git/ewah/ewah_io.c

135 lines
3.8 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, see <http://www.gnu.org/licenses/>.
*/
#include "git-compat-util.h"
#include "ewok.h"
#include "strbuf.h"
int ewah_serialize_to(struct ewah_bitmap *self,
int (*write_fun)(void *, const void *, size_t),
void *data)
{
size_t i;
eword_t dump[2048];
const size_t words_per_dump = sizeof(dump) / sizeof(eword_t);
uint32_t bitsize, word_count, rlw_pos;
const eword_t *buffer;
size_t words_left;
/* 32 bit -- bit size for the map */
bitsize = htonl((uint32_t)self->bit_size);
if (write_fun(data, &bitsize, 4) != 4)
return -1;
/** 32 bit -- number of compressed 64-bit words */
word_count = htonl((uint32_t)self->buffer_size);
if (write_fun(data, &word_count, 4) != 4)
return -1;
/** 64 bit x N -- compressed words */
buffer = self->buffer;
words_left = self->buffer_size;
while (words_left >= words_per_dump) {
for (i = 0; i < words_per_dump; ++i, ++buffer)
dump[i] = htonll(*buffer);
if (write_fun(data, dump, sizeof(dump)) != sizeof(dump))
return -1;
words_left -= words_per_dump;
}
if (words_left) {
for (i = 0; i < words_left; ++i, ++buffer)
dump[i] = htonll(*buffer);
if (write_fun(data, dump, words_left * 8) != words_left * 8)
return -1;
}
/** 32 bit -- position for the RLW */
rlw_pos = (uint8_t*)self->rlw - (uint8_t *)self->buffer;
rlw_pos = htonl(rlw_pos / sizeof(eword_t));
if (write_fun(data, &rlw_pos, 4) != 4)
return -1;
return (3 * 4) + (self->buffer_size * 8);
}
static int write_strbuf(void *user_data, const void *data, size_t len)
{
struct strbuf *sb = user_data;
strbuf_add(sb, data, len);
return len;
}
int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *sb)
{
return ewah_serialize_to(self, write_strbuf, sb);
}
ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len)
{
const uint8_t *ptr = map;
size_t data_len;
size_t i;
if (len < sizeof(uint32_t))
return error("corrupt ewah bitmap: eof before bit size");
self->bit_size = get_be32(ptr);
ptr += sizeof(uint32_t);
len -= sizeof(uint32_t);
if (len < sizeof(uint32_t))
return error("corrupt ewah bitmap: eof before length");
self->buffer_size = self->alloc_size = get_be32(ptr);
ptr += sizeof(uint32_t);
len -= sizeof(uint32_t);
REALLOC_ARRAY(self->buffer, self->alloc_size);
/*
* Copy the raw data for the bitmap as a whole chunk;
* if we're in a little-endian platform, we'll perform
* the endianness conversion in a separate pass to ensure
* we're loading 8-byte aligned words.
*/
data_len = st_mult(self->buffer_size, sizeof(eword_t));
if (len < data_len)
return error("corrupt ewah bitmap: eof in data "
"(%"PRIuMAX" bytes short)",
(uintmax_t)(data_len - len));
memcpy(self->buffer, ptr, data_len);
ptr += data_len;
len -= data_len;
for (i = 0; i < self->buffer_size; ++i)
self->buffer[i] = ntohll(self->buffer[i]);
if (len < sizeof(uint32_t))
return error("corrupt ewah bitmap: eof before rlw");
self->rlw = self->buffer + get_be32(ptr);
ptr += sizeof(uint32_t);
len -= sizeof(uint32_t);
return ptr - (const uint8_t *)map;
}