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zinflate.h

#ifndef CRYPTOPP_ZINFLATE_H
#define CRYPTOPP_ZINFLATE_H

#include "filters.h"

NAMESPACE_BEGIN(CryptoPP)

class LowFirstBitReader
{
public:
        LowFirstBitReader(BufferedTransformation &store)
                : m_store(store), m_buffer(0), m_bitsBuffered(0) {}
        unsigned long BitsLeft() const {return m_store.MaxRetrievable() * 8 + m_bitsBuffered;}
        unsigned int BitsBuffered() const {return m_bitsBuffered;}
        unsigned long PeekBuffer() const {return m_buffer;}
        bool FillBuffer(unsigned int length);
        unsigned long PeekBits(unsigned int length);
        void SkipBits(unsigned int length);
        unsigned long GetBits(unsigned int length);

private:
        BufferedTransformation &m_store;
        unsigned long m_buffer;
        unsigned int m_bitsBuffered;
};

class HuffmanDecoder
{
public:
        typedef unsigned int code_t;
        typedef unsigned int value_t;
        enum {MAX_CODE_BITS = sizeof(code_t)*8};

        class Err : public Exception {public: Err(const std::string &what) : Exception("HuffmanDecoder: " + what) {}};

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

        void Initialize(const unsigned int *codeBits, unsigned int nCodes);
        unsigned int Decode(code_t code, /* out */ value_t &value) const;
        bool Decode(LowFirstBitReader &reader, value_t &value) const;

private:
        struct CodeInfo
        {
                CodeInfo(code_t code=0, unsigned int len=0, value_t value=0) : code(code), len(len), value(value) {}
                bool operator<(const CodeInfo &rhs) const {return code < rhs.code;}
                friend bool CodeLessThan(code_t lhs, const CodeInfo &rhs) {return lhs < rhs.code;}
                code_t code;
                unsigned int len;
                value_t value;
        };

        struct LookupEntry
        {
                unsigned int type;
                union
                {
                        value_t value;
                        const CodeInfo *begin;
                };
                union
                {
                        unsigned int len;
                        const CodeInfo *end;
                };
        };

        static code_t NormalizeCode(code_t code, unsigned int codeBits);

        unsigned int m_maxCodeBits, m_cacheBits, m_cacheMask;
        SecBlock<CodeInfo> m_codeToValue;
        SecBlock<LookupEntry> m_cache;
};


class Inflator : public Filter, public BufferedTransformationWithAutoSignal
{
public:
        class Err : public BufferedTransformation::Err
        {
        public:
                Err(ErrorType e, const std::string &s)
                        : BufferedTransformation::Err(e, s) {}
        };
        class UnexpectedEndErr : public Err {public: UnexpectedEndErr() : Err(INVALID_DATA_FORMAT, "Inflator: unexpected end of compressed block") {}};
        class BadBlockErr : public Err {public: BadBlockErr() : Err(INVALID_DATA_FORMAT, "Inflator: error in compressed block") {}};

        Inflator(BufferedTransformation *outQueue = NULL, bool repeat = false);
        void Put(byte b) {Inflator::Put(&b, 1);}
        void Put(const byte *inString, unsigned int length);

        void Flush(bool completeFlush, int propagation=-1);
        void MessageEnd(int propagation=-1);

        virtual unsigned int GetLog2WindowSize() const {return 15;}

protected:
        ByteQueue m_inQueue;

private:
        virtual unsigned int MaxPrestreamHeaderSize() const {return 0;}
        virtual void ProcessPrestreamHeader() {}
        virtual void ProcessDecompressedData(const byte *string, unsigned int length)
                {AttachedTransformation()->Put(string, length);}
        virtual unsigned int MaxPoststreamTailSize() const {return 0;}
        virtual void ProcessPoststreamTail() {}

        void ProcessInput(bool flush);
        void DecodeHeader();
        bool DecodeBody();
        void FlushOutput();
        void OutputByte(byte b);
        void OutputString(const byte *string, unsigned int length);
        void OutputPast(unsigned int length, unsigned int distance);

        enum State {PRE_STREAM, WAIT_HEADER, DECODING_BODY, POST_STREAM, AFTER_END};
        State m_state;
        bool m_repeat, m_eof, m_decodersInitializedWithFixedCodes;
        byte m_blockType;
        word16 m_storedLen;
        enum NextDecode {LITERAL, LENGTH_BITS, DISTANCE, DISTANCE_BITS};
        NextDecode m_nextDecode;
        unsigned int m_literal, m_distance;     // for LENGTH_BITS or DISTANCE_BITS
        HuffmanDecoder m_literalDecoder, m_distanceDecoder;
        LowFirstBitReader m_reader;
        SecByteBlock m_window;
        unsigned int m_maxDistance, m_current, m_lastFlush;
};

NAMESPACE_END

#endif

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