/** repeated weakCompareAndSet succeeds in changing values when equal to expected */
  public void testWeakCompareAndSet() {
    int[] mark = new int[1];
    AtomicStampedReference ai = new AtomicStampedReference(one, 0);
    assertSame(one, ai.get(mark));
    assertEquals(0, ai.getStamp());
    assertEquals(0, mark[0]);

    do {} while (!ai.weakCompareAndSet(one, two, 0, 0));
    assertSame(two, ai.get(mark));
    assertEquals(0, mark[0]);

    do {} while (!ai.weakCompareAndSet(two, m3, 0, 1));
    assertSame(m3, ai.get(mark));
    assertEquals(1, mark[0]);
  }