9. XOR Gate Using Basic Gates

// ============================================================
// Basic Gates (given)
// ============================================================
module and_gate(input a, b, output y);
    assign y = a & b;
endmodule

module or_gate(input a, b, output y);
    // write code here for or gate
    assign y = a | b;
endmodule

module not_gate(input a, output y);
    // write code here for not gate
    assign y = ~a;
endmodule

// ============================================================
// XOR Gate
// ============================================================
module xor_gate (
    input  a, b,
    output y
);
    // TODO: declare intermediate wires
    wire y1,y2,na,nb;
    // TODO: instantiate required gates
    not_gate n1 (a,na);
    not_gate n2 (b,nb);
    and_gate a1 (a,nb,y1);
    and_gate a2(na,b,y2);
    or_gate o1 (y1,y2,y);
endmodule