//======================================================================
//
// tb_fpga_mkm_spi_slave.v
// -----------------------
// Testbench for the SPI slave interface for the FPGA based 
// Master Key Memory (MKM).
//
//
// Author: Joachim Strombergson
// Copyright (c) 2019, 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_fpga_mkm_spi_slave();

  //----------------------------------------------------------------
  // Parameters.
  //----------------------------------------------------------------
  parameter DEBUG = 1;

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


  //----------------------------------------------------------------
  // Variables, regs and wires.
  //----------------------------------------------------------------
  integer cycle_ctr;
  integer error_ctr;
  integer tc_ctr;

  reg          tb_clk;
  reg          tb_ss;
  reg          tb_sclk;
  reg          tb_mosi;
  wire         tb_miso;
  wire         tb_spi_active;
  wire         tb_rx_byte_available;
  wire [7 : 0] tb_rx_byte;
  reg          tb_tx_byte_available;
  reg [7 : 0]  tb_tx_byte; 
  wire         tb_tx_byte_ack;


  //----------------------------------------------------------------
  // Device Under Test.
  //----------------------------------------------------------------
  fpga_mkm_spi_slave dut(
                         .clk(tb_clk),
                         .ss(tb_ss),
                         .sclk(tb_sclk),
                         .mosi(tb_mosi),
                         .miso(tb_miso),

                         .spi_active(tb_spi_active),
                         .rx_byte_available(tb_rx_byte_available),
                         .rx_byte(tb_rx_byte),

                         .tx_byte_available(tb_tx_byte_available),
                         .tx_byte(tb_tx_byte),
                         .tx_byte_ack(tb_tx_byte_ack)
                         );


  //----------------------------------------------------------------
  // clk_gen
  //
  // Always running clock generator process.
  //----------------------------------------------------------------
  always
    begin : clk_gen
      #(CLK_HALF_PERIOD);
      tb_clk = !tb_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);
    end


  //----------------------------------------------------------------
  // display_test_results()
  //
  // Display the accumulated test results.
  //----------------------------------------------------------------
  task display_test_results;
    begin
      if (error_ctr == 0)
        begin
          $display("*** All %02d test cases completed successfully", tc_ctr);
        end
      else
        begin
          $display("*** %02d tests completed - %02d test cases did not complete successfully.",
                   tc_ctr, error_ctr);
        end
    end
  endtask // display_test_results


  //----------------------------------------------------------------
  // init_sim
  //
  // Initialize DUT inputs, test case counters, clock etc.
  //----------------------------------------------------------------
  task init_sim;
    begin : init_sim
      cycle_ctr = 0;
      error_ctr = 0;
      tc_ctr    = 0;

      tb_clk    = 1'h0;
      tb_ss     = 1'h1;
      tb_sclk   = 1'h0;
      tb_mosi   = 1'h0;
    end
  endtask // init_sim


  //----------------------------------------------------------------
  // wait_cycles
  //----------------------------------------------------------------
  task wait_cycles (input integer cycles);
    begin : wait_cycles
      #(cycles);
    end
  endtask // wait_cycles


  //----------------------------------------------------------------
  // init_sim()
  //
  // Initialize all counters and testbed functionality as well
  // as setting the DUT inputs to defined values.
  //----------------------------------------------------------------
  initial
    begin
      $display("   -= Testbench for fpga_mkm_spi_slave started =-");
      $display("    =============================================");
      $display("");

      init_sim();
      wait_cycles(100);
      display_test_results();

      $display("");
      $display("   -= Testbench for fpga_mkm_spi_slave completed =-");
      $display("    ===============================================");
      $finish;
    end

endmodule // tb_fpga_mkm_spi_slave

//======================================================================
// EOF tb_fpga_mkm_spi_slave.v
//======================================================================