4-bits ripple_carry_adder

module ripple_carry_adder (in0, in1, out, cout,s_overflow,u_overflow);
    // declare input signals
    input [3:0] in0;
    input [3:0] in1;

    // declare output signals
    output [3:0] out;
    output cout;
    output s_overflow;
    output u_overflow;

    // here is your design
    wire [3:0] in0;
    wire [3:0] in1;
    wire c1, c2, c3, w1, w2, w3, w4, w5, w6, w7, w8, w9;
    wire [3:0] out;
    wire cout, s_overflow, u_overflow;

    xor xor1(out[0], in0[0], in1[0]);
    and and1(c1, in0[0], in1[0]);

    xor xor2(w1, in0[1], in1[1]);
    and and2(w2, w1, c1);
    and and3(w3, in0[1], in1[1]);
    xor xor3(out[1], w1, c1);
    or  or1(c2, w2, w3);

    xor xor4(w4, in0[2], in1[2]);
    and and4(w5, w4, c2);
    and and5(w6, in0[2], in1[2]);
    xor xor5(out[2], w4, c2);
    or  or2(c3, w5, w6);

    xor xor6(w7, in0[3], in1[3]);
    and and6(w8, w7, c3);
    and and7(w9, in0[3], in1[3]);
    xor xor7(out[3], w7, c3);
    or  or3(cout, w8, w9);

    xor (s_overflow, cout, c3);
    or  or4(u_overflow, w8, w9);


endmodule