LZencoder.h

#pragma once


#include <libutl/Encoder.h>
#include <libutl/HuffmanEncoder.h>


UTL_NS_BEGIN;


#define LZ_LEN_CODES 28
#define LZ_DIST_CODES 30



class LZencoder : public Encoder
{
    UTL_CLASS_DECL(LZencoder, Encoder);

public:
    LZencoder(uint_t mode, Stream* stream, bool owner = true, uint_t level = 9)
    {
        init();
        start(mode, stream, owner, level);
    }

    virtual size_t decode(byte_t* block, size_t num);

    virtual size_t encode(const byte_t* block, size_t num);

    void start(uint_t mode, Stream* stream, bool owner = true, uint_t level = 9);

protected:
    virtual void clear();
    virtual void finishEncoding();

private:
    void init();
    void
    deInit()
    {
        close();
    }
    void addString(uint_t pos);
    uint_t matchString(uint_t pos);
    void removeString(uint_t pos);

private:
    uint_t _lab, _repc, _pos;
    // sliding window, look-ahead buffer
    byte_t* _wind;
    byte_t* _look;
    // match information
    uint_t _prevMatchLen, _prevMatchDist, _prevLiteral;
    uint_t _matchLen, _matchDist, _literal;
    bool _matchAvailable;
    // compress configuration
    uint_t _goodLen;    // reduce lazy search above this length
    uint_t _maxLazyLen; // do not perform lazy search above this match length
    uint_t _niceLen;    // quit search above this match length
    uint_t _maxChain;   // follow at most this many hash chains
    // coding distances, lengths
    uint_t* _baseLen;
    uint_t* _lenCode;
    uint_t* _baseDist;
    uint_t* _distCode;
    static const uint_t eob;
    static const uint_t lenBits[LZ_LEN_CODES];
    static const uint_t distBits[LZ_DIST_CODES];
    // hashing
    uint_t* _head;
    uint_t* _tail;
    uint_t* _pred;
    uint_t* _succ;
    // H-coders
    HuffmanEncoder _lEnc;
    HuffmanEncoder _dEnc;
};


UTL_NS_END;