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package org.jruby.util;
import java.lang.reflect.Field;
import java.util.zip.CRC32;
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 CRC32Ext implements Checksum {
private int crc;
private final CRC32 intern;
private static final Field intern_crc;
static {
try {
intern_crc = CRC32.class.getDeclaredField("crc");
intern_crc.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 CRC32Ext() {
this(1);
}
/**
* Creates the basic object with the adler provided.
*
* @param adler the number to use as starting point for the CRC-32 algorithm
*/
public CRC32Ext(final int crc) {
super();
this.crc=crc;
this.intern = new CRC32();
setCRCRef(this.crc);
}
/**
* Sets the adler running total to the specified value.
*
* @param adler the number to use as current value for the CRC-32 algorithm
*/
public void setAdler(final int crc) {
this.crc = crc;
setCRCRef(this.crc);
}
/**
* @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.crc = 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 setCRCRef(final int val) {
try {
intern_crc.setInt(intern,val);
} catch(final IllegalAccessException e) {
throw new IllegalStateException(e.toString());
}
}
}