30. PWM with 4-bit Resolution

How do you plan to solve it?

/*Write your code here*/
module pwm4_basic (
    input clk, rst,
    input [3:0] duty,
    output reg pwm_out
);
    reg [3:0] ctr;
    always @(posedge clk) begin
        if (rst) begin
            ctr <=0;
            pwm_out <=0;
        end
        else begin
            if (ctr < duty) pwm_out <= 1;
            else pwm_out <= 0;
            ctr <= ctr + 1;
        end 
    end
endmodule