1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
|
#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 ¶meters, 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 ¶meters);
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
|