/**********************************************************************
 * $show_value example -- Verilog HDL test bench.
 *
 * Verilog test bench to test the $show_value PLI application on a 
 * 1-bit adder modeled using gate primitives.
 *
 * For the book, "The Verilog PLI Handbook" by Stuart Sutherland
 *  Book copyright 1999, Kluwer Academic Publishers, Norwell, MA, USA
 *   Contact: www.wkap.il
 *  Example copyright 1998, Sutherland HDL Inc, Portland, Oregon, USA
 *   Contact: www.sutherland.com or (503) 692-0898
 *********************************************************************/
`timescale 1ns / 1ns
module test;
  reg  a, b, ci, clk;
  wire sum, co;

  addbit i1 (a, b, ci, sum, co);

  initial
    begin
//      $monitor("At %0d: \t a=%b  b=%b  ci=%b  sum=%b  co=%b",
//               $time, a, b, ci, sum, co);
      clk = 0;
      a = 0;
      b = 0;
      ci = 0;
      #10 a = 1;
      #10 b = 1;

      $show_value(sum);
      $show_value(co);
      $show_value(i1.n3);

      #10 $stop;
      $finish;
    end
endmodule

/*** A gate level 1 bit adder model ***/
`timescale 1ns / 1ns
module addbit (a, b, ci, sum, co);
  input  a, b, ci;
  output sum, co;

  wire  a, b, ci, sum, co,
        n1, n2, n3;

  xor    (n1, a, b);
  xor #2 (sum, n1, ci);
  and    (n2, a, b);
  and    (n3, n1, ci);
  or  #2 (co, n2, n3);

endmodule
/**********************************************************************/



[ [ ['module', 'test', ';'],
    [ ['reg', ['a'], ['b'], ['ci'], ['clk'], ';'],
      ['wire', ['sum', 'co'], ';'],
      [ 'addbit',
        [['i1'], ['(', ['a'], ['b'], ['ci'], ['sum'], ['co'], ')']],
        ';'],
      [ 'initial',
        [ 'begin',
          [ [[['clk'], '=', '0'], ';'],
            [[['a'], '=', '0'], ';'],
            [[['b'], '=', '0'], ';'],
            [[['ci'], '=', '0'], ';'],
            [['#', '10'], [[['a'], '=', '1'], ';']],
            [['#', '10'], [[['b'], '=', '1'], ';']],
            ['$show_value', '(', ['sum'], ')', ';'],
            ['$show_value', '(', ['co'], ')', ';'],
            ['$show_value', '(', ['i1.n3'], ')', ';'],
            [['#', '10'], ['$stop', ';']],
            ['$finish', ';']],
          'end']]],
    'endmodule'],
  [ [ 'module',
      'addbit',
      '(',
      [['a'], ['b'], ['ci'], ['sum'], ['co']],
      ')',
      ';'],
    [ ['input', 'a', 'b', 'ci', ';'],
      ['output', 'sum', 'co', ';'],
      ['wire', ['a', 'b', 'ci', 'sum', 'co', 'n1', 'n2', 'n3'], ';'],
      ['xor', '(', [['n1'], ['a'], ['b']], ')', ';'],
      ['xor', ['#', '2'], '(', [['sum'], ['n1'], ['ci']], ')', ';'],
      ['and', '(', [['n2'], ['a'], ['b']], ')', ';'],
      ['and', '(', [['n3'], ['n1'], ['ci']], ')', ';'],
      ['or', ['#', '2'], '(', [['co'], ['n2'], ['n3']], ')', ';']],
    'endmodule']]
