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Message Queues API Changes

Message Queues API Changes

Mar 23, 2021

This table shows the difference in API for message-queue management.

Message Queues API

µC/OS-II (os_q.c)

µC/OS-III (os_q.c)

Note

void * OSQAccept( OS_EVENT *pevent, INT8U *perr);

(1)

OS_EVENT * OSQCreate( void **start, INT16U size);

void OSQCreate( OS_Q *p_q, CPU_CHAR *p_name, OS_MSG_QTY max_qty, OS_ERR *p_err);

(2)

OS_EVENT * OSQDel( OS_EVENT *pevent, INT8U opt, INT8U *perr);

OS_OBJ_QTY, OSQDel( OS_Q *p_q, OS_OPT opt, OS_ERR *p_err);

INT8U OSQFlush( OS_EVENT *pevent);

OS_MSG_QTY OSQFlush( OS_Q *p_q, OS_ERR *p_err);

void * OSQPend( OS_EVENT *pevent, INT32U timeout, INT8U *perr);

void * OSQPend( OS_Q *p_q, OS_MSG_SIZE *p_msg_size, OS_TICK timeout, OS_OPT opt, CPU_TS *p_ts, OS_ERR *p_err);

(3)

INT8U OSQPendAbort( OS_EVENT *pevent, INT8U opt, INT8U *perr);

OS_OBJ_QTY OSQPendAbort( OS_Q *p_q, OS_OPT opt, OS_ERR *p_err);

INT8U OSQPost( OS_EVENT *pevent, void *pmsg);

void OSQPost( OS_Q *p_q, void *p_void, OS_MSG_SIZE msg_size, OS_OPT opt, OS_ERR *p_err);

(4)

INT8U OSQPostFront( OS_EVENT *pevent, void *pmsg);

INT8U OSQPostOpt( OS_EVENT *pevent, void *pmsg, INT8U opt);

(4)

INT8U OSQQuery( OS_EVENT *pevent, OS_Q_DATA *p_q_data);

(5)

(1) In µC/OS-III, there is no “accept” API as this feature is built into the OSQPend() by specifying the OS_OPT_PEND_NON_BLOCKING option.

(2) In µC/OS-II, OSQCreate() returns the address of an OS_EVENT, which is used as the “handle” to the message queue. In µC/OS-III, the application must allocate storage for an OS_Q object, which serves the same purpose as the OS_EVENT. The benefit in µC/OS-III is that it is not necessary to predetermine at compile time, the number of message queues.

(3) µC/OS-III returns additional information when a message queue is posted. Specifically, the sender includes the size of the message and takes a snapshot of the current timestamp and stores it in the message. The receiver of the message therefore knows when the message was posted.

(4) In µC/OS-III, OSQPost() offers a number of options that replaces the three post functions provided in µC/OS-II.

(5) µC/OS-III does not provide query services as they were rarely used.