EventBits_t xEventGroupWaitBits()

in event_groups.c [317:470]

• 108 lines of code
• 13 McCabe index (conditional complexity)

EventBits_t xEventGroupWaitBits( EventGroupHandle_t xEventGroup,
                                 const EventBits_t uxBitsToWaitFor,
                                 const BaseType_t xClearOnExit,
                                 const BaseType_t xWaitForAllBits,
                                 TickType_t xTicksToWait )
{
    EventGroup_t * pxEventBits = xEventGroup;
    EventBits_t uxReturn, uxControlBits = 0;
    BaseType_t xWaitConditionMet, xAlreadyYielded;
    BaseType_t xTimeoutOccurred = pdFALSE;

    /* Check the user is not attempting to wait on the bits used by the kernel
     * itself, and that at least one bit is being requested. */
    configASSERT( xEventGroup );
    configASSERT( ( uxBitsToWaitFor & eventEVENT_BITS_CONTROL_BYTES ) == 0 );
    configASSERT( uxBitsToWaitFor != 0 );
    #if ( ( INCLUDE_xTaskGetSchedulerState == 1 ) || ( configUSE_TIMERS == 1 ) )
    {
        configASSERT( !( ( xTaskGetSchedulerState() == taskSCHEDULER_SUSPENDED ) && ( xTicksToWait != 0 ) ) );
    }
    #endif

    vTaskSuspendAll();
    {
        const EventBits_t uxCurrentEventBits = pxEventBits->uxEventBits;

        /* Check to see if the wait condition is already met or not. */
        xWaitConditionMet = prvTestWaitCondition( uxCurrentEventBits, uxBitsToWaitFor, xWaitForAllBits );

        if( xWaitConditionMet != pdFALSE )
        {
            /* The wait condition has already been met so there is no need to
             * block. */
            uxReturn = uxCurrentEventBits;
            xTicksToWait = ( TickType_t ) 0;

            /* Clear the wait bits if requested to do so. */
            if( xClearOnExit != pdFALSE )
            {
                pxEventBits->uxEventBits &= ~uxBitsToWaitFor;
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
        else if( xTicksToWait == ( TickType_t ) 0 )
        {
            /* The wait condition has not been met, but no block time was
             * specified, so just return the current value. */
            uxReturn = uxCurrentEventBits;
            xTimeoutOccurred = pdTRUE;
        }
        else
        {
            /* The task is going to block to wait for its required bits to be
             * set.  uxControlBits are used to remember the specified behaviour of
             * this call to xEventGroupWaitBits() - for use when the event bits
             * unblock the task. */
            if( xClearOnExit != pdFALSE )
            {
                uxControlBits |= eventCLEAR_EVENTS_ON_EXIT_BIT;
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }

            if( xWaitForAllBits != pdFALSE )
            {
                uxControlBits |= eventWAIT_FOR_ALL_BITS;
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }

            /* Store the bits that the calling task is waiting for in the
             * task's event list item so the kernel knows when a match is
             * found.  Then enter the blocked state. */
            vTaskPlaceOnUnorderedEventList( &( pxEventBits->xTasksWaitingForBits ), ( uxBitsToWaitFor | uxControlBits ), xTicksToWait );

            /* This is obsolete as it will get set after the task unblocks, but
             * some compilers mistakenly generate a warning about the variable
             * being returned without being set if it is not done. */
            uxReturn = 0;

            traceEVENT_GROUP_WAIT_BITS_BLOCK( xEventGroup, uxBitsToWaitFor );
        }
    }
    xAlreadyYielded = xTaskResumeAll();

    if( xTicksToWait != ( TickType_t ) 0 )
    {
        if( xAlreadyYielded == pdFALSE )
        {
            portYIELD_WITHIN_API();
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }

        /* The task blocked to wait for its required bits to be set - at this
         * point either the required bits were set or the block time expired.  If
         * the required bits were set they will have been stored in the task's
         * event list item, and they should now be retrieved then cleared. */
        uxReturn = uxTaskResetEventItemValue();

        if( ( uxReturn & eventUNBLOCKED_DUE_TO_BIT_SET ) == ( EventBits_t ) 0 )
        {
            taskENTER_CRITICAL();
            {
                /* The task timed out, just return the current event bit value. */
                uxReturn = pxEventBits->uxEventBits;

                /* It is possible that the event bits were updated between this
                 * task leaving the Blocked state and running again. */
                if( prvTestWaitCondition( uxReturn, uxBitsToWaitFor, xWaitForAllBits ) != pdFALSE )
                {
                    if( xClearOnExit != pdFALSE )
                    {
                        pxEventBits->uxEventBits &= ~uxBitsToWaitFor;
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }

                xTimeoutOccurred = pdTRUE;
            }
            taskEXIT_CRITICAL();
        }
        else
        {
            /* The task unblocked because the bits were set. */
        }

        /* The task blocked so control bits may have been set. */
        uxReturn &= ~eventEVENT_BITS_CONTROL_BYTES;
    }

    traceEVENT_GROUP_WAIT_BITS_END( xEventGroup, uxBitsToWaitFor, xTimeoutOccurred );

    /* Prevent compiler warnings when trace macros are not used. */
    ( void ) xTimeoutOccurred;

    return uxReturn;
}