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package org.jruby.util;
import java.lang.reflect.Field;
import java.util.zip.Adler32;
import java.util.zip.Checksum;
/**
* This class is a wrapper around Adler32 which provides the capability to
* update the running total. This functionality is provided by quite risky
* reflection and should be fixed in a better way later on.
*/
public class Adler32Ext implements Checksum {
private int adler;
private final Adler32 intern;
private static final Field intern_adler;
static {
try {
intern_adler = Adler32.class.getDeclaredField("adler");
intern_adler.setAccessible(true);
} catch(final NoSuchFieldException nsfe) {
throw new RuntimeException("This class have stopped working, it should be updated and FIXED now.");
}
}
/**
* Creates the basic object with default initial adler.
*/
public Adler32Ext() {
this(1);
}
/**
* Creates the basic object with the adler provided.
*
* @param adler the number to use as starting point for the Adler-32 algorithm
*/
public Adler32Ext(final int adler) {
super();
this.adler=adler;
this.intern = new Adler32();
setAdlerRef(this.adler);
}
/**
* Sets the adler running total to the specified value.
*
* @param adler the number to use as current value for the Adler-32 algorithm
*/
public void setAdler(final int adler) {
this.adler = adler;
setAdlerRef(this.adler);
}
/**
* @see java.util.zip.Checksum#update
*/
public void update(final int b) {
this.intern.update(b);
}
/**
* @see java.util.zip.Checksum#update
*/
public void update(final byte[] b, final int off, final int len) {
this.intern.update(b,off,len);
}
/**
* @see java.util.zip.Checksum#update
*/
public void update(final byte[] b) {
this.intern.update(b);
}
/**
* @see java.util.zip.Checksum#reset
*/
public void reset() {
this.intern.reset();
this.adler = 1;
}
/**
* @see java.util.zip.Checksum#getValue
*/
public long getValue() {
return this.intern.getValue();
}
/**
* Helper method to set the reference through reflection.
*
* @param val the value to set.
*/
private void setAdlerRef(final int val) {
try {
intern_adler.setInt(intern,val);
} catch(final IllegalAccessException e) {
throw new IllegalStateException(e.toString());
}
}
}