Half Adder

Half Adder :

It contains two inputs and two outputs , the inputs are those which are to be added and the outputs are sum and carry .

Program :

(a) Dataflow modeling

`timescale 1ns / 1ps
module half_adder_dataflow(a,b,s,c);
input a,b;
output s,c;
assign s=a^b;
assign c=a&b;
endmodule 

(b) Behavioral Modeling

`timescale 1ns / 1ps
module half_adder_behav(a,b,s,c);
input a,b;
output reg s,c;
always@*
begin
if(a==1'b0 & b==1'b0)
begin
s<=1'b0;
c<=1'b0;
end
else if(a==1'b0 & b==1'b1)
begin
s<=1'b1;
c<=1'b0;
end
else if(a==1'b1 & b==1'b0)
begin
s<=1'b1;
c<=1'b0;
end 
else if(a==1'b1 & b==1'b1)
begin
s<=1'b1;
c<=1'b1;
end
end
endmodule 

(c) Structural Modeling

`timescale 1ns / 1ps
module half_adder_struct(a,b,s,c);
input a,b;
output s,c;
xor21 u1(a,b,s);
and21 u2(a,b,c);
endmodule 

module and21(a,b,y);
input a,b;
output y;
assign y=a&b;
endmodule

module xor21(a,b,y);
input a,b;
output y;
assign y=a^b;
endmodule