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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.
Author:
     David Connelly
See Also:
Checksum/**
 * 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.
/**
     * Creates a new Adler32 object.
     */
    public Adler32() {
    }


    
Updates checksum with specified byte.
Params:
b – an array of bytes/**
     * 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.
/**
     * 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 > b.length - len) {
            throw new ArrayIndexOutOfBoundsException();
        }
        adler = updateBytes(adler, b, off, len);
    }

    
Updates checksum with specified array of bytes.
/**
     * Updates checksum with specified array of bytes.
     */
    public void update(byte[] b) {
        adler = updateBytes(adler, b, 0, b.length);
    }

    
Resets checksum to initial value.
/**
     * Resets checksum to initial value.
     */
    public void reset() {
        adler = 1;
    }

    
Returns checksum value.
/**
     * 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);
}