全加器的分层测试平台输出不正确

Question

我设计了一个全加器，只是为了获得全加器的实践分层测试平台方法，包括设计、接口、事务类、生成器类、驱动程序类、监视器类、记分板类、环境类、测试程序和顶部试验台。 我得到以下输出：

------------------------------
Generator
------------------------------
a = 0, b = 1, c = 1
sum = 0, carry = 0
------------------------------
------------------------------
Driver
------------------------------
a = 0, b = 1, c = 1
sum = 0, carry = 0
------------------------------
------------------------------
Monitor
------------------------------
a = 0, b = 1, c = 1
sum = 0, carry = 0
------------------------------
Result is as Expected
------------------------------
Scoreboard
------------------------------
a = 0, b = 1, c = 1
sum = 0, carry = 0
------------------------------
$finish at simulation time                 3000
           V C S   S i m u l a t i o n   R e p o r t 
Time: 3000 ps

监视器和记分板的输出似乎是错误的。请提供以下代码所需的必要修改，以便更正输出。

`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: 
// 
// Create Date: 04/15/2024 10:31:04 AM
// Design Name: 
// Module Name: tbench_top
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//////////////////////////////////////////////////////////////////////////////////


module tbench_top;

    fa_if i_inf();

    test t1(i_inf);

    full_adder f1 (i_inf);

endmodule

module full_adder(fa_if inf);

    wire s0, c0, c1;
    half_adder HA1 (inf.a, inf.b, s0, c0);
    half_adder HA2 (s0, inf.c, inf.s_out, c1);

    assign inf.c_out = c0 | c1;

endmodule

module half_adder(a,b,s,c);

    input a,b;
    output s,c;

    xor x1(s,a,b);
    and a1(s,a,b);

endmodule


interface fa_if;

    logic a, b, c;
    logic s_out, c_out;

endinterface


class transaction;

// Stimulus are declared with rand keyword

    rand bit a;

    rand bit b;

    rand bit c;

    bit s_out;

    bit c_out;

    //Function for Displaying values of a, b, c and sum , carry 1

    function void display(string name);

        $display("------------------------------");

        $display(" %s", name);

        $display("------------------------------");

        $display("a = %0d, b = %0d, c = %0d",a, b, c);

        $display("sum = %0d, carry = %0d",s_out, c_out);

        $display("------------------------------");

    endfunction

endclass


class generator;

    transaction trans; //Handle of Transaction class

    mailbox gen2driv; //Mailbox declaration

    function new(mailbox gen2driv); //creation of mailbox and constructor
   
        this.gen2driv = gen2driv;
   
    endfunction

    task main();

        repeat (1)
        begin

            trans = new();
            trans.randomize();
            trans.display("Generator");
            gen2driv.put(trans);

        end

    endtask

endclass


class driver;

    virtual fa_if vif;

    mailbox gen2driv;

    function new(virtual fa_if vif, mailbox gen2driv);

        this.vif = vif;

        this.gen2driv = gen2driv;

    endfunction

    task main;

        repeat(1)

        begin

            transaction trans;

            gen2driv.get(trans);

            vif.a <= trans.a;

            vif.b <=trans.b;
       
            vif.c <=trans.c;

            trans.s_out = vif.s_out;

            trans.c_out = vif.c_out;

            trans.display("Driver");

        end

    endtask

endclass


class monitor;

    virtual fa_if vif;

    mailbox mon2scb;

    function new(virtual fa_if vif, mailbox mon2scb);

        this.vif = vif;

        this.mon2scb = mon2scb;

    endfunction

    task main;

        repeat (1)

        #3;

        begin

            transaction trans;

            trans = new();

            trans.a = vif.a;

            trans.b = vif.b;
       
            trans.c = vif.c;

            trans.s_out = vif.s_out;

            trans.c_out = vif.c_out;

            mon2scb.put(trans);

            trans.display("Monitor");

        end

    endtask

endclass


class scoreboard;

    mailbox mon2scb;

    function new(mailbox mon2scb);
   
        this.mon2scb = mon2scb;

    endfunction

    task main;

        transaction trans;

        repeat (1)

        begin

            mon2scb.get(trans);

            if(((trans.a ^ trans.b ^ trans.c) == trans.s_out) && ((trans.a & trans.b) |(trans.b & trans.c) |(trans.c & trans.a) == trans.c_out))
       
                $display("Result is as Expected");

            else

                $error ("Wrong Result");

            trans.display("Scoreboard");

        end

    endtask

endclass


class environment;

    generator gen;

    driver driv;

    monitor mon;

    scoreboard scb;

    mailbox m1;

    mailbox m2;

    virtual fa_if vif;

    function new(virtual fa_if vif);

        this.vif = vif;

        m1 = new();

        m2 = new();

        gen = new(m1);

        driv = new(vif,m1);

        mon = new(vif,m2);

        scb = new(m2);

    endfunction

    task test();

        fork

            gen.main();

            driv.main();

            mon.main();

            scb.main();

        join

    endtask

    task run;

        test();

        //$finish;

    endtask

endclass


program test(fa_if i_inf);

    environment env;

    initial

    begin

        env = new(i_inf);

        env.run();

    end

endprogram

Answer 1

half_adder

模块中存在连接错误。变化：

and a1(s,a,b);

至：

and a1(c,a,b);

您需要使用波形来调试模拟，例如VCD。当我查看全加器内部的波形时，我注意到一些信号是未知的。然后我追踪到半加法器。