ICSharpCode.SharpZipLib.LZW.LzwInputStream Class Reference

This filter stream is used to decompress a LZW format stream. Specifically, a stream that uses the LZC compression method. This file format is usually associated with the .Z file extension. More...

Inheritance diagram for ICSharpCode.SharpZipLib.LZW.LzwInputStream:

Collaboration diagram for ICSharpCode.SharpZipLib.LZW.LzwInputStream:

Public Member Functions
	LzwInputStream (Stream baseInputStream)
	Creates a LzwInputStream.
override int	ReadByte ()
	See System.IO.Stream.ReadByte
override int	Read (byte[] buffer, int offset, int count)
	Reads decompressed data into the provided buffer byte array.
override void	Flush ()
	Flushes the baseInputStream.
override long	Seek (long offset, SeekOrigin origin)
	Sets the position within the current stream Always throws a NotSupportedException.
override void	SetLength (long value)
	Set the length of the current stream Always throws a NotSupportedException.
override void	Write (byte[] buffer, int offset, int count)
	Writes a sequence of bytes to stream and advances the current position This method always throws a NotSupportedException.
override void	WriteByte (byte value)
	Writes one byte to the current stream and advances the current position Always throws a NotSupportedException.
override IAsyncResult	BeginWrite (byte[] buffer, int offset, int count, AsyncCallback callback, object state)
	Entry point to begin an asynchronous write. Always throws a NotSupportedException.
override void	Close ()
	Closes the input stream. When IsStreamOwner is true the underlying stream is also closed.

Properties
bool	IsStreamOwner [get, set]
	Get/set flag indicating ownership of underlying stream. When the flag is true Close will close the underlying stream also.
override bool	CanRead [get]
	Gets a value indicating whether the current stream supports reading.
override bool	CanSeek [get]
	Gets a value of false indicating seeking is not supported for this stream.
override bool	CanWrite [get]
	Gets a value of false indicating that this stream is not writeable.
override long	Length [get]
	A value representing the length of the stream in bytes.
override long	Position [get, set]
	The current position within the stream. Throws a NotSupportedException when attempting to set the position.

Private Member Functions
int	ResetBuf (int bitPosition)
	Moves the unread data in the buffer to the beginning and resets the pointers.
void	Fill ()
void	ParseHeader ()

Private Attributes
Stream	baseInputStream
bool	isStreamOwner = true
	Flag indicating wether this instance is designated the stream owner. When closing if this flag is true the underlying stream is closed.
bool	isClosed
	Flag indicating wether this instance has been closed or not.
readonly byte[]	one = new byte[1]
bool	headerParsed
int[]	tabPrefix
byte[]	tabSuffix
readonly int[]	zeros = new int[256]
byte[]	stack
bool	blockMode
int	nBits
int	maxBits
int	maxMaxCode
int	maxCode
int	bitMask
int	oldCode
byte	finChar
int	stackP
int	freeEnt
readonly byte[]	data = new byte[1024 * 8]
int	bitPos
int	end
int	got
bool	eof

Static Private Attributes
const int	TBL_CLEAR = 0x100
const int	TBL_FIRST = TBL_CLEAR + 1
const int	EXTRA = 64

Detailed Description

This filter stream is used to decompress a LZW format stream. Specifically, a stream that uses the LZC compression method. This file format is usually associated with the .Z file extension.

See http://en.wikipedia.org/wiki/Compress See http://wiki.wxwidgets.org/Development:_Z_File_Format

The file header consists of 3 (or optionally 4) bytes. The first two bytes contain the magic marker "0x1f 0x9d", followed by a byte of flags.

Based on Java code by Ronald Tschalar, which in turn was based on the unlzw.c code in the gzip package.

This sample shows how to unzip a compressed file

using System;
using System.IO;
 
using ICSharpCode.SharpZipLib.Core;
using ICSharpCode.SharpZipLib.LZW;
 
class MainClass
{
    public static void Main(string[] args)
    {
        using (Stream inStream = new LzwInputStream(File.OpenRead(args[0])))
        using (FileStream outStream = File.Create(Path.GetFileNameWithoutExtension(args[0]))) {
            byte[] buffer = new byte[4096];
            StreamUtils.Copy(inStream, outStream, buffer);
                        // OR
                        inStream.Read(buffer, 0, buffer.Length);
                        // now do something with the buffer
        }
    }
}   <br>

Constructor & Destructor Documentation

LzwInputStream()

ICSharpCode.SharpZipLib.LZW.LzwInputStream.LzwInputStream

(

Stream

baseInputStream

)

Creates a LzwInputStream.

Parameters

baseInputStream

The stream to read compressed data from (baseInputStream LZW format)

Member Function Documentation

BeginWrite()

override IAsyncResult ICSharpCode.SharpZipLib.LZW.LzwInputStream.BeginWrite	(	byte[]	buffer,
		int	offset,
		int	count,
		AsyncCallback	callback,
		object	state )

Entry point to begin an asynchronous write. Always throws a NotSupportedException.

Parameters

buffer	The buffer to write data from
offset	Offset of first byte to write
count	The maximum number of bytes to write
callback	The method to be called when the asynchronous write operation is completed
state	A user-provided object that distinguishes this particular asynchronous write request from other requests

Returns

An IAsyncResult that references the asynchronous write

Exceptions

NotSupportedException

Any access

Close()

override void ICSharpCode.SharpZipLib.LZW.LzwInputStream.Close

(

)

Closes the input stream. When IsStreamOwner is true the underlying stream is also closed.

Fill()

void ICSharpCode.SharpZipLib.LZW.LzwInputStream.Fill ( )

private

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Flush()

override void ICSharpCode.SharpZipLib.LZW.LzwInputStream.Flush

(

)

Flushes the baseInputStream.

ParseHeader()

void ICSharpCode.SharpZipLib.LZW.LzwInputStream.ParseHeader ( )

private

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Read()

override int ICSharpCode.SharpZipLib.LZW.LzwInputStream.Read	(	byte[]	buffer,
		int	offset,
		int	count )

Reads decompressed data into the provided buffer byte array.

Parameters

buffer	The array to read and decompress data into
offset	The offset indicating where the data should be placed
count	The number of bytes to decompress

Returns

The number of bytes read. Zero signals the end of stream

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ReadByte()

override int ICSharpCode.SharpZipLib.LZW.LzwInputStream.ReadByte

(

)

See System.IO.Stream.ReadByte

Returns

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ResetBuf()

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.ResetBuf ( int bitPosition )

private

Moves the unread data in the buffer to the beginning and resets the pointers.

Parameters

bitPosition

Returns

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Seek()

override long ICSharpCode.SharpZipLib.LZW.LzwInputStream.Seek	(	long	offset,
		SeekOrigin	origin )

Sets the position within the current stream Always throws a NotSupportedException.

Parameters

offset	The relative offset to seek to.
origin	The SeekOrigin defining where to seek from.

Returns

The new position in the stream.

Exceptions

NotSupportedException

Any access

SetLength()

override void ICSharpCode.SharpZipLib.LZW.LzwInputStream.SetLength

(

long

value

)

Set the length of the current stream Always throws a NotSupportedException.

Parameters

value

The new length value for the stream.

Exceptions

NotSupportedException

Any access

Write()

override void ICSharpCode.SharpZipLib.LZW.LzwInputStream.Write	(	byte[]	buffer,
		int	offset,
		int	count )

Writes a sequence of bytes to stream and advances the current position This method always throws a NotSupportedException.

Parameters

buffer	Thew buffer containing data to write.
offset	The offset of the first byte to write.
count	The number of bytes to write.

Exceptions

NotSupportedException

Any access

WriteByte()

override void ICSharpCode.SharpZipLib.LZW.LzwInputStream.WriteByte

(

byte

value

)

Writes one byte to the current stream and advances the current position Always throws a NotSupportedException.

Parameters

value

The byte to write.

Exceptions

NotSupportedException

Any access

Member Data Documentation

baseInputStream

Stream ICSharpCode.SharpZipLib.LZW.LzwInputStream.baseInputStream

private

bitMask

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.bitMask

private

bitPos

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.bitPos

private

blockMode

bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.blockMode

private

data

readonly byte [] ICSharpCode.SharpZipLib.LZW.LzwInputStream.data = new byte[1024 * 8]

private

end

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.end

private

eof

bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.eof

private

EXTRA

const int ICSharpCode.SharpZipLib.LZW.LzwInputStream.EXTRA = 64

staticprivate

finChar

byte ICSharpCode.SharpZipLib.LZW.LzwInputStream.finChar

private

freeEnt

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.freeEnt

private

got

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.got

private

headerParsed

bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.headerParsed

private

isClosed

bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.isClosed

private

Flag indicating wether this instance has been closed or not.

isStreamOwner

bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.isStreamOwner = true

private

Flag indicating wether this instance is designated the stream owner. When closing if this flag is true the underlying stream is closed.

maxBits

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.maxBits

private

maxCode

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.maxCode

private

maxMaxCode

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.maxMaxCode

private

nBits

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.nBits

private

oldCode

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.oldCode

private

one

readonly byte [] ICSharpCode.SharpZipLib.LZW.LzwInputStream.one = new byte[1]

private

stack

byte [] ICSharpCode.SharpZipLib.LZW.LzwInputStream.stack

private

stackP

int ICSharpCode.SharpZipLib.LZW.LzwInputStream.stackP

private

tabPrefix

int [] ICSharpCode.SharpZipLib.LZW.LzwInputStream.tabPrefix

private

tabSuffix

byte [] ICSharpCode.SharpZipLib.LZW.LzwInputStream.tabSuffix

private

TBL_CLEAR

const int ICSharpCode.SharpZipLib.LZW.LzwInputStream.TBL_CLEAR = 0x100

staticprivate

TBL_FIRST

const int ICSharpCode.SharpZipLib.LZW.LzwInputStream.TBL_FIRST = TBL_CLEAR + 1

staticprivate

zeros

readonly int [] ICSharpCode.SharpZipLib.LZW.LzwInputStream.zeros = new int[256]

private

Property Documentation

CanRead

override bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.CanRead

get

Gets a value indicating whether the current stream supports reading.

CanSeek

override bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.CanSeek

get

Gets a value of false indicating seeking is not supported for this stream.

CanWrite

override bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.CanWrite

get

Gets a value of false indicating that this stream is not writeable.

IsStreamOwner

bool ICSharpCode.SharpZipLib.LZW.LzwInputStream.IsStreamOwner

getset

Get/set flag indicating ownership of underlying stream. When the flag is true Close will close the underlying stream also.

The default value is true.

Length

override long ICSharpCode.SharpZipLib.LZW.LzwInputStream.Length

get

A value representing the length of the stream in bytes.

Position

override long ICSharpCode.SharpZipLib.LZW.LzwInputStream.Position

getset

The current position within the stream. Throws a NotSupportedException when attempting to set the position.

Exceptions

NotSupportedException

Attempting to set the position

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

• ICSharpCode.SharpZLib/Lzw/LzwInputStream.cs