Verilog: 4 Bit Full Adder with Carry Select Dataflow Modelling with Testbench Code

 Verilog Code for 4 Bit Full Adder with Carry Select Dataflow Modelling:

module FACS( 
    input [3:0]x,cin, 
    input [3:0]y,     
    output [3:0]s, 
    output cout, 
); 
//for carry '0' 
    fa f0(a0,c0,0,x[0],y[0]); 
    fa f1(a1,c1,c0,x[1],y[1]); 
    fa f2(a2,c2,c1,x[2],y[2]); 
    fa f3(a3,c3,c2,x[3],y[3]); 
//for carry '1' 
    fa f4(a4,c4,1,x[0],y[0]); 
    fa f5(a5,c5,c4,x[1],y[1]); 
    fa f6(a6,c6,c5,x[2],y[2]); 
    fa f7(a7,c7,c6,x[3],y[3]); 
//two:one MUX
    mux m0(s[0],cin,a0,a4); 
    mux m1(s[1],cin,a1,a5); 
    mux m2(s[2],cin,a2,a6); 
    mux m3(s[3],cin,a3,a7); 
    mux m4(cout,cin,c7,c3); 
endmodule 
 
//full adder
 
module fa(sum,carry,a,b,c4); 
    output sum,carry; 
    input a,b,c4
    assign p = (a^b); 
    assign r = a & b; 
    assign sum = p ^ c4; 
    assign q = p ^ c4; 
    assign carry = q ^ r; 
endmodule 
 
//mux 
 
module mux( 
    output Y, 
    input D0, D1, S, ); 
    assign T1 = D1 & S; 
    assign T2 = D0 & Sbar; 
    assign Sbar = ~ S; 
    assign Y = T1 | T2; 
endmodule 

//Testbench  Code
initial begin 
// Initialize Inputs 
x = 0;y = 0;cin = 0; 
// Wait 100 ns for global reset to finish 
#100; 
// Add stimulus here 
#100;x = 0;y = 0;cin = 1; 
#100;x = 0;y = 1;cin = 0; 
#100;x = 0;y = 1;cin = 1; 
#100;x = 1;y = 0;cin = 0; 
#100;x = 1;y = 0;cin = 1; 
#100;x = 1;y = 1;cin = 0; 
#100;x = 1;y = 1;cin = 1; 
end

4 Bit Full Adder with Carry Select Dataflow Modelling Xillinx Output

Also See:

List of Verilog Programs