+extern __xdata struct ao_packet_recv ao_rx_packet;
+extern __xdata struct ao_packet ao_tx_packet;
+extern __xdata struct ao_task ao_packet_task;
+extern __xdata uint8_t ao_packet_enable;
+extern __xdata uint8_t ao_packet_master_sleeping;
+extern __pdata uint8_t ao_packet_rx_len, ao_packet_rx_used, ao_packet_tx_used;
+
+void
+ao_packet_send(void);
+
+uint8_t
+ao_packet_recv(void);
+
+void
+ao_packet_flush(void);
+
+void
+ao_packet_putchar(char c) __reentrant;
+
+char
+ao_packet_pollchar(void) __critical;
+
+/* ao_packet_master.c */
+
+void
+ao_packet_master_init(void);
+
+/* ao_packet_slave.c */
+
+void
+ao_packet_slave_start(void);
+
+void
+ao_packet_slave_stop(void);
+