CompSel.vhd

------------------------------------------------------------------------
--  CompSel.vhd -- Component Selector
------------------------------------------------------------------------
--  Author : Mircea Dabacan
--           Copyright 2004 Digilent, Inc.
------------------------------------------------------------------------
-- Software version: Xilinx ISE 6.2.03i
--                   WebPack
------------------------------------------------------------------------
-- This file decodes regEppAdrIn 
-- to generate "SELECT" signals named CS0_7, CS80_9F, CS8_F, CS10, CSB0. 
-- 	CS0_7 	is active (HIGH) whenever regEppAdrIn = "00000xxx".
-- 	CS8_F 	is active (HIGH) whenever regEppAdrIn = "00001xxx".
-- 	CS10 		is active (HIGH) whenever regEppAdrIn = "00010000".
--		CS80_9F 	is active (HIGH) whenever regEppAdrIn = "100xxxxx".
-- 	CSB0 		is active (HIGH) whenever regEppAdrIn = "10110000".
--
-- The selected component is assigned to the address range 0 to 7.
-- CompSel.vhd can be enhanced to select multiple components, 
-- with various address ranges assigned.
------------------------------------------------------------------------

-- Revision History:
-- 	10/21/2004(MirceaD): created
--		08/15/2007(TudorC):	added extra signals for the Nexys2 BIST (Xilinx ISE 9.2i)
------------------------------------------------------------------------

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity CompSel is
    Port (regEppAdrIn : in std_logic_vector(7 downto 0);
          CS80_9F : out std_logic;
          CS0_7 : out std_logic;
          CS8_F : out std_logic;
          CS10 : out std_logic;
          CSB0 : out std_logic
			 );
end CompSel;

architecture Behavioral of CompSel is

begin

 CS0_7 <= '1' when regEppAdrIn(7 downto 3) = "00000" else '0';
 CS8_F <= '1' when regEppAdrIn(7 downto 3) = "00001" else '0';
 CS10 <= '1' when regEppAdrIn = "00010000" else '0';
 CS80_9F <= '1' when regEppAdrIn(7 downto 5) = "100" else '0';
 CSB0 <= '1' when regEppAdrIn = "10110000" else '0';

end Behavioral;