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/* ScummVM - Graphic Adventure Engine | ||
* | ||
* ScummVM is the legal property of its developers, whose names | ||
* are too numerous to list here. Please refer to the COPYRIGHT | ||
* file distributed with this source distribution. | ||
* | ||
* 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, write to the Free Software | ||
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | ||
* | ||
*/ | ||
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#include "common/debug.h" | ||
#include "common/endian.h" | ||
#include "common/util.h" | ||
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#include "access/decompress.h" | ||
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namespace Access { | ||
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void LzwDecompressor::decompress(byte *source, byte *dest) { | ||
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_source = source; | ||
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byte litByte; | ||
uint16 copyLength, maxCodeValue, code, nextCode, lastCode, oldCode; | ||
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byte *copyBuf = new byte[8192]; | ||
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struct { uint16 code; byte value; } codeTable[8192]; | ||
memset(codeTable, 0, sizeof(codeTable)); | ||
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_codeLength = 9; | ||
nextCode = 258; | ||
maxCodeValue = 512; | ||
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copyLength = 0; | ||
_bitPos = 0; | ||
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while (1) { | ||
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code = getCode(); | ||
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if (code == 257) | ||
break; | ||
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if (code == 256) { | ||
_codeLength = 9; | ||
nextCode = 258; | ||
maxCodeValue = 512; | ||
lastCode = getCode(); | ||
oldCode = lastCode; | ||
litByte = lastCode; | ||
*dest++ = litByte; | ||
} else { | ||
lastCode = code; | ||
if (code >= nextCode) { | ||
lastCode = oldCode; | ||
copyBuf[copyLength++] = litByte; | ||
} | ||
while (lastCode > 255) { | ||
copyBuf[copyLength++] = codeTable[lastCode].value; | ||
lastCode = codeTable[lastCode].code; | ||
} | ||
litByte = lastCode; | ||
copyBuf[copyLength++] = lastCode; | ||
while (copyLength > 0) | ||
*dest++ = copyBuf[--copyLength]; | ||
codeTable[nextCode].value = lastCode; | ||
codeTable[nextCode].code = oldCode; | ||
nextCode++; | ||
oldCode = code; | ||
if (nextCode >= maxCodeValue && _codeLength <= 12) { | ||
_codeLength++; | ||
maxCodeValue <<= 1; | ||
} | ||
} | ||
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} | ||
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delete[] copyBuf; | ||
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} | ||
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uint16 LzwDecompressor::getCode() { | ||
const byte bitMasks[9] = { | ||
0x00, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F, 0x7F, 0x0FF | ||
}; | ||
uint16 bits, loCode, hiCode; | ||
loCode = (READ_LE_UINT16(_source) >> _bitPos) & 0xFF; | ||
_source++; | ||
bits = _codeLength - 8; | ||
hiCode = (READ_LE_UINT16(_source) >> _bitPos) & bitMasks[bits]; | ||
_bitPos += bits; | ||
if (_bitPos > 8) { | ||
_source++; | ||
_bitPos -= 8; | ||
} | ||
return (hiCode << 8) | loCode; | ||
} | ||
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uint32 decompressDBE(byte *source, byte **dest) { | ||
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uint32 destSize = READ_LE_UINT32(source + 4); | ||
*dest = new byte[destSize]; | ||
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debug(1, "decompressDBE() destSize = %d", destSize); | ||
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LzwDecompressor dec; | ||
dec.decompress(source + 16, *dest); | ||
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debug(1, "decompressDBE() ok"); | ||
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return destSize; | ||
} | ||
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} // End of namespace Access |
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,48 @@ | ||
/* ScummVM - Graphic Adventure Engine | ||
* | ||
* ScummVM is the legal property of its developers, whose names | ||
* are too numerous to list here. Please refer to the COPYRIGHT | ||
* file distributed with this source distribution. | ||
/* ScummVM - Graphic Adventure Engine | ||
* | ||
* ScummVM is the legal property of its developers, whose names | ||
* are too numerous to list here. Please refer to the COPYRIGHT | ||
* file distributed with this source distribution. | ||
* | ||
* 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, write to the Free Software | ||
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | ||
* | ||
*/ | ||
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#ifndef ACCESS_DECOMPRESS_H | ||
#define ACCESS_DECOMPRESS_H | ||
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#include "common/scummsys.h" | ||
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namespace Access { | ||
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class LzwDecompressor { | ||
public: | ||
void decompress(byte *source, byte *dest); | ||
private: | ||
byte *_source; | ||
byte _codeLength, _bitPos; | ||
uint16 getCode(); | ||
}; | ||
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uint32 decompressDBE(byte *source, byte **dest); | ||
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} // End of namespace Access | ||
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#endif |
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