private void setSuccessor(int entry, int succ) {
    requireSuccessors()[entry] = succ + 1;
  }

  private void setPredecessor(int entry, int pred) {
    requirePredecessors()[entry] = pred + 1;
  }

  private void setSucceeds(int pred, int succ) {
    if (pred == ENDPOINT) {
      firstEntry = succ;
    } else {
      setSuccessor(pred, succ);
    }

    if (succ == ENDPOINT) {
      lastEntry = pred;

  }

  private void setSuccessor(int entry, int succ) {
    long succMask = (~0L) >>> 32;
    links[entry] = (links[entry] & ~succMask) | (succ & succMask);
  }

  private void setPredecessor(int entry, int pred) {
    long predMask = (~0L) << 32;
    links[entry] = (links[entry] & ~predMask) | ((long) pred << 32);
  }

  private void setSucceeds(int pred, int succ) {
    if (pred == ENDPOINT) {