utl::ArithmeticEncoder Class Reference
[Data Compression]

DCC95 arithmetic coder. More...

#include <ArithmeticEncoder.h>

Inheritance diagram for utl::ArithmeticEncoder:

[legend]

List of all members.

Public Member Functions
	ArithmeticEncoder (uint_t mode, Stream *stream=NULL, bool owner=true, ArithContext *ctx=NULL, bool eob=false)
	Constructor.
virtual uint_t	decode (byte_t *block, uint_t num)
	Decode data from the associated stream.
uint_t	decode (ArithContext *ctx)
	Decode a symbol with the given context.
virtual uint_t	encode (const byte_t *block, uint_t num)
	Encode data to the associated stream.
void	encode (uint_t symbol, ArithContext *ctx)
	Encode a symbol with the given context.
void	setContext (ArithContext *ctx)
	Set the default context.
void	start (uint_t mode, Stream *stream, bool owner=true, ArithContext *ctx=NULL, bool eob=false)
	Initialize for encoding or decoding.
Protected Member Functions
virtual void	clear ()
	Revert to initial state.
virtual void	finishEncoding ()
	Perform any necessary clean-up when encoding is finished.

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Detailed Description

DCC95 arithmetic coder.

This implementation is really due to Alistair Moffat. All I have really done here is "UTL-ify" it.

See Alistair's home page at: http://www.cs.mu.oz.au/~alistair/

Attributes

• ctx : Default context. This context is used by encoding/decoding methods that don't take an explicit context as a parameter.

• eob flag : If true, encode end-of-block when encoding is finished, so that the end of the block can be recognized when decoding.

Author:

Alistair Moffat, Adam McKee

Definition at line 138 of file ArithmeticEncoder.h.

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Constructor & Destructor Documentation

utl::ArithmeticEncoder::ArithmeticEncoder	(	uint_t	mode,
		Stream *	stream = NULL,
		bool	owner = true,
		ArithContext *	ctx = NULL,
		bool	eob = false
	)			[inline]

Constructor.

Parameters:

	mode	io_rd to decode, io_wr to encode (see io_t)
	stream	(optional) associated stream
	owner	(optional : true) owner flag for stream
	ctx	(optional) default context
	eob	(optional : false) encode end-of-block?

Definition at line 150 of file ArithmeticEncoder.h.

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Member Function Documentation

virtual uint_t utl::ArithmeticEncoder::decode	(	byte_t *	block,
		uint_t	num
	)			[virtual]

Decode data from the associated stream.

Returns:

number of bytes decoded

Parameters:

	block	block to decode into
	num	size of block

Implements utl::Encoder.

uint_t utl::ArithmeticEncoder::decode

(

ArithContext *

ctx

)

[inline]

Decode a symbol with the given context.

Returns:

symbol

Parameters:

ctx

context

Definition at line 274 of file ArithmeticEncoder.h.

References utl::Stream::getBit(), utl::ArithContext::interval(), utl::min(), utl::ArithContext::symbol(), utl::ArithContext::totFreq(), and utl::ArithContext::update().

virtual uint_t utl::ArithmeticEncoder::encode	(	const byte_t *	block,
		uint_t	num
	)			[virtual]

Encode data to the associated stream.

Returns:

number of bytes encoded

Parameters:

	block	block to encode
	num	size of block

Implements utl::Encoder.

void utl::ArithmeticEncoder::encode	(	uint_t	symbol,
		ArithContext *	ctx
	)			[inline]

Encode a symbol with the given context.

Parameters:

	symbol	symbol to encode
	ctx	context

Definition at line 227 of file ArithmeticEncoder.h.

References utl::ArithContext::interval(), utl::ArithContext::totFreq(), and utl::ArithContext::update().

void utl::ArithmeticEncoder::setContext

(

ArithContext *

ctx

)

[inline]

Set the default context.

Definition at line 177 of file ArithmeticEncoder.h.

void utl::ArithmeticEncoder::start	(	uint_t	mode,
		Stream *	stream,
		bool	owner = true,
		ArithContext *	ctx = NULL,
		bool	eob = false
	)

Initialize for encoding or decoding.

Parameters:

	mode	io_rd to encode, io_wr to decode (see io_t)
	stream	(optional) associated stream
	owner	(optional : true) owner flag for stream
	ctx	(optional) default context
	eob	(optional : false) encode end-of-block?

virtual void utl::ArithmeticEncoder::clear

(

)

[protected, virtual]

Revert to initial state.

Reimplemented from utl::Encoder.

virtual void utl::ArithmeticEncoder::finishEncoding

(

)

[protected, virtual]

Perform any necessary clean-up when encoding is finished.

Reimplemented from utl::Encoder.

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

• ArithmeticEncoder.h