/*
* Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
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*/
package java.util.zip;
/**
* A class that can be used to compute the CRC-32 of a data stream.
*
* @see Checksum
* @author David Connelly
*/
public
class CRC32 implements Checksum {
private int crc;
/**
* Creates a new CRC32 object.
*/
public CRC32() {
}
/**
* Updates the CRC-32 checksum with the specified byte (the low
* eight bits of the argument b).
*
* @param b the byte to update the checksum with
*/
public void update(int b) {
crc = update(crc, b);
}
/**
* Updates the CRC-32 checksum with the specified array of bytes.
*/
public void update(byte[] b, int off, int len) {
if (b == null) {
throw new NullPointerException();
}
if (off < 0 || len < 0 || off > b.length - len) {
throw new ArrayIndexOutOfBoundsException();
}
crc = updateBytes(crc, b, off, len);
}
/**
* Updates the CRC-32 checksum with the specified array of bytes.
*
* @param b the array of bytes to update the checksum with
*/
public void update(byte[] b) {
crc = updateBytes(crc, b, 0, b.length);
}
/**
* Resets CRC-32 to initial value.
*/
public void reset() {
crc = 0;
}
/**
* Returns CRC-32 value.
*/
public long getValue() {
return (long)crc & 0xffffffffL;
}
private native static int update(int crc, int b);
private native static int updateBytes(int crc, byte[] b, int off, int len);
}