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/*
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* Copyright 1996-2005 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package java.util.zip;
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/**
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* A class that can be used to compute the CRC-32 of a data stream.
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*
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* @see Checksum
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* @author David Connelly
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*/
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public
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class CRC32 implements Checksum {
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private int crc;
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/**
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* Creates a new CRC32 object.
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*/
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public CRC32() {
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}
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/**
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* Updates CRC-32 with specified byte.
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*/
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public void update(int b) {
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crc = update(crc, b);
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}
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/**
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* Updates CRC-32 with specified array of bytes.
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*/
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public void update(byte[] b, int off, int len) {
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if (b == null) {
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throw new NullPointerException();
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}
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if (off < 0 || len < 0 || off > b.length - len) {
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throw new ArrayIndexOutOfBoundsException();
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}
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crc = updateBytes(crc, b, off, len);
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}
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/**
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* Updates checksum with specified array of bytes.
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*
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* @param b the array of bytes to update the checksum with
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*/
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public void update(byte[] b) {
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crc = updateBytes(crc, b, 0, b.length);
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}
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/**
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* Resets CRC-32 to initial value.
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*/
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public void reset() {
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crc = 0;
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}
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/**
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* Returns CRC-32 value.
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*/
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public long getValue() {
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return (long)crc & 0xffffffffL;
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}
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private native static int update(int crc, int b);
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private native static int updateBytes(int crc, byte[] b, int off, int len);
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}
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