package com.vaadin.tests.util;
import java.util.concurrent.atomic.AtomicLong;
public class PortableRandom {
private final static long multiplier = 0x5DEECE66DL;
private final static long addend = 0xBL;
private final static long mask = (1L << 48) - 1;
private AtomicLong seed;
public PortableRandom(long seed) {
this.seed = new AtomicLong(0L);
setSeed(seed);
}
synchronized public void setSeed(long seed) {
seed = (seed ^ multiplier) & mask;
this.seed.set(seed);
}
public int nextInt(int n) {
if (n <= 0) {
throw new IllegalArgumentException("n must be positive");
}
if ((n & -n) == n) {
return (int) ((n * (long) next(31)) >> 31);
}
int bits, val;
do {
bits = next(31);
val = bits % n;
} while (bits - val + (n - 1) < 0);
return val;
}
protected int next(int bits) {
long oldseed, nextseed;
AtomicLong seed = this.seed;
do {
oldseed = seed.get();
nextseed = (oldseed * multiplier + addend) & mask;
} while (!seed.compareAndSet(oldseed, nextseed));
return (int) (nextseed >>> (48 - bits));
}
public boolean nextBoolean() {
return next(1) != 0;
}
}