30. PWM with 4-bit Resolution

How do you plan to solve it?

module pwm4_basic ( input clk,rst,
                    input [3:0] duty,
                    output reg pwm_out);
reg [3:0]counter;
always @ (posedge clk or posedge rst)
  begin
    if(rst)
      begin
        counter <= 4'b0;
        pwm_out <= 1'b0;
      end
    else
      begin
        counter <= counter + 1'b1;
        if(counter < duty)
         pwm_out <= 1'b1;
        else
         pwm_out <= 1'b0;
      end
  end
endmodule