int result = getSuccessor(index);
    return (result == ENDPOINT) ? -1 : result;
  }

  @Override
  int nextIndexAfterRemove(int oldNextIndex, int removedIndex) {
    return (oldNextIndex == size()) ? removedIndex : oldNextIndex;
  }

  private int getPredecessor(int entry) {
    return (int) (links[entry] >>> 32);
  }

  private int getSuccessor(int entry) {
    return (int) links[entry];

   */

  private int getPredecessor(int entry) {
    return requirePredecessors()[entry] - 1;
  }

  @Override
  int getSuccessor(int entry) {
    return requireSuccessors()[entry] - 1;
  }

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

  private void setPredecessor(int entry, int pred) {