decompressor.h

/* 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 3 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, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef SCI_RESOURCE_DECOMPRESSOR_H
#define SCI_RESOURCE_DECOMPRESSOR_H

#include "common/scummsys.h"

namespace Common {
class ReadStream;
}

namespace Sci {

enum ResourceCompression {
    kCompUnknown = -1,
    kCompNone = 0,
    kCompLZW,           // LZW compression used in SCI0
    kCompHuffman,       // Huffman compression used for vector pics
    kCompLZW1,          // LZW compression used in SCI01 and SCI1
    kCompLZW1View,      // LZW + view post-processing
    kCompLZW1Pic,       // LZW + pic post-processing
    kCompDCL            // SCI11
#ifdef ENABLE_SCI32
,   kCompSTACpack       // SCI32
#endif
};

class Decompressor {
public:
    Decompressor() :
        _dwBits(0),
        _nBits(0),
        _szPacked(0),
        _szUnpacked(0),
        _dwRead(0),
        _dwWrote(0),
        _src(nullptr),
        _dest(nullptr)
    {}

    virtual ~Decompressor() {}

    virtual int unpack(Common::ReadStream *src, byte *dest, uint32 nPacked, uint32 nUnpacked);

protected:
    virtual void init(Common::ReadStream *src, byte *dest, uint32 nPacked, uint32 nUnpacked);

    uint32 getBitsMSB(int n);

    uint32 getBitsLSB(int n);

    byte getByteMSB();
    byte getByteLSB();

    void fetchBitsMSB();
    void fetchBitsLSB();

    virtual void putByte(byte b);

    bool isFinished() {
        return (_dwWrote == _szUnpacked) && (_dwRead >= _szPacked);
    }

    uint32 _dwBits;     
    byte _nBits;        
    uint32 _szPacked;   
    uint32 _szUnpacked; 
    uint32 _dwRead;     
    uint32 _dwWrote;    
    Common::ReadStream *_src;
    byte *_dest;
};

class DecompressorHuffman : public Decompressor {
public:
    int unpack(Common::ReadStream *src, byte *dest, uint32 nPacked, uint32 nUnpacked) override;

protected:
    int16 getc2();

    byte *_nodes;
};

class DecompressorLZW : public Decompressor {
public:
    DecompressorLZW(ResourceCompression compression) : _compression(compression) {}
    int unpack(Common::ReadStream *src, byte *dest, uint32 nPacked, uint32 nUnpacked) override;

protected:
    int unpackLZW(Common::ReadStream *src, byte *dest, uint32 nPacked, uint32 nUnpacked);

    // post-processing functions for view and pic resources
    static void unpackView(byte *src, byte *dest);
    static void unpackPic(byte *src, byte *dest, int unpackedSize);
    static void decodeRLE(byte **rleData, byte **pixelData, byte *dest, int decodedSize);
    static void skipRLE(byte **rleData, int decodedSize);

    ResourceCompression _compression;
};

class DecompressorDCL : public Decompressor {
public:
    int unpack(Common::ReadStream *src, byte *dest, uint32 nPacked, uint32 nUnpacked) override;
};

#ifdef ENABLE_SCI32

class DecompressorLZS : public Decompressor {
public:
    int unpack(Common::ReadStream *src, byte *dest, uint32 nPacked, uint32 nUnpacked) override;

protected:
    int unpackLZS();
    uint32 getCompLen();
    void copyComp(int offs, uint32 clen);
};

#endif

} // End of namespace Sci

#endif // SCI_RESOURCE_DECOMPRESSOR_H