Subversion Repositories xucpu

-- Copyright 2015, Jürgen Defurne

--

-- This file is part of the Experimental Unstable CPU System.

--

-- The Experimental Unstable CPU System Is free software: you can redistribute

-- it and/or modify it under the terms of the GNU Lesser General Public License

-- as published by the Free Software Foundation, either version 3 of the

-- License, or (at your option) any later version.

--

-- The Experimental Unstable CPU System is distributed in the hope that it will

-- be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of

-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser

-- General Public License for more details.

--

-- You should have received a copy of the GNU Lesser General Public License

-- along with Experimental Unstable CPU System. If not, see

-- http://www.gnu.org/licenses/lgpl.txt.

LIBRARY ieee;

USE ieee.std_logic_1164.ALL;

USE ieee.numeric_std.ALL;

ENTITY ALU IS

  PORT (

    I1 : IN  STD_LOGIC_VECTOR(7 DOWNTO 0);

    I2 : IN  STD_LOGIC_VECTOR(7 DOWNTO 0);

    R1 : OUT STD_LOGIC_VECTOR(7 DOWNTO 0);

    F1 : IN  STD_LOGIC_VECTOR(1 DOWNTO 0));

END ENTITY ALU;

ARCHITECTURE Behavioral OF ALU IS

BEGIN  -- ARCHITECTURE Behavioral

  PROCESS (I1, I2, F1)

  BEGIN

    CASE F1 IS

      WHEN "00" =>

        R1 <= "00000000";

      WHEN "01" =>

        R1 <= STD_LOGIC_VECTOR(UNSIGNED(I1) + UNSIGNED(I2));

      WHEN "10" =>

        R1 <= STD_LOGIC_VECTOR(UNSIGNED(I1) + 1);

      WHEN "11" =>

        R1 <= "11111111";

      WHEN OTHERS

        => NULL;

    END CASE;

  END PROCESS;

END ARCHITECTURE Behavioral;