public static extern int fp_print_data_delete(ref fp_dev dev, fp_finger finger);
public static extern int fp_print_data_save(ref fp_print_data data, fp_finger finger);
public static extern int fp_print_data_load(ref fp_dev dev, fp_finger finger, ref IntPtr data);
public static extern int fp_print_data_load(ref fp_dev dev, fp_finger finger, ref System.IntPtr data);