Verilog Code for Carry Ripple Adder

Carry Ripple Adder:

It is possible to create a logical circuit using multiple full adders to add N-bit numbers. Each full adder inputs a C_in, which is the C_out of the previous adder. This kind of adder is called a ripple-carry adder (RCA), since each carry bit "ripples" to the next full adder. Note that the first (and only the first) full adder may be replaced by a half adder (under the assumption that C_in = 0).

Verilog Code for Carry Ripple Adder:

module carry_ripple_adder(sum,cout,a,b,cin); 

input [3:0]a,b;//4bit input a and b. 

input cin;//carry input. 

output [3:0]sum;//4bit outputsum. 

output cout;//carry output. 

wire w1,w2,w3; 

//Full Adder Module Instantiation. 

Full_Adder cr1(.sum(sum[0]),.cout(w1),.a(a[0]),. b(b[0]),.cin(cin)); 

Full_Adder cr2(.sum(sum[1]),.cout(w2),.a(a[1]),. b(b[1]),.cin(w1)); 

Full_Adder cr3(.sum(sum[2]),.cout(w3),.a(a[2]),. b(b[2]),.cin(w2)); 

Full_Adder cr4(.sum(sum[3]),.cout(cout),.a(a[3]),. b(b[3]),.cin(w3)); 

endmodule                                                                                                                    

module Full_Adder(a,b,cin,sum,cout); 

input a,b,cin;  //input a , b and carry input. 

output sum,cout; //output sum and carry output. 

assign sum=a^b^cin; //Ex-oring of inputs. 

assign cout=(a&b)|(b&cin)|(cin&a);//carry out equation. 

endmodule 

OUTPUT: