--------------------------------------------------------------------------------
--  File Name: cxo.vhd
--------------------------------------------------------------------------------
--  Copyright (C) 1998 Free Model Foundry; http://www.FreeModelFoundry.com
-- 
--  This program is free software; you can redistribute it and/or modify
--  it under the terms of the GNU General Public License version 2 as
--  published by the Free Software Foundation.
-- 
--  MODIFICATION HISTORY:
-- 
--  version: |  author:  | mod date: | changes made:
--    V1.0    R. Munden    98 MAY 27   Initial release
-- 
--------------------------------------------------------------------------------
--  PART DESCRIPTION:
-- 
--  Library:    MISC
--  Technology: TTL
--  Part:       CXO
-- 
--  Desciption: Crystal Controled Oscillator
--------------------------------------------------------------------------------

LIBRARY IEEE;   USE IEEE.std_logic_1164.ALL;
                USE IEEE.VITAL_timing.ALL;
                USE IEEE.VITAL_primitives.ALL;
LIBRARY FMF;    USE FMF.gen_utils.ALL;

--------------------------------------------------------------------------------
-- ENTITY DECLARATION
--------------------------------------------------------------------------------
ENTITY cxo IS
    GENERIC (
        -- tipd delays: interconnect path delays
        -- tpd delays
        -- oscillator period
        period              : TIME      := 100 ns;
        -- generic control parameters
        InstancePath        : STRING    := DefaultInstancePath;
        MsgOn               : BOOLEAN   := DefaultMsgOn;
        XOn                 : BOOLEAN   := DefaultXon;
        -- For FMF SDF technology file usage
        TimingModel         : STRING    := DefaultTimingModel
    );
    PORT (
        O               : OUT std_logic := '0'
    );
    ATTRIBUTE VITAL_LEVEL0 of cxo : ENTITY IS TRUE;
END cxo;

--------------------------------------------------------------------------------
-- ARCHITECTURE DECLARATION
--------------------------------------------------------------------------------
ARCHITECTURE vhdl_behavioral of cxo IS
    ATTRIBUTE VITAL_LEVEL0 of vhdl_behavioral : ARCHITECTURE IS TRUE;

BEGIN

    ----------------------------------------------------------------------------
    -- Main Behavior Process
    ----------------------------------------------------------------------------
    Osc_process : PROCESS 

    BEGIN

        wait for period;
        O <= '0', '1' after period/2;

    END PROCESS;


END vhdl_behavioral;