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If no tasks are waiting on the semaphore. In this case, the return value is also 0.
OS_ERR_INT_Q_FULL
If OS_CFG_ISR_POST_DEFERRED_EN is to DEF_ENABLED in os_cfg.h: If the deferred interrupt post queue is full.
OS_ERR_OBJ_PTR_NULL
If OS_CFG_ARG_CHK_EN is set to 1 DEF_ENABLED in os_cfg.h: if p_sem is a NULL pointer.
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If OS_CFG_OBJ_TYPE_CHK_EN is set to 1 in DEF_ENABLED in os_cfg.h: if p_sem is not pointing to a semaphore.
OS_ERR_OPT_INVALID
If OS_CFG_ARG_CHK_EN is set to DEF_ENABLED in os_cfg.h: if a valid option is not specified.
OS_ERR_OS_NOT_RUNNING
If OS_CFG_INVALID_OS_CALLS_CHK_EN is set to DEF_ENABLED in os_cfg.h: if µC/OS-III is not running yet.
OS_ERR_SEM_OVF
If the post would have caused the semaphore counter to overflow.
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OS_CFG_SEM_EN must be enabled in os_cfg.h. Refer to uCµC-OS-III Configuration Manual.
Callers
Application and ISRs.
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