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
43typedef 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
51struct 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
63struct util_bitmask *
64util_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 */
88static INLINE boolean
89util_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 */
134static INLINE void
135util_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
147static INLINE void
148util_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
159unsigned
160util_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   }
184found:
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
197unsigned
198util_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
223void
224util_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
246boolean
247util_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
273unsigned
274util_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
313unsigned
314util_bitmask_get_first_index(struct util_bitmask *bm)
315{
316   return util_bitmask_get_next_index(bm, 0);
317}
318
319
320void
321util_bitmask_destroy(struct util_bitmask *bm)
322{
323   assert(bm);
324
325   FREE(bm->words);
326   FREE(bm);
327}
328
329