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/*
 * Copyright @ 2015 Atlassian Pty Ltd
 *
 * 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 org.jitsi.impl.neomedia;

/**
 * Implements a circular byte array.
 *
 * @author Lyubomir Marinov
 */
public class CircularByteArray
{
    /**
     * The elements of this CircularByteArray.
     */
    private final byte[] elements;

    /**
     * The index at which the next invocation of {@link #push(byte)} is to
     * insert an element.
     */
    private int tail;

    /**
     * Initializes a new CircularBufferArray instance with a specific
     * length.
     *
     * @param length the length i.e. the number of elements of the new instance
     */
    public CircularByteArray(int length)
    {
        elements = new byte[length];
        tail = 0;
    }

    /**
     * Adds a specific element at the end of this CircularByteArray.
     *
     * @param element the element to add at the end of this
     * CircularByteArray
     */
    public synchronized void push(byte element)
    {
        int tail = this.tail;

        elements[tail] = element;
        tail++;
        if (tail >= elements.length)
            tail = 0;
        this.tail = tail;
    }

    /**
     * Copies the elements of this CircularByteArray into a new
     * byte array.
     *
     * @return a new byte array which contains the same elements and in
     * the same order as this CircularByteArray
     */
    public synchronized byte[] toArray()
    {
        byte[] elements = this.elements;
        byte[] array;

        if (elements == null)
        {
            array = null;
        }
        else
        {
            array = new byte[elements.length];
            for (int i = 0, index = tail; i < elements.length; i++)
            {
                array[i] = elements[index];
                index++;
                if (index >= elements.length)
                    index = 0;
            }
        }
        return array;
    }
}