CristalCaveGem » LustreC » Lustrec-Tests

-- Copyright (C) 1996 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 

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

--

-- $Id: ch_05_fg_05_19.vhd,v 1.2 2001-10-26 16:29:34 paw Exp $

-- $Revision: 1.2 $

--

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

entity fg_05_19 is

end entity fg_05_19;

architecture test of fg_05_19 is

  constant scheduling_delay : delay_length := 5 ns;

  subtype request_type is natural range 0 to 20;

  type server_status_type is (ready, busy);

  signal first_priority_request,

    first_normal_request,

    reset_request : request_type := 0;

  signal functional_request, equivalent_request : request_type;

  signal priority_waiting : boolean := false;

  signal server_status : server_status_type := busy;

begin

  functional_scheduler : block is

                                 port ( request : out request_type );

                               port map ( request => functional_request );

  begin

    -- code from book

    scheduler :

      request <= first_priority_request after scheduling_delay

                 when priority_waiting and server_status = ready else

                 first_normal_request after scheduling_delay

                 when not priority_waiting and server_status = ready else

                 unaffected

                 when server_status = busy else

                 reset_request after scheduling_delay;

    -- end code from book

  end block functional_scheduler;

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

  equivalent_scheduler : block is

                                 port ( request : out request_type );

                               port map ( request => equivalent_request );

  begin

    -- code from book

    scheduler : process is

    begin

      if priority_waiting and server_status = ready then

        request <= first_priority_request after scheduling_delay;

      elsif not priority_waiting and server_status = ready then

        request <= first_normal_request after scheduling_delay;

      elsif server_status = busy then

        null;

      else

        request <= reset_request after scheduling_delay;

      end if;

      wait on first_priority_request, priority_waiting, server_status,

        first_normal_request, reset_request;

    end process scheduler;

    -- end code from book

  end block equivalent_scheduler;

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

  stimulus : process is

  begin

    first_priority_request <= 10;	wait for 20 ns;

    first_normal_request <= 5;		wait for 20 ns;

    server_status <= ready;		wait for 20 ns;

    server_status <= busy;		wait for 20 ns;

    priority_waiting <= true;		wait for 20 ns;

    server_status <= ready;		wait for 20 ns;

    first_normal_request <= 7;		wait for 20 ns;

    first_priority_request <= 12;	wait for 20 ns;

    wait;

  end process stimulus;

  verifier :

    assert functional_request = equivalent_request

      report "Functional and equivalent models give different results";

end architecture test;