+SR_PRIV void hung_chang_dso_2100_reset_port(struct parport *port);
+SR_PRIV gboolean hung_chang_dso_2100_check_id(struct parport *port);
+SR_PRIV void hung_chang_dso_2100_write_mbox(struct parport *port, uint8_t val);
+SR_PRIV uint8_t hung_chang_dso_2100_read_mbox(struct parport *port, float timeout);
+SR_PRIV int hung_chang_dso_2100_move_to(const struct sr_dev_inst *sdi, uint8_t target);
+SR_PRIV int hung_chang_dso_2100_poll(int fd, int revents, void *cb_data);