}

  /** repeated weakCompareAndSet succeeds in changing value when equal to expected */
  public void testWeakCompareAndSet() {
    double prev = Math.E;
    double unused = Math.E + Math.PI;
    AtomicDouble at = new AtomicDouble(prev);
    for (double x : VALUES) {
      assertBitEquals(prev, at.get());
      assertFalse(at.weakCompareAndSet(unused, x));
      assertBitEquals(prev, at.get());

      double unused = Math.E + Math.PI;
      for (double x : VALUES) {
        assertBitEquals(prev, aa.get(i));
        assertFalse(aa.weakCompareAndSet(i, unused, x));
        assertBitEquals(prev, aa.get(i));
        while (!aa.weakCompareAndSet(i, prev, x)) {
          ;
        }
        assertBitEquals(x, aa.get(i));
        prev = x;
      }
    }
  }