totalcross.json.zip

Class Huff

java.lang.Object

totalcross.json.zip.Huff

All Implemented Interfaces:

None, PostMortem

public class Huff
extends java.lang.Object
implements None, PostMortem

A Huffman encoder/decoder. It operates over a domain of integers, which may map to characters or other symbols. Symbols that are used frequently are given shorter codes than symbols that are used infrequently. This usually produces shorter messages. Initially, all of the symbols are given the same weight. The weight of a symbol is incremented by the tick method. The generate method is used to generate the encoding table. The table must be generated before encoding or decoding. You may regenerate the table with the latest weights at any time. After a million ticks, it is assumed that the distribution is well understood and that no more regeneration will be required.

Field Summary

Fields

Modifier and Type	Field and Description
static int	education The number of characters to process before generation is no longer done.

Fields inherited from interface totalcross.json.zip.None

none

Constructor Summary

Constructors

Constructor and Description
Huff(int domain) Construct a Huffman encoder/decoder.

Method Summary

Modifier and Type	Method and Description
void	generate() Generate the encoding/decoding table.
boolean	postMortem(PostMortem pm) Compare two Huffman tables.
int	read(BitReader bitreader) Read bits until a symbol can be identified.
void	tick(int value) Increase the weight associated with a value by 1.
void	write(int value, BitWriter bitwriter) Write the bits corresponding to a symbol.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

education

public static final int education

The number of characters to process before generation is no longer done.

See Also:

Constant Field Values

Constructor Detail

Huff

public Huff(int domain)

Construct a Huffman encoder/decoder.

Parameters:

domain - The number of values known to the object.

Method Detail

generate

public void generate()

Generate the encoding/decoding table. The table determines the bit sequences used by the read and write methods.

postMortem

public boolean postMortem(PostMortem pm)

Compare two Huffman tables.

Specified by:

postMortem in interface PostMortem

Parameters:

pm - Another object of the same type.

Returns:

true if they match.

read

public int read(BitReader bitreader)
         throws JSONException

Read bits until a symbol can be identified. The weight of the read symbol will be incremented.

Parameters:

bitreader - The source of bits.

Returns:

The integer value of the symbol.

Throws:

JSONException

tick

public void tick(int value)

Increase the weight associated with a value by 1.

Parameters:

value - The number of the symbol to tick

write

public void write(int value,
                  BitWriter bitwriter)
           throws JSONException

Write the bits corresponding to a symbol. The weight of the symbol will be incremented.

Parameters:

value - The number of the symbol to write

bitwriter - The destination of the bits.

Throws:

JSONException