aluctrl.vhd

关于C++编程方向的一些经验

-- aluctrl.vhd

-- This circuit generates control signal for the ALU so that ALU can execute 
-- different operations.

-- Inputs: 
--    ALUop    - 4-bit Select for ALU operation
--    Func     - 3-bit Select for ALU operation

-- Outputs: 
--    ALUcs    - 4-bit control signal for ALU

-- Author:    Easyright
-- E-mail:    [e-mail]
-- Date:      27-08-2003
-- Copyright: http://www.EasyRight.net

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library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity aluctrl is
  port (
    ALUop:    in std_logic_vector(3 downto 0);
    Func:     in std_logic_vector(2 downto 0);
    ALUcs:    out std_logic_vector(3 downto 0)
  );
end aluctrl;

architecture arc_aluctrl of aluctrl is
begin
  process(ALUop, Func)
  begin
    if (ALUop(3)='1' and ALUop(2)='0') then  -- beqz
      ALUcs <= "0001";
    elsif (ALUop(3)='1' and ALUop(2)='1') then  -- lw, sw
      ALUcs <= "0011";
    elsif ALUop(3)='0' then  -- test and arithmetic
      ALUcs(3) <= not ALUop(0);
      ALUcs(2) <= Func(2);
      ALUcs(1) <= Func(1);
      ALUcs(0) <= Func(0);
    end if;
  end process;
end arc_aluctrl;