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samba-mirror/lib/compression/lzxpress.c
Matthieu Patou 58db821de1 Fix endianess problems as discovered on the build farm
Autobuild-User: Matthieu Patou <mat@samba.org>
Autobuild-Date: Fri Nov 26 22:32:16 CET 2010 on sn-devel-104
2010-11-26 22:32:16 +01:00

316 lines
8.7 KiB
C

/*
* Copyright (C) Matthieu Suiche 2008
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the author nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include "replace.h"
#include "lzxpress.h"
#include "../lib/util/byteorder.h"
#define __BUF_POS_CONST(buf,ofs)(((const uint8_t *)buf)+(ofs))
#define __PULL_BYTE(buf,ofs) \
((uint8_t)((*__BUF_POS_CONST(buf,ofs)) & 0xFF))
#ifndef PULL_LE_UINT16
#define PULL_LE_UINT16(buf,ofs) ((uint16_t)( \
((uint16_t)(((uint16_t)(__PULL_BYTE(buf,(ofs)+0))) << 0)) | \
((uint16_t)(((uint16_t)(__PULL_BYTE(buf,(ofs)+1))) << 8)) \
))
#endif
#ifndef PULL_LE_UINT32
#define PULL_LE_UINT32(buf,ofs) ((uint32_t)( \
((uint32_t)(((uint32_t)(__PULL_BYTE(buf,(ofs)+0))) << 0)) | \
((uint32_t)(((uint32_t)(__PULL_BYTE(buf,(ofs)+1))) << 8)) | \
((uint32_t)(((uint32_t)(__PULL_BYTE(buf,(ofs)+2))) << 16)) | \
((uint32_t)(((uint32_t)(__PULL_BYTE(buf,(ofs)+3))) << 24)) \
))
#endif
ssize_t lzxpress_compress(const uint8_t *uncompressed,
uint32_t uncompressed_size,
uint8_t *compressed,
uint32_t max_compressed_size)
{
uint32_t uncompressed_pos, compressed_pos, byte_left;
uint32_t max_offset, best_offset;
int32_t offset;
uint32_t max_len, len, best_len;
const uint8_t *str1, *str2;
uint32_t indic;
uint8_t *indic_pos;
uint32_t indic_bit, nibble_index;
uint32_t metadata_size;
uint16_t metadata;
uint16_t *dest;
if (!uncompressed_size) {
return 0;
}
uncompressed_pos = 0;
indic = 0;
*(uint32_t *)compressed = 0;
compressed_pos = sizeof(uint32_t);
indic_pos = &compressed[0];
byte_left = uncompressed_size;
indic_bit = 0;
nibble_index = 0;
if (uncompressed_pos > XPRESS_BLOCK_SIZE)
return 0;
do {
bool found = false;
max_offset = uncompressed_pos;
str1 = &uncompressed[uncompressed_pos];
best_len = 2;
best_offset = 0;
max_offset = MIN(0x1FFF, max_offset);
/* search for the longest match in the window for the lookahead buffer */
for (offset = 1; (uint32_t)offset <= max_offset; offset++) {
str2 = &str1[-offset];
/* maximum len we can encode into metadata */
max_len = MIN((255 + 15 + 7 + 3), byte_left);
for (len = 0; (len < max_len) && (str1[len] == str2[len]); len++);
/*
* We check if len is better than the value found before, including the
* sequence of identical bytes
*/
if (len > best_len) {
found = true;
best_len = len;
best_offset = offset;
}
}
if (found) {
metadata_size = 0;
dest = (uint16_t *)&compressed[compressed_pos];
if (best_len < 10) {
/* Classical meta-data */
metadata = (uint16_t)(((best_offset - 1) << 3) | (best_len - 3));
SSVAL(dest, metadata_size / sizeof(uint16_t), metadata);
metadata_size += sizeof(uint16_t);
} else {
metadata = (uint16_t)(((best_offset - 1) << 3) | 7);
SSVAL(dest, metadata_size / sizeof(uint16_t), metadata);
metadata_size = sizeof(uint16_t);
if (best_len < (15 + 7 + 3)) {
/* Shared byte */
if (!nibble_index) {
compressed[compressed_pos + metadata_size] = (best_len - (3 + 7)) & 0xF;
metadata_size += sizeof(uint8_t);
} else {
compressed[nibble_index] &= 0xF;
compressed[nibble_index] |= (best_len - (3 + 7)) * 16;
}
} else if (best_len < (3 + 7 + 15 + 255)) {
/* Shared byte */
if (!nibble_index) {
compressed[compressed_pos + metadata_size] = 15;
metadata_size += sizeof(uint8_t);
} else {
compressed[nibble_index] &= 0xF;
compressed[nibble_index] |= (15 * 16);
}
/* Additional best_len */
compressed[compressed_pos + metadata_size] = (best_len - (3 + 7 + 15)) & 0xFF;
metadata_size += sizeof(uint8_t);
} else {
/* Shared byte */
if (!nibble_index) {
compressed[compressed_pos + metadata_size] |= 15;
metadata_size += sizeof(uint8_t);
} else {
compressed[nibble_index] |= 15 << 4;
}
/* Additional best_len */
compressed[compressed_pos + metadata_size] = 255;
metadata_size += sizeof(uint8_t);
compressed[compressed_pos + metadata_size] = (best_len - 3) & 0xFF;
compressed[compressed_pos + metadata_size + 1] = ((best_len - 3) >> 8) & 0xFF;
metadata_size += sizeof(uint16_t);
}
}
indic |= 1 << (32 - ((indic_bit % 32) + 1));
if (best_len > 9) {
if (nibble_index == 0) {
nibble_index = compressed_pos + sizeof(uint16_t);
} else {
nibble_index = 0;
}
}
compressed_pos += metadata_size;
uncompressed_pos += best_len;
byte_left -= best_len;
} else {
compressed[compressed_pos++] = uncompressed[uncompressed_pos++];
byte_left--;
}
indic_bit++;
if ((indic_bit - 1) % 32 > (indic_bit % 32)) {
SIVAL(indic_pos, 0, indic);
indic = 0;
indic_pos = &compressed[compressed_pos];
compressed_pos += sizeof(uint32_t);
}
} while (byte_left > 3);
do {
compressed[compressed_pos] = uncompressed[uncompressed_pos];
indic_bit++;
uncompressed_pos++;
compressed_pos++;
if (((indic_bit - 1) % 32) > (indic_bit % 32)){
SIVAL(indic_pos, 0, indic);
indic = 0;
indic_pos = &compressed[compressed_pos];
compressed_pos += sizeof(uint32_t);
}
} while (uncompressed_pos < uncompressed_size);
if ((indic_bit % 32) > 0) {
for (; (indic_bit % 32) != 0; indic_bit++)
indic |= 0 << (32 - ((indic_bit % 32) + 1));
*(uint32_t *)&compressed[compressed_pos] = 0;
SIVAL(indic_pos, 0, indic);
compressed_pos += sizeof(uint32_t);
}
return compressed_pos;
}
ssize_t lzxpress_decompress(const uint8_t *input,
uint32_t input_size,
uint8_t *output,
uint32_t max_output_size)
{
uint32_t output_index, input_index;
uint32_t indicator, indicator_bit;
uint32_t length;
uint32_t offset;
uint32_t nibble_index;
output_index = 0;
input_index = 0;
indicator = 0;
indicator_bit = 0;
length = 0;
offset = 0;
nibble_index = 0;
do {
if (indicator_bit == 0) {
indicator = PULL_LE_UINT32(input, input_index);
input_index += sizeof(uint32_t);
indicator_bit = 32;
}
indicator_bit--;
/*
* check whether the bit specified by indicator_bit is set or not
* set in indicator. For example, if indicator_bit has value 4
* check whether the 4th bit of the value in indicator is set
*/
if (((indicator >> indicator_bit) & 1) == 0) {
output[output_index] = input[input_index];
input_index += sizeof(uint8_t);
output_index += sizeof(uint8_t);
} else {
length = PULL_LE_UINT16(input, input_index);
input_index += sizeof(uint16_t);
offset = length / 8;
length = length % 8;
if (length == 7) {
if (nibble_index == 0) {
nibble_index = input_index;
length = input[input_index] % 16;
input_index += sizeof(uint8_t);
} else {
length = input[nibble_index] / 16;
nibble_index = 0;
}
if (length == 15) {
length = input[input_index];
input_index += sizeof(uint8_t);
if (length == 255) {
length = PULL_LE_UINT16(input, input_index);
input_index += sizeof(uint16_t);
length -= (15 + 7);
}
length += 15;
}
length += 7;
}
length += 3;
do {
if ((output_index >= max_output_size) || ((offset + 1) > output_index)) break;
output[output_index] = output[output_index - offset - 1];
output_index += sizeof(uint8_t);
length -= sizeof(uint8_t);
} while (length != 0);
}
} while ((output_index < max_output_size) && (input_index < (input_size)));
return output_index;
}