if (x->tavl_tag[0] == TAVL_CHILD) y->tavl_link[1] = x->tavl_link[0]; else { y->tavl_tag[1] = TAVL_THREAD; x->tavl_tag[0] = TAVL_CHILD; } x->tavl_link[0] = y; y->tavl_balance = x->tavl_balance = 0;