/*
* @(#)CRC32.java 1.35 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.util.zip;
/**
* A class that can be used to compute the CRC-32 of a data stream.
*
* @see Checksum
* @version 1.25, 05/03/00
* @author David Connelly
*/
public
class CRC32 implements Checksum {
private int crc;
/*
* Loads the ZLIB library.
*/
private static native void init();
static {
java.security.AccessController.doPrivileged(
new sun.security.action.LoadLibraryAction("zip"));
/* Work-around for Symbian tool bug. No longer needed. */
init();
}
/**
* Creates a new CRC32 object.
*/
public CRC32() {
}
/**
* Updates CRC-32 with specified byte.
*/
public void update(int b) {
crc = update(crc, b);
}
/**
* Updates CRC-32 with 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 checksum with 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);
}