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zdeflate.h

    00001 #ifndef CRYPTOPP_ZDEFLATE_H
    00002 #define CRYPTOPP_ZDEFLATE_H
    00003
    00004 #include "filters.h"
    00005 #include "misc.h"
    00006
    00007 NAMESPACE_BEGIN(CryptoPP)
    00008
    00009 //! _
    00010 class LowFirstBitWriter : public Filter
    00011 {
    00012 public:
    00013     LowFirstBitWriter(BufferedTransformation *attachment);
    00014     void PutBits(unsigned long value, unsigned int length);
    00015     void FlushBitBuffer();
    00016     void ClearBitBuffer();
    00017
    00018     void StartCounting();
    00019     unsigned long FinishCounting();
    00020
    00021 protected:
    00022     bool m_counting;
    00023     unsigned long m_bitCount;
    00024     unsigned long m_buffer;
    00025     unsigned int m_bitsBuffered, m_bytesBuffered;
    00026     FixedSizeSecBlock<byte, 256> m_outputBuffer;
    00027 };
    00028
    00029 //! Huffman Encoder
    00030 class HuffmanEncoder
    00031 {
    00032 public:
    00033     typedef unsigned int code_t;
    00034     typedef unsigned int value_t;
    00035
    00036     HuffmanEncoder() {}
    00037     HuffmanEncoder(const unsigned int *codeBits, unsigned int nCodes);
    00038     void Initialize(const unsigned int *codeBits, unsigned int nCodes);
    00039
    00040     static void GenerateCodeLengths(unsigned int *codeBits, unsigned int maxCodeBits, const unsigned int *codeCounts, size_t nCodes);
    00041
    00042     void Encode(LowFirstBitWriter &writer, value_t value) const;
    00043
    00044     struct Code
    00045     {
    00046         unsigned int code;
    00047         unsigned int len;
    00048     };
    00049
    00050     SecBlock<Code> m_valueToCode;
    00051 };
    00052
    00053 //! DEFLATE (RFC 1951) compressor
    00054
    00055 class Deflator : public LowFirstBitWriter
    00056 {
    00057 public:
    00058     enum {MIN_DEFLATE_LEVEL = 0, DEFAULT_DEFLATE_LEVEL = 6, MAX_DEFLATE_LEVEL = 9};
    00059     enum {MIN_LOG2_WINDOW_SIZE = 9, DEFAULT_LOG2_WINDOW_SIZE = 15, MAX_LOG2_WINDOW_SIZE = 15};
    00060     /*! \note detectUncompressible makes it faster to process uncompressible files, but
    00061         if a file has both compressible and uncompressible parts, it may fail to compress some of the
    00062         compressible parts. */
    00063     Deflator(BufferedTransformation *attachment=NULL, int deflateLevel=DEFAULT_DEFLATE_LEVEL, int log2WindowSize=DEFAULT_LOG2_WINDOW_SIZE, bool detectUncompressible=true);
    00064     //! possible parameter names: Log2WindowSize, DeflateLevel, DetectUncompressible
    00065     Deflator(const NameValuePairs &parameters, BufferedTransformation *attachment=NULL);
    00066
    00067     //! this function can be used to set the deflate level in the middle of compression
    00068     void SetDeflateLevel(int deflateLevel);
    00069     int GetDeflateLevel() const {return m_deflateLevel;}
    00070     int GetLog2WindowSize() const {return m_log2WindowSize;}
    00071
    00072     void IsolatedInitialize(const NameValuePairs &parameters);
    00073     size_t Put2(const byte *inString, size_t length, int messageEnd, bool blocking);
    00074     bool IsolatedFlush(bool hardFlush, bool blocking);
    00075
    00076 protected:
    00077     virtual void WritePrestreamHeader() {}
    00078     virtual void ProcessUncompressedData(const byte *string, size_t length) {}
    00079     virtual void WritePoststreamTail() {}
    00080
    00081     enum {STORED = 0, STATIC = 1, DYNAMIC = 2};
    00082     enum {MIN_MATCH = 3, MAX_MATCH = 258};
    00083
    00084     void InitializeStaticEncoders();
    00085     void Reset(bool forceReset = false);
    00086     unsigned int FillWindow(const byte *str, size_t length);
    00087     unsigned int ComputeHash(const byte *str) const;
    00088     unsigned int LongestMatch(unsigned int &bestMatch) const;
    00089     void InsertString(unsigned int start);
    00090     void ProcessBuffer();
    00091
    00092     void LiteralByte(byte b);
    00093     void MatchFound(unsigned int distance, unsigned int length);
    00094     void EncodeBlock(bool eof, unsigned int blockType);
    00095     void EndBlock(bool eof);
    00096
    00097     struct EncodedMatch
    00098     {
    00099         unsigned literalCode : 9;
    00100         unsigned literalExtra : 5;
    00101         unsigned distanceCode : 5;
    00102         unsigned distanceExtra : 13;
    00103     };
    00104
    00105     int m_deflateLevel, m_log2WindowSize, m_compressibleDeflateLevel;
    00106     unsigned int m_detectSkip, m_detectCount;
    00107     unsigned int DSIZE, DMASK, HSIZE, HMASK, GOOD_MATCH, MAX_LAZYLENGTH, MAX_CHAIN_LENGTH;
    00108     bool m_headerWritten, m_matchAvailable;
    00109     unsigned int m_dictionaryEnd, m_stringStart, m_lookahead, m_minLookahead, m_previousMatch, m_previousLength;
    00110     HuffmanEncoder m_staticLiteralEncoder, m_staticDistanceEncoder, m_dynamicLiteralEncoder, m_dynamicDistanceEncoder;
    00111     SecByteBlock m_byteBuffer;
    00112     SecBlock<word16> m_head, m_prev;
    00113     FixedSizeSecBlock<unsigned int, 286> m_literalCounts;
    00114     FixedSizeSecBlock<unsigned int, 30> m_distanceCounts;
    00115     SecBlock<EncodedMatch> m_matchBuffer;
    00116     unsigned int m_matchBufferEnd, m_blockStart, m_blockLength;
    00117 };
    00118
    00119 NAMESPACE_END
    00120
    00121 #endif