Subversion Repositories tinycpu

LIBRARY ieee;

USE ieee.std_logic_1164.ALL;

USE ieee.numeric_std.ALL;

ENTITY registerfile_tb IS

END registerfile_tb;

ARCHITECTURE behavior OF registerfile_tb IS

-- Component Declaration for the Unit Under Test (UUT)

  component registerfile

    port(

      Write:in std_logic_vector(7 downto 0); --what should be put into the write register

      SelRead:in std_logic_vector(2 downto 0); --select which register to read

      SelWrite:in std_logic_vector(2 downto 0); --select which register to write

      UseWrite:in std_logic; --if the register should actually be written to

      Clock:in std_logic;

      Read:out std_logic_vector(7 downto 0) --register to be read output

    );

  end component;

  --Inputs

  signal Write : std_logic_vector(7 downto 0) := (others => '0');

  signal SelRead: std_logic_vector(2 downto 0) := (others => '0');

  signal SelWrite: std_logic_vector(2 downto 0) := (others => '0');

  signal UseWrite: std_logic := '0';

  --Outputs

  signal Read : std_logic_vector(7 downto 0);

  signal Clock: std_logic;

  constant clock_period : time := 10 ns;

BEGIN

  -- Instantiate the Unit Under Test (UUT)

  uut: registerfile PORT MAP (

    Write => Write,

    SelRead => SelRead,

    SelWrite => SelWrite,

    UseWrite => UseWrite,

    Clock => Clock,

    Read => Read

  );

  -- Clock process definitions

  clock_process :process

  begin

    Clock <= '0';

    wait for clock_period/2;

    Clock <= '1';

    wait for clock_period/2;

  end process;

  -- Stimulus process

  stim_proc: process

    variable err_cnt: integer :=0;

  begin

    -- hold reset state for 100 ns.

    wait for 100 ns;

    wait for clock_period*10;

    -- case 1

    SelWrite <= "000";

    Write <= "11110000";

    UseWrite <= '1';

    wait for 10 ns;

    SelRead <= "000";

    UseWrite <= '0';

    wait for 10 ns;

    assert (Read="11110000") report "Storage error case 1" severity error;

    if (Read/="11110000") then

        err_cnt:=err_cnt+1;

    end if;

    -- case 2

    SelWrite <= "100";

    Write <= "11110001";

    UseWrite <= '1';

    wait for 10 ns;

    SelRead <= "100";

    UseWrite <= '0';

    wait for 10 ns;

    assert (Read="11110001") report "Storage selector error case 2" severity error;

    if (Read/="11110001") then

        err_cnt:=err_cnt+1;

    end if;

    -- case 3

    SelRead <= "000";

    UseWrite <= '0';

    wait for 10 ns;

    assert (Read="11110000") report "Storage selector(remembering) error case 3" severity error;

    if (Read/="11110000") then

        err_cnt:=err_cnt+1;

    end if;

    -- summary of testbench

    if (err_cnt=0) then

      assert false

      report "Testbench of registerfile completed successfully!"

      severity note;

    else

      assert true

      report "Something wrong, try again"

      severity error;

    end if;

    wait;

    -- insert stimulus here 

    wait;

  end process;

END;