| /* |
| * Copyright (c) 2003-2005 The Regents of The University of Michigan |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer; |
| * 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; |
| * neither the name of the copyright holders 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 COPYRIGHT HOLDERS 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 COPYRIGHT |
| * OWNER 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. |
| */ |
| |
| #ifndef __LZSS_COMPRESSION_HH__ |
| #define __LZSS_COMPRESSION_HH__ |
| |
| /** @file |
| * LZSSCompression declarations. |
| */ |
| |
| #include "sim/host.hh" // for uint8_t |
| |
| /** |
| * Simple LZSS compression scheme. |
| */ |
| class LZSSCompression |
| { |
| /** |
| * Finds the longest substring for the given offset. |
| * @param src The source block that we search for substrings. |
| * @param back The larger offset. |
| * @param size The size of the source block. |
| * @param L The length of the largest substring. |
| * @param P The starting offset of the largest substring. |
| */ |
| void findSubString(uint8_t *src, int back, int size, uint16_t &L, |
| uint16_t &P); |
| |
| /** |
| * Emit an encoded byte to the compressed data array. If the 2 high |
| * order bits can be signed extended, use 1 byte encoding, if not use 2 |
| * bytes. |
| * @param dest The compressed data. |
| * @param byte The byte to emit. |
| * @return The number of bytes used to encode. |
| */ |
| int emitByte(uint8_t *dest, uint8_t byte); |
| |
| /** |
| * Emit a string reference to the compressed data array. A string reference |
| * always uses 3 bytes. 1 flag bit, 12 bits for the starting position, and |
| * 11 bits for the length of the string. This allows compression of 4096 |
| * byte blocks with string lengths of up to 2048 bytes. |
| * @param dest The compressed data. |
| * @param P The starting position in the uncompressed data. |
| * @param L The length in bytes of the string. |
| */ |
| void emitString(uint8_t *dest, uint16_t P, uint16_t L); |
| |
| public: |
| /** |
| * Compresses the source block and stores it in the destination block. If |
| * the compressed block grows to larger than the source block, it aborts |
| * and just performs a copy. |
| * @param dest The destination block. |
| * @param src The block to be compressed. |
| * @param size The size of the source block. |
| * @return The size of the compressed block. |
| * |
| * @pre Destination has enough storage to hold the compressed block. |
| */ |
| int compress(uint8_t *dest, uint8_t *src, int size); |
| |
| /** |
| * Unompresses the source block and stores it in the destination block. |
| * @param dest The destination block. |
| * @param src The block to be uncompressed. |
| * @param size The size of the source block. |
| * @return The size of the uncompressed block. |
| * |
| * @pre Destination has enough storage to hold the uncompressed block. |
| */ |
| int uncompress(uint8_t *dest, uint8_t *src, int size); |
| }; |
| |
| #endif //__LZSS_COMPRESSION_HH__ |