com.nothome.delta
Class Checksum

java.lang.Object
  com.nothome.delta.Checksum

public class Checksum
extends Object

Checksum computation class.

Constructor Summary

Checksum(SeekableSource source, int chunkSize)
Initialize checksums for source.

Method Summary

int	findChecksumIndex(long hashf) Finds the index of a checksum.
static char[]	getSingleHash() 256 random hash values.
static long	incrementChecksum(long checksum, byte out, byte in, int chunkSize) Increments a checksum.
static long	queryChecksum(ByteBuffer bb, int len) Finds the checksum computed from the buffer.
String	toString() Returns a debug String.

Methods inherited from class java.lang.Object

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

Constructor Detail

Checksum

public Checksum(SeekableSource source,
                int chunkSize)
         throws IOException

Initialize checksums for source. The checksum for the chunkSize bytes at offset chunkSize * i is inserted into a hash map.

Throws:

IOException

Method Detail

queryChecksum

public static long queryChecksum(ByteBuffer bb,
                                 int len)

Finds the checksum computed from the buffer. Marks, gets, then resets the buffer.

incrementChecksum

public static long incrementChecksum(long checksum,
                                     byte out,
                                     byte in,
                                     int chunkSize)

Increments a checksum.

Parameters:

checksum - initial checksum

out - byte leaving view

in - byte entering view

chunkSize - size of chunks

Returns:

new checksum

getSingleHash

public static char[] getSingleHash()

256 random hash values.

findChecksumIndex

public int findChecksumIndex(long hashf)

Finds the index of a checksum.

toString

public String toString()

Returns a debug String.

Overrides:

toString in class Object