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Contains classes not specific to fuzzydb implementation which
could be used in any implementation of fuzzy matching, or as
general utility classes such as those in the geo package.
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/******************************************************************************
* Copyright (c) 2004-2008 Whirlwind Match Limited. All rights reserved.
*
* This is open source software; you can use, redistribute and/or modify
* it under the terms of the Open Software Licence v 3.0 as published by the
* Open Source Initiative.
*
* You should have received a copy of the Open Software Licence along with this
* application. if not, contact the Open Source Initiative (www.opensource.org)
*****************************************************************************/
package org.fuzzydb.util;
import java.util.zip.Checksum;
/**This is a home-rolled version of the Adler32 checksum algo.
* It has been expanded for 64 bit operation using the same rules.
* This is not guaranteed to be the same algo as some other Adler64.
*/
public final class Adler64 implements Checksum {
private long s1; // These are used as unsigned 32 bit
private long s2;
private final static long crcBase = 4294967291l; // prime less than 2^32
public Adler64() {
super();
reset();
}
@Override
public final void update(int b) {
s1 += b;
if (s1>=crcBase)
{
s1 -= crcBase; // same as mod % but with no risk of costly 64 bit math
}
s2 += s1;
if (s2>=crcBase) {
s2 -= crcBase;
}
}
@Override
public final void update(byte[] b, int off, int len) {
for (int i=0; i