path: root/src/tb/tb_modexp.v

//======================================================================
//
// tb_modexp.v
// -----------
// Testbench modular exponentiation core.
//
//
// Author: Joachim Strombergson, Peter Magnusson
// Copyright (c) 2015, 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.
//
//======================================================================

//------------------------------------------------------------------
// Simulator directives.
//------------------------------------------------------------------
`timescale 1ns/100ps


//------------------------------------------------------------------
// Test module.
//------------------------------------------------------------------
module tb_modexp();

  //----------------------------------------------------------------
  // Internal constant and parameter definitions.
  //----------------------------------------------------------------
  parameter DEBUG     = 0;

  localparam CLK_HALF_PERIOD = 1;
  localparam CLK_PERIOD      = 2 * CLK_HALF_PERIOD;

  // The DUT address map.
  localparam ADDR_NAME0       = 8'h00;
  localparam ADDR_NAME1       = 8'h01;
  localparam ADDR_VERSION     = 8'h02;

  localparam ADDR_CTRL        = 8'h08;
  localparam CTRL_INIT_BIT    = 0;
  localparam CTRL_NEXT_BIT    = 1;


  //----------------------------------------------------------------
  // Register and Wire declarations.
  //----------------------------------------------------------------
  reg [31 : 0]  cycle_ctr;
  reg [31 : 0]  error_ctr;
  reg [31 : 0]  tc_ctr;

  reg [31 : 0]  read_data;
  reg [127 : 0] result_data;

  reg           tb_clk;
  reg           tb_reset_n;
  reg           tb_cs;
  reg           tb_we;
  reg [11  : 0]  tb_address;
  reg [31 : 0]  tb_write_data;
  wire [31 : 0] tb_read_data;
  wire          tb_error;


  //----------------------------------------------------------------
  // Device Under Test.
  //----------------------------------------------------------------
  modexp dut(
             .clk(tb_clk),
             .reset_n(tb_reset_n),
             .cs(tb_cs),
             .we(tb_we),
             .address(tb_address),
             .write_data(tb_write_data),
             .read_data(tb_read_data)
            );


  //----------------------------------------------------------------
  // 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);

      if (DEBUG)
        begin
          dump_dut_state();
        end
    end


  //----------------------------------------------------------------
  // dump_dut_state()
  //
  // Dump the state of the dump when needed.
  //----------------------------------------------------------------
  task dump_dut_state();
    begin
      $display("cycle: 0x%016x", cycle_ctr);
      $display("State of DUT");
      $display("------------");
      $display("");

    end
  endtask // dump_dut_state


  //----------------------------------------------------------------
  // reset_dut()
  //
  // Toggle reset to put the DUT into a well known state.
  //----------------------------------------------------------------
  task reset_dut();
    begin
      $display("*** Toggle reset.");
      tb_reset_n = 0;

      #(2 * CLK_PERIOD);
      tb_reset_n = 1;
      $display("");
    end
  endtask // reset_dut


  //----------------------------------------------------------------
  // 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 all counters and testbed functionality as well
  // as setting the DUT inputs to defined values.
  //----------------------------------------------------------------
  task init_sim();
    begin
      cycle_ctr          = 0;
      error_ctr          = 0;
      tc_ctr             = 0;

      tb_clk             = 0;
      tb_reset_n         = 1;

      tb_cs              = 0;
      tb_we              = 0;
      tb_address         = 8'h00;
      tb_write_data      = 32'h00000000;
    end
  endtask // init_sim


  //----------------------------------------------------------------
  // write_word()
  //
  // Write the given word to the DUT using the DUT interface.
  //----------------------------------------------------------------
  task write_word(input [11 : 0]  address,
                  input [31 : 0] word);
    begin
      if (DEBUG)
        begin
          $display("*** Writing 0x%08x to 0x%02x.", word, address);
          $display("");
        end

      tb_address = address;
      tb_write_data = word;
      tb_cs = 1;
      tb_we = 1;
      #(2 * CLK_PERIOD);
      tb_cs = 0;
      tb_we = 0;
    end
  endtask // write_word


  //----------------------------------------------------------------
  // read_word()
  //
  // Read a data word from the given address in the DUT.
  // the word read will be available in the global variable
  // read_data.
  //----------------------------------------------------------------
  task read_word(input [11 : 0]  address);
    begin
      tb_address = address;
      tb_cs = 1;
      tb_we = 0;
      #(CLK_PERIOD);
      read_data = tb_read_data;
      tb_cs = 0;

      if (DEBUG)
        begin
          $display("*** Reading 0x%08x from 0x%02x.", read_data, address);
          $display("");
        end
    end
  endtask // read_word


  //----------------------------------------------------------------
  // main
  //
  // The main test functionality.
  //----------------------------------------------------------------
  initial
    begin : main

      $display("   -= Testbench for modexp started =-");
      $display("    =================================");
      $display("");

      init_sim();
      dump_dut_state();
      reset_dut();
      dump_dut_state();

      display_test_results();

      $display("");
      $display("*** modexp simulation done. ***");
      $finish;
    end // main
endmodule // tb_modexp

//======================================================================
// EOF tb_modexp.v
//======================================================================