-- in architecture --

type ctrl_state is (Halted, S_01, S_02, S_03, S_04, S_05, S_06, S_07, S_08, S_09,S_10,S_11,S_12,
 Pause_0,Pause_1);
signal State, Next_state : ctrl_state;

begin

Assign_Next_State : process (clk, reset)
begin
  if (Reset = '1') then
    State <= Halted;
  elsif (rising_edge(clk)) then
    State <= Next_State;
  end if;
end process;
Get_Next_State : process (State, Opcode, Run, Continue)
begin
  case State is
    when Halted => 
      if (run = '0') then
        Next_state <= Halted;
      else
        Next_state <= S_18;
      end if;
    when S_18 =>
      Next_state <= S_33;
    when S_33 =>
      Next_state <= S_35;
    when S_35 =>
      Next_state <= S_32;

    when S_32 =>
      case Opcode is
        when "0001" => -- ADD
          Next_state <= S_01;

		  when "0101" => -- AND

		    Next_state <= S_02;

		  when "1001" => -- NOT

		    Next_state <= S_03;

		  when "0000" => -- BR

		    Next_state <= S_04;

		  when "1100" => -- JMP

		    Next_state <= S_05;

		  when "0100" => -- JSR

		    Next_state <= S_06;

		  when "0110" => -- LDR

		    Next_state <= S_07;

		  when "0111" => -- STR

		    Next_state <= S_10;

		  when "1101" => -- Pause

		    Next_state <= Pause_0;
        when others =>
          Next_state <= S_18;
      end case;
    when S_01 =>
      Next_state <= S_18;

	 when S_02 =>
      Next_state <= S_18;

	 when S_03 =>
      Next_state <= S_18;

	 when S_04 =>
      Next_state <= S_18;

	 when S_05 =>
      Next_state <= S_18;

	 when S_06 =>
      Next_state <= S_18;

	 when S_07 => -- Continue LDR
		Next_state <= S_08;
	 when S_08 => -- Continue LDR
		Next_state <= S_09;

	 when S_09 =>
      Next_state <= S_18;
	 when S_10 => -- Continue STR
		Next_state <= S_11;
	 when S_11 => -- Continue STR
		Next_state <= S_12;

	 when S_12 =>
      Next_state <= S_18;

	 when Pause_0 =>

		if (Continue = '0') then

			Next_state <= Pause_1;

		else

			Next_state <= Pause_0;

		end if;

	 when Pause_1 =>

		if (Continue = '1') then

			Next_state <= S_18; --Done w/ pause

		else

			Next_state <= Pause_1;

		end if;
    when others =>
      NULL;
  end case;
end process;