git/ewah/bitmap.c
Jeff King 08c95df8fa ewah: convert to REALLOC_ARRAY, etc
Now that we're built around xmalloc and friends, we can use
helpers like REALLOC_ARRAY, ALLOC_GROW, and so on to make
the code shorter and protect against integer overflow.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-02-22 14:51:09 -08:00

214 lines
4.9 KiB
C

/**
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "cache.h"
#include "ewok.h"
#define EWAH_MASK(x) ((eword_t)1 << (x % BITS_IN_EWORD))
#define EWAH_BLOCK(x) (x / BITS_IN_EWORD)
struct bitmap *bitmap_new(void)
{
struct bitmap *bitmap = xmalloc(sizeof(struct bitmap));
bitmap->words = xcalloc(32, sizeof(eword_t));
bitmap->word_alloc = 32;
return bitmap;
}
void bitmap_set(struct bitmap *self, size_t pos)
{
size_t block = EWAH_BLOCK(pos);
if (block >= self->word_alloc) {
size_t old_size = self->word_alloc;
self->word_alloc = block * 2;
REALLOC_ARRAY(self->words, self->word_alloc);
memset(self->words + old_size, 0x0,
(self->word_alloc - old_size) * sizeof(eword_t));
}
self->words[block] |= EWAH_MASK(pos);
}
void bitmap_clear(struct bitmap *self, size_t pos)
{
size_t block = EWAH_BLOCK(pos);
if (block < self->word_alloc)
self->words[block] &= ~EWAH_MASK(pos);
}
int bitmap_get(struct bitmap *self, size_t pos)
{
size_t block = EWAH_BLOCK(pos);
return block < self->word_alloc &&
(self->words[block] & EWAH_MASK(pos)) != 0;
}
struct ewah_bitmap *bitmap_to_ewah(struct bitmap *bitmap)
{
struct ewah_bitmap *ewah = ewah_new();
size_t i, running_empty_words = 0;
eword_t last_word = 0;
for (i = 0; i < bitmap->word_alloc; ++i) {
if (bitmap->words[i] == 0) {
running_empty_words++;
continue;
}
if (last_word != 0)
ewah_add(ewah, last_word);
if (running_empty_words > 0) {
ewah_add_empty_words(ewah, 0, running_empty_words);
running_empty_words = 0;
}
last_word = bitmap->words[i];
}
ewah_add(ewah, last_word);
return ewah;
}
struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah)
{
struct bitmap *bitmap = bitmap_new();
struct ewah_iterator it;
eword_t blowup;
size_t i = 0;
ewah_iterator_init(&it, ewah);
while (ewah_iterator_next(&blowup, &it)) {
ALLOC_GROW(bitmap->words, i + 1, bitmap->word_alloc);
bitmap->words[i++] = blowup;
}
bitmap->word_alloc = i;
return bitmap;
}
void bitmap_and_not(struct bitmap *self, struct bitmap *other)
{
const size_t count = (self->word_alloc < other->word_alloc) ?
self->word_alloc : other->word_alloc;
size_t i;
for (i = 0; i < count; ++i)
self->words[i] &= ~other->words[i];
}
void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other)
{
size_t original_size = self->word_alloc;
size_t other_final = (other->bit_size / BITS_IN_EWORD) + 1;
size_t i = 0;
struct ewah_iterator it;
eword_t word;
if (self->word_alloc < other_final) {
self->word_alloc = other_final;
REALLOC_ARRAY(self->words, self->word_alloc);
memset(self->words + original_size, 0x0,
(self->word_alloc - original_size) * sizeof(eword_t));
}
ewah_iterator_init(&it, other);
while (ewah_iterator_next(&word, &it))
self->words[i++] |= word;
}
void bitmap_each_bit(struct bitmap *self, ewah_callback callback, void *data)
{
size_t pos = 0, i;
for (i = 0; i < self->word_alloc; ++i) {
eword_t word = self->words[i];
uint32_t offset;
if (word == (eword_t)~0) {
for (offset = 0; offset < BITS_IN_EWORD; ++offset)
callback(pos++, data);
} else {
for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
if ((word >> offset) == 0)
break;
offset += ewah_bit_ctz64(word >> offset);
callback(pos + offset, data);
}
pos += BITS_IN_EWORD;
}
}
}
size_t bitmap_popcount(struct bitmap *self)
{
size_t i, count = 0;
for (i = 0; i < self->word_alloc; ++i)
count += ewah_bit_popcount64(self->words[i]);
return count;
}
int bitmap_equals(struct bitmap *self, struct bitmap *other)
{
struct bitmap *big, *small;
size_t i;
if (self->word_alloc < other->word_alloc) {
small = self;
big = other;
} else {
small = other;
big = self;
}
for (i = 0; i < small->word_alloc; ++i) {
if (small->words[i] != big->words[i])
return 0;
}
for (; i < big->word_alloc; ++i) {
if (big->words[i] != 0)
return 0;
}
return 1;
}
void bitmap_reset(struct bitmap *bitmap)
{
memset(bitmap->words, 0x0, bitmap->word_alloc * sizeof(eword_t));
}
void bitmap_free(struct bitmap *bitmap)
{
if (bitmap == NULL)
return;
free(bitmap->words);
free(bitmap);
}