Subversion Repositories ca_prng

//========================================================================

//

// tb_ca_prng.v

// ------------

// Testbench for the rule cellular automata based PRNG ca_prng.

// This version is for ca_prng with 32 bit pattern output.

// 

// 

// Author: Joachim Strombergson

// Copyright (c) 2008, InformAsic AB

// 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.

// 

// THIS SOFTWARE IS PROVIDED BY InformAsic AB ''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 InformAsic AB 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 etc.

//------------------------------------------------------------------

`timescale 1ns / 1ps

//------------------------------------------------------------------

// tb_ca_prng

//

// The self contained testbench module.

//------------------------------------------------------------------

module tb_ca_prng();

  //----------------------------------------------------------------

  // Parameter declarations

  //----------------------------------------------------------------

  // CLK_HALF_PERIOD

  // Half period (assuming 50/50 duty cycle) in ns.

  parameter CLK_HALF_PERIOD = 5;

  // RULE_2

  // This rule generates a single angled line. 

  // See the following link for more info:

  // http://mathworld.wolfram.com/ElementaryCellularAutomaton.html

  parameter [7 : 0] RULE_2 = 8'b00000010;

  // RULE_90

  // This rule generates Pascals triangle from a single

  // bit input. See the following link for more info:

  // http://mathworld.wolfram.com/ElementaryCellularAutomaton.html

  parameter [7 : 0] RULE_90 = 8'b01011010;

  // MIDDLE_BIT_INIT_PATTERN

  // An initial bgit pattern with a single bit set in the middle

  // of the 32 bit word.

  parameter  [31 : 0] MIDDLE_BIT_INIT_PATTERN = 32'b00000000000000010000000000000000;

  // COMPLEX_INIT_PATTERN

  // A more complex init pattern.

  parameter  [31 : 0] COMPLEX_INIT_PATTERN = 32'b01011000000000010000111000001100;

  // TC1_RESPONSE

  // Expected PRNG pattern response after TC1.

  parameter  [31 : 0] TC1_RESPONSE = 32'b01110001010110000000111010001001;

  // TC2_RESPONSE

  // Expected PRNG pattern response after TC2.

  parameter  [31 : 0] TC2_RESPONSE = 32'b10111101001101000001100001101001;

  // TC3_RESPONSE

  // Expected PRNG pattern response after TC3.

  parameter  [31 : 0] TC3_RESPONSE = 32'b00000000000000000001000000000000;

  // TC4_RESPONSE

  // Expected PRNG pattern response after TC4.

  parameter  [31 : 0] TC4_RESPONSE = 32'b10101010101010101010101010101010;

  //----------------------------------------------------------------

  // Wire declarations.

  //----------------------------------------------------------------

  // Wires needed to connect the DUT.

  reg           tb_clk;

  reg           tb_reset_n;

  reg [31 : 0]  tb_init_pattern_data;

  reg           tb_load_init_pattern;

  reg           tb_next_pattern;

  reg [7 : 0]   tb_update_rule;

  reg           tb_load_update_rule;

  wire [31 : 0] tb_prng_data;

  //----------------------------------------------------------------

  // Testbench variables.

  //----------------------------------------------------------------

  // num_errors

  // Number of errors detected.

  integer num_errors;

  //----------------------------------------------------------------

  // ca_prng_dut

  // 

  // Instantiation of the ca_prng core as device under test.

  //----------------------------------------------------------------

  ca_prng ca_prng_dut(

                      .clk(tb_clk),

                      .reset_n(tb_reset_n),

                      .init_pattern_data(tb_init_pattern_data),

                      .load_init_pattern(tb_load_init_pattern),

                      .next_pattern(tb_next_pattern),

                      .update_rule(tb_update_rule),

                      .load_update_rule(tb_load_update_rule),

                      .prng_data(tb_prng_data)

                     );

  //----------------------------------------------------------------

  // check_pattern

  //

  // Check that the reusult pattern matches the expected pattern.

  // If the patterns don't match increase the error counter.

  //----------------------------------------------------------------

  task check_pattern;

    input [31 : 0] expected_pattern;

    input [31 : 0] result_pattern;

    begin

      if (expected_pattern != result_pattern)

        begin

          $display("Error: Expected %b, got: %b",

                   expected_pattern, result_pattern);

          num_errors = num_errors + 1;

        end

    end

  endtask // check_pattern

  //----------------------------------------------------------------

  // init_sim

  //

  // Initialize all DUT inputs variables, testbench variables etc 

  // to defined values.

  //----------------------------------------------------------------

  task init_sim;

    begin

      tb_clk               = 0;

      tb_reset_n           = 0;

      tb_init_pattern_data = MIDDLE_BIT_INIT_PATTERN;

      tb_load_init_pattern = 1'b0;

      tb_next_pattern      = 1'b0;

      tb_update_rule       = 8'b00000000;

      tb_load_update_rule  = 1'b0;

      num_errors           = 0;

    end

  endtask // init_sim 

  //----------------------------------------------------------------

  // end_sim

  //

  // Perform any clean up as needed and check the simulation 

  // results from the test cases, reporting number of errors etc.

  //----------------------------------------------------------------

  task end_sim;

    begin

      if (num_errors == 0)

        begin

          $display("Simulation completed ok.");

        end

      else

        begin

          $display("Simulation completed, but %d test cases had errors.", num_errors);

        end

    end

  endtask // end_sim 

  //----------------------------------------------------------------

  // release_reset

  //

  // Wait a few cycles and then release the reset in sync

  // with the clock.

  //----------------------------------------------------------------

  task release_reset;

    begin

      #(20 * CLK_HALF_PERIOD);

      @(negedge tb_clk)

        tb_reset_n = 1'b1;

    end

  endtask // release_reset 

  //----------------------------------------------------------------

  // test_tc1

  //

  // Verify that the default rule30 update rule uns ok from the 

  // start using a simple init pattern.

  //----------------------------------------------------------------

  task test_tc1;

    begin

      $display("TC1: Default rule30 update rule with simple init pattern.");

      // Load the init pattern into the dut and then

      // start asserting the next pattern pin for a while.

      #(4 * CLK_HALF_PERIOD);

      @(negedge tb_clk)

        tb_load_init_pattern = 1'b1;

      @(negedge tb_clk)

        tb_load_init_pattern = 1'b0;

      @(negedge tb_clk)

        tb_next_pattern      = 1'b1;

      // Run the DUT for a number of cycles.

      #(100 * CLK_HALF_PERIOD);

      // Drop the next pattern signal and check the results.

      @(negedge tb_clk)

        tb_next_pattern = 1'b0;

      check_pattern(TC1_RESPONSE, tb_prng_data);

    end

  endtask // test_tc1

  //----------------------------------------------------------------

  // test_tc2

  //

  // Verify that we can change state by changing the init pattern

  // and get a new set of PRNG data.

  //----------------------------------------------------------------

  task test_tc2;

    begin

      $display("TC2: Default rule30 update rule with complex init pattern.");

      // Load a new init pattern and run that pattern

      @(negedge tb_clk)

      tb_init_pattern_data = COMPLEX_INIT_PATTERN;

      tb_load_init_pattern = 1'b1;

      @(negedge tb_clk)

      tb_load_init_pattern = 1'b0;

      tb_next_pattern      = 1'b1;

      // Run the DUT for a number of cycles.

      #(200 * CLK_HALF_PERIOD);

      // Drop the next pattern signal and check the results.

      @(negedge tb_clk)

        tb_next_pattern = 1'b0;

      check_pattern(TC2_RESPONSE, tb_prng_data);

    end

  endtask // test_tc2

  //----------------------------------------------------------------

  // test_tc3

  //

  // Verify that the we can change the rule and get another set

  // of PRNG data.

  //----------------------------------------------------------------

  task test_tc3;

    begin

      $display("TC3: rule2 update rule with simple init pattern.");

      // Change update rule to RULE_2 and the simple init pattern.

      @(negedge tb_clk)

      tb_update_rule       = RULE_2;

      tb_load_update_rule  = 1'b1;

      tb_init_pattern_data = MIDDLE_BIT_INIT_PATTERN;

      tb_load_init_pattern = 1'b1;

      @(negedge tb_clk)

      tb_load_update_rule  = 1'b0;

      tb_load_init_pattern = 1'b0;

      tb_next_pattern      = 1'b1;

      // Run the DUT for a number of cycles.

      #(200 * CLK_HALF_PERIOD);

      // Drop the next pattern signal and check the results.

      @(negedge tb_clk)

        tb_next_pattern = 1'b0;

      check_pattern(TC3_RESPONSE, tb_prng_data);

    end

  endtask // test_tc3

  //----------------------------------------------------------------

  // test_tc4

  //

  // Verify that the we can generate Pascals triangle.

  //----------------------------------------------------------------

  task test_tc4;

    begin

      $display("TC4: rule90 (Pascals triangle) update rule with simple init pattern.");

      // Change update rule to RULE_90 and the simple init pattern.

      @(negedge tb_clk)

      tb_update_rule       = RULE_90;

      tb_load_update_rule  = 1'b1;

      tb_init_pattern_data = MIDDLE_BIT_INIT_PATTERN;

      tb_load_init_pattern = 1'b1;

      @(negedge tb_clk)

      tb_load_update_rule  = 1'b0;

      tb_load_init_pattern = 1'b0;

      tb_next_pattern      = 1'b1;

      // Run the DUT for a number of cycles.

      #(30 * CLK_HALF_PERIOD);

      // Drop the next pattern signal and check the results.

      @(negedge tb_clk)

        tb_next_pattern = 1'b0;

      check_pattern(TC4_RESPONSE, tb_prng_data);

    end

  endtask // test_tc4

  //----------------------------------------------------------------

  // clk_gen

  //

  // Clock generator process. 50/50 duty cycle.

  //----------------------------------------------------------------

  always

    begin : clk_gen

      #CLK_HALF_PERIOD tb_clk = !tb_clk;

    end // clk_gen

  //--------------------------------------------------------------------

  // dut_monitor

  //

  // Monitor for observing the inputs and outputs to the dut.

  //--------------------------------------------------------------------

  always @ (posedge tb_clk)

    begin : dut_monitor

      $display("reset = %b, init_pattern = %b, load_init_pattern = %b, next_pattern = %b, prng_data = %b",

               tb_reset_n, tb_init_pattern_data, tb_load_init_pattern, tb_next_pattern, tb_prng_data);

    end // dut_monitor

  //----------------------------------------------------------------

  // ca_prng_test

  //

  // The main test logic. Basically calls the tasks to init the

  // simulation, all test cases and finish the simulation.

  //----------------------------------------------------------------

  initial

    begin : ca_prng_test

      $display("   -- Testbench for for ca_prng module started --");

      // Call tasks as needed to init and executing test cases.

      init_sim;

      release_reset;

      test_tc1;

      test_tc2;

      test_tc3;

      test_tc4;

      end_sim;

      $display("   -- Testbench for for ca_prng module stopped --");

      $finish;

    end // ca_prng_test

endmodule // tb_ca_prng

//========================================================================

// EOF tb_ca_prng.v

//========================================================================