fi.helsinki.cs.ohtu.mpeg2.util
Class CRC16

java.lang.Object
  fi.helsinki.cs.ohtu.mpeg2.util.CRC16

All Implemented Interfaces:

java.util.zip.Checksum

public class CRC16
extends java.lang.Object
implements java.util.zip.Checksum

A class for computing CRC-16 checksums. The generator polynomial is x^16 + x^15 + x^2 + 1.

Field Summary

private static int	CRC16_POLY
private int	reg

Constructor Summary

CRC16()
Creates a new CRC-16 instance.

Method Summary

long	getValue() Returns CRC-16 value.
void	reset() Resets CRC-16 to the initial value.
void	update(byte[] b) Updates CRC-16 with specified array of bytes.
void	update(byte[] b, int off, int len) Updates CRC-16 with specified array of bytes.
void	update(int b) Updates CRC-16 with specified byte.
void	updateBit(int b) Updates CRC-16 with specified bit.
void	updateBits(int word, int len) Updates CRC-16 with specified bits.

Methods inherited from class java.lang.Object

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

Field Detail

CRC16_POLY

private static final int CRC16_POLY

See Also:

Constant Field Values

reg

private int reg

Constructor Detail

CRC16

public CRC16()

Creates a new CRC-16 instance.

Method Detail

getValue

public long getValue()

Returns CRC-16 value.

Specified by:

getValue in interface java.util.zip.Checksum

Returns:

The current CRC-16 checksum value

reset

public void reset()

Resets CRC-16 to the initial value.

Specified by:

reset in interface java.util.zip.Checksum

update

public void update(byte[] b,
                   int off,
                   int len)

Updates CRC-16 with specified array of bytes.

Specified by:

update in interface java.util.zip.Checksum

Parameters:

b - The array of bytes to update the checksum with

off - The start offset of the data

len - The number of bytes to use

update

public void update(byte[] b)

Updates CRC-16 with specified array of bytes.

Parameters:

b - The array of bytes to update the checksum with

update

public void update(int b)

Updates CRC-16 with specified byte.

Specified by:

update in interface java.util.zip.Checksum

Parameters:

b - The byte to update the checksum with

updateBit

public void updateBit(int b)

Updates CRC-16 with specified bit.

Parameters:

b - The bit to update the checksum with

updateBits

public void updateBits(int word,
                       int len)

Updates CRC-16 with specified bits.

Parameters:

word - The bits to update the checksum with

len - The number of the least significant bits to use