zdeflate.h

#ifndef CRYPTOPP_ZDEFLATE_H
#define CRYPTOPP_ZDEFLATE_H

#include "filters.h"
#include "misc.h"

NAMESPACE_BEGIN(CryptoPP)

//! _
class LowFirstBitWriter : public Filter
{
public:
        LowFirstBitWriter(BufferedTransformation *attachment);
        void PutBits(unsigned long value, unsigned int length);
        void FlushBitBuffer();
        void ClearBitBuffer();

        void StartCounting();
        unsigned long FinishCounting();

protected:
        bool m_counting;
        unsigned long m_bitCount;
        unsigned long m_buffer;
        unsigned int m_bitsBuffered, m_bytesBuffered;
        FixedSizeSecBlock<byte, 256> m_outputBuffer;
};

//! Huffman Encoder
class HuffmanEncoder
{
public:
        typedef unsigned int code_t;
        typedef unsigned int value_t;

        HuffmanEncoder() {}
        HuffmanEncoder(const unsigned int *codeBits, unsigned int nCodes);
        void Initialize(const unsigned int *codeBits, unsigned int nCodes);

        static void GenerateCodeLengths(unsigned int *codeBits, unsigned int maxCodeBits, const unsigned int *codeCounts, size_t nCodes);

        void Encode(LowFirstBitWriter &writer, value_t value) const;

        struct Code
        {
                unsigned int code;
                unsigned int len;
        };

        SecBlock<Code> m_valueToCode;
};

//! DEFLATE (RFC 1951) compressor

class Deflator : public LowFirstBitWriter
{
public:
        enum {MIN_DEFLATE_LEVEL = 0, DEFAULT_DEFLATE_LEVEL = 6, MAX_DEFLATE_LEVEL = 9};
        enum {MIN_LOG2_WINDOW_SIZE = 9, DEFAULT_LOG2_WINDOW_SIZE = 15, MAX_LOG2_WINDOW_SIZE = 15};
        /*! \note detectUncompressible makes it faster to process uncompressible files, but
                if a file has both compressible and uncompressible parts, it may fail to compress some of the
                compressible parts. */
        Deflator(BufferedTransformation *attachment=NULL, int deflateLevel=DEFAULT_DEFLATE_LEVEL, int log2WindowSize=DEFAULT_LOG2_WINDOW_SIZE, bool detectUncompressible=true);
        //! possible parameter names: Log2WindowSize, DeflateLevel, DetectUncompressible
        Deflator(const NameValuePairs &parameters, BufferedTransformation *attachment=NULL);

        //! this function can be used to set the deflate level in the middle of compression
        void SetDeflateLevel(int deflateLevel);
        int GetDeflateLevel() const {return m_deflateLevel;}
        int GetLog2WindowSize() const {return m_log2WindowSize;}

        void IsolatedInitialize(const NameValuePairs &parameters);
        size_t Put2(const byte *inString, size_t length, int messageEnd, bool blocking);
        bool IsolatedFlush(bool hardFlush, bool blocking);

protected:
        virtual void WritePrestreamHeader() {}
        virtual void ProcessUncompressedData(const byte *string, size_t length) {}
        virtual void WritePoststreamTail() {}

        enum {STORED = 0, STATIC = 1, DYNAMIC = 2};
        enum {MIN_MATCH = 3, MAX_MATCH = 258};

        void InitializeStaticEncoders();
        void Reset(bool forceReset = false);
        unsigned int FillWindow(const byte *str, size_t length);
        unsigned int ComputeHash(const byte *str) const;
        unsigned int LongestMatch(unsigned int &bestMatch) const;
        void InsertString(unsigned int start);
        void ProcessBuffer();

        void LiteralByte(byte b);
        void MatchFound(unsigned int distance, unsigned int length);
        void EncodeBlock(bool eof, unsigned int blockType);
        void EndBlock(bool eof);

        struct EncodedMatch
        {
                unsigned literalCode : 9;
                unsigned literalExtra : 5;
                unsigned distanceCode : 5;
                unsigned distanceExtra : 13;
        };

        int m_deflateLevel, m_log2WindowSize, m_compressibleDeflateLevel;
        unsigned int m_detectSkip, m_detectCount;
        unsigned int DSIZE, DMASK, HSIZE, HMASK, GOOD_MATCH, MAX_LAZYLENGTH, MAX_CHAIN_LENGTH;
        bool m_headerWritten, m_matchAvailable;
        unsigned int m_dictionaryEnd, m_stringStart, m_lookahead, m_minLookahead, m_previousMatch, m_previousLength;
        HuffmanEncoder m_staticLiteralEncoder, m_staticDistanceEncoder, m_dynamicLiteralEncoder, m_dynamicDistanceEncoder;
        SecByteBlock m_byteBuffer;
        SecBlock<word16> m_head, m_prev;
        FixedSizeSecBlock<unsigned int, 286> m_literalCounts;
        FixedSizeSecBlock<unsigned int, 30> m_distanceCounts;
        SecBlock<EncodedMatch> m_matchBuffer;
        unsigned int m_matchBufferEnd, m_blockStart, m_blockLength;
};

NAMESPACE_END

#endif

---