Modelsim SE 64 10.4中，代码编译可以通过没有报错或警告但是仿真的时候点击一次Run波形图仅运行一个单位时间

2019-07-15 20:42发布

//BCD.v

module BCD(A,B,Sum,Cout);
      input [3:0]A,B;
      output [3:0]Sum;
      output Cout;
//       reg [3:0]Sum;
//       reg Cout?
      wire [4:0]Temp;

      assign Temp = A + B;
      assign {Cout , Sum} = (Temp > 9 )? Temp +6 : Temp;

/*       always@(A or B)
            begin
            {Cout , Sum} = A + B;
            if({Cout , Sum} > 9 )
                     {Cout , Sum} = {Cout , Sum} + 6;
            end
*/
endmodule

//BCD_tb.v

`timescale 1ns/1ns
module BCD_tb;
  reg [3:0]addend1,addend2;
  wire [3:0]sum;
  wire C;

  parameter DELAY = 100;    //
  integer i,j;

  BCD U1( .A(addend1),
      .B(addend2),
      .Cout(C),
      .Sum(sum)
      );


  initial
  begin
addend1 = 0;
addend2 = 0;
for(i = 0;i < 10;i = i + 1)
for(j = 0;j < 10;j = j + 1)
begin
   #DELAY addend1 = i;
         addend2 = j;
end
  end

  initial
  $monitor($time,,,"%d + %d = %d , carry = %d ",addend1,addend2,sum,C);

endmodule