//
// Copyright (c) 1999 Steven Wilson (stevew@home.com)
//
//    This source code is free software; you can redistribute it
//    and/or modify it in source code form under the terms of the GNU
//    General Public License as published by the Free Software
//    Foundation; either version 2 of the License, or (at your option)
//    any later version.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    You should have received a copy of the GNU General Public License
//    along with this program; if not, write to the Free Software
//    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
//
//  SDW - multiply operator

module top () ;

reg [3:0] a,b;
wire [3:0] wa,wb;
reg [7:0] result;
wire [8:0] wresult;

assign wa = a;
assign wb = b;
assign wresult = wa * wb;

always @(a or b)
   result = a * b;
 
initial
  begin
    #1;
    a = 0;
    b = 0;
    # 1;
    if( result !== 8'b0)
      begin
        $display("FAILED - Mult 0*0 reg assign failed - is %b",result);
        $finish;
      end
    if( wresult !== 9'b0)
      begin
        $display("FAILED - Mult 0*0 wire assign failed - is %b",result);
        $finish;
      end

    #1;
    a = 1;
    #1;
    if( result !== 8'b0)
      begin
        $display("FAILED - Mult 0*1 reg assign failed - is %b",result);
        $finish;
      end
    if( wresult !== 9'b0)
      begin
        $display("FAILED - Mult 0*1 wire assign failed - is %b",result);
        $finish;
      end

    #1;
    b = 1;
    #1;
    if( result !== 8'b1)
      begin
        $display("FAILED - Mult 1*1 reg assign failed - is %b",result);
        $finish;
      end
    if( wresult !== 9'b1)
      begin
        $display("FAILED - Mult 1*1 wire assign failed - is %b",result);
        $finish;
      end

    #1;
    a = 2;
    #1;
    if( result !== 8'h2)
      begin
        $display("FAILED - Mult 2*1 reg assign failed - is %b",result);
        $finish;
      end
    if( wresult !== 9'h2)
      begin
        $display("FAILED - Mult 2*1 wire assign failed - is %b",result);
        $finish;
      end

    #1;
    a = 2;
    b = 3;
    #1;
    if( result !== 8'h6)
      begin
        $display("FAILED - Mult 2*3 reg assign failed - is %b",result);
        $finish;
      end
    if( wresult !== 9'h6)
      begin
        $display("FAILED - Mult 2*3 wire assign failed - is %b",result);
        $finish;
      end

    #1;
    a = 1'bx;
    b = 3;
    #1;
    if( result !== 8'bxxxx_xxxx)
      begin
        $display("FAILED - Mult 2*x reg assign failed - is %b",result);
        $finish;
      end
    if( wresult !== 9'bx_xxxx_xxxx)
      begin
        $display("FAILED - Mult 2*x wire assign failed - is %b",wresult);
        $finish;
      end

    $display("PASSED");

  end

endmodule