- /*
- * @(#)Adler32.java 1.22 00/02/02
- *
- * Copyright 1996-2000 Sun Microsystems, Inc. All Rights Reserved.
- *
- * This software is the proprietary information of Sun Microsystems, Inc.
- * Use is subject to license terms.
- *
- */
-
- 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
- * @version 1.22, 02/02/00
- * @author David Connelly
- */
- public
- class Adler32 implements Checksum {
- private int adler = 1;
-
- /*
- * Loads the ZLIB library.
- */
- static {
- java.security.AccessController.doPrivileged(
- new sun.security.action.LoadLibraryAction("zip"));
- }
-
- /**
- * Creates a new Adler32 class.
- */
- public Adler32() {
- }
-
-
- /**
- * Updates checksum with specified byte.
- *
- * @param b an array of bytes
- */
- public void update(int b) {
- adler = update(adler, b);
- }
-
- /**
- * Updates checksum 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 + len > b.length) {
- throw new ArrayIndexOutOfBoundsException();
- }
- adler = updateBytes(adler, b, off, len);
- }
-
- /**
- * Updates checksum with specified array of bytes.
- */
- public void update(byte[] b) {
- adler = updateBytes(adler, b, 0, b.length);
- }
-
- /**
- * Resets checksum to initial value.
- */
- public void reset() {
- adler = 1;
- }
-
- /**
- * Returns 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);
- }