alib::bitbuffer::ac_v1::HuffmanEncoder Class Reference

Description:

This class, together with sibling HuffmanDecoder implements the well known Huffman compression . The class uses type BitWriter to write the bit stream into an underlying BitBuffer.

The use of this class is quite straight forward:

• Create an instance of this class
• Feed the data to be compressed once to the algorithm using method CountSymbol
• Invoke method Generate
• Feed all data a second time using method Write.

Definition at line 22 of file huffman.hpp.

#include <huffman.hpp>

Collaboration diagram for alib::bitbuffer::ac_v1::HuffmanEncoder:

Inner Type Index:
struct	Symbol

Public Static Field Index:
static constexpr int	MAX_CODE_LENGTH = 64
static constexpr int	MAX_WORDS = 2
static constexpr int	WORD_SIZE = 32

Public Method Index:
	HuffmanEncoder (BitWriter &bitWriter)
void	CountSymbol (uint8_t symbol)
void	Generate ()
	Generates the huffman encoding table and writes this information to the bit writer.
void	Write (uint8_t symbol)

Protected Field Index:
BitWriter &	bw
	The bit writer to use for encoding the data.
Symbol	symbols [256]
	The symbol table.

Field Details:

bw

BitWriter& alib::bitbuffer::ac_v1::HuffmanEncoder::bw

protected

The bit writer to use for encoding the data.

Definition at line 47 of file huffman.hpp.

MAX_CODE_LENGTH

int alib::bitbuffer::ac_v1::HuffmanEncoder::MAX_CODE_LENGTH = 64

staticconstexpr

The maximum length of a huffman code. In theory, with 256 symbols, a maximum code length of 255 could occur. For this, each next symbol needed to have the double frequency than the previous. Hence, setting the value to 64, limits the encoded data size to 2^64 symbols, which should be more than enough for the next decades.

Definition at line 34 of file huffman.hpp.

MAX_WORDS

int alib::bitbuffer::ac_v1::HuffmanEncoder::MAX_WORDS = 2

staticconstexpr

Codes are stored in two (this constant) words of size 32.

Definition at line 26 of file huffman.hpp.

symbols

Symbol alib::bitbuffer::ac_v1::HuffmanEncoder::symbols[256]

protected

The symbol table.

Definition at line 48 of file huffman.hpp.

WORD_SIZE

int alib::bitbuffer::ac_v1::HuffmanEncoder::WORD_SIZE = 32

staticconstexpr

Codes are stored in two words of size 32 (this constant)

Definition at line 24 of file huffman.hpp.

Constructor(s) / Destructor Details:

HuffmanEncoder()

alib::bitbuffer::ac_v1::HuffmanEncoder::HuffmanEncoder ( BitWriter & bitWriter )

inline

Constructor.

Parameters

bitWriter

The bit writer to write the encoding information as well as the encoded symbols to. (Stored in field bw.)

Definition at line 56 of file huffman.hpp.

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Method Details:

CountSymbol()

void alib::bitbuffer::ac_v1::HuffmanEncoder::CountSymbol ( uint8_t symbol )

inline

Counts a symbol. This method has to be invoked for each byte to compress later.

Parameters

symbol

The symbol to count.

Definition at line 62 of file huffman.hpp.

Generate()

void alib::bitbuffer::ac_v1::HuffmanEncoder::Generate

(

)

Generates the huffman encoding table and writes this information to the bit writer.

Definition at line 81 of file huffman.cpp.

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Write()

void alib::bitbuffer::ac_v1::HuffmanEncoder::Write ( uint8_t symbol )

inline

Writes the given symbol to the bit stream.

Parameters

symbol

The symbol to write.

Definition at line 70 of file huffman.hpp.

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

• huffman.hpp
• huffman.cpp