code: public void
  restoreActive(int pos) {
  	if (pos > byteBuffer.capacity()) {
  		throw new IllegalArgumentException("cannot set active " +
  						   "region past end of input");
  	}
  	byteBuffer.limit(byteBuffer.position());
  }
docs: Restores the previously set active region.  This differs from setActive() in
  that restoreActive() takes an absolute position, and setActive takes an
  offset from the current location.
  @param pos The end of the active region.