| /* |
| * Copyright (c) 1996, 2005, Oracle and/or its affiliates. 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. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.util.zip; |
| |
| /** |
| * A class that can be used to compute the Adler-32 checksum of a data |
| * stream. An Adler-32 checksum is almost as reliable as a CRC-32 but |
| * can be computed much faster. |
| * |
| * @see Checksum |
| * @author David Connelly |
| */ |
| public |
| class Adler32 implements Checksum { |
| private int adler = 1; |
| |
| /** |
| * Creates a new Adler32 object. |
| */ |
| public Adler32() { |
| } |
| |
| /** |
| * Updates the 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) { |
| adler = update(adler, b); |
| } |
| |
| /** |
| * Updates the 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(); |
| } |
| adler = updateBytes(adler, b, off, len); |
| } |
| |
| /** |
| * Updates the checksum with the specified array of bytes. |
| * |
| * @param b the byte array to update the checksum with |
| */ |
| public void update(byte[] b) { |
| adler = updateBytes(adler, b, 0, b.length); |
| } |
| |
| /** |
| * Resets the checksum to initial value. |
| */ |
| public void reset() { |
| adler = 1; |
| } |
| |
| /** |
| * Returns the checksum value. |
| */ |
| public long getValue() { |
| return (long)adler & 0xffffffffL; |
| } |
| |
| private native static int update(int adler, int b); |
| private native static int updateBytes(int adler, byte[] b, int off, |
| int len); |
| } |