-------------------------------------------------------------------------------
--  EE126 Project #1, part I Testbench
--  by: Frank Bruno
-------------------------------------------------------------------------------

ENTITY test_alu_1 IS
  
END test_alu_1;

ARCHITECTURE b_alu_1 OF test_alu_1 IS
  COMPONENT alu_1
  PORT(opcode       : IN    bit_vector(2 DOWNTO 0);
       a            : IN    bit;
       b            : IN    bit;
       cin          : IN    bit;
       clock        : IN    bit;
       s            : OUT   bit;
       cout         : OUT   bit);
  END COMPONENT;
  
  SIGNAL opcode : bit_vector(2 DOWNTO 0);
  SIGNAL a : bit;
  SIGNAL b : bit;
  SIGNAL cin : bit;
  SIGNAL s : bit;
  SIGNAL cout : bit;
  SIGNAL clock : bit;
BEGIN  --  b_alu_1
  u1: alu_1
  PORT MAP(opcode => opcode,
           a => a,
           b => b,
           cin => cin,
           clock => clock,
           s => s,
           cout => cout);

clock_gen:
PROCESS
  BEGIN
    clock <= '0' AFTER 40 ns;
    WAIT FOR 40 ns;
    clock <= '1' AFTER 40 ns;
    WAIT FOR 40 ns;
END PROCESS;

PROCESS
  VARIABLE state : integer := 0;
  VARIABLE jump : integer;
  
  BEGIN
    WAIT UNTIL clock'EVENT AND clock ='1';
    CASE state IS
      WHEN 0 =>
        a <= '0';
        b <= '0';
        cin <= '0';
        jump := 1;
        state := 1;
      WHEN 1 => 
        opcode <= "000";
        state := 2;
      WHEN 2 =>
        opcode <= "001";
        state := 3;
      WHEN 3 =>
        opcode <= "010";
        state := 4;
      WHEN 4 =>
        opcode <= "011";
        state := 5;
      WHEN 5 =>
        opcode <= "100";
        state := 6;
      WHEN 6 =>
        opcode <= "101";
        state := 7;
      WHEN 7 =>
        opcode <= "110";
        state := 8;
      WHEN 8 =>
        opcode <= "111";
        state := (8 + jump);
      WHEN 9 =>
        a <= '0';
        b <= '0';
        cin  <= '1';
        jump := 2;
        state := 1;
      WHEN 10 =>
        a <= '0';
        b <= '1';
        cin <= '0';
        jump := 3;
        state := 1;
      WHEN 11 =>
        cin <= '1';
        jump := 4;
        state := 1;
      WHEN 12 =>
        a <= '1';
        b <= '0';
        cin <= '0';
        jump := 5;
        state := 1;
      WHEN 13 =>
        cin <= '1';
        jump := 6;
        state := 1;
      WHEN 15 =>
        b <= '1';
        cin <= '0';
        jump := 7;
        state := 1;
      WHEN 16 =>
        cin <= '1';
        jump := 8;
        state := 1;
        
      WHEN OTHERS =>
    END CASE;
END PROCESS;

END b_alu_1;

CONFIGURATION config1 OF test_alu_1 IS
FOR b_alu_1
  FOR u1: alu_1
    USE ENTITY work.alu_1;
  END FOR;
END FOR;
END config1;

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