALLOC((void *)bm->words,
115 bm->size / UTIL_BITMASK_BITS_PER_BYTE,
116 new_size / UTIL_BITMASK_BITS_PER_BYTE);
117 if(!new_words)
118 return FALSE;
119
120 memset(new_words + bm->size/UTIL_BITMASK_BITS_PER_WORD,
121 0,
122 (new_size - bm->size)/UTIL_BITMASK_BITS_PER_BYTE);
123
124 bm->size = new_size;
125 bm->words = new_words;
126
127 return TRUE;
128 }
129
130
131 /**
132 * Lazily update the filled.
133 */
134 static INLINE void
util_bitmask_filled_set(struct util_bitmask * bm,unsigned index)135 util_bitmask_filled_set(struct util_bitmask *bm,
136 unsigned index)
137 {
138 assert(bm->filled <= bm->size);
139 assert(index < bm->size);
140
141 if(index == bm->filled) {
142 ++bm->filled;
143 assert(bm->filled <= bm->size);
144 }
145 }
146
147 static INLINE void
util_bitmask_filled_unset(struct util_bitmask * bm,unsigned index)148 util_bitmask_filled_unset(struct util_bitmask *bm,
149 unsigned index)
150 {
151 assert(bm->filled <= bm->size);
152 assert(index < bm->size);
153
154 if(index < bm->filled)
155 bm->filled = index;
156 }
157
158
159 unsigned
util_bitmask_add(struct util_bitmask * bm)160 util_bitmask_add(struct util_bitmask *bm)
161 {
162 unsigned word;
163 unsigned bit;
164 util_bitmask_word mask;
165
166 assert(bm);
167
168 /* linear search for an empty index */
169 word = bm->filled / UTIL_BITMASK_BITS_PER_WORD;
170 bit = bm->filled % UTIL_BITMASK_BITS_PER_WORD;
171 mask = 1 << bit;
172 while(word < bm->size / UTIL_BITMASK_BITS_PER_WORD) {
173 while(bit < UTIL_BITMASK_BITS_PER_WORD) {
174 if(!(bm->words[word] & mask))
175 goto found;
176 ++bm->filled;
177 ++bit;
178 mask <<= 1;
179 }
180 ++word;
181 bit = 0;
182 mask = 1;
183 }
184 found:
185
186 /* grow the bitmask if necessary */
187 if(!util_bitmask_resize(bm, bm->filled))
188 return UTIL_BITMASK_INVALID_INDEX;
189
190 assert(!(bm->words[word] & mask));
191 bm->words[word] |= mask;
192
193 return bm->filled++;
194 }
195
196
197 unsigned
util_bitmask_set(struct util_bitmask * bm,unsigned index)198 util_bitmask_set(struct util_bitmask *bm,
199 unsigned index)
200 {
201 unsigned word;
202 unsigned bit;
203 util_bitmask_word mask;
204
205 assert(bm);
206
207 /* grow the bitmask if necessary */
208 if(!util_bitmask_resize(bm, index))
209 return UTIL_BITMASK_INVALID_INDEX;
210
211 word = index / UTIL_BITMASK_BITS_PER_WORD;
212 bit = index % UTIL_BITMASK_BITS_PER_WORD;
213 mask = 1 << bit;
214
215 bm->words[word] |= mask;
216
217 util_bitmask_filled_set(bm, index);
218
219 return index;
220 }
221
222
223 void
util_bitmask_clear(struct util_bitmask * bm,unsigned index)224 util_bitmask_clear(struct util_bitmask *bm,
225 unsigned index)
226 {
227 unsigned word;
228 unsigned bit;
229 util_bitmask_word mask;
230
231 assert(bm);
232
233 if(index >= bm->size)
234 return;
235
236 word = index / UTIL_BITMASK_BITS_PER_WORD;
237 bit = index % UTIL_BITMASK_BITS_PER_WORD;
238 mask = 1 << bit;
239
240 bm->words[word] &= ~mask;
241
242 util_bitmask_filled_unset(bm, index);
243 }
244
245
246 boolean
util_bitmask_get(struct util_bitmask * bm,unsigned index)247 util_bitmask_get(struct util_bitmask *bm,
248 unsigned index)
249 {
250 unsigned word = index / UTIL_BITMASK_BITS_PER_WORD;
251 unsigned bit = index % UTIL_BITMASK_BITS_PER_WORD;
252 util_bitmask_word mask = 1 << bit;
253
254 assert(bm);
255
256 if(index < bm->filled) {
257 assert(bm->words[word] & mask);
258 return TRUE;
259 }
260
261 if(index >= bm->size)
262 return FALSE;
263
264 if(bm->words[word] & mask) {
265 util_bitmask_filled_set(bm, index);
266 return TRUE;
267 }
268 else
269 return FALSE;
270 }
271
272
273 unsigned
util_bitmask_get_next_index(struct util_bitmask * bm,unsigned index)274 util_bitmask_get_next_index(struct util_bitmask *bm,
275 unsigned index)
276 {
277 unsigned word = index / UTIL_BITMASK_BITS_PER_WORD;
278 unsigned bit = index % UTIL_BITMASK_BITS_PER_WORD;
279 util_bitmask_word mask = 1 << bit;
280
281 if(index < bm->filled) {
282 assert(bm->words[word] & mask);
283 return index;
284 }
285
286 if(index >= bm->size) {
287 return UTIL_BITMASK_INVALID_INDEX;
288 }
289
290 /* Do a linear search */
291 while(word < bm->size / UTIL_BITMASK_BITS_PER_WORD) {
292 while(bit < UTIL_BITMASK_BITS_PER_WORD) {
293 if(bm->words[word] & mask) {
294 if(index == bm->filled) {
295 ++bm->filled;
296 assert(bm->filled <= bm->size);
297 }
298 return index;
299 }
300 ++index;
301 ++bit;
302 mask <<= 1;
303 }
304 ++word;
305 bit = 0;
306 mask = 1;
307 }
308
309 return UTIL_BITMASK_INVALID_INDEX;
310 }
311
312
313 unsigned
util_bitmask_get_first_index(struct util_bitmask * bm)314 util_bitmask_get_first_index(struct util_bitmask *bm)
315 {
316 return util_bitmask_get_next_index(bm, 0);
317 }
318
319
320 void
util_bitmask_destroy(struct util_bitmask * bm)321 util_bitmask_destroy(struct util_bitmask *bm)
322 {
323 assert(bm);
324
325 FREE(bm->words);
326 FREE(bm);
327 }
328
329