*How to compare the output waveform produced by both structural and behavioural models *how to explain the waveform of both structural and behavioural models related to the coding *how to explain both structural and behavioural models coding execute and work (add some comments) Structural Module Model: structural module code: module adder1(A,B,Cin,Sum,Cout);   input [3:0] A, B;   input Cin;   output [3:0] Sum;   output Cout;      wire C0, C1, C2;      fulladder M1(A[0], B[0], Cin, Sum[0], C0);   fulladder M2(A[1], B[1], C0, Sum[1], C1);   fulladder M3(A[2], B[2], C1, Sum[2], C2);   fulladder M4(A[3], B[3], C2, Sum[3], Cout);    endmodule module fulladder (A, B, Cin, Sum, Cout);   input A, B, Cin;   output Sum, Cout;      wire n1, n2 ,x1;   xor u1 (x1, A, B);   xor u2 (Sum, x1, Cin);   and u3(n1, Cin, x1);   and u4(n2, A, B);   or u5(Cout, n1, n2);    endmodule Testbench code for structural module code: module adder1_tb(); timeunit 1us; timeprecision 100ns; reg[3:0] A, B; reg Cin; reg[3:0] Sum; reg Cout; adder1 u1(A, B, Cin, Sum, Cout); initial   begin     $dumpfile("dump.vcd");     $dumpvars(0, adder1_tb.u1);      A=4'b1010; B=4'b0101; Cin=0;     #10 A=4'b0011; B=4'b1101; Cin=1;     #10 A=4'b1111; B=4'b1111; Cin =0;     #10 $finish;   end endmodule     behavioural module code: module adder2(A, B, Cin, Sum, Cout);   input [3:0] A, B;   input Cin;   output [3:0] Sum;   output Cout;      assign {Cout, Sum} = A + B + {3'b0, Cin};    endmodule   Testbench for behavioural module code: module adder2_tb();   timeunit 1us;   timeprecision 100ns;      reg [3:0] A, B;   reg Cin;   reg [3:0] Sum;   reg Cout;      adder2 u1(A, B, Cin, Sum, Cout);      initial   begin     $dumpfile("dump.vcd"); //To save the waveforms     $dumpvars(0, adder2_tb.u1); //To save the waveforms          A=4'b1010; B=4'b0101; Cin=0;       #10 A=4'b0011; B=4'b1101; Cin=1;       #10 A=4'b1111; B=4'b1111; Cin=0;       #10 $finish;   end endmodule

*How to compare the output waveform produced by both structural and behavioural models

*how to explain the waveform of both structural and behavioural models related to the coding

*how to explain both structural and behavioural models coding execute and work (add some comments)

Structural Module Model:

structural module code:

module adder1(A,B,Cin,Sum,Cout);

  input [3:0] A, B;

  input Cin;

  output [3:0] Sum;

  output Cout;

  wire C0, C1, C2;

  fulladder M1(A[0], B[0], Cin, Sum[0], C0);

  fulladder M2(A[1], B[1], C0, Sum[1], C1);

  fulladder M3(A[2], B[2], C1, Sum[2], C2);

  fulladder M4(A[3], B[3], C2, Sum[3], Cout);

endmodule

module fulladder (A, B, Cin, Sum, Cout);

  input A, B, Cin;

  output Sum, Cout;

  wire n1, n2 ,x1;

  xor u1 (x1, A, B);

  xor u2 (Sum, x1, Cin);

  and u3(n1, Cin, x1);

  and u4(n2, A, B);

  or u5(Cout, n1, n2);

endmodule

Testbench code for structural module code:

module adder1_tb();

timeunit 1us;

timeprecision 100ns;

reg[3:0] A, B;

reg Cin;

reg[3:0] Sum;

reg Cout;

adder1 u1(A, B, Cin, Sum, Cout);

initial

  begin

    $dumpfile("dump.vcd");

    $dumpvars(0, adder1_tb.u1);

     A=4'b1010; B=4'b0101; Cin=0;

    #10 A=4'b0011; B=4'b1101; Cin=1;

    #10 A=4'b1111; B=4'b1111; Cin =0;

    #10 $finish;

  end

endmodule

behavioural module code:

module adder2(A, B, Cin, Sum, Cout);

  input [3:0] A, B;

  input Cin;

  output [3:0] Sum;

  output Cout;

  assign {Cout, Sum} = A + B + {3'b0, Cin};

endmodule

Testbench for behavioural module code:

module adder2_tb();

  timeunit 1us;

  timeprecision 100ns;

  reg [3:0] A, B;

  reg Cin;

  reg [3:0] Sum;

  reg Cout;

  adder2 u1(A, B, Cin, Sum, Cout);

  initial

  begin

    $dumpfile("dump.vcd"); //To save the waveforms

    $dumpvars(0, adder2_tb.u1); //To save the waveforms

         A=4'b1010; B=4'b0101; Cin=0;

      #10 A=4'b0011; B=4'b1101; Cin=1;

      #10 A=4'b1111; B=4'b1111; Cin=0;

      #10 $finish;

  end

endmodule