/*
* @(#)$Id$
*
* Copyright 2006-2008 Makoto YUI
*
* 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.
*
* Contributors:
* Makoto YUI - initial implementation
*/
//package xbird.util.concurrent.lang;
import java.util.concurrent.atomic.AtomicInteger;
/**
*
* <DIV lang="en"></DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI ([email protected])
*/
public final class AtomicPseudoRandom {
private final AtomicInteger seed;
public AtomicPseudoRandom() {
this((int) System.nanoTime());
}
public AtomicPseudoRandom(int seed) {
this.seed = new AtomicInteger(seed);
}
public int nextInt(int n) {
while(true) {
int s = seed.get();
int nextSeed = calculateNext(s);
if(seed.compareAndSet(s, nextSeed)) {
int remainder = s % n;
return remainder > 0 ? remainder : remainder + n;
}
}
}
private int calculateNext(int s) {
s ^= s << 6;
s ^= s >>> 21;
s ^= (s << 7);
return s;
}
}
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