/* callback to get the buf for receiving commands from USB FIFO */
VBUF* (*get_command_buf)(void);
/* callback when receiving a command */
/* callback to get the buf for receiving commands from USB FIFO */
VBUF* (*get_command_buf)(void);
/* callback when receiving a command */
/* callback to get the buf for event to send to the host */
VBUF* (*get_event_buf)(void);
/* callback to indicate the event has been sent to the host */
void (*send_event_done)(VBUF *buf);
/* callback to get the buf for event to send to the host */
VBUF* (*get_event_buf)(void);
/* callback to indicate the event has been sent to the host */
void (*send_event_done)(VBUF *buf);