// ============================================================
// Basic Gates (given)
// ============================================================
module and_gate(input a, b, output y);
assign y = a & b;
endmodule
module or_gate(input a, b, output y);
assign y = a | b;
endmodule
module not_gate(input a, output y);
assign y = ~a;
endmodule
// ============================================================
// XOR Gate
// ============================================================
module xor_gate (
input a, b,
output y
);
wire w1,w2,y1,y2;
not_gate n1(a,w1);
not_gate n2(b,w2);
and_gate a1(a,w2,y1);
and_gate a2(b,w1,y2);
or_gate o1(y1,y2,y);
endmodule