-- Albert Coba 1727
  -- Shawn Nematbakhsh 8551			
  
  -- cs161 proj2: Datapath:
  -- a MIPS control
  
-- this is the ALU control file, it recieves the ALUop signal and the
-- opcode from the control and then sends the necessary signals
-- to the ALU to do the correct operation.
 
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_arith.all;

entity ALUControl is
    port(
	alu_op : in std_logic_vector( 1 downto 0 );
   	ins_5_0   : in std_logic_vector( 5 downto 0 );
    alu_control : out std_logic_vector( 2 downto 0 )
);
    
end ALUControl;

architecture bhv of ALUControl is

begin
	process(alu_op)
	begin
		case alu_op is
			-- when 00 or 01, opcode doesn't matter
			when "00" => alu_control <= "010";
			when "01" => alu_control <= "110";
			when others =>
			
			-- when 10, send different signal depending on opcode
			case ins_5_0(3 downto 0) is
				when "0000" => alu_control <= "010";
				when "0010" => alu_control <= "110";
				when "0100" => alu_control <= "000";
				when "0101" => alu_control <= "001";
				when "1010" => alu_control <= "111";
				when others =>
			end case;
		end case;
	end process;
end bhv;