(freeRTOS)EventGroup的使用

typedef struct xEventGroupDefinition {
		EventBits_t uxEventBits;
		List_t xTasksWaitingForBits;  
}EventGroup_t;

EventGroupHandle_t xEventGroupCreate( void )
{
EventGroup_t *pxEventBits;

    /* Allocate the event group. */
    pxEventBits = ( EventGroup_t * ) pvPortMalloc( sizeof( EventGroup_t ) );

    if( pxEventBits != NULL )
    {
        pxEventBits->uxEventBits = 0;
        vListInitialise( &( pxEventBits->xTasksWaitingForBits ) );

#if( configSUPPORT_STATIC_ALLOCATION == 1 )
        {
            /* Both static and dynamic allocation can be used, so note this
            event group was allocated statically in case the event group is
            later deleted. */
            pxEventBits->ucStaticallyAllocated = pdFALSE;
        }
#endif /* configSUPPORT_STATIC_ALLOCATION */

        traceEVENT_GROUP_CREATE( pxEventBits );
    }
    else
    {
        traceEVENT_GROUP_CREATE_FAILED();
    }

    return ( EventGroupHandle_t ) pxEventBits;
}

void vEventGroupDelete(EventGroupHandle_t xEventGroup) {
    EventGroup_t *pxEventBits = (EventGroup_t *) xEventGroup;
    const List_t *pxTasksWaitingForBits = &(pxEventBits->xTasksWaitingForBits);

    vTaskSuspendAll();
    {
        traceEVENT_GROUP_DELETE(xEventGroup);

        while (listCURRENT_LIST_LENGTH(pxTasksWaitingForBits) > (UBaseType_t) 0) {
            /* Unblock the task, returning 0 as the event list is being deleted
            and cannot therefore have any bits set. */
            configASSERT(
                    pxTasksWaitingForBits->xListEnd.pxNext != (const ListItem_t *) &(pxTasksWaitingForBits->xListEnd));
            vTaskRemoveFromUnorderedEventList(pxTasksWaitingForBits->xListEnd.pxNext, eventUNBLOCKED_DUE_TO_BIT_SET);
        }

#if((configSUPPORT_DYNAMIC_ALLOCATION == 1) && (configSUPPORT_STATIC_ALLOCATION == 0))
        {
            /* The event group can only have been allocated dynamically - free
            it again. */
            vPortFree( pxEventBits );
        }
#elif((configSUPPORT_DYNAMIC_ALLOCATION == 1) && (configSUPPORT_STATIC_ALLOCATION == 1))
        {
            /* The event group could have been allocated statically or
            dynamically, so check before attempting to free the memory. */
            if( pxEventBits->ucStaticallyAllocated == ( uint8_t ) pdFALSE )
            {
                vPortFree( pxEventBits );
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
#endif /* configSUPPORT_DYNAMIC_ALLOCATION */
    }
    (void) xTaskResumeAll();
}