jdk/src/share/classes/sun/security/util/ByteArrayTagOrder.java

/*
 * Copyright 1997-2006 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.
 */


/**
 * ByteArrayTagOrder: a class for comparing two DER encodings by the
 * order of their tags.
 *
 * @author D. N. Hoover
 */

package sun.security.util;

import java.util.Comparator;

public class ByteArrayTagOrder implements Comparator<byte[]> {

    /**
     * Compare two byte arrays, by the order of their tags,
     * as defined in ITU-T X.680, sec. 6.4.  (First compare
     *  tag classes, then tag numbers, ignoring the constructivity bit.)
     *
     * @param  bytes1 first byte array to compare.
     * @param  bytes2 second byte array to compare.
     * @return negative number if bytes1 < bytes2, 0 if bytes1 == bytes2,
     * positive number if bytes1 > bytes2.
     *
     * @exception <code>ClassCastException</code>
     * if either argument is not a byte array.
     */

    public final int compare(byte[] bytes1, byte[] bytes2) {
        // tag order is same as byte order ignoring any difference in
        // the constructivity bit (0x02)
        return (bytes1[0] | 0x20) - (bytes2[0] | 0x20);
    }


}