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TrueZIP is a Java based Virtual File System (VFS) to enable transparent, multi-threaded read/write access to archive files (ZIP, TAR etc.) as if they were directories. Archive files may be arbitrarily nested and the nesting level is only limited by heap and file system size.

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/*
 * Copyright (C) 2005-2010 Schlichtherle IT Services
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.schlichtherle.util;

/**
 * @author Christian Schlichtherle
 * @version $Id$
 */
public class Arrays {

    /**
     * Compares {@code max} bytes at the specified offsets of the given
     * arrays.
     * If the remaining bytes at the given offset of any array is smaller than
     * {@code max} bytes, it must match the number of remaining bytes at the
     * given offset in the other array.
     */
    public static boolean equals(
            final byte[] b1,
            final int b1off,
            final byte[] b2,
            final int b2off,
            int max) {
        if (b1 == null)
            throw new NullPointerException("b1");
        if (b2 == null)
            throw new NullPointerException("b2");
        if (0 > b1off || b1off > b1.length)
            throw new IndexOutOfBoundsException("b1off = " + b1off + ": not in [0, " + b1.length + "[!");
        if (0 > b2off || b2off > b2.length)
            throw new IndexOutOfBoundsException("b2off = " + b2off + ": not in [0, " + b2.length + "[!");
        if (max < 1)
            throw new IllegalArgumentException("len = " + max + ": too small");

        final int b1rem = b1.length - b1off;
        final int b2rem = b2.length - b2off;
        if (max > b1rem) {
            max = b1rem;
            if (max != b2rem)
                return false;
        } else if (max > b2rem) {
            max = b2rem;
            if (max != b1rem)
                return false;
        }

        while (--max >= 0)
            if (b1[b1off + max] != b2[b2off + max])
                return false;

        return true;
    }
    
    protected Arrays() {
    }
}