米勒型状态机.vhd

含有各类寄存器

--Mealy State Machine with Registered Outputs
library ieee;
use ieee.std_logic_1164.all;
entity mealy1 is port(
                 clk, rst: in std_logic;
                 id: in std_logic_vector(3 downto 0);
                  y: out std_logic_vector(1 downto 0));
end mealy1;
architecture archmealy of mealy1 is
type states is (state0, state1, state2, state3, state4);
signal state: states;
begin
moore: process (clk, rst)
begin
           if rst='1' then
              state <= state0;
            y <= "00";
        elsif (clk'event and clk='1') then
case state is
when state0 =>
          if id = x"3" then
            state <= state1;
           y <= "10";
           else
            state <= state0;
            y <= "00";
            end if;
 when state1 =>
           state <= state2;
           y <= "11";
when state2 =>
           if id = x"7" then
           state <= state3;
             y <= "10";
            else
            state <= state2;
            y <= "11";
         end if;
when state3 =>
            if id < x"7" then
            state <= state0;
               y <= "00";
             elsif id = x"9" then
             state <= state4;
                 y <= "11";
            else
                state <= state3;
                 y <= "10";
          end if;
when state4 =>
               if id = x"b" then
                 state <= state0;
                     y <= "00";
                else
                 state <= state4;
                  y <= "11";
                    end if;
                end case;
                end if;
               end process;
end archmealy;