The twelfth batch
[git/gitster.git] / ewah / bitmap.c
blob55928dada86a37f3dd291c775f7f109f908e74a4
1 /**
2 * Copyright 2013, GitHub, Inc
3 * Copyright 2009-2013, Daniel Lemire, Cliff Moon,
4 * David McIntosh, Robert Becho, Google Inc. and Veronika Zenz
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.
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.
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/>.
19 #include "git-compat-util.h"
20 #include "ewok.h"
22 #define EWAH_MASK(x) ((eword_t)1 << (x % BITS_IN_EWORD))
23 #define EWAH_BLOCK(x) (x / BITS_IN_EWORD)
25 struct bitmap *bitmap_word_alloc(size_t word_alloc)
27 struct bitmap *bitmap = xmalloc(sizeof(struct bitmap));
28 CALLOC_ARRAY(bitmap->words, word_alloc);
29 bitmap->word_alloc = word_alloc;
30 return bitmap;
33 struct bitmap *bitmap_new(void)
35 return bitmap_word_alloc(32);
38 struct bitmap *bitmap_dup(const struct bitmap *src)
40 struct bitmap *dst = bitmap_word_alloc(src->word_alloc);
41 COPY_ARRAY(dst->words, src->words, src->word_alloc);
42 return dst;
45 static void bitmap_grow(struct bitmap *self, size_t word_alloc)
47 size_t old_size = self->word_alloc;
48 ALLOC_GROW(self->words, word_alloc, self->word_alloc);
49 memset(self->words + old_size, 0x0,
50 (self->word_alloc - old_size) * sizeof(eword_t));
53 void bitmap_set(struct bitmap *self, size_t pos)
55 size_t block = EWAH_BLOCK(pos);
57 bitmap_grow(self, block + 1);
58 self->words[block] |= EWAH_MASK(pos);
61 void bitmap_unset(struct bitmap *self, size_t pos)
63 size_t block = EWAH_BLOCK(pos);
65 if (block < self->word_alloc)
66 self->words[block] &= ~EWAH_MASK(pos);
69 int bitmap_get(struct bitmap *self, size_t pos)
71 size_t block = EWAH_BLOCK(pos);
72 return block < self->word_alloc &&
73 (self->words[block] & EWAH_MASK(pos)) != 0;
76 struct ewah_bitmap *bitmap_to_ewah(struct bitmap *bitmap)
78 struct ewah_bitmap *ewah = ewah_new();
79 size_t i, running_empty_words = 0;
80 eword_t last_word = 0;
82 for (i = 0; i < bitmap->word_alloc; ++i) {
83 if (bitmap->words[i] == 0) {
84 running_empty_words++;
85 continue;
88 if (last_word != 0)
89 ewah_add(ewah, last_word);
91 if (running_empty_words > 0) {
92 ewah_add_empty_words(ewah, 0, running_empty_words);
93 running_empty_words = 0;
96 last_word = bitmap->words[i];
99 ewah_add(ewah, last_word);
100 return ewah;
103 struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah)
105 struct bitmap *bitmap = bitmap_new();
106 struct ewah_iterator it;
107 eword_t blowup;
108 size_t i = 0;
110 ewah_iterator_init(&it, ewah);
112 while (ewah_iterator_next(&blowup, &it)) {
113 ALLOC_GROW(bitmap->words, i + 1, bitmap->word_alloc);
114 bitmap->words[i++] = blowup;
117 bitmap->word_alloc = i;
118 return bitmap;
121 void bitmap_and_not(struct bitmap *self, struct bitmap *other)
123 const size_t count = (self->word_alloc < other->word_alloc) ?
124 self->word_alloc : other->word_alloc;
126 size_t i;
128 for (i = 0; i < count; ++i)
129 self->words[i] &= ~other->words[i];
132 void bitmap_or(struct bitmap *self, const struct bitmap *other)
134 size_t i;
136 bitmap_grow(self, other->word_alloc);
137 for (i = 0; i < other->word_alloc; i++)
138 self->words[i] |= other->words[i];
141 int ewah_bitmap_is_subset(struct ewah_bitmap *self, struct bitmap *other)
143 struct ewah_iterator it;
144 eword_t word;
145 size_t i;
147 ewah_iterator_init(&it, self);
149 for (i = 0; i < other->word_alloc; i++) {
150 if (!ewah_iterator_next(&word, &it)) {
152 * If we reached the end of `self`, and haven't
153 * rejected `self` as a possible subset of
154 * `other` yet, then we are done and `self` is
155 * indeed a subset of `other`.
157 return 1;
159 if (word & ~other->words[i]) {
161 * Otherwise, compare the next two pairs of
162 * words. If the word from `self` has bit(s) not
163 * in the word from `other`, `self` is not a
164 * subset of `other`.
166 return 0;
171 * If we got to this point, there may be zero or more words
172 * remaining in `self`, with no remaining words left in `other`.
173 * If there are any bits set in the remaining word(s) in `self`,
174 * then `self` is not a subset of `other`.
176 while (ewah_iterator_next(&word, &it))
177 if (word)
178 return 0;
180 /* `self` is definitely a subset of `other` */
181 return 1;
184 void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other)
186 size_t original_size = self->word_alloc;
187 size_t other_final = (other->bit_size / BITS_IN_EWORD) + 1;
188 size_t i = 0;
189 struct ewah_iterator it;
190 eword_t word;
192 if (self->word_alloc < other_final) {
193 self->word_alloc = other_final;
194 REALLOC_ARRAY(self->words, self->word_alloc);
195 memset(self->words + original_size, 0x0,
196 (self->word_alloc - original_size) * sizeof(eword_t));
199 ewah_iterator_init(&it, other);
201 while (ewah_iterator_next(&word, &it))
202 self->words[i++] |= word;
205 size_t bitmap_popcount(struct bitmap *self)
207 size_t i, count = 0;
209 for (i = 0; i < self->word_alloc; ++i)
210 count += ewah_bit_popcount64(self->words[i]);
212 return count;
215 size_t ewah_bitmap_popcount(struct ewah_bitmap *self)
217 struct ewah_iterator it;
218 eword_t word;
219 size_t count = 0;
221 ewah_iterator_init(&it, self);
223 while (ewah_iterator_next(&word, &it))
224 count += ewah_bit_popcount64(word);
226 return count;
229 int bitmap_is_empty(struct bitmap *self)
231 size_t i;
232 for (i = 0; i < self->word_alloc; i++)
233 if (self->words[i])
234 return 0;
235 return 1;
238 int bitmap_equals(struct bitmap *self, struct bitmap *other)
240 struct bitmap *big, *small;
241 size_t i;
243 if (self->word_alloc < other->word_alloc) {
244 small = self;
245 big = other;
246 } else {
247 small = other;
248 big = self;
251 for (i = 0; i < small->word_alloc; ++i) {
252 if (small->words[i] != big->words[i])
253 return 0;
256 for (; i < big->word_alloc; ++i) {
257 if (big->words[i] != 0)
258 return 0;
261 return 1;
264 int bitmap_equals_ewah(struct bitmap *self, struct ewah_bitmap *other)
266 struct ewah_iterator it;
267 eword_t word;
268 size_t i = 0;
270 ewah_iterator_init(&it, other);
272 while (ewah_iterator_next(&word, &it))
273 if (word != (i < self->word_alloc ? self->words[i++] : 0))
274 return 0;
276 for (; i < self->word_alloc; i++)
277 if (self->words[i])
278 return 0;
280 return 1;
283 int bitmap_is_subset(struct bitmap *self, struct bitmap *other)
285 size_t common_size, i;
287 if (self->word_alloc < other->word_alloc)
288 common_size = self->word_alloc;
289 else {
290 common_size = other->word_alloc;
291 for (i = common_size; i < self->word_alloc; i++) {
292 if (self->words[i])
293 return 1;
297 for (i = 0; i < common_size; i++) {
298 if (self->words[i] & ~other->words[i])
299 return 1;
301 return 0;
304 void bitmap_free(struct bitmap *bitmap)
306 if (!bitmap)
307 return;
309 free(bitmap->words);
310 free(bitmap);