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![Jeff King](/assets/img/avatar_default.png)
This code was originally written with the idea that it could be spun off into its own ewah library, and uses the overrideable ewah_malloc to do allocations. We plug in xmalloc as our ewah_malloc, of course. But over the years the ewah code itself has become more entangled with git, and the return value of many ewah_malloc sites is not checked. Let's just drop the level of indirection and use xmalloc and friends directly. This saves a few lines, and will let us adapt these sites to our more advanced malloc helpers. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
226 lines
6.5 KiB
C
226 lines
6.5 KiB
C
/**
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* Copyright 2013, GitHub, Inc
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* Copyright 2009-2013, Daniel Lemire, Cliff Moon,
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* David McIntosh, Robert Becho, Google Inc. and Veronika Zenz
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef __EWOK_BITMAP_H__
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#define __EWOK_BITMAP_H__
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struct strbuf;
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typedef uint64_t eword_t;
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#define BITS_IN_EWORD (sizeof(eword_t) * 8)
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/**
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* Do not use __builtin_popcountll. The GCC implementation
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* is notoriously slow on all platforms.
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*
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* See: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36041
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*/
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static inline uint32_t ewah_bit_popcount64(uint64_t x)
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{
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x = (x & 0x5555555555555555ULL) + ((x >> 1) & 0x5555555555555555ULL);
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x = (x & 0x3333333333333333ULL) + ((x >> 2) & 0x3333333333333333ULL);
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x = (x & 0x0F0F0F0F0F0F0F0FULL) + ((x >> 4) & 0x0F0F0F0F0F0F0F0FULL);
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return (x * 0x0101010101010101ULL) >> 56;
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}
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/* __builtin_ctzll was not available until 3.4.0 */
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#if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR > 3))
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#define ewah_bit_ctz64(x) __builtin_ctzll(x)
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#else
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static inline int ewah_bit_ctz64(uint64_t x)
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{
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int n = 0;
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if ((x & 0xffffffff) == 0) { x >>= 32; n += 32; }
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if ((x & 0xffff) == 0) { x >>= 16; n += 16; }
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if ((x & 0xff) == 0) { x >>= 8; n += 8; }
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if ((x & 0xf) == 0) { x >>= 4; n += 4; }
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if ((x & 0x3) == 0) { x >>= 2; n += 2; }
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if ((x & 0x1) == 0) { x >>= 1; n += 1; }
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return n + !x;
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}
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#endif
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struct ewah_bitmap {
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eword_t *buffer;
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size_t buffer_size;
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size_t alloc_size;
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size_t bit_size;
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eword_t *rlw;
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};
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typedef void (*ewah_callback)(size_t pos, void *);
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struct ewah_bitmap *ewah_pool_new(void);
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void ewah_pool_free(struct ewah_bitmap *self);
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/**
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* Allocate a new EWAH Compressed bitmap
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*/
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struct ewah_bitmap *ewah_new(void);
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/**
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* Clear all the bits in the bitmap. Does not free or resize
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* memory.
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*/
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void ewah_clear(struct ewah_bitmap *self);
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/**
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* Free all the memory of the bitmap
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*/
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void ewah_free(struct ewah_bitmap *self);
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int ewah_serialize_to(struct ewah_bitmap *self,
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int (*write_fun)(void *out, const void *buf, size_t len),
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void *out);
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int ewah_serialize(struct ewah_bitmap *self, int fd);
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int ewah_serialize_native(struct ewah_bitmap *self, int fd);
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int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *);
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int ewah_deserialize(struct ewah_bitmap *self, int fd);
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int ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len);
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uint32_t ewah_checksum(struct ewah_bitmap *self);
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/**
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* Logical not (bitwise negation) in-place on the bitmap
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*
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* This operation is linear time based on the size of the bitmap.
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*/
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void ewah_not(struct ewah_bitmap *self);
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/**
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* Call the given callback with the position of every single bit
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* that has been set on the bitmap.
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*
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* This is an efficient operation that does not fully decompress
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* the bitmap.
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*/
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void ewah_each_bit(struct ewah_bitmap *self, ewah_callback callback, void *payload);
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/**
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* Set a given bit on the bitmap.
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*
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* The bit at position `pos` will be set to true. Because of the
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* way that the bitmap is compressed, a set bit cannot be unset
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* later on.
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*
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* Furthermore, since the bitmap uses streaming compression, bits
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* can only set incrementally.
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*
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* E.g.
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* ewah_set(bitmap, 1); // ok
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* ewah_set(bitmap, 76); // ok
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* ewah_set(bitmap, 77); // ok
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* ewah_set(bitmap, 8712800127); // ok
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* ewah_set(bitmap, 25); // failed, assert raised
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*/
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void ewah_set(struct ewah_bitmap *self, size_t i);
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struct ewah_iterator {
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const eword_t *buffer;
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size_t buffer_size;
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size_t pointer;
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eword_t compressed, literals;
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eword_t rl, lw;
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int b;
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};
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/**
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* Initialize a new iterator to run through the bitmap in uncompressed form.
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*
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* The iterator can be stack allocated. The underlying bitmap must not be freed
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* before the iteration is over.
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*
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* E.g.
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*
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* struct ewah_bitmap *bitmap = ewah_new();
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* struct ewah_iterator it;
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*
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* ewah_iterator_init(&it, bitmap);
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*/
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void ewah_iterator_init(struct ewah_iterator *it, struct ewah_bitmap *parent);
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/**
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* Yield every single word in the bitmap in uncompressed form. This is:
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* yield single words (32-64 bits) where each bit represents an actual
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* bit from the bitmap.
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*
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* Return: true if a word was yield, false if there are no words left
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*/
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int ewah_iterator_next(eword_t *next, struct ewah_iterator *it);
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void ewah_or(
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struct ewah_bitmap *ewah_i,
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struct ewah_bitmap *ewah_j,
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struct ewah_bitmap *out);
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void ewah_and_not(
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struct ewah_bitmap *ewah_i,
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struct ewah_bitmap *ewah_j,
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struct ewah_bitmap *out);
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void ewah_xor(
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struct ewah_bitmap *ewah_i,
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struct ewah_bitmap *ewah_j,
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struct ewah_bitmap *out);
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void ewah_and(
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struct ewah_bitmap *ewah_i,
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struct ewah_bitmap *ewah_j,
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struct ewah_bitmap *out);
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/**
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* Direct word access
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*/
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size_t ewah_add_empty_words(struct ewah_bitmap *self, int v, size_t number);
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void ewah_add_dirty_words(
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struct ewah_bitmap *self, const eword_t *buffer, size_t number, int negate);
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size_t ewah_add(struct ewah_bitmap *self, eword_t word);
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/**
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* Uncompressed, old-school bitmap that can be efficiently compressed
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* into an `ewah_bitmap`.
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*/
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struct bitmap {
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eword_t *words;
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size_t word_alloc;
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};
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struct bitmap *bitmap_new(void);
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void bitmap_set(struct bitmap *self, size_t pos);
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void bitmap_clear(struct bitmap *self, size_t pos);
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int bitmap_get(struct bitmap *self, size_t pos);
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void bitmap_reset(struct bitmap *self);
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void bitmap_free(struct bitmap *self);
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int bitmap_equals(struct bitmap *self, struct bitmap *other);
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int bitmap_is_subset(struct bitmap *self, struct bitmap *super);
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struct ewah_bitmap * bitmap_to_ewah(struct bitmap *bitmap);
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struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah);
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void bitmap_and_not(struct bitmap *self, struct bitmap *other);
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void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other);
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void bitmap_or(struct bitmap *self, const struct bitmap *other);
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void bitmap_each_bit(struct bitmap *self, ewah_callback callback, void *data);
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size_t bitmap_popcount(struct bitmap *self);
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#endif
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