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-rw-r--r--lib/compression/lzxpress.c312
1 files changed, 312 insertions, 0 deletions
diff --git a/lib/compression/lzxpress.c b/lib/compression/lzxpress.c
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+++ b/lib/compression/lzxpress.c
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+/*
+ * 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;
+}
generated by cgit (git 2.34.1) at 2024-06-02 18:04:23 +0000