-- Copyright (C) 2002 Morgan Kaufmann Publishers, Inc

-- This file is part of VESTs (Vhdl tESTs).

-- VESTs is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at
-- your option) any later version. 

-- VESTs 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 General Public License
-- for more details. 

-- You should have received a copy of the GNU General Public License
-- along with VESTs; if not, write to the Free Software Foundation,
-- Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

-- not in book

library ieee_proposed;  use ieee_proposed.electrical_systems.all;

package transmission_lines_types is

  type word is array (0 to 31) of bit;

  subtype bus_lines is integer range 0 to 31;
  nature electrical_bus is array (bus_lines) of electrical;

end package transmission_lines_types;



library ieee_proposed;  use ieee_proposed.electrical_systems.all;

use work.transmission_lines_types.all;

-- end not in book

entity transmission_lines is
  port ( terminal data_bus : electrical_bus;
         signal clk : in bit;  signal data_out : out word );
end entity transmission_lines;

----------------------------------------------------------------

architecture abstract of transmission_lines is
  constant threshold : voltage := 1.5;
  quantity bus_voltages across bus_currents through
           data_bus to electrical_ref;
begin
  
  logic_value_maps : process (clk) is
  begin
    if clk = '1' then
      for index in bus_lines loop
        if bus_voltages(index) > threshold then
          data_out(index) <= '1';
        else
          data_out(index) <= '0';
        end if;
      end loop;
    end if;
  end process logic_value_maps;
  
  -- additional VHDL-AMS code to describe reflections and attenuation
  -- ...
  
end architecture abstract;