diff options
| -rw-r--r-- | engines/zvision/lzss_read_stream.cpp | 134 | ||||
| -rw-r--r-- | engines/zvision/lzss_read_stream.h | 75 |
2 files changed, 209 insertions, 0 deletions
diff --git a/engines/zvision/lzss_read_stream.cpp b/engines/zvision/lzss_read_stream.cpp new file mode 100644 index 0000000000..69b49c596c --- /dev/null +++ b/engines/zvision/lzss_read_stream.cpp @@ -0,0 +1,134 @@ +/* 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. +* +*/ + +#include "common/scummsys.h" + +#include "zvision/lzss_read_stream.h" + +namespace ZVision { + +LzssReadStream::LzssReadStream(Common::SeekableReadStream *source, bool stream, uint32 decompressedSize) + : _source(source), + // It's convention to set the starting cursor position to blockSize - 16 + _windowCursor(0x0FEE), + _readCursor(0) { + // Clear the window to null + memset(_window, 0, blockSize); + + // Reserve space in the destination buffer + // TODO: Make a better guess + if (decompressedSize == npos) { + decompressedSize = source->size(); + } + _destination.reserve(decompressedSize); + + if (stream) + decompressBytes(blockSize); + else + decompressAll(); +} + +void LzssReadStream::decompressBytes(uint32 numberOfBytes) { + uint32 bytesRead = 0; + + while (!_source->eos() && bytesRead <= numberOfBytes) { + byte flagbyte = _source->readByte(); + byte mask = 1; + + for (uint32 i = 0; i < 8; i++) { + if (!_source->eos()) { + if ((flagbyte & mask) == mask) + { + byte data = _source->readByte(); + bytesRead++; + if (_source->eos()) + break; + + _window[_windowCursor] = data; + _destination.push_back(data); + + // Increment and wrap the window cursor + _windowCursor = (_windowCursor + 1) & 0xFFF; + } + else + { + byte low = _source->readByte(); + bytesRead++; + if (_source->eos()) + break; + + byte high = _source->readByte(); + bytesRead++; + if (_source->eos()) + break; + + uint16 length = (high & 0xF) + 2; + uint16 offset = low | ((high & 0xF0)<<4); + + for(byte j = 0; j <= length; j++) + { + byte temp = _window[(offset + j) & 0xFFF]; + _window[_windowCursor] = temp; + _destination.push_back(temp); + _windowCursor = (_windowCursor + 1) & 0xFFF; + } + }; + + mask = mask << 1; + } + } + } +} + +void LzssReadStream::decompressAll() { + decompressBytes(_source->size()); +} + +bool LzssReadStream::eos() const { + // Make sure that we've read all of the source + return _readCursor >= _destination.size() && _source->eos(); +} + +uint32 LzssReadStream::read(void *dataPtr, uint32 dataSize) { + // Check if there are enough bytes available + // If not, keep decompressing until we have enough bytes or until we reach EOS + while (dataSize > _destination.size() - _readCursor) { + // Check if we can read any more data from source + if (_source->eos()) { + dataSize = _destination.size() - _readCursor; + break; + } + + decompressBytes(blockSize); + } + + memcpy(dataPtr, _destination.begin() + _readCursor, dataSize); + _readCursor += dataSize; + + return dataSize; +} + +uint32 LzssReadStream::currentSize() const { + return _destination.size(); +} + +} // End of namespace ZVision diff --git a/engines/zvision/lzss_read_stream.h b/engines/zvision/lzss_read_stream.h new file mode 100644 index 0000000000..7e6511a5a9 --- /dev/null +++ b/engines/zvision/lzss_read_stream.h @@ -0,0 +1,75 @@ +/* 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. +* +*/ + +#ifndef ZVISION_LZSS_STREAM_H +#define ZVISION_LZSS_STREAM_H + +#include "common/types.h" +#include "common/stream.h" +#include "common/memstream.h" +#include "common/array.h" + +namespace ZVision { + +class LzssReadStream : public Common::ReadStream { +public: + /** + * A class that decompresses LZSS data and implements ReadStream for easy access + * to the decompiled data. It can either decompress all the data in the beginning + * or decompress as needed by read(). + * + * @param source The source data + * @param stream Decompress the data as needed (true) or all at once (false) + * @param decompressedSize The size of the decompressed data. If npos, the class will choose a size and grow as needed + */ + LzssReadStream(Common::SeekableReadStream *source, bool stream = true, uint32 decompressedSize = npos); + +public: + static const uint32 npos = 0xFFFFFFFFu; + static const uint16 blockSize = 0x1000u; + +private: + Common::SeekableReadStream *_source; + Common::Array<char> _destination; + char _window[blockSize]; + uint16 _windowCursor; + uint32 _readCursor; + +public: + bool eos() const; + uint32 read(void *dataPtr, uint32 dataSize); + uint32 currentSize() const; + +private: + /** + * Decompress the next <numberOfBytes> from the source stream. Or until EOS + * + * @param numberOfBytes How many bytes to decompress. This is a count of source bytes, not destination bytes + */ + void decompressBytes(uint32 numberOfBytes); + /** Decompress all of the source stream. */ + void decompressAll(); +}; + +} + +#endif |