HuffmanDecoder Class Reference

Description:

This class, together with sibling HuffmanEncoder implements the well known Huffman compression . The class uses type BitReader to read the bit stream from an underlying BitBuffer.

The use of this class is quite straight forward:

• Prepare a BitReader to point to the beginning of the bit stream generated with class HuffmanEncoder.
• Invoke method ReadTree once.
• For each encoded byte, invoke Read.

Note, that the length of the stream (the number of bytes to be decompressed) have to be known by the using software. This class is not responsible for storing this piece of information.

Definition at line 127 of file huffman.hpp.

#include <huffman.hpp>

Collaboration diagram for HuffmanDecoder:

Inner Type Index:
struct	Node
	Internal struct representing nodes of the huffman code tree. More...

Public Method Index:
	HuffmanDecoder (BitReader &bitReader)
uint8_t	Read ()
ALIB_API void	ReadTree ()

Protected Static Field Index:
static constexpr int	MAX_NODES = 511
	The maximum number of nodes in the tree.

Protected Field Index:
BitReader &	br
	The bit reader given in the constructor.
Node	nodePool [MAX_NODES]
	Pre-allocated node objects.
int	npNext = 0
	The next node in nodePool to use.
Node	tree
	The root node of the symbol tree.

Field Details:

br

BitReader& br

protected

The bit reader given in the constructor.

Definition at line 147 of file huffman.hpp.

MAX_NODES

int MAX_NODES = 511

staticconstexprprotected

The maximum number of nodes in the tree.

Definition at line 145 of file huffman.hpp.

nodePool

Node nodePool[MAX_NODES]

protected

Pre-allocated node objects.

Definition at line 149 of file huffman.hpp.

npNext

int npNext = 0

protected

The next node in nodePool to use.

Definition at line 150 of file huffman.hpp.

tree

Node tree

protected

The root node of the symbol tree.

Definition at line 148 of file huffman.hpp.

Constructor(s) / Destructor Details:

HuffmanDecoder()

HuffmanDecoder ( BitReader & bitReader )

inline

Constructor.

Parameters

bitReader

The bit reader to read the huffman encoding table and then the encoded symbols from. (Stored in field br.)

Definition at line 156 of file huffman.hpp.

Method Details:

Read()

uint8_t Read ( )

inline

Reads a symbol from the bit stream. This method has to be invoked for every symbol stored, after once reading the encoding information with method ReadTree.

Returns

The symbol read.

Definition at line 169 of file huffman.hpp.

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ReadTree()

void ReadTree

(

)

Reads the information to decode the data from the beginning of the bit stream. This method has to be invoked once before reading the symbols with method Read.

Definition at line 213 of file huffman.cpp.

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

• huffman.hpp
• huffman.cpp