| /* |
| * Copyright 1996-2005 Sun Microsystems, Inc. All Rights Reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code 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. Sun designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Sun in the LICENSE file that accompanied this code. |
| * |
| * This code 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 in the LICENSE file that |
| * accompanied this code). |
| * |
| * 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 USA 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 |
| * @author David Connelly |
| */ |
| public |
| class CRC32 implements Checksum { |
| private int crc; |
| |
| /** |
| * 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); |
| } |