//======================================================================
//
// tb_toggle
// ---------
// Testbench for the gpio pin toggler.
//
//
// Author: Joachim Strombergson
// Copyright (c) 2018, NORDUnet A/S
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// - Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
//
// - Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the
//   documentation and/or other materials provided with the distribution.
//
// - Neither the name of the NORDUnet nor the names of its contributors may
//   be used to endorse or promote products derived from this software
//   without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
//======================================================================

module tb_toggle();

  parameter CLK_HALF_PERIOD = 1;
  parameter CLK_PERIOD      = 2 * CLK_HALF_PERIOD;

  reg tb_sys_clk;
  reg tb_reset_n;
  wire [7 : 0] tb_gpio_b;
  reg [31 : 0]  cycle_ctr;

  toggle dut(
           .sys_clk(tb_sys_clk),
           .reset_n(tb_reset_n),
           .gpio_b(tb_gpio_b)
          );


  //----------------------------------------------------------------
  // clk_gen
  //
  // Always running clock generator process.
  //----------------------------------------------------------------
  always
    begin : clk_gen
      #CLK_HALF_PERIOD;
      tb_sys_clk = !tb_sys_clk;
    end // clk_gen


  //----------------------------------------------------------------
  // sys_monitor()
  //
  // An always running process that creates a cycle counter and
  // conditionally displays information about the DUT.
  //----------------------------------------------------------------
  always
    begin : sys_monitor
      cycle_ctr = cycle_ctr + 1;

      #(CLK_PERIOD);

      $display("cycle: 0x%016x gpio_b: 0x%08x  toggle_ctr: 0x%08x  toggle_reg: 0x%01x",
               cycle_ctr, tb_gpio_b, dut.toggle_ctr_reg, dut.toggle_reg);
    end


  //----------------------------------------------------------------
  // init_sim()
  //
  // Initialize all counters and testbed functionality as well
  // as setting the DUT inputs to defined values.
  //----------------------------------------------------------------
  initial
    begin
      cycle_ctr     = 0;
      tb_sys_clk    = 0;
      tb_reset_n    = 0;

      #(CLK_PERIOD * 10);

      tb_reset_n    = 1;

      #(CLK_PERIOD * 10000);
      $finish;
    end

endmodule // tb_toggle

//======================================================================
// EOF tb_toggle.v
//======================================================================