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is a pointer to a variable used to hold an error code:
OS_ERR_NONE
if If the count was changed or, not changed, because one or more tasks was waiting on the semaphore.
OS_ERR_OBJ_PTR_NULL
if If OS_CFG_ARG_CHK_EN is set to 1 in os_cfg.h: if p_sem is a NULL pointer.
OS_ERR_OBJ_TYPE
if If OS_CFG_OBJ_TYPE_CHK_EN is set to 1 in os_cfg.h: if p_sem is not pointing to a semaphore.
OS_ERR_SET_ISR
if If OS_CFG_CALLED_FROM_ISR_CHK_EN set to 1 in os_cfg.h: if this function was called from an ISR.
OS_ERR_TASK_WAITING
if If tasks are waiting on the semaphore.
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