net.tomp2p.synchronization

Class RSync.RollingChecksum

java.lang.Object

net.tomp2p.synchronization.RSync.RollingChecksum

Enclosing class:

RSync

public static class RSync.RollingChecksum
extends Object

Variation of Adler as used in Rsync. Inspired by:

 https://github.com/epeli/rollsum/blob/master/ref/adler32.py
 http://stackoverflow.com/questions/9699315/differences-in-calculation-of-adler32-rolling-checksum-python
 http://de.wikipedia.org/wiki/Adler-32
 http://developer.classpath.org/doc/java/util/zip/Adler32-source.html
 

Author:

Thomas Bocek

Constructor Summary

Constructors

Constructor and Description
RSync.RollingChecksum()

Method Summary

Methods

Modifier and Type	Method and Description
RSync.RollingChecksum	reset() Resets the checksum to its initial state 1.
RSync.RollingChecksum	update(byte[] array, int offset, int length) Iterates over the array and calculates a variation of Adler.
RSync.RollingChecksum	updateRolling(byte[] array) Slide the window of the array by 1.
int	value()
RSync.RollingChecksum	value(int checksum) Sets the checksum to this value.

Methods inherited from class java.lang.Object

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

Constructor Detail

RSync.RollingChecksum

public RSync.RollingChecksum()

Method Detail

reset

public RSync.RollingChecksum reset()

Resets the checksum to its initial state 1.

Returns:

this class

update

public RSync.RollingChecksum update(byte[] array,
                           int offset,
                           int length)

Iterates over the array and calculates a variation of Adler.

Parameters:

array - The array for the checksum calculation

offset - The offset of the array

length - The length of the data to iterate over (the length of the sliding window). Once this is set, updateRolling(byte[]) will use the same value

Returns:

this class

value

public int value()

Returns:

The calculated checksum

value

public RSync.RollingChecksum value(int checksum)

Sets the checksum to this value.

Parameters:

checksum - The checksum to set

Returns:

this class

updateRolling

public RSync.RollingChecksum updateRolling(byte[] array)

Slide the window of the array by 1.

Parameters:

array - The array for the checksum calculation

offset - The offset of the array

Returns:

this class