The table below shows the API for message mailbox management. Note that µC/OS-III does not directly provide services for managing message mailboxes. Given that a message mailbox is a message queue of size one, µC/OS-III can easily emulate message mailboxes.
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µC/OS-II (os_mbox.c ) | µC/OS-III (os_q.c ) | Note |
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void *
OSMboxAccept(
OS_EVENT *pevent); |
| (1) | OS_EVENT *
OSMboxCreate(
void *pmsg); | void
OSQCreate(
OS_Q *p_q,
CPU_CHAR *p_name,
OS_MSG_QTY max_qty,
OS_ERR *p_err); | (2) | void *
OSMboxDel(
OS_EVENT *pevent,
INT8U opt,
INT8U *perr); | OS_OBJ_QTY,
OSQDel(
OS_Q *p_q,
OS_OPT opt,
OS_ERR *p_err); |
| void *
OSMboxPend(
OS_EVENT *pevent,
INT32U timeout,
INT8U *perr); | void *
OSQPend(
OS_Q *p_q,
OS_TICK timeout,
OS_OPT opt,
OS_MSG_SIZE *p_msg_size,
CPU_TS *p_ts,
OS_ERR *p_err); | (3) | INT8U
OSMBoxPendAbort(
OS_EVENT *pevent,
INT8U opt,
INT8U *perr); | OS_OBJ_QTY
OSQPendAbort(
OS_Q *p_q,
OS_OPT opt
OS_ERR *p_err); |
| INT8U
OSMboxPost(
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
OSMboxPostOpt(
OS_EVENT *pevent,
void *pmsg,
INT8U opt); |
| (4) | INT8U
OSMboxQuery(
OS_EVENT *pevent,
OS_MBOX_DATA *p_mbox_data); |
| (5) |
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(1) In µC/OS-III, there is no “accept” API since this feature is built into the OSQPend() by specifying the OS_OPT_PEND_NON_BLOCKING option. (2) In µC/OS-II, OSMboxCreate() returns the address of an OS_EVENT , which is used as the “handle” to the message mailbox. In µC/OS-III, the application must allocate storage for an OS_Q , which serves the same purpose as the OS_EVENT . The benefit in µC/OS-III is that it is not necessary to predetermine the number of message queues at compile time. Also, to create the equivalent of a message mailbox, you would specify 1 for the max_qty argument. (3) µC/OS-III returns additional information about the message received. Specifically, the sender specifies the size of the message as a snapshot of the current timestamp is taken and stored as part of the message. The receiver of the message therefore knows when the message was sent. (4) In µC/OS-III, OSQPost() offers a number of options that replaces the two post functions provided in µC/OS-II. (5) µC/OS-III does not provide query services, as they were rarely used in µC/OS-II. |