os_error_t os_sem_pend(struct os_sem *sem, uint32_t timeout)
Wait for a semaphore for a given amount of time.
| Arguments | Description |
|---|---|
| *sem | Pointer to semaphore |
| timeout | Amount of time, in os ticks, to wait for semaphore. A value of 0 means no wait. A value of 0xFFFFFFFF means wait forever. |
OS_INVALID_PARM: returned when *sem is NULL on entry.
OS_OK: semaphore acquired successfully.
OS_TIMEOUT: the semaphore was not available within the timeout specified.
OS_NOT_STARTED: Attempt to release a semaphore before os started.
If a timeout of 0 is used and the function returns OS_TIMEOUT, the semaphore was not available and was not acquired. No release of the semaphore should occur and the calling task does not own the semaphore.
struct os_sem g_os_sem; os_error_t err; err = os_sem_pend(&g_os_sem, OS_TIMEOUT_NEVER); assert(err == OS_OK); /* Perform operations requiring semaphore lock */ err = os_sem_release(&g_os_sem); assert(err == OS_OK);