/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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.apache.myfaces.util;

 /**

  * A simple XORShift Random generator.

  * This class is NOT synchronized, you need to do that yourself if needed!

  */

 public class XorShiftRandom

 {

     private long value;

     public XorShiftRandom( long initialSeed )

     {

         value = initialSeed;

     }

     /**

      * Calculate a random value based on the previous value stored in this instance.

      * If you use this method in a concurring way, you need to synchronize the access!

      * @return

      */

     public long random()

     {

         value = random(value);

         return value;

     }

     /**

      * Calculate a random value based on the given start Value.

      * @param randomStart the start value. Usually the result of the previous invocation

      * @return the new random value.

      */

     public static long random(final long randomStart)

     {

         long randomValue = randomStart;

         randomValue ^= (randomValue << 21);

         randomValue ^= (randomValue >>> 35);

         randomValue ^= (randomValue << 4);

         return randomValue;

     }

 }