Low level compression engine for deflate algorithm which uses a 32K sliding window with secondary compression from Huffman/Shannon-Fano codes. More...

Inheritance diagram for ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine:

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Collaboration diagram for ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine:

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Public Member Functions
	DeflaterEngine (DeflaterPending pending)
	Construct instance with pending buffer.
bool	Deflate (bool flush, bool finish)
	Deflate drives actual compression of data.
void	SetInput (byte[] buffer, int offset, int count)
	Sets input data to be deflated. Should only be called when.
bool	NeedsInput ()
	Determines if more input is needed.
void	SetDictionary (byte[] buffer, int offset, int length)
	Set compression dictionary.
void	Reset ()
	Reset internal state.
void	ResetAdler ()
	Reset Adler checksum.
void	SetLevel (int level)
	Set the deflate level (0-9)
void	FillWindow ()
	Fill the window.

Properties
int	Adler `[get]`
	Get current value of Adler checksum.
long	TotalIn `[get]`
	Total data processed.
DeflateStrategy	Strategy `[get, set]`
	Get/set the deflate strategy

Private Member Functions
void	UpdateHash ()
int	InsertString ()
	Inserts the current string in the head hash and returns the previous value for this hash.
void	SlideWindow ()
bool	FindLongestMatch (int curMatch)
	Find the best (longest) string in the window matching the string starting at strstart.
bool	DeflateStored (bool flush, bool finish)
bool	DeflateFast (bool flush, bool finish)
bool	DeflateSlow (bool flush, bool finish)

Private Attributes
int	ins_h
short[]	head
	Hashtable, hashing three characters to an index for window, so that window[index]..window[index+2] have this hash code. Note that the array should really be unsigned short, so you need to and the values with 0xffff.
short[]	prev
int	matchStart
int	matchLen
bool	prevAvailable
int	blockStart
int	strstart
	Points to the current character in the window.
int	lookahead
	lookahead is the number of characters starting at strstart in window that are valid. So window[strstart] until window[strstart+lookahead-1] are valid characters.
byte[]	window
	This array contains the part of the uncompressed stream that is of relevance. The current character is indexed by strstart.
DeflateStrategy	strategy
int	max_chain
int	max_lazy
int	niceLength
int	goodLength
int	compressionFunction
	The current compression function.
byte[]	inputBuf
	The input data for compression.
long	totalIn
	The total bytes of input read.
int	inputOff
	The offset into inputBuf, where input data starts.
int	inputEnd
	The end offset of the input data.
DeflaterPending	pending
DeflaterHuffman	huffman
Adler32	adler
	The adler checksum.

Static Private Attributes
const int	TooFar = 4096

Additional Inherited Members
Static Public Attributes inherited from ICSharpCode.SharpZipLib.Zip.Compression.DeflaterConstants
const bool	DEBUGGING = false
	Set to true to enable debugging.
const int	STORED_BLOCK = 0
	Written to Zip file to identify a stored block.
const int	STATIC_TREES = 1
	Identifies static tree in Zip file.
const int	DYN_TREES = 2
	Identifies dynamic tree in Zip file.
const int	PRESET_DICT = 0x20
	Header flag indicating a preset dictionary for deflation.
const int	DEFAULT_MEM_LEVEL = 8
	Sets internal buffer sizes for Huffman encoding.
const int	MAX_MATCH = 258
	Internal compression engine constant.
const int	MIN_MATCH = 3
	Internal compression engine constant.
const int	MAX_WBITS = 15
	Internal compression engine constant.
const int	WSIZE = 1 << MAX_WBITS
	Internal compression engine constant.
const int	WMASK = WSIZE - 1
	Internal compression engine constant.
const int	HASH_BITS = DEFAULT_MEM_LEVEL + 7
	Internal compression engine constant.
const int	HASH_SIZE = 1 << HASH_BITS
	Internal compression engine constant.
const int	HASH_MASK = HASH_SIZE - 1
	Internal compression engine constant.
const int	HASH_SHIFT = (HASH_BITS + MIN_MATCH - 1) / MIN_MATCH
	Internal compression engine constant.
const int	MIN_LOOKAHEAD = MAX_MATCH + MIN_MATCH + 1
	Internal compression engine constant.
const int	MAX_DIST = WSIZE - MIN_LOOKAHEAD
	Internal compression engine constant.
const int	PENDING_BUF_SIZE = 1 << (DEFAULT_MEM_LEVEL + 8)
	Internal compression engine constant.
static int	MAX_BLOCK_SIZE = Math.Min(65535, PENDING_BUF_SIZE - 5)
	Internal compression engine constant.
const int	DEFLATE_STORED = 0
	Internal compression engine constant.
const int	DEFLATE_FAST = 1
	Internal compression engine constant.
const int	DEFLATE_SLOW = 2
	Internal compression engine constant.
static int[]	GOOD_LENGTH = { 0, 4, 4, 4, 4, 8, 8, 8, 32, 32 }
	Internal compression engine constant.
static int[]	MAX_LAZY = { 0, 4, 5, 6, 4, 16, 16, 32, 128, 258 }
	Internal compression engine constant.
static int[]	NICE_LENGTH = { 0, 8, 16, 32, 16, 32, 128, 128, 258, 258 }
	Internal compression engine constant.
static int[]	MAX_CHAIN = { 0, 4, 8, 32, 16, 32, 128, 256, 1024, 4096 }
	Internal compression engine constant.
static int[]	COMPR_FUNC = { 0, 1, 1, 1, 1, 2, 2, 2, 2, 2 }
	Internal compression engine constant.

Detailed Description

Low level compression engine for deflate algorithm which uses a 32K sliding window with secondary compression from Huffman/Shannon-Fano codes.

Constructor & Destructor Documentation

◆ DeflaterEngine()

ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.DeflaterEngine ( DeflaterPending pending )

Construct instance with pending buffer.

Parameters

pending Pending buffer to use

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Member Function Documentation

◆ Deflate()

bool ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.Deflate	(	bool	flush,
		bool	finish )

Deflate drives actual compression of data.

Parameters

flush	True to flush input buffers
finish	Finish deflation with the current input.

Returns: Returns true if progress has been made.

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◆ DeflateFast()

bool ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.DeflateFast	(	bool	flush,
		bool	finish )

private

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◆ DeflateSlow()

bool ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.DeflateSlow	(	bool	flush,
		bool	finish )

private

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◆ DeflateStored()

bool ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.DeflateStored	(	bool	flush,
		bool	finish )

private

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◆ FillWindow()

void ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.FillWindow ( )

Fill the window.

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◆ FindLongestMatch()

bool ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.FindLongestMatch ( int curMatch )

private

Find the best (longest) string in the window matching the string starting at strstart.

Preconditions:

strstart + MAX_MATCH <= window.length.

ICSharpCode.SharpZipLib.Zip.Compression.DeflaterConstants.MAX_MATCH

const int MAX_MATCH

Internal compression engine constant.

Definition DeflaterConstants.cs:83

ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.strstart

int strstart

Points to the current character in the window.

Definition DeflaterEngine.cs:816

ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.window

byte[] window

This array contains the part of the uncompressed stream that is of relevance. The current character i...

Definition DeflaterEngine.cs:830

Parameters

curMatch

Returns: True if a match greater than the minimum length is found

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◆ InsertString()

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.InsertString ( )

private

Inserts the current string in the head hash and returns the previous value for this hash.

Returns: The previous hash value

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◆ NeedsInput()

bool ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.NeedsInput ( )

Determines if more input is needed.

Returns: Return true if input is needed via SetInput

◆ Reset()

void ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.Reset ( )

Reset internal state.

◆ ResetAdler()

void ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.ResetAdler ( )

Reset Adler checksum.

◆ SetDictionary()

void ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.SetDictionary	(	byte[]	buffer,
		int	offset,
		int	length )

Set compression dictionary.

Parameters

buffer	The buffer containing the dictionary data
offset	The offset in the buffer for the first byte of data
length	The length of the dictionary data.

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◆ SetInput()

void ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.SetInput	(	byte[]	buffer,
		int	offset,
		int	count )

Sets input data to be deflated. Should only be called when.

NeedsInput()

ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.NeedsInput

bool NeedsInput()

Determines if more input is needed.

Definition DeflaterEngine.cs:206

returns true

Parameters

buffer	The buffer containing input data.
offset	The offset of the first byte of data.
count	The number of bytes of data to use as input.

◆ SetLevel()

void ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.SetLevel ( int level )

Set the deflate level (0-9)

Parameters

level The value to set the level to.

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◆ SlideWindow()

void ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.SlideWindow ( )

private

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◆ UpdateHash()

void ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.UpdateHash ( )

private

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Member Data Documentation

◆ adler

Adler32 ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.adler

private

The adler checksum.

◆ blockStart

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.blockStart

private

◆ compressionFunction

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.compressionFunction

private

The current compression function.

◆ goodLength

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.goodLength

private

◆ head

short [] ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.head

private

Hashtable, hashing three characters to an index for window, so that window[index]..window[index+2] have this hash code.
Note that the array should really be unsigned short, so you need to and the values with 0xffff.

◆ huffman

DeflaterHuffman ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.huffman

private

◆ inputBuf

byte [] ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.inputBuf

private

The input data for compression.

◆ inputEnd

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.inputEnd

private

The end offset of the input data.

◆ inputOff

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.inputOff

private

The offset into inputBuf, where input data starts.

◆ ins_h

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.ins_h

private

◆ lookahead

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.lookahead

private

lookahead is the number of characters starting at strstart in window that are valid. So window[strstart] until window[strstart+lookahead-1] are valid characters.

◆ matchLen

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.matchLen

private

◆ matchStart

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.matchStart

private

◆ max_chain

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.max_chain

private

◆ max_lazy

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.max_lazy

private

◆ niceLength

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.niceLength

private

◆ pending

DeflaterPending ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.pending

private

◆ prev

short [] ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.prev

private

prev[index & WMASK]

ICSharpCode.SharpZipLib.Zip.Compression.DeflaterConstants.WMASK

const int WMASK

Internal compression engine constant.

Definition DeflaterConstants.cs:103

ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.prev

short[] prev

Definition DeflaterEngine.cs:804

points to the previous index that has the same hash code as the string starting at index. This way entries with the same hash code are in a linked list. Note that the array should really be unsigned short, so you need to and the values with 0xffff.

◆ prevAvailable

bool ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.prevAvailable

private

◆ strategy

DeflateStrategy ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.strategy

private

◆ strstart

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.strstart

private

Points to the current character in the window.

◆ TooFar

const int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.TooFar = 4096

staticprivate

◆ totalIn

long ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.totalIn

private

The total bytes of input read.

◆ window

byte [] ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.window

private

This array contains the part of the uncompressed stream that is of relevance. The current character is indexed by strstart.

Property Documentation

◆ Adler

int ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.Adler

get

Get current value of Adler checksum.

◆ Strategy

DeflateStrategy ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.Strategy

getset

Get/set the deflate strategy

◆ TotalIn

long ICSharpCode.SharpZipLib.Zip.Compression.DeflaterEngine.TotalIn

get

Total data processed.

The documentation for this class was generated from the following file:

ICSharpCode.SharpZLib/Zip/Compression/DeflaterEngine.cs

Public Member Functions

Properties

Private Member Functions

Private Attributes

Static Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ DeflaterEngine()

Member Function Documentation

◆ Deflate()

◆ DeflateFast()

◆ DeflateSlow()

◆ DeflateStored()

◆ FillWindow()

◆ FindLongestMatch()

◆ InsertString()

◆ NeedsInput()

◆ Reset()

◆ ResetAdler()

◆ SetDictionary()

◆ SetInput()

◆ SetLevel()

◆ SlideWindow()

◆ UpdateHash()

Member Data Documentation

◆ adler

◆ blockStart

◆ compressionFunction

◆ goodLength

◆ head

◆ huffman

◆ inputBuf

◆ inputEnd

◆ inputOff

◆ ins_h

◆ lookahead

◆ matchLen

◆ matchStart

◆ max_chain

◆ max_lazy

◆ niceLength

◆ pending

◆ prev

◆ prevAvailable

◆ strategy

◆ strstart

◆ TooFar

◆ totalIn

◆ window

Property Documentation

◆ Adler

◆ Strategy

◆ TotalIn