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-- 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;

-- Uncomment the following library declaration if using

-- arithmetic functions with Signed or Unsigned values

--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating

-- any Xilinx primitives in this code.

--library UNISIM;

--use UNISIM.VComponents.all;

ENTITY decoder IS

  PORT (address : IN  STD_LOGIC_VECTOR (14 DOWNTO 0);

        device  : OUT STD_LOGIC_VECTOR(7 DOWNTO 0);

        bussel  : OUT STD_LOGIC_VECTOR(7 DOWNTO 0));

END decoder;

ARCHITECTURE Behavioral OF decoder IS

BEGIN

  -- purpose: Decode the address to control devices

  -- type   : combinational

  -- inputs : address

  -- outputs: 

  decode : PROCESS (address)

  BEGIN  -- PROCESS decode

    CASE address IS

      WHEN "111111111110000" =>

        device <= "00000001";

        bussel <= "00000001";

      WHEN "111111111110001" =>

        device <= "00000010";

        bussel <= "00000010";

      WHEN "111111111110010" =>

        device <= "00000100";

        bussel <= "00000100";

      WHEN "111111111110011" =>

        device <= "00001000";

        bussel <= "00001000";

      WHEN OTHERS =>

        device <= "00000000";

        bussel <= "00010000";

    END CASE;

  END PROCESS decode;

END Behavioral;