w = x;
if (x->rtavl_link[0] == NULL)
  {
    y->rtavl_rtag = RTAVL_THREAD;
    y->rtavl_link[1] = x;
  }
else
  y->rtavl_link[1] = x->rtavl_link[0];
x->rtavl_link[0] = y;
x->rtavl_balance = y->rtavl_balance = 0;