com.colloquial.arithcode
Class ArithCoder

java.lang.Object
  |
  +--com.colloquial.arithcode.ArithCoder

Direct Known Subclasses:

ArithDecoder, ArithEncoder

class ArithCoder

extends java.lang.Object

A generic arithmetic coding subclass containing elements common to both arithmetic decoding and arithmetic coding.

Since:

1.0

Version:

1.1

Author:

Bob Carpenter

Field Summary

protected long	_high The high bound on the current interval for coding.
protected long	_low The low bound on the current interval for coding.
protected static int	CODE_VALUE_BITS Precision of coding, expressed in number of bits used for arithmetic before shifting out partial results.
protected static long	FIRST_QUARTER 1/4 of the largest possible value plus one.
protected static long	HALF 1/2 of the largest possible value; 2 * FIRST_QUARTER
protected static long	THIRD_QUARTER 3/4 of the largest possible value; 3 * FIRST_QUARTER
protected static long	TOP_VALUE The largest possible interval value.

Constructor Summary

protected

ArithCoder() Construct a generic arithmetic coder.

Methods inherited from class java.lang.Object

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

Field Detail

_low

protected long _low

The low bound on the current interval for coding. Initialized to zero.

_high

protected long _high

The high bound on the current interval for coding. Initialized to top value possible.

CODE_VALUE_BITS

protected static final int CODE_VALUE_BITS

Precision of coding, expressed in number of bits used for arithmetic before shifting out partial results.

See Also:

Constant Field Values

TOP_VALUE

protected static final long TOP_VALUE

The largest possible interval value. All 1s.

See Also:

Constant Field Values

FIRST_QUARTER

protected static final long FIRST_QUARTER

1/4 of the largest possible value plus one.

See Also:

Constant Field Values

HALF

protected static final long HALF

1/2 of the largest possible value; 2 * FIRST_QUARTER

See Also:

Constant Field Values

THIRD_QUARTER

protected static final long THIRD_QUARTER

3/4 of the largest possible value; 3 * FIRST_QUARTER

See Also:

Constant Field Values

Constructor Detail

ArithCoder

protected ArithCoder()

Construct a generic arithmetic coder.