Package org.tmatesoft.svn.core.internal.io.fs.index

Class FSFnv1aInterleavedChecksumCalculator

java.lang.Object

org.tmatesoft.svn.core.internal.io.fs.index.FSFnv1aInterleavedChecksumCalculator

public class FSFnv1aInterleavedChecksumCalculator
extends java.lang.Object

A modification of FNV-1a algorithm. When given an input of 4k+b bytes the first 4k bytes input is divided into 4 arrays: of the 1st, 5th, 9th, 13th, ... bytes of the 2nd, 6th, 10th, 14th, ... bytes of the 3rd, 7th, 11th, 15th, ... bytes of the 4th, 8th, 12th, 16th, ... bytes Then 4 normal FNV-1a checksums are calculated from them. Then the checksums are written as raw a byte array and the last b bytes are appended. Finally normal FNV-1a checksum is calculated.

Field Summary

Fields

Modifier and Type	Field	Description
private byte[]	buffer
private int	buffered
private static long	FNV1_BASE_32
private static long	FNV1_PRIME_32
private static int	HASH_SIZE_IN_BYTES
private long[]	hashes
private static int	SCALING

Constructor Summary

Constructors

Constructor	Description
FSFnv1aInterleavedChecksumCalculator()

Method Summary

Modifier and Type	Method	Description
int	finalizeChecksum()
private int	finalizeChecksum(byte[] data, int offset, int length)
private long	fnv1a(long hash, byte[] data, int offset, int length)
private int	fnv1aInterleaved(byte[] data, int offset, int length)
protected void	resetChecksum()
void	update(byte[] data, int offset, int length)

Methods inherited from class java.lang.Object

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

Field Detail

SCALING

private static final int SCALING

See Also:

Constant Field Values

HASH_SIZE_IN_BYTES

private static final int HASH_SIZE_IN_BYTES

See Also:

Constant Field Values

FNV1_BASE_32

private static final long FNV1_BASE_32

See Also:

Constant Field Values

FNV1_PRIME_32

private static final long FNV1_PRIME_32

See Also:

Constant Field Values

hashes

private final long[] hashes

buffer

private final byte[] buffer

buffered

private int buffered

Constructor Detail

FSFnv1aInterleavedChecksumCalculator

public FSFnv1aInterleavedChecksumCalculator()

Method Detail

update

public void update(byte[] data,
                   int offset,
                   int length)

finalizeChecksum

public int finalizeChecksum()

finalizeChecksum

private int finalizeChecksum(byte[] data,
                             int offset,
                             int length)

fnv1aInterleaved

private int fnv1aInterleaved(byte[] data,
                             int offset,
                             int length)

fnv1a

private long fnv1a(long hash,
                   byte[] data,
                   int offset,
                   int length)

resetChecksum

protected void resetChecksum()