ALib C++ Library
Library Version: 2402 R1
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HuffmanEncoder Class Reference


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 31 of file huffman.hpp.

#include <huffman.hpp>

Collaboration diagram for 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)
ALIB_FORCE_INLINE void CountSymbol (uint8_t symbol)
ALIB_API void Generate ()
void Write (uint8_t symbol)

Field Details:

◆ bw

BitWriter& bw

The bit writer to use for encoding the data.

Definition at line 62 of file huffman.hpp.


constexpr int MAX_CODE_LENGTH = 64

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 enaugh for the next decades.

Definition at line 46 of file huffman.hpp.


constexpr int MAX_WORDS = 2

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

Definition at line 36 of file huffman.hpp.

◆ symbols

Symbol symbols[256]

The symbol table.

Definition at line 63 of file huffman.hpp.


constexpr int WORD_SIZE = 32

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

Definition at line 34 of file huffman.hpp.

Constructor(s) / Destructor Details::

◆ HuffmanEncoder()

HuffmanEncoder ( BitWriter & bitWriter)


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

Definition at line 73 of file huffman.hpp.

Method Details:

◆ CountSymbol()

ALIB_FORCE_INLINE void CountSymbol ( uint8_t symbol)

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

symbolThe symbol to count.

Definition at line 83 of file huffman.hpp.

◆ Generate()

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

Definition at line 104 of file huffman.cpp.

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◆ Write()

void Write ( uint8_t symbol)

Writes the given symbol to the bit stream.

symbolThe symbol to write.

Definition at line 100 of file huffman.hpp.

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