HDLBits答案——Verification: Writing Testbenches

1 clock

module top_module ( );
    
    reg clk;
    
    dut U1(.clk(clk));
    
    initial begin
        clk = 0;
    end
    
    always begin
        #5;
        clk = ~clk;
    end

endmodule

2 Tb/tb1

module top_module ( output reg A, output reg B );//

    // generate input patterns here
    initial begin
		A = 0;
        B = 0;
        #10;
        A = 1;
        #5;
        B = 1;
        #5;
        A = 0;
        #20;
        B = 0;
    end

endmodule

3 Tb/and

module top_module();
    
    reg a,b,out;
    
    initial begin
        a = 0;
        b = 0;
        #10;
        a = 0;
        b = 1;
        #10;
        a = 1;
        b = 0;
        #10;
        a = 1;
        b = 1;
    end
    
    andgate U1({a,b},out);

endmodule

4 Tb/tb2

module top_module();
    
    reg clk;
    reg in;
    reg [2:0] s;
    reg out;
    
    q7 U1(.clk(clk), .in(in), .s(s), .out(out));
    
    initial begin
        clk = 0;
        in = 0;
        s = 3'd2;
        #10;
        in = 0;
        s = 3'd6;
        #10;
        in = 1;
        s = 3'd2;
        #10;
        in = 0;
        s = 3'd7;
        #10;
        in = 1;
        s = 3'd0;
        #30;
        in = 0;
    end
    
    always begin
        #5;
        clk = ~clk;
    end

endmodule

5 Tb/tff

module top_module ();
    
    reg clk,reset,t,q;
    
    tff U1(.clk(clk),
           .reset(reset),
           .t(t),
           .q(q));
    
    initial begin
        clk = 0;
        t = 0;
        reset = 0;
    end
    
    always begin
        #5;
        clk = ~clk;
    end
    
    initial begin
        reset = 1'b0;
        #3;
        reset = 1'b1;
        #10;
        reset = 1'b0;   
    end
    
    always@(posedge clk)begin
        if(reset)
            t = 1;
        else
            t = 0;
    end
    

endmodule