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
  22 #define EWAH_MASK(x) ((eword_t)1 << (x % BITS_IN_EWORD))
  23 #define EWAH_BLOCK(x) (x / BITS_IN_EWORD)
  24
  25 struct bitmap *bitmap_word_alloc(size_t word_alloc)
  26 {
  27         struct bitmap *bitmap = xmalloc(sizeof(struct bitmap));
  28         CALLOC_ARRAY(bitmap->words, word_alloc);
  29         bitmap->word_alloc = word_alloc;
  30         return bitmap;
  31 }
  32
  33 struct bitmap *bitmap_new(void)
  34 {
  35         return bitmap_word_alloc(32);
  36 }
  37
  38 struct bitmap *bitmap_dup(const struct bitmap *src)
  39 {
  40         struct bitmap *dst = bitmap_word_alloc(src->word_alloc);
  41         COPY_ARRAY(dst->words, src->words, src->word_alloc);
  42         return dst;
  43 }
  44
  45 static void bitmap_grow(struct bitmap *self, size_t word_alloc)
  46 {
  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));
  51 }
  52
  53 void bitmap_set(struct bitmap *self, size_t pos)
  54 {
  55         size_t block = EWAH_BLOCK(pos);
  56
  57         bitmap_grow(self, block + 1);
  58         self->words[block] |= EWAH_MASK(pos);
  59 }
  60
  61 void bitmap_unset(struct bitmap *self, size_t pos)
  62 {
  63         size_t block = EWAH_BLOCK(pos);
  64
  65         if (block < self->word_alloc)
  66                 self->words[block] &= ~EWAH_MASK(pos);
  67 }
  68
  69 int bitmap_get(struct bitmap *self, size_t pos)
  70 {
  71         size_t block = EWAH_BLOCK(pos);
  72         return block < self->word_alloc &&
  73                 (self->words[block] & EWAH_MASK(pos)) != 0;
  74 }
  75
  76 struct ewah_bitmap *bitmap_to_ewah(struct bitmap *bitmap)
  77 {
  78         struct ewah_bitmap *ewah = ewah_new();
  79         size_t i, running_empty_words = 0;
  80         eword_t last_word = 0;
  81
  82         for (i = 0; i < bitmap->word_alloc; ++i) {
  83                 if (bitmap->words[i] == 0) {
  84                         running_empty_words++;
  85                         continue;
  86                 }
  87
  88                 if (last_word != 0)
  89                         ewah_add(ewah, last_word);
  90
  91                 if (running_empty_words > 0) {
  92                         ewah_add_empty_words(ewah, 0, running_empty_words);
  93                         running_empty_words = 0;
  94                 }
  95
  96                 last_word = bitmap->words[i];
  97         }
  98
  99         ewah_add(ewah, last_word);
 100         return ewah;
 101 }
 102
 103 struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah)
 104 {
 105         struct bitmap *bitmap = bitmap_new();
 106         struct ewah_iterator it;
 107         eword_t blowup;
 108         size_t i = 0;
 109
 110         ewah_iterator_init(&it, ewah);
 111
 112         while (ewah_iterator_next(&blowup, &it)) {
 113                 ALLOC_GROW(bitmap->words, i + 1, bitmap->word_alloc);
 114                 bitmap->words[i++] = blowup;
 115         }
 116
 117         bitmap->word_alloc = i;
 118         return bitmap;
 119 }
 120
 121 void bitmap_and_not(struct bitmap *self, struct bitmap *other)
 122 {
 123         const size_t count = (self->word_alloc < other->word_alloc) ?
 124                 self->word_alloc : other->word_alloc;
 125
 126         size_t i;
 127
 128         for (i = 0; i < count; ++i)
 129                 self->words[i] &= ~other->words[i];
 130 }
 131
 132 void bitmap_or(struct bitmap *self, const struct bitmap *other)
 133 {
 134         size_t i;
 135
 136         bitmap_grow(self, other->word_alloc);
 137         for (i = 0; i < other->word_alloc; i++)
 138                 self->words[i] |= other->words[i];
 139 }
 140
 141 int ewah_bitmap_is_subset(struct ewah_bitmap *self, struct bitmap *other)
 142 {
 143         struct ewah_iterator it;
 144         eword_t word;
 145         size_t i;
 146
 147         ewah_iterator_init(&it, self);
 148
 149         for (i = 0; i < other->word_alloc; i++) {
 150                 if (!ewah_iterator_next(&word, &it)) {
 151                         /*
 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`.
 156                          */
 157                         return 1;
 158                 }
 159                 if (word & ~other->words[i]) {
 160                         /*
 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`.
 165                          */
 166                         return 0;
 167                 }
 168         }
 169
 170         /*
 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`.
 175          */
 176         while (ewah_iterator_next(&word, &it))
 177                 if (word)
 178                         return 0;
 179
 180         /* `self` is definitely a subset of `other` */
 181         return 1;
 182 }
 183
 184 void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other)
 185 {
 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;
 191
 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));
 197         }
 198
 199         ewah_iterator_init(&it, other);
 200
 201         while (ewah_iterator_next(&word, &it))
 202                 self->words[i++] |= word;
 203 }
 204
 205 size_t bitmap_popcount(struct bitmap *self)
 206 {
 207         size_t i, count = 0;
 208
 209         for (i = 0; i < self->word_alloc; ++i)
 210                 count += ewah_bit_popcount64(self->words[i]);
 211
 212         return count;
 213 }
 214
 215 size_t ewah_bitmap_popcount(struct ewah_bitmap *self)
 216 {
 217         struct ewah_iterator it;
 218         eword_t word;
 219         size_t count = 0;
 220
 221         ewah_iterator_init(&it, self);
 222
 223         while (ewah_iterator_next(&word, &it))
 224                 count += ewah_bit_popcount64(word);
 225
 226         return count;
 227 }
 228
 229 int bitmap_is_empty(struct bitmap *self)
 230 {
 231         size_t i;
 232         for (i = 0; i < self->word_alloc; i++)
 233                 if (self->words[i])
 234                         return 0;
 235         return 1;
 236 }
 237
 238 int bitmap_equals(struct bitmap *self, struct bitmap *other)
 239 {
 240         struct bitmap *big, *small;
 241         size_t i;
 242
 243         if (self->word_alloc < other->word_alloc) {
 244                 small = self;
 245                 big = other;
 246         } else {
 247                 small = other;
 248                 big = self;
 249         }
 250
 251         for (i = 0; i < small->word_alloc; ++i) {
 252                 if (small->words[i] != big->words[i])
 253                         return 0;
 254         }
 255
 256         for (; i < big->word_alloc; ++i) {
 257                 if (big->words[i] != 0)
 258                         return 0;
 259         }
 260
 261         return 1;
 262 }
 263
 264 int bitmap_equals_ewah(struct bitmap *self, struct ewah_bitmap *other)
 265 {
 266         struct ewah_iterator it;
 267         eword_t word;
 268         size_t i = 0;
 269
 270         ewah_iterator_init(&it, other);
 271
 272         while (ewah_iterator_next(&word, &it))
 273                 if (word != (i < self->word_alloc ? self->words[i++] : 0))
 274                         return 0;
 275
 276         for (; i < self->word_alloc; i++)
 277                 if (self->words[i])
 278                         return 0;
 279
 280         return 1;
 281 }
 282
 283 int bitmap_is_subset(struct bitmap *self, struct bitmap *other)
 284 {
 285         size_t common_size, i;
 286
 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;
 294                 }
 295         }
 296
 297         for (i = 0; i < common_size; i++) {
 298                 if (self->words[i] & ~other->words[i])
 299                         return 1;
 300         }
 301         return 0;
 302 }
 303
 304 void bitmap_free(struct bitmap *bitmap)
 305 {
 306         if (!bitmap)
 307                 return;
 308
 309         free(bitmap->words);
 310         free(bitmap);
 311 }