Ok, here's a cleaner implementation. Look at test3, subtest3. Note
how we pingpong between states 3 & 5. Somehow that's either a
problem, or I'm missing something obvious....
Steve
Mutex.vhd
----------------------------------------------------------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use IEEE.NUMERIC_STD.all;
entity Mutex is port
(
clk : in std_logic;
reset : in std_logic;
HatfieldReq : in std_logic;
McCoyReq : in std_logic;
StateOut : out std_logic_vector(3 downto 0);
NextStateOut : out std_logic_vector(3 downto 0);
HatfieldGrant : out std_logic;
McCoyGrant : out std_logic--;
);
end Mutex;
architecture Behavioral of Mutex is
type states is
(
Check_Req,
Issue_HatfieldGrant, Wait4_HatfieldReqDone,
Issue_McCoyGrant, Wait4_McCoyReqDone
);
signal NextState : states;
signal CurrentState: states;
begin
Mutex_states : process(clk, reset, CurrentState, HatfieldReq, McCoyReq)
begin
if reset = '1' then
CurrentState <= Check_Req;
NextState <= Check_Req;
HatfieldGrant <= '0';
McCoyGrant <= '0';
StateOut <= x"0";
NextStateOut <= x"1";
elsif rising_edge(clk) then
CurrentState <= NextState;
case CurrentState is
when Check_Req =>
StateOut <= x"1";
--Just to be sure
HatfieldGrant <= '0';
McCoyGrant <= '0';
if HatfieldReq = '1' then
NextState <=
Issue_HatfieldGrant;
NextStateOut <= x"2";
else
if McCoyReq = '1' then
NextState <=
Issue_McCoyGrant;
NextStateOut <= x"4";
else
NextState <= Check_Req;
NextStateOut <= x"1";
end if;
end if;
-- Grant ARM access to resource
when Issue_HatfieldGrant =>
StateOut <= x"2";
NextStateOut <= x"3";
HatfieldGrant <= '1';
McCoyGrant <= '0';
NextState <= Wait4_HatfieldReqDone;
when Wait4_HatfieldReqDone =>
StateOut <= x"3";
if HatfieldReq = '1' then
NextState <=
Wait4_HatfieldReqDone;
NextStateOut <= x"3";
else
HatfieldGrant <= '0';
NextState <= Check_Req;
NextStateOut <= x"1";
end if;
-- End of ARM access
-- Grant PC access to resource
when Issue_McCoyGrant =>
StateOut <= x"4";
McCoyGrant <= '1';
HatfieldGrant <= '0';
NextState <= Wait4_McCoyReqDone;
NextStateOut <= x"5";
when Wait4_McCoyReqDone =>
StateOut <= x"5";
if McCoyReq = '1' then
NextState <= Wait4_McCoyReqDone;
NextStateOut <= x"5";
else
McCoyGrant <= '0';
NextState <= Check_Req;
NextStateOut <= x"1";
end if;
-- End of PC access
when others =>
StateOut <= x"F";
NextState <= Check_Req;
end case;
end if;
end process Mutex_states;
end Behavioral;
Mutex_tb.vhd
--------------------------------------------------------------------------------
LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE ieee.std_logic_unsigned.all;
USE ieee.numeric_std.ALL;
ENTITY Mutex_tb IS
END Mutex_tb;
ARCHITECTURE behavior OF Mutex_tb IS
-- Component Declaration for the Unit Under Test (UUT)
COMPONENT Mutex
PORT(
HatfieldReq : IN std_logic;
McCoyReq : IN std_logic;
StateOut : out std_logic_vector(3 downto 0);
NextStateOut : out std_logic_vector(3 downto 0);
HatfieldGrant : OUT std_logic;
McCoyGrant : OUT std_logic;
clk : IN std_logic;
reset : IN std_logic
);
END COMPONENT;
--Inputs
signal HatfieldReq : std_logic := '0';
signal McCoyReq : std_logic := '0';
signal clk : std_logic := '0';
signal reset : std_logic := '0';
--Outputs
signal HatfieldGrant : std_logic;
signal McCoyGrant : std_logic;
-- Clock period definitions
constant clk_period : time := 21 ns;
--Info
signal State : std_logic_vector(3 downto 0);
signal NextState : std_logic_vector(3 downto 0);
signal Testnum : std_logic_vector(3 downto 0);
signal SubTestnum : std_logic_vector(3 downto 0);
BEGIN
-- Instantiate the Unit Under Test (UUT)
uut: Mutex PORT MAP (
HatfieldReq => HatfieldReq,
McCoyReq => McCoyReq,
StateOut => State,
NextStateOut => NextState,
HatfieldGrant => HatfieldGrant,
McCoyGrant => McCoyGrant,
clk => clk,
reset => reset
);
-- Clock process definitions
clk_process :process
begin
clk <= '0';
wait for clk_period/2;
clk <= '1';
wait for clk_period/2;
end process;
-- Stimulus process
stim_proc: process
begin
-- hold reset state for 100ms.
wait for 10 ns;
wait for clk_period*10;
Testnum <= x"0";
SubTestnum <= x"0";
reset <= '1';
HatfieldReq <= '0';
McCoyReq <= '0';
wait for clk_period*10;
reset <= '0';
wait for 10 us;
--Slow
Testnum <= x"1";
SubTestnum <= x"0";
SubTestnum <= x"0";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
HatfieldReq <= '1';
McCoyReq <= '0';
wait for 999 ns;
SubTestnum <= x"1";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
HatfieldReq <= '0';
McCoyReq <= '1';
wait for 999 ns;
SubTestnum <= x"2";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
HatfieldReq <= '1';
McCoyReq <= '1';
wait for 999 ns;
--Fast
Testnum <= x"2";
SubTestnum <= x"0";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 10 us;
SubTestnum <= x"0";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for clk_period;
HatfieldReq <= '1';
McCoyReq <= '0';
wait for clk_period;
SubTestnum <= x"1";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for clk_period;
HatfieldReq <= '0';
McCoyReq <= '1';
wait for clk_period;
SubTestnum <= x"2";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for clk_period;
HatfieldReq <= '1';
McCoyReq <= '1';
wait for clk_period;
--Staggered
Testnum <= x"3";
SubTestnum <= x"0";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 10 us;
SubTestnum <= x"0";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
HatfieldReq <= '1';
wait for clk_period;
McCoyReq <= '0';
wait for 999 ns;
SubTestnum <= x"1";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
HatfieldReq <= '0';
wait for clk_period;
McCoyReq <= '1';
wait for 999 ns;
SubTestnum <= x"2";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
HatfieldReq <= '1';
wait for clk_period;
McCoyReq <= '1';
wait for 999 ns;
SubTestnum <= x"3";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
McCoyReq <= '1';
wait for clk_period;
HatfieldReq <= '1';
wait for 999 ns;
--Switched
Testnum <= x"4";
SubTestnum <= x"0";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 10 us;
SubTestnum <= x"0";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
McCoyReq <= '1';
wait for clk_period;
HatfieldReq <= '1';
wait for clk_period;
McCoyReq <= '0';
wait for 999 ns;
SubTestnum <= x"1";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 999 ns;
HatfieldReq <= '1';
wait for clk_period;
McCoyReq <= '1';
wait for clk_period;
HatfieldReq <= '0';
wait for 999 ns;
--Nuts
Testnum <= x"5";
SubTestnum <= x"0";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for 10 us;
SubTestnum <= x"0";
HatfieldReq <= '1';
McCoyReq <= '1';
wait for clk_period;
SubTestnum <= x"1";
HatfieldReq <= '0';
McCoyReq <= '1';
wait for clk_period;
SubTestnum <= x"2";
HatfieldReq <= '1';
McCoyReq <= '0';
wait for clk_period;
SubTestnum <= x"3";
HatfieldReq <= '1';
McCoyReq <= '1';
wait for clk_period;
SubTestnum <= x"4";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for clk_period;
SubTestnum <= x"5";
HatfieldReq <= '1';
McCoyReq <= '0';
wait for clk_period;
SubTestnum <= x"6";
HatfieldReq <= '1';
McCoyReq <= '1';
wait for clk_period;
SubTestnum <= x"7";
HatfieldReq <= '0';
McCoyReq <= '1';
wait for clk_period;
SubTestnum <= x"8";
HatfieldReq <= '1';
McCoyReq <= '1';
wait for clk_period;
SubTestnum <= x"9";
HatfieldReq <= '0';
McCoyReq <= '0';
wait for clk_period;
wait for 999 ns;
wait;
end process;
END;
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