module NSG_function
(
        input x, [1:0] q, // current_state,
        output [1:0] d // next_state
);

assign d[1] = ~x&q[0]&q[1] | x&~q[0]&q[1] | x&q[0]&~q[1];
assign d[0] = ~x | ~q[0]&q[1];

endmodule

module NSG_function
(
        input x,
        input [1:0] q, // current_state
        output [1:0] d // next_state
);

assign d[1] = ~x&q[0]&q[1] | x&~q[0]&q[1] | x&q[0]&~q[1];
assign d[0] = ~x | ~q[0]&q[1];

endmodule

input x,
input [1:0] q, // current_state,