URL
https://opencores.org/ocsvn/w11/w11/trunk
Subversion Repositories w11
[/] [w11/] [tags/] [w11a_V0.6/] [rtl/] [vlib/] [simlib/] [simclk.vhd] - Rev 24
Compare with Previous | Blame | View Log
-- $Id: simclk.vhd 444 2011-12-25 10:04:58Z mueller $ -- -- Copyright 2007-2011 by Walter F.J. Mueller <W.F.J.Mueller@gsi.de> -- -- This program is free software; you may redistribute and/or modify it under -- the terms of the GNU General Public License as published by the Free -- Software Foundation, either version 2, or at your option any later version. -- -- This program 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 complete details. -- ------------------------------------------------------------------------------ -- Module Name: simclk - sim -- Description: Clock generator for test benches -- -- Dependencies: - -- Test bench: - -- Target Devices: generic -- Tool versions: xst 8.2, 9.1, 9.2, 13.1; ghdl 0.18-0.29 -- -- Revision History: -- Date Rev Version Comment -- 2011-12-23 444 2.0 remove CLK_CYCLE output port -- 2011-11-18 427 1.0.3 now numeric_std clean -- 2008-03-24 129 1.0.2 CLK_CYCLE now 31 bits -- 2007-10-12 88 1.0.1 avoid ieee.std_logic_unsigned, use cast to unsigned -- 2007-08-10 72 1.0 Initial version ------------------------------------------------------------------------------ library ieee; use ieee.std_logic_1164.all; use work.slvtypes.all; entity simclk is -- test bench clock generator generic ( PERIOD : time := 20 ns; -- clock period OFFSET : time := 200 ns); -- clock offset (first up transition) port ( CLK : out slbit; -- clock CLK_STOP : in slbit -- clock stop trigger ); end entity simclk; architecture sim of simclk is begin proc_clk: process constant clock_halfperiod : time := PERIOD/2; begin CLK <= '0'; wait for OFFSET; clk_loop: loop CLK <= '1'; wait for clock_halfperiod; CLK <= '0'; wait for PERIOD-clock_halfperiod; exit clk_loop when CLK_STOP = '1'; end loop; CLK <= '1'; -- final clock cycle for clk_sim wait for clock_halfperiod; CLK <= '0'; wait for PERIOD-clock_halfperiod; wait; -- endless wait, simulator will stop end process proc_clk; end sim;