Merge branch 'ab/unconditional-free-and-null'
[git] / ewah / ewah_bitmap.c
1 /**
2  * Copyright 2013, GitHub, Inc
3  * Copyright 2009-2013, Daniel Lemire, Cliff Moon,
4  *      David McIntosh, Robert Becho, Google Inc. and Veronika Zenz
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version 2
9  * of the License, or (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 #include "git-compat-util.h"
20 #include "ewok.h"
21 #include "ewok_rlw.h"
22
23 static inline size_t min_size(size_t a, size_t b)
24 {
25         return a < b ? a : b;
26 }
27
28 static inline size_t max_size(size_t a, size_t b)
29 {
30         return a > b ? a : b;
31 }
32
33 static inline void buffer_grow(struct ewah_bitmap *self, size_t new_size)
34 {
35         size_t rlw_offset = (uint8_t *)self->rlw - (uint8_t *)self->buffer;
36
37         if (self->alloc_size >= new_size)
38                 return;
39
40         self->alloc_size = new_size;
41         REALLOC_ARRAY(self->buffer, self->alloc_size);
42         self->rlw = self->buffer + (rlw_offset / sizeof(eword_t));
43 }
44
45 static inline void buffer_push(struct ewah_bitmap *self, eword_t value)
46 {
47         if (self->buffer_size + 1 >= self->alloc_size)
48                 buffer_grow(self, self->buffer_size * 3 / 2);
49
50         self->buffer[self->buffer_size++] = value;
51 }
52
53 static void buffer_push_rlw(struct ewah_bitmap *self, eword_t value)
54 {
55         buffer_push(self, value);
56         self->rlw = self->buffer + self->buffer_size - 1;
57 }
58
59 static size_t add_empty_words(struct ewah_bitmap *self, int v, size_t number)
60 {
61         size_t added = 0;
62         eword_t runlen, can_add;
63
64         if (rlw_get_run_bit(self->rlw) != v && rlw_size(self->rlw) == 0) {
65                 rlw_set_run_bit(self->rlw, v);
66         } else if (rlw_get_literal_words(self->rlw) != 0 ||
67                         rlw_get_run_bit(self->rlw) != v) {
68                 buffer_push_rlw(self, 0);
69                 if (v) rlw_set_run_bit(self->rlw, v);
70                 added++;
71         }
72
73         runlen = rlw_get_running_len(self->rlw);
74         can_add = min_size(number, RLW_LARGEST_RUNNING_COUNT - runlen);
75
76         rlw_set_running_len(self->rlw, runlen + can_add);
77         number -= can_add;
78
79         while (number >= RLW_LARGEST_RUNNING_COUNT) {
80                 buffer_push_rlw(self, 0);
81                 added++;
82                 if (v) rlw_set_run_bit(self->rlw, v);
83                 rlw_set_running_len(self->rlw, RLW_LARGEST_RUNNING_COUNT);
84                 number -= RLW_LARGEST_RUNNING_COUNT;
85         }
86
87         if (number > 0) {
88                 buffer_push_rlw(self, 0);
89                 added++;
90
91                 if (v) rlw_set_run_bit(self->rlw, v);
92                 rlw_set_running_len(self->rlw, number);
93         }
94
95         return added;
96 }
97
98 size_t ewah_add_empty_words(struct ewah_bitmap *self, int v, size_t number)
99 {
100         if (number == 0)
101                 return 0;
102
103         self->bit_size += number * BITS_IN_EWORD;
104         return add_empty_words(self, v, number);
105 }
106
107 static size_t add_literal(struct ewah_bitmap *self, eword_t new_data)
108 {
109         eword_t current_num = rlw_get_literal_words(self->rlw);
110
111         if (current_num >= RLW_LARGEST_LITERAL_COUNT) {
112                 buffer_push_rlw(self, 0);
113
114                 rlw_set_literal_words(self->rlw, 1);
115                 buffer_push(self, new_data);
116                 return 2;
117         }
118
119         rlw_set_literal_words(self->rlw, current_num + 1);
120
121         /* sanity check */
122         assert(rlw_get_literal_words(self->rlw) == current_num + 1);
123
124         buffer_push(self, new_data);
125         return 1;
126 }
127
128 void ewah_add_dirty_words(
129         struct ewah_bitmap *self, const eword_t *buffer,
130         size_t number, int negate)
131 {
132         size_t literals, can_add;
133
134         while (1) {
135                 literals = rlw_get_literal_words(self->rlw);
136                 can_add = min_size(number, RLW_LARGEST_LITERAL_COUNT - literals);
137
138                 rlw_set_literal_words(self->rlw, literals + can_add);
139
140                 if (self->buffer_size + can_add >= self->alloc_size)
141                         buffer_grow(self, (self->buffer_size + can_add) * 3 / 2);
142
143                 if (negate) {
144                         size_t i;
145                         for (i = 0; i < can_add; ++i)
146                                 self->buffer[self->buffer_size++] = ~buffer[i];
147                 } else {
148                         memcpy(self->buffer + self->buffer_size,
149                                 buffer, can_add * sizeof(eword_t));
150                         self->buffer_size += can_add;
151                 }
152
153                 self->bit_size += can_add * BITS_IN_EWORD;
154
155                 if (number - can_add == 0)
156                         break;
157
158                 buffer_push_rlw(self, 0);
159                 buffer += can_add;
160                 number -= can_add;
161         }
162 }
163
164 static size_t add_empty_word(struct ewah_bitmap *self, int v)
165 {
166         int no_literal = (rlw_get_literal_words(self->rlw) == 0);
167         eword_t run_len = rlw_get_running_len(self->rlw);
168
169         if (no_literal && run_len == 0) {
170                 rlw_set_run_bit(self->rlw, v);
171                 assert(rlw_get_run_bit(self->rlw) == v);
172         }
173
174         if (no_literal && rlw_get_run_bit(self->rlw) == v &&
175                 run_len < RLW_LARGEST_RUNNING_COUNT) {
176                 rlw_set_running_len(self->rlw, run_len + 1);
177                 assert(rlw_get_running_len(self->rlw) == run_len + 1);
178                 return 0;
179         } else {
180                 buffer_push_rlw(self, 0);
181
182                 assert(rlw_get_running_len(self->rlw) == 0);
183                 assert(rlw_get_run_bit(self->rlw) == 0);
184                 assert(rlw_get_literal_words(self->rlw) == 0);
185
186                 rlw_set_run_bit(self->rlw, v);
187                 assert(rlw_get_run_bit(self->rlw) == v);
188
189                 rlw_set_running_len(self->rlw, 1);
190                 assert(rlw_get_running_len(self->rlw) == 1);
191                 assert(rlw_get_literal_words(self->rlw) == 0);
192                 return 1;
193         }
194 }
195
196 size_t ewah_add(struct ewah_bitmap *self, eword_t word)
197 {
198         self->bit_size += BITS_IN_EWORD;
199
200         if (word == 0)
201                 return add_empty_word(self, 0);
202
203         if (word == (eword_t)(~0))
204                 return add_empty_word(self, 1);
205
206         return add_literal(self, word);
207 }
208
209 void ewah_set(struct ewah_bitmap *self, size_t i)
210 {
211         const size_t dist =
212                 DIV_ROUND_UP(i + 1, BITS_IN_EWORD) -
213                 DIV_ROUND_UP(self->bit_size, BITS_IN_EWORD);
214
215         assert(i >= self->bit_size);
216
217         self->bit_size = i + 1;
218
219         if (dist > 0) {
220                 if (dist > 1)
221                         add_empty_words(self, 0, dist - 1);
222
223                 add_literal(self, (eword_t)1 << (i % BITS_IN_EWORD));
224                 return;
225         }
226
227         if (rlw_get_literal_words(self->rlw) == 0) {
228                 rlw_set_running_len(self->rlw,
229                         rlw_get_running_len(self->rlw) - 1);
230                 add_literal(self, (eword_t)1 << (i % BITS_IN_EWORD));
231                 return;
232         }
233
234         self->buffer[self->buffer_size - 1] |=
235                 ((eword_t)1 << (i % BITS_IN_EWORD));
236
237         /* check if we just completed a stream of 1s */
238         if (self->buffer[self->buffer_size - 1] == (eword_t)(~0)) {
239                 self->buffer[--self->buffer_size] = 0;
240                 rlw_set_literal_words(self->rlw,
241                         rlw_get_literal_words(self->rlw) - 1);
242                 add_empty_word(self, 1);
243         }
244 }
245
246 void ewah_each_bit(struct ewah_bitmap *self, void (*callback)(size_t, void*), void *payload)
247 {
248         size_t pos = 0;
249         size_t pointer = 0;
250         size_t k;
251
252         while (pointer < self->buffer_size) {
253                 eword_t *word = &self->buffer[pointer];
254
255                 if (rlw_get_run_bit(word)) {
256                         size_t len = rlw_get_running_len(word) * BITS_IN_EWORD;
257                         for (k = 0; k < len; ++k, ++pos)
258                                 callback(pos, payload);
259                 } else {
260                         pos += rlw_get_running_len(word) * BITS_IN_EWORD;
261                 }
262
263                 ++pointer;
264
265                 for (k = 0; k < rlw_get_literal_words(word); ++k) {
266                         int c;
267
268                         /* todo: zero count optimization */
269                         for (c = 0; c < BITS_IN_EWORD; ++c, ++pos) {
270                                 if ((self->buffer[pointer] & ((eword_t)1 << c)) != 0)
271                                         callback(pos, payload);
272                         }
273
274                         ++pointer;
275                 }
276         }
277 }
278
279 /**
280  * Clear all the bits in the bitmap. Does not free or resize
281  * memory.
282  */
283 static void ewah_clear(struct ewah_bitmap *self)
284 {
285         self->buffer_size = 1;
286         self->buffer[0] = 0;
287         self->bit_size = 0;
288         self->rlw = self->buffer;
289 }
290
291 struct ewah_bitmap *ewah_new(void)
292 {
293         struct ewah_bitmap *self;
294
295         self = xmalloc(sizeof(struct ewah_bitmap));
296         self->alloc_size = 32;
297         ALLOC_ARRAY(self->buffer, self->alloc_size);
298
299         ewah_clear(self);
300         return self;
301 }
302
303 void ewah_free(struct ewah_bitmap *self)
304 {
305         if (!self)
306                 return;
307
308         if (self->alloc_size)
309                 free(self->buffer);
310
311         free(self);
312 }
313
314 static void read_new_rlw(struct ewah_iterator *it)
315 {
316         const eword_t *word = NULL;
317
318         it->literals = 0;
319         it->compressed = 0;
320
321         while (1) {
322                 word = &it->buffer[it->pointer];
323
324                 it->rl = rlw_get_running_len(word);
325                 it->lw = rlw_get_literal_words(word);
326                 it->b = rlw_get_run_bit(word);
327
328                 if (it->rl || it->lw)
329                         return;
330
331                 if (it->pointer < it->buffer_size - 1) {
332                         it->pointer++;
333                 } else {
334                         it->pointer = it->buffer_size;
335                         return;
336                 }
337         }
338 }
339
340 int ewah_iterator_next(eword_t *next, struct ewah_iterator *it)
341 {
342         if (it->pointer >= it->buffer_size)
343                 return 0;
344
345         if (it->compressed < it->rl) {
346                 it->compressed++;
347                 *next = it->b ? (eword_t)(~0) : 0;
348         } else {
349                 assert(it->literals < it->lw);
350
351                 it->literals++;
352                 it->pointer++;
353
354                 assert(it->pointer < it->buffer_size);
355
356                 *next = it->buffer[it->pointer];
357         }
358
359         if (it->compressed == it->rl && it->literals == it->lw) {
360                 if (++it->pointer < it->buffer_size)
361                         read_new_rlw(it);
362         }
363
364         return 1;
365 }
366
367 void ewah_iterator_init(struct ewah_iterator *it, struct ewah_bitmap *parent)
368 {
369         it->buffer = parent->buffer;
370         it->buffer_size = parent->buffer_size;
371         it->pointer = 0;
372
373         it->lw = 0;
374         it->rl = 0;
375         it->compressed = 0;
376         it->literals = 0;
377         it->b = 0;
378
379         if (it->pointer < it->buffer_size)
380                 read_new_rlw(it);
381 }
382
383 void ewah_xor(
384         struct ewah_bitmap *ewah_i,
385         struct ewah_bitmap *ewah_j,
386         struct ewah_bitmap *out)
387 {
388         struct rlw_iterator rlw_i;
389         struct rlw_iterator rlw_j;
390         size_t literals;
391
392         rlwit_init(&rlw_i, ewah_i);
393         rlwit_init(&rlw_j, ewah_j);
394
395         while (rlwit_word_size(&rlw_i) > 0 && rlwit_word_size(&rlw_j) > 0) {
396                 while (rlw_i.rlw.running_len > 0 || rlw_j.rlw.running_len > 0) {
397                         struct rlw_iterator *prey, *predator;
398                         size_t index;
399                         int negate_words;
400
401                         if (rlw_i.rlw.running_len < rlw_j.rlw.running_len) {
402                                 prey = &rlw_i;
403                                 predator = &rlw_j;
404                         } else {
405                                 prey = &rlw_j;
406                                 predator = &rlw_i;
407                         }
408
409                         negate_words = !!predator->rlw.running_bit;
410                         index = rlwit_discharge(prey, out,
411                                 predator->rlw.running_len, negate_words);
412
413                         ewah_add_empty_words(out, negate_words,
414                                 predator->rlw.running_len - index);
415
416                         rlwit_discard_first_words(predator,
417                                 predator->rlw.running_len);
418                 }
419
420                 literals = min_size(
421                         rlw_i.rlw.literal_words,
422                         rlw_j.rlw.literal_words);
423
424                 if (literals) {
425                         size_t k;
426
427                         for (k = 0; k < literals; ++k) {
428                                 ewah_add(out,
429                                         rlw_i.buffer[rlw_i.literal_word_start + k] ^
430                                         rlw_j.buffer[rlw_j.literal_word_start + k]
431                                 );
432                         }
433
434                         rlwit_discard_first_words(&rlw_i, literals);
435                         rlwit_discard_first_words(&rlw_j, literals);
436                 }
437         }
438
439         if (rlwit_word_size(&rlw_i) > 0)
440                 rlwit_discharge(&rlw_i, out, ~0, 0);
441         else
442                 rlwit_discharge(&rlw_j, out, ~0, 0);
443
444         out->bit_size = max_size(ewah_i->bit_size, ewah_j->bit_size);
445 }
446
447 #define BITMAP_POOL_MAX 16
448 static struct ewah_bitmap *bitmap_pool[BITMAP_POOL_MAX];
449 static size_t bitmap_pool_size;
450
451 struct ewah_bitmap *ewah_pool_new(void)
452 {
453         if (bitmap_pool_size)
454                 return bitmap_pool[--bitmap_pool_size];
455
456         return ewah_new();
457 }
458
459 void ewah_pool_free(struct ewah_bitmap *self)
460 {
461         if (self == NULL)
462                 return;
463
464         if (bitmap_pool_size == BITMAP_POOL_MAX ||
465                 self->alloc_size == 0) {
466                 ewah_free(self);
467                 return;
468         }
469
470         ewah_clear(self);
471         bitmap_pool[bitmap_pool_size++] = self;
472 }
473
474 uint32_t ewah_checksum(struct ewah_bitmap *self)
475 {
476         const uint8_t *p = (uint8_t *)self->buffer;
477         uint32_t crc = (uint32_t)self->bit_size;
478         size_t size = self->buffer_size * sizeof(eword_t);
479
480         while (size--)
481                 crc = (crc << 5) - crc + (uint32_t)*p++;
482
483         return crc;
484 }