+++ /dev/null
-/*
- * 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"
-
-
-#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;
- 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));
- dest[metadata_size / sizeof(uint16_t)] = metadata;
- metadata_size += sizeof(uint16_t);
- } else {
- metadata = (uint16_t)(((best_offset - 1) << 3) | 7);
- 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);
- }
-
- /* Additionnal 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;
- }
-
- /* Additionnal 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)) {
- *(uint32_t *)indic_pos = 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)){
- *(uint32_t *)indic_pos = 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 *)indic_pos = 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;
-}
git.samba.org / samba.git / blobdiff