Table C-13 The table below shows the difference in API for semaphore management.
µC/OS-II (os_sem.c) | µC/OS-III (os_sem.c) | Note |
|---|---|---|
INT16UOSSemAccept( OS_EVENT *pevent); | (1) | |
OS_EVENT * OSSemCreate(INT16U INT16U cnt); | voidOSSemCreate( OS_SEM *p_sem, CPU_CHAR *p_name, OS_SEM_CTR cnt, OS_ERR *p_err); | (2) |
OS_EVENT * OSSemDel( OS_EVENT *pevent,
INT8U opt, INT8U *perr); | OS_OBJ_QTY,OSSemDel( OS_SEM *p_sem, OS_OPT opt, OS_ERR *p_err); | |
voidOSSemPend( OS_EVENT *pevent,
INT32U timeout, INT8U *perr); | OS_SEM_CTROSSemPend( OS_SEM *p_sem, OS_TICK timeout, OS_OPT opt, CPU_TS *p_ts, OS_ERR *p_err); | (3)
|
INT8U OSSemPendAbort( OS_EVENT *pevent,
INT8U opt, INT8U *perr); | OS_OBJ_QTYOSSemPendAbort( OS_SEM *p_sem, OS_OPT opt, OS_ERR *p_err); | |
voidOSSemPost( OS_EVENT *pevent); | voidOSSemPost( OS_SEM *p_sem, OS_OPT opt, OS_ERR *p_err); | |
INT8UOSSemQuery( OS_EVENT *pevent, OS_SEM_DATA *p_sem_data); | (4) | |
voidOSSemSet( OS_EVENT *pevent,
INT16U cnt, INT8U *perr); | voidOSSemSet( OS_SEM *p_sem, OS_SEM_CTR cnt, OS_ERR *p_err); |
Table C-13 Semaphore Management API
TC-13(1) In µC/OS-III, there is no “accept” API since this feature is built into the OSSemPend() by specifying the OS_OPT_PEND_NON_BLOCKING option.
TC-13(2) In µC/OS-II, OSSemCreate() returns the address of an OS_EVENT, which is used as the “handle” to the semaphore. In µC/OS-III, the application must allocate storage for an OS_SEM object, 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 semaphores at compile time.
TC-13(3) µC/OS-III returns additional information when a semaphore is signaled. The ISR or task that signals the semaphore takes a snapshot of the current timestamp and stores this in the OS_SEM object signaled. The receiver of the signal therefore knows when the signal was sent.
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