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

-- Title      : Clock generator for simulation

-- Project    : Nocbench & Funbase

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

-- File       : clk_gen.vhd

-- Author     : ege

-- Created    : 2012-01-27

-- Last update: 2012-01-31

-- Description: Just toggles the 1-bit clock output forever.

-- 

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

-- Copyright (c) 2010

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

-- Revisions  :

-- Date        Version  Author  Description

-- April 2010   1.0     ege     First version

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

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

-- Funbase IP library Copyright (C) 2011 TUT Department of Computer Systems

--

--

-- This source file may be used and distributed without

-- restriction provided that this copyright statement is not

-- removed from the file and that any derivative work contains

-- the original copyright notice and the associated disclaimer.

--

-- This source file 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 2.1 of the License, or (at your option) any

-- later version.

--

-- This source 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 this source; if not, download it

-- from http://www.opencores.org/lgpl.shtml

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

library ieee;

use ieee.std_logic_1164.all;

entity clk_gen is

  generic (

    hi_period_ns_g : integer := 1;      -- In nanoseconds

    lo_period_ns_g : integer := 1       -- In nanoseconds

    );

  port (

    clk_out : out std_logic

    );

end clk_gen;

architecture behav of clk_gen is

  signal clk_tmp : std_logic := '0';

begin  -- behav

  clk_out <= clk_tmp;

  toggle : process (clk_tmp)

  begin  -- process toggle

    if clk_tmp = '0' then

      clk_tmp <= '1' after lo_period_ns_g * 1 ns;

    else

      clk_tmp <= '0' after hi_period_ns_g * 1 ns;

    end if;

  end process toggle;

end behav;