Table C-11 The table below shows the difference in API for mutual exclusion semaphore management.
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| title | Mutual Exclusion Semaphores API |
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| µC/OS-II (os_mutex.c) | µC/OS-III (os_mutex.c) | Note |
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BOOLEAN |
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OS_ERR *p_err); | (2) | OS_EVENT * |
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OS_MUTEX_DATA *p_mutex_data); |
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Table C-11 Mutual Exclusion Semaphore Management API
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(1) In µC/OS-III, there is no “accept” API, since this feature is built into the OSMutexPend() by specifying the OS_OPT_PEND_NON_BLOCKING option. |
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(2) In µC/OS-II, OSMutexCreate() 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_MUTEX, 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 mutual-exclusion semaphores at compile time. |
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(3) µC/OS-III returns additional information when a mutex is released. The releaser takes a snapshot of the current time stamp and stores it in the OS_MUTEX. The new owner of the mutex therefore knows when the mutex was released. |
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(4) µC/OS-III does not provide query services as they were rarely used. |