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Diffstat (limited to 'third_party/git/ewah/ewok.h')
| -rw-r--r-- | third_party/git/ewah/ewok.h | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/third_party/git/ewah/ewok.h b/third_party/git/ewah/ewok.h new file mode 100644 index 000000000000..011852bef179 --- /dev/null +++ b/third_party/git/ewah/ewok.h @@ -0,0 +1,193 @@ +/** + * Copyright 2013, GitHub, Inc + * Copyright 2009-2013, Daniel Lemire, Cliff Moon, + * David McIntosh, Robert Becho, Google Inc. and Veronika Zenz + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ +#ifndef __EWOK_BITMAP_H__ +#define __EWOK_BITMAP_H__ + +struct strbuf; +typedef uint64_t eword_t; +#define BITS_IN_EWORD (sizeof(eword_t) * 8) + +/** + * Do not use __builtin_popcountll. The GCC implementation + * is notoriously slow on all platforms. + * + * See: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36041 + */ +static inline uint32_t ewah_bit_popcount64(uint64_t x) +{ + x = (x & 0x5555555555555555ULL) + ((x >> 1) & 0x5555555555555555ULL); + x = (x & 0x3333333333333333ULL) + ((x >> 2) & 0x3333333333333333ULL); + x = (x & 0x0F0F0F0F0F0F0F0FULL) + ((x >> 4) & 0x0F0F0F0F0F0F0F0FULL); + return (x * 0x0101010101010101ULL) >> 56; +} + +/* __builtin_ctzll was not available until 3.4.0 */ +#if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR > 3)) +#define ewah_bit_ctz64(x) __builtin_ctzll(x) +#else +static inline int ewah_bit_ctz64(uint64_t x) +{ + int n = 0; + if ((x & 0xffffffff) == 0) { x >>= 32; n += 32; } + if ((x & 0xffff) == 0) { x >>= 16; n += 16; } + if ((x & 0xff) == 0) { x >>= 8; n += 8; } + if ((x & 0xf) == 0) { x >>= 4; n += 4; } + if ((x & 0x3) == 0) { x >>= 2; n += 2; } + if ((x & 0x1) == 0) { x >>= 1; n += 1; } + return n + !x; +} +#endif + +struct ewah_bitmap { + eword_t *buffer; + size_t buffer_size; + size_t alloc_size; + size_t bit_size; + eword_t *rlw; +}; + +typedef void (*ewah_callback)(size_t pos, void *); + +struct ewah_bitmap *ewah_pool_new(void); +void ewah_pool_free(struct ewah_bitmap *self); + +/** + * Allocate a new EWAH Compressed bitmap + */ +struct ewah_bitmap *ewah_new(void); + +/** + * Free all the memory of the bitmap + */ +void ewah_free(struct ewah_bitmap *self); + +int ewah_serialize_to(struct ewah_bitmap *self, + int (*write_fun)(void *out, const void *buf, size_t len), + void *out); +int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *); + +ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len); + +uint32_t ewah_checksum(struct ewah_bitmap *self); + +/** + * Call the given callback with the position of every single bit + * that has been set on the bitmap. + * + * This is an efficient operation that does not fully decompress + * the bitmap. + */ +void ewah_each_bit(struct ewah_bitmap *self, ewah_callback callback, void *payload); + +/** + * Set a given bit on the bitmap. + * + * The bit at position `pos` will be set to true. Because of the + * way that the bitmap is compressed, a set bit cannot be unset + * later on. + * + * Furthermore, since the bitmap uses streaming compression, bits + * can only set incrementally. + * + * E.g. + * ewah_set(bitmap, 1); // ok + * ewah_set(bitmap, 76); // ok + * ewah_set(bitmap, 77); // ok + * ewah_set(bitmap, 8712800127); // ok + * ewah_set(bitmap, 25); // failed, assert raised + */ +void ewah_set(struct ewah_bitmap *self, size_t i); + +struct ewah_iterator { + const eword_t *buffer; + size_t buffer_size; + + size_t pointer; + eword_t compressed, literals; + eword_t rl, lw; + int b; +}; + +/** + * Initialize a new iterator to run through the bitmap in uncompressed form. + * + * The iterator can be stack allocated. The underlying bitmap must not be freed + * before the iteration is over. + * + * E.g. + * + * struct ewah_bitmap *bitmap = ewah_new(); + * struct ewah_iterator it; + * + * ewah_iterator_init(&it, bitmap); + */ +void ewah_iterator_init(struct ewah_iterator *it, struct ewah_bitmap *parent); + +/** + * Yield every single word in the bitmap in uncompressed form. This is: + * yield single words (32-64 bits) where each bit represents an actual + * bit from the bitmap. + * + * Return: true if a word was yield, false if there are no words left + */ +int ewah_iterator_next(eword_t *next, struct ewah_iterator *it); + +void ewah_xor( + struct ewah_bitmap *ewah_i, + struct ewah_bitmap *ewah_j, + struct ewah_bitmap *out); + +/** + * Direct word access + */ +size_t ewah_add_empty_words(struct ewah_bitmap *self, int v, size_t number); +void ewah_add_dirty_words( + struct ewah_bitmap *self, const eword_t *buffer, size_t number, int negate); +size_t ewah_add(struct ewah_bitmap *self, eword_t word); + + +/** + * Uncompressed, old-school bitmap that can be efficiently compressed + * into an `ewah_bitmap`. + */ +struct bitmap { + eword_t *words; + size_t word_alloc; +}; + +struct bitmap *bitmap_new(void); +struct bitmap *bitmap_word_alloc(size_t word_alloc); +void bitmap_set(struct bitmap *self, size_t pos); +void bitmap_unset(struct bitmap *self, size_t pos); +int bitmap_get(struct bitmap *self, size_t pos); +void bitmap_reset(struct bitmap *self); +void bitmap_free(struct bitmap *self); +int bitmap_equals(struct bitmap *self, struct bitmap *other); +int bitmap_is_subset(struct bitmap *self, struct bitmap *super); + +struct ewah_bitmap * bitmap_to_ewah(struct bitmap *bitmap); +struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah); + +void bitmap_and_not(struct bitmap *self, struct bitmap *other); +void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other); +void bitmap_or(struct bitmap *self, const struct bitmap *other); + +size_t bitmap_popcount(struct bitmap *self); + +#endif |