98 lines
2.5 KiB
C++
98 lines
2.5 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "common/file.h"
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#include "common/memstream.h"
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#include "bagel/hodjnpodj/hnplibs/lzss.h"
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namespace Bagel {
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namespace HodjNPodj {
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Common::SeekableReadStream *makeLzssStream(const Common::Path &filename) {
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Common::File file;
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if (!file.open(filename))
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return nullptr;
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// First part of the signature
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if (file.readUint32BE() != MKTAG('S', 'Z', 'D', 'D'))
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return nullptr;
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// Second part of the signature
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if (file.readUint32BE() != 0x88F02733)
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return nullptr;
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// Compression mode must be 'A'
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if (file.readByte() != 'A')
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return nullptr;
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file.readByte(); // file name character change
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uint32 unpackedLength = file.readUint32LE();
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byte *window = new byte[0x1000]();
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int pos = 0x1000 - 16;
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byte *unpackedData = (byte *)malloc(unpackedLength);
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assert(unpackedData);
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byte *dataPos = unpackedData;
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uint32 remaining = unpackedLength;
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// Apply simple LZSS decompression
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for (;;) {
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byte controlByte = file.readByte();
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if (remaining == 0 || file.eos())
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break;
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for (byte i = 0; i < 8; i++) {
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if (controlByte & (1 << i)) {
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*dataPos++ = window[pos++] = file.readByte();
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pos &= 0xFFF;
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if (--remaining == 0)
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break;
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} else {
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int matchPos = file.readByte();
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int matchLen = file.readByte();
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matchPos |= (matchLen & 0xF0) << 4;
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matchLen = (matchLen & 0xF) + 3;
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if ((uint32)matchLen > remaining)
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matchLen = remaining;
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remaining -= matchLen;
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while (matchLen--) {
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*dataPos++ = window[pos++] = window[matchPos++];
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pos &= 0xFFF;
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matchPos &= 0xFFF;
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}
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if (remaining == 0)
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break;
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}
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}
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}
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delete[] window;
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return new Common::MemoryReadStream(unpackedData, unpackedLength);
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}
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} // namespace HodjNPodj
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} // namespace Bagel
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