process(clk,wren)
begin
IF wren='0' THEN state<=st0;wen<='1';dout<=“ZZZZZZZZ”;
elsif rising_edge(clk)then
case state is
when st0=> state<=st1;
when st1=> state<=st2; addrout<=addrl; dout<=data;
when st2=> state<=st3; wen<='0';
when st3=> state<=st4;
when st4=> state<=st5;
when st5=> state<=st6; wen<='1';
when st6=> state<=st7;
when st7=> state<=st7;
when others => state<=st0;
end case;
end if;
end process;
该进程中这样引入三态门是不正确的，但小弟实在不知道在这个进程中该怎样引入三态？
