4-Bit Array Multiplier using structural Modeling

4-Bit Array Multiplier using structural Modeling:

 

module Multiply_4x4(

    input [3:0] a,

    input [3:0] b,

    output [7:0] p );

             wire [3:0]pp0,pp1,pp2,pp3;

             wire c1,c2,c3,c4,c5,c6,c7,c8;

             wire s1,s2,s3,s4,s5,s6;

assign pp0=a[0]*b[3:0];

assign pp1=a[1]*b[3:0];

assign pp2=a[2]*b[3:0];

assign pp3=a[3]*b[3:0];

assign p[0]=pp0[0];

halfadder HA1(pp0[1],pp1[0],p[1],c1);

fulladder FA1(c1,pp0[2],pp1[1],s1,c2);

halfadder HA2(s1,pp2[0],p[2],c3);

fulladder FA2(c2,c3,pp0[3],s2,c4);

fulladder FA3(s2,pp1[2],pp2[1],s3,c5);

halfadder HA3(s3,pp3[0],p[3],c6);

fulladder FA4(c4,c5,c6,s4,c7);

fulladder FA5(s4,pp1[3],pp2[2],s5,c8);

halfadder HA4(s5,pp3[1],p[4],c9);

fulladder FA6(c7,c8,c9,s6,c10);

fulladder FA7(s6,pp2[3],pp3[2],p[5],c11);

fulladder FA8(c10,c11,pp3[3],p[6],p[7]);

endmodule

 

Hint: For fulladder, halfadder module refer previous posts

Testbench code:

 

module multiplier_tb;

            reg [3:0] a;

            reg [3:0] b;

            wire [7:0] p;

            Multiply_4x4 uut (

                        .a(a),

                        .b(b),

                        .p(p)

            );

            initial begin

                        a = 0; b = 0; #100;

                        a = 1; b = 10; #100;

                        a = 11; b = 11; #100;

                        a = 11; b = 15; #100;

                        a = 15; b = 15; #100;

                        a = 12; b = 8; #100;

                        a = 4; b = 13; #100;       

            end

endmodule