检查没错误,但是功能仿真有结果,时序仿真没有结果
求大神教
代码如下:
library ieee;
use ieee.std_logic_1164.all;
entity Sell is
port ( clk,rst:in std_logic;--clk
A,B: in std_logic;
Y,Z:out std_logic);
end Sell;
architecture struct of Sell is
type state is (S0,S1,S2,S3);
signal S:state;
signal M:std_logic_vector(1 downto 0);
begin
M<=A&B;
process (clk,rst,M)
begin
if rst='1' then
S<=S0;
elsif (clk'event and clk='1') then
case S is
when S0 =>
if (M="01") then
S<=S1;
Y<='0';Z<='0';
elsif (M="10") then
S<=S2;
Y<='0';Z<='0';
else
S<=S;
Y<='0';Z<='0';
end if;
when S1 =>
if (M="01") then
S<=S2;
Y<='0';Z<='0';
elsif (M="10") then
S<=S0;
Y<='1';Z<='0';
else
S<=S;
end if;
when S2 =>
if (M="01") then
S<=S0;
Y<='1';Z<='0';
elsif (M="10") then
S<=S0;
Y<='1';Z<='1';
else
S<=S;
end if;
when others =>
S<=S0;
end case;
end if;
end process;
end struct;