queue.c

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/*
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    VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation >>>> AND MODIFIED BY <<<< the FreeRTOS exception.

    ***************************************************************************
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    >>!   outside of the FreeRTOS kernel.                                   !<<
    ***************************************************************************

    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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    ***************************************************************************
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*/

#include <stdlib.h>
#include <string.h>

/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
all the API functions to use the MPU wrappers.  That should only be done when
task.h is included from an application file. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE

#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"

#if ( configUSE_CO_ROUTINES == 1 )
    #include "croutine.h"
#endif

/* Lint e961 and e750 are suppressed as a MISRA exception justified because the
MPU ports require MPU_WRAPPERS_INCLUDED_FROM_API_FILE to be defined for the
header files above, but not in this file, in order to generate the correct
privileged Vs unprivileged linkage and placement. */
#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE /*lint !e961 !e750. */


/* Constants used with the xRxLock and xTxLock structure members. */
#define queueUNLOCKED                   ( ( BaseType_t ) -1 )
#define queueLOCKED_UNMODIFIED          ( ( BaseType_t ) 0 )

/* When the Queue_t structure is used to represent a base queue its pcHead and
pcTail members are used as pointers into the queue storage area.  When the
Queue_t structure is used to represent a mutex pcHead and pcTail pointers are
not necessary, and the pcHead pointer is set to NULL to indicate that the
pcTail pointer actually points to the mutex holder (if any).  Map alternative
names to the pcHead and pcTail structure members to ensure the readability of
the code is maintained despite this dual use of two structure members.  An
alternative implementation would be to use a union, but use of a union is
against the coding standard (although an exception to the standard has been
permitted where the dual use also significantly changes the type of the
structure member). */
#define pxMutexHolder                   pcTail
#define uxQueueType                     pcHead
#define queueQUEUE_IS_MUTEX             NULL

/* Semaphores do not actually store or copy data, so have an item size of
zero. */
#define queueSEMAPHORE_QUEUE_ITEM_LENGTH ( ( UBaseType_t ) 0 )
#define queueMUTEX_GIVE_BLOCK_TIME       ( ( TickType_t ) 0U )

#if( configUSE_PREEMPTION == 0 )
    /* If the cooperative scheduler is being used then a yield should not be
    performed just because a higher priority task has been woken. */
    #define queueYIELD_IF_USING_PREEMPTION()
#else
    #define queueYIELD_IF_USING_PREEMPTION() portYIELD_WITHIN_API()
#endif

/*
 * Definition of the queue used by the scheduler.
 * Items are queued by copy, not reference.  See the following link for the
 * rationale: http://www.freertos.org/Embedded-RTOS-Queues.html
 */
typedef struct QueueDefinition
{
    int8_t *pcHead;                 /*< Points to the beginning of the queue storage area. */
    int8_t *pcTail;                 /*< Points to the byte at the end of the queue storage area.  Once more byte is allocated than necessary to store the queue items, this is used as a marker. */
    int8_t *pcWriteTo;              /*< Points to the free next place in the storage area. */

    union                           /* Use of a union is an exception to the coding standard to ensure two mutually exclusive structure members don't appear simultaneously (wasting RAM). */
    {
        int8_t *pcReadFrom;         /*< Points to the last place that a queued item was read from when the structure is used as a queue. */
        UBaseType_t uxRecursiveCallCount;/*< Maintains a count of the number of times a recursive mutex has been recursively 'taken' when the structure is used as a mutex. */
    } u;

    List_t xTasksWaitingToSend;     /*< List of tasks that are blocked waiting to post onto this queue.  Stored in priority order. */
    List_t xTasksWaitingToReceive;  /*< List of tasks that are blocked waiting to read from this queue.  Stored in priority order. */

    volatile UBaseType_t uxMessagesWaiting;/*< The number of items currently in the queue. */
    UBaseType_t uxLength;           /*< The length of the queue defined as the number of items it will hold, not the number of bytes. */
    UBaseType_t uxItemSize;         /*< The size of each items that the queue will hold. */

    volatile BaseType_t xRxLock;    /*< Stores the number of items received from the queue (removed from the queue) while the queue was locked.  Set to queueUNLOCKED when the queue is not locked. */
    volatile BaseType_t xTxLock;    /*< Stores the number of items transmitted to the queue (added to the queue) while the queue was locked.  Set to queueUNLOCKED when the queue is not locked. */

    #if ( configUSE_TRACE_FACILITY == 1 )
        UBaseType_t uxQueueNumber;
        uint8_t ucQueueType;
    #endif

    #if ( configUSE_QUEUE_SETS == 1 )
        struct QueueDefinition *pxQueueSetContainer;
    #endif

} xQUEUE;

/* The old xQUEUE name is maintained above then typedefed to the new Queue_t
name below to enable the use of older kernel aware debuggers. */
typedef xQUEUE Queue_t;

/*-----------------------------------------------------------*/

/*
 * The queue registry is just a means for kernel aware debuggers to locate
 * queue structures.  It has no other purpose so is an optional component.
 */
#if ( configQUEUE_REGISTRY_SIZE > 0 )

    /* The type stored within the queue registry array.  This allows a name
    to be assigned to each queue making kernel aware debugging a little
    more user friendly. */
    typedef struct QUEUE_REGISTRY_ITEM
    {
        const char *pcQueueName; /*lint !e971 Unqualified char types are allowed for strings and single characters only. */
        QueueHandle_t xHandle;
    } xQueueRegistryItem;

    /* The old xQueueRegistryItem name is maintained above then typedefed to the
    new xQueueRegistryItem name below to enable the use of older kernel aware
    debuggers. */
    typedef xQueueRegistryItem QueueRegistryItem_t;

    /* The queue registry is simply an array of QueueRegistryItem_t structures.
    The pcQueueName member of a structure being NULL is indicative of the
    array position being vacant. */
    PRIVILEGED_DATA QueueRegistryItem_t xQueueRegistry[ configQUEUE_REGISTRY_SIZE ];

#endif /* configQUEUE_REGISTRY_SIZE */

/*
 * Unlocks a queue locked by a call to prvLockQueue.  Locking a queue does not
 * prevent an ISR from adding or removing items to the queue, but does prevent
 * an ISR from removing tasks from the queue event lists.  If an ISR finds a
 * queue is locked it will instead increment the appropriate queue lock count
 * to indicate that a task may require unblocking.  When the queue in unlocked
 * these lock counts are inspected, and the appropriate action taken.
 */
static void prvUnlockQueue( Queue_t * const pxQueue ) PRIVILEGED_FUNCTION;

/*
 * Uses a critical section to determine if there is any data in a queue.
 *
 * @return pdTRUE if the queue contains no items, otherwise pdFALSE.
 */
static BaseType_t prvIsQueueEmpty( const Queue_t *pxQueue ) PRIVILEGED_FUNCTION;

/*
 * Uses a critical section to determine if there is any space in a queue.
 *
 * @return pdTRUE if there is no space, otherwise pdFALSE;
 */
static BaseType_t prvIsQueueFull( const Queue_t *pxQueue ) PRIVILEGED_FUNCTION;

/*
 * Copies an item into the queue, either at the front of the queue or the
 * back of the queue.
 */
static BaseType_t prvCopyDataToQueue( Queue_t * const pxQueue, const void *pvItemToQueue, const BaseType_t xPosition ) PRIVILEGED_FUNCTION;

/*
 * Copies an item out of a queue.
 */
static void prvCopyDataFromQueue( Queue_t * const pxQueue, void * const pvBuffer ) PRIVILEGED_FUNCTION;

#if ( configUSE_QUEUE_SETS == 1 )
    /*
     * Checks to see if a queue is a member of a queue set, and if so, notifies
     * the queue set that the queue contains data.
     */
    static BaseType_t prvNotifyQueueSetContainer( const Queue_t * const pxQueue, const BaseType_t xCopyPosition ) PRIVILEGED_FUNCTION;
#endif

/*-----------------------------------------------------------*/

/*
 * Macro to mark a queue as locked.  Locking a queue prevents an ISR from
 * accessing the queue event lists.
 */
#define prvLockQueue( pxQueue )                             \
    taskENTER_CRITICAL();                                   \
    {                                                       \
        if( ( pxQueue )->xRxLock == queueUNLOCKED )         \
        {                                                   \
            ( pxQueue )->xRxLock = queueLOCKED_UNMODIFIED;  \
        }                                                   \
        if( ( pxQueue )->xTxLock == queueUNLOCKED )         \
        {                                                   \
            ( pxQueue )->xTxLock = queueLOCKED_UNMODIFIED;  \
        }                                                   \
    }                                                       \
    taskEXIT_CRITICAL()
/*-----------------------------------------------------------*/

BaseType_t xQueueGenericReset( QueueHandle_t xQueue, BaseType_t xNewQueue )
{
Queue_t * const pxQueue = ( Queue_t * ) xQueue;

    configASSERT( pxQueue );

    taskENTER_CRITICAL();
    {
        pxQueue->pcTail = pxQueue->pcHead + ( pxQueue->uxLength * pxQueue->uxItemSize );
        pxQueue->uxMessagesWaiting = ( UBaseType_t ) 0U;
        pxQueue->pcWriteTo = pxQueue->pcHead;
        pxQueue->u.pcReadFrom = pxQueue->pcHead + ( ( pxQueue->uxLength - ( UBaseType_t ) 1U ) * pxQueue->uxItemSize );
        pxQueue->xRxLock = queueUNLOCKED;
        pxQueue->xTxLock = queueUNLOCKED;

        if( xNewQueue == pdFALSE )
        {
            /* If there are tasks blocked waiting to read from the queue, then
            the tasks will remain blocked as after this function exits the queue
            will still be empty.  If there are tasks blocked waiting to write to
            the queue, then one should be unblocked as after this function exits
            it will be possible to write to it. */
            if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
            {
                if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) == pdTRUE )
                {
                    queueYIELD_IF_USING_PREEMPTION();
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
        else
        {
            /* Ensure the event queues start in the correct state. */
            vListInitialise( &( pxQueue->xTasksWaitingToSend ) );
            vListInitialise( &( pxQueue->xTasksWaitingToReceive ) );
        }
    }
    taskEXIT_CRITICAL();

    /* A value is returned for calling semantic consistency with previous
    versions. */
    return pdPASS;
}
/*-----------------------------------------------------------*/

QueueHandle_t xQueueGenericCreate( const UBaseType_t uxQueueLength, const UBaseType_t uxItemSize, const uint8_t ucQueueType )
{
Queue_t *pxNewQueue;
size_t xQueueSizeInBytes;
QueueHandle_t xReturn = NULL;

    /* Remove compiler warnings about unused parameters should
    configUSE_TRACE_FACILITY not be set to 1. */
    ( void ) ucQueueType;

    configASSERT( uxQueueLength > ( UBaseType_t ) 0 );

    if( uxItemSize == ( UBaseType_t ) 0 )
    {
        /* There is not going to be a queue storage area. */
        xQueueSizeInBytes = ( size_t ) 0;
    }
    else
    {
        /* The queue is one byte longer than asked for to make wrap checking
        easier/faster. */
        xQueueSizeInBytes = ( size_t ) ( uxQueueLength * uxItemSize ) + ( size_t ) 1; /*lint !e961 MISRA exception as the casts are only redundant for some ports. */
    }

    /* Allocate the new queue structure and storage area. */
    pxNewQueue = ( Queue_t * ) pvPortMalloc( sizeof( Queue_t ) + xQueueSizeInBytes );

    if( pxNewQueue != NULL )
    {
        if( uxItemSize == ( UBaseType_t ) 0 )
        {
            /* No RAM was allocated for the queue storage area, but PC head
            cannot be set to NULL because NULL is used as a key to say the queue
            is used as a mutex.  Therefore just set pcHead to point to the queue
            as a benign value that is known to be within the memory map. */
            pxNewQueue->pcHead = ( int8_t * ) pxNewQueue;
        }
        else
        {
            /* Jump past the queue structure to find the location of the queue
            storage area. */
            pxNewQueue->pcHead = ( ( int8_t * ) pxNewQueue ) + sizeof( Queue_t );
        }

        /* Initialise the queue members as described above where the queue type
        is defined. */
        pxNewQueue->uxLength = uxQueueLength;
        pxNewQueue->uxItemSize = uxItemSize;
        ( void ) xQueueGenericReset( pxNewQueue, pdTRUE );

        #if ( configUSE_TRACE_FACILITY == 1 )
        {
            pxNewQueue->ucQueueType = ucQueueType;
        }
        #endif /* configUSE_TRACE_FACILITY */

        #if( configUSE_QUEUE_SETS == 1 )
        {
            pxNewQueue->pxQueueSetContainer = NULL;
        }
        #endif /* configUSE_QUEUE_SETS */

        traceQUEUE_CREATE( pxNewQueue );
        xReturn = pxNewQueue;
    }
    else
    {
        mtCOVERAGE_TEST_MARKER();
    }

    configASSERT( xReturn );

    return xReturn;
}
/*-----------------------------------------------------------*/

#if ( configUSE_MUTEXES == 1 )

    QueueHandle_t xQueueCreateMutex( const uint8_t ucQueueType )
    {
    Queue_t *pxNewQueue;

        /* Prevent compiler warnings about unused parameters if
        configUSE_TRACE_FACILITY does not equal 1. */
        ( void ) ucQueueType;

        /* Allocate the new queue structure. */
        pxNewQueue = ( Queue_t * ) pvPortMalloc( sizeof( Queue_t ) );
        if( pxNewQueue != NULL )
        {
            /* Information required for priority inheritance. */
            pxNewQueue->pxMutexHolder = NULL;
            pxNewQueue->uxQueueType = queueQUEUE_IS_MUTEX;

            /* Queues used as a mutex no data is actually copied into or out
            of the queue. */
            pxNewQueue->pcWriteTo = NULL;
            pxNewQueue->u.pcReadFrom = NULL;

            /* Each mutex has a length of 1 (like a binary semaphore) and
            an item size of 0 as nothing is actually copied into or out
            of the mutex. */
            pxNewQueue->uxMessagesWaiting = ( UBaseType_t ) 0U;
            pxNewQueue->uxLength = ( UBaseType_t ) 1U;
            pxNewQueue->uxItemSize = ( UBaseType_t ) 0U;
            pxNewQueue->xRxLock = queueUNLOCKED;
            pxNewQueue->xTxLock = queueUNLOCKED;

            #if ( configUSE_TRACE_FACILITY == 1 )
            {
                pxNewQueue->ucQueueType = ucQueueType;
            }
            #endif

            #if ( configUSE_QUEUE_SETS == 1 )
            {
                pxNewQueue->pxQueueSetContainer = NULL;
            }
            #endif

            /* Ensure the event queues start with the correct state. */
            vListInitialise( &( pxNewQueue->xTasksWaitingToSend ) );
            vListInitialise( &( pxNewQueue->xTasksWaitingToReceive ) );

            traceCREATE_MUTEX( pxNewQueue );

            /* Start with the semaphore in the expected state. */
            ( void ) xQueueGenericSend( pxNewQueue, NULL, ( TickType_t ) 0U, queueSEND_TO_BACK );
        }
        else
        {
            traceCREATE_MUTEX_FAILED();
        }

        return pxNewQueue;
    }

#endif /* configUSE_MUTEXES */
/*-----------------------------------------------------------*/

#if ( ( configUSE_MUTEXES == 1 ) && ( INCLUDE_xSemaphoreGetMutexHolder == 1 ) )

    void* xQueueGetMutexHolder( QueueHandle_t xSemaphore )
    {
    void *pxReturn;

        /* This function is called by xSemaphoreGetMutexHolder(), and should not
        be called directly.  Note:  This is a good way of determining if the
        calling task is the mutex holder, but not a good way of determining the
        identity of the mutex holder, as the holder may change between the
        following critical section exiting and the function returning. */
        taskENTER_CRITICAL();
        {
            if( ( ( Queue_t * ) xSemaphore )->uxQueueType == queueQUEUE_IS_MUTEX )
            {
                pxReturn = ( void * ) ( ( Queue_t * ) xSemaphore )->pxMutexHolder;
            }
            else
            {
                pxReturn = NULL;
            }
        }
        taskEXIT_CRITICAL();

        return pxReturn;
    } /*lint !e818 xSemaphore cannot be a pointer to const because it is a typedef. */

#endif
/*-----------------------------------------------------------*/

#if ( configUSE_RECURSIVE_MUTEXES == 1 )

    BaseType_t xQueueGiveMutexRecursive( QueueHandle_t xMutex )
    {
    BaseType_t xReturn;
    Queue_t * const pxMutex = ( Queue_t * ) xMutex;

        configASSERT( pxMutex );

        /* If this is the task that holds the mutex then pxMutexHolder will not
        change outside of this task.  If this task does not hold the mutex then
        pxMutexHolder can never coincidentally equal the tasks handle, and as
        this is the only condition we are interested in it does not matter if
        pxMutexHolder is accessed simultaneously by another task.  Therefore no
        mutual exclusion is required to test the pxMutexHolder variable. */
        if( pxMutex->pxMutexHolder == ( void * ) xTaskGetCurrentTaskHandle() ) /*lint !e961 Not a redundant cast as TaskHandle_t is a typedef. */
        {
            traceGIVE_MUTEX_RECURSIVE( pxMutex );

            /* uxRecursiveCallCount cannot be zero if pxMutexHolder is equal to
            the task handle, therefore no underflow check is required.  Also,
            uxRecursiveCallCount is only modified by the mutex holder, and as
            there can only be one, no mutual exclusion is required to modify the
            uxRecursiveCallCount member. */
            ( pxMutex->u.uxRecursiveCallCount )--;

            /* Have we unwound the call count? */
            if( pxMutex->u.uxRecursiveCallCount == ( UBaseType_t ) 0 )
            {
                /* Return the mutex.  This will automatically unblock any other
                task that might be waiting to access the mutex. */
                ( void ) xQueueGenericSend( pxMutex, NULL, queueMUTEX_GIVE_BLOCK_TIME, queueSEND_TO_BACK );
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }

            xReturn = pdPASS;
        }
        else
        {
            /* The mutex cannot be given because the calling task is not the
            holder. */
            xReturn = pdFAIL;

            traceGIVE_MUTEX_RECURSIVE_FAILED( pxMutex );
        }

        return xReturn;
    }

#endif /* configUSE_RECURSIVE_MUTEXES */
/*-----------------------------------------------------------*/

#if ( configUSE_RECURSIVE_MUTEXES == 1 )

    BaseType_t xQueueTakeMutexRecursive( QueueHandle_t xMutex, TickType_t xTicksToWait )
    {
    BaseType_t xReturn;
    Queue_t * const pxMutex = ( Queue_t * ) xMutex;

        configASSERT( pxMutex );

        /* Comments regarding mutual exclusion as per those within
        xQueueGiveMutexRecursive(). */

        traceTAKE_MUTEX_RECURSIVE( pxMutex );

        if( pxMutex->pxMutexHolder == ( void * ) xTaskGetCurrentTaskHandle() ) /*lint !e961 Cast is not redundant as TaskHandle_t is a typedef. */
        {
            ( pxMutex->u.uxRecursiveCallCount )++;
            xReturn = pdPASS;
        }
        else
        {
            xReturn = xQueueGenericReceive( pxMutex, NULL, xTicksToWait, pdFALSE );

            /* pdPASS will only be returned if the mutex was successfully
            obtained.  The calling task may have entered the Blocked state
            before reaching here. */
            if( xReturn == pdPASS )
            {
                ( pxMutex->u.uxRecursiveCallCount )++;
            }
            else
            {
                traceTAKE_MUTEX_RECURSIVE_FAILED( pxMutex );
            }
        }

        return xReturn;
    }

#endif /* configUSE_RECURSIVE_MUTEXES */
/*-----------------------------------------------------------*/

#if ( configUSE_COUNTING_SEMAPHORES == 1 )

    QueueHandle_t xQueueCreateCountingSemaphore( const UBaseType_t uxMaxCount, const UBaseType_t uxInitialCount )
    {
    QueueHandle_t xHandle;

        configASSERT( uxMaxCount != 0 );
        configASSERT( uxInitialCount <= uxMaxCount );

        xHandle = xQueueGenericCreate( uxMaxCount, queueSEMAPHORE_QUEUE_ITEM_LENGTH, queueQUEUE_TYPE_COUNTING_SEMAPHORE );

        if( xHandle != NULL )
        {
            ( ( Queue_t * ) xHandle )->uxMessagesWaiting = uxInitialCount;

            traceCREATE_COUNTING_SEMAPHORE();
        }
        else
        {
            traceCREATE_COUNTING_SEMAPHORE_FAILED();
        }

        configASSERT( xHandle );
        return xHandle;
    }

#endif /* configUSE_COUNTING_SEMAPHORES */
/*-----------------------------------------------------------*/

BaseType_t xQueueGenericSend( QueueHandle_t xQueue, const void * const pvItemToQueue, TickType_t xTicksToWait, const BaseType_t xCopyPosition )
{
BaseType_t xEntryTimeSet = pdFALSE, xYieldRequired;
TimeOut_t xTimeOut;
Queue_t * const pxQueue = ( Queue_t * ) xQueue;

    configASSERT( pxQueue );
    configASSERT( !( ( pvItemToQueue == NULL ) && ( pxQueue->uxItemSize != ( UBaseType_t ) 0U ) ) );
    configASSERT( !( ( xCopyPosition == queueOVERWRITE ) && ( pxQueue->uxLength != 1 ) ) );
    #if ( ( INCLUDE_xTaskGetSchedulerState == 1 ) || ( configUSE_TIMERS == 1 ) )
    {
        configASSERT( !( ( xTaskGetSchedulerState() == taskSCHEDULER_SUSPENDED ) && ( xTicksToWait != 0 ) ) );
    }
    #endif


    /* This function relaxes the coding standard somewhat to allow return
    statements within the function itself.  This is done in the interest
    of execution time efficiency. */
    for( ;; )
    {
        taskENTER_CRITICAL();
        {
            /* Is there room on the queue now?  The running task must be the
            highest priority task wanting to access the queue.  If the head item
            in the queue is to be overwritten then it does not matter if the
            queue is full. */
            if( ( pxQueue->uxMessagesWaiting < pxQueue->uxLength ) || ( xCopyPosition == queueOVERWRITE ) )
            {
                traceQUEUE_SEND( pxQueue );
                xYieldRequired = prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );

                #if ( configUSE_QUEUE_SETS == 1 )
                {
                    if( pxQueue->pxQueueSetContainer != NULL )
                    {
                        if( prvNotifyQueueSetContainer( pxQueue, xCopyPosition ) == pdTRUE )
                        {
                            /* The queue is a member of a queue set, and posting
                            to the queue set caused a higher priority task to
                            unblock. A context switch is required. */
                            queueYIELD_IF_USING_PREEMPTION();
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        /* If there was a task waiting for data to arrive on the
                        queue then unblock it now. */
                        if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                        {
                            if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) == pdTRUE )
                            {
                                /* The unblocked task has a priority higher than
                                our own so yield immediately.  Yes it is ok to
                                do this from within the critical section - the
                                kernel takes care of that. */
                                queueYIELD_IF_USING_PREEMPTION();
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        else if( xYieldRequired != pdFALSE )
                        {
                            /* This path is a special case that will only get
                            executed if the task was holding multiple mutexes
                            and the mutexes were given back in an order that is
                            different to that in which they were taken. */
                            queueYIELD_IF_USING_PREEMPTION();
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                }
                #else /* configUSE_QUEUE_SETS */
                {
                    /* If there was a task waiting for data to arrive on the
                    queue then unblock it now. */
                    if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                    {
                        if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) == pdTRUE )
                        {
                            /* The unblocked task has a priority higher than
                            our own so yield immediately.  Yes it is ok to do
                            this from within the critical section - the kernel
                            takes care of that. */
                            queueYIELD_IF_USING_PREEMPTION();
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else if( xYieldRequired != pdFALSE )
                    {
                        /* This path is a special case that will only get
                        executed if the task was holding multiple mutexes and
                        the mutexes were given back in an order that is
                        different to that in which they were taken. */
                        queueYIELD_IF_USING_PREEMPTION();
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                #endif /* configUSE_QUEUE_SETS */

                taskEXIT_CRITICAL();
                return pdPASS;
            }
            else
            {
                if( xTicksToWait == ( TickType_t ) 0 )
                {
                    /* The queue was full and no block time is specified (or
                    the block time has expired) so leave now. */
                    taskEXIT_CRITICAL();

                    /* Return to the original privilege level before exiting
                    the function. */
                    traceQUEUE_SEND_FAILED( pxQueue );
                    return errQUEUE_FULL;
                }
                else if( xEntryTimeSet == pdFALSE )
                {
                    /* The queue was full and a block time was specified so
                    configure the timeout structure. */
                    vTaskSetTimeOutState( &xTimeOut );
                    xEntryTimeSet = pdTRUE;
                }
                else
                {
                    /* Entry time was already set. */
                    mtCOVERAGE_TEST_MARKER();
                }
            }
        }
        taskEXIT_CRITICAL();

        /* Interrupts and other tasks can send to and receive from the queue
        now the critical section has been exited. */

        vTaskSuspendAll();
        prvLockQueue( pxQueue );

        /* Update the timeout state to see if it has expired yet. */
        if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
        {
            if( prvIsQueueFull( pxQueue ) != pdFALSE )
            {
                traceBLOCKING_ON_QUEUE_SEND( pxQueue );
                vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToSend ), xTicksToWait );

                /* Unlocking the queue means queue events can effect the
                event list.  It is possible that interrupts occurring now
                remove this task from the event list again - but as the
                scheduler is suspended the task will go onto the pending
                ready last instead of the actual ready list. */
                prvUnlockQueue( pxQueue );

                /* Resuming the scheduler will move tasks from the pending
                ready list into the ready list - so it is feasible that this
                task is already in a ready list before it yields - in which
                case the yield will not cause a context switch unless there
                is also a higher priority task in the pending ready list. */
                if( xTaskResumeAll() == pdFALSE )
                {
                    portYIELD_WITHIN_API();
                }
            }
            else
            {
                /* Try again. */
                prvUnlockQueue( pxQueue );
                ( void ) xTaskResumeAll();
            }
        }
        else
        {
            /* The timeout has expired. */
            prvUnlockQueue( pxQueue );
            ( void ) xTaskResumeAll();

            /* Return to the original privilege level before exiting the
            function. */
            traceQUEUE_SEND_FAILED( pxQueue );
            return errQUEUE_FULL;
        }
    }
}
/*-----------------------------------------------------------*/

#if ( configUSE_ALTERNATIVE_API == 1 )

    BaseType_t xQueueAltGenericSend( QueueHandle_t xQueue, const void * const pvItemToQueue, TickType_t xTicksToWait, BaseType_t xCopyPosition )
    {
    BaseType_t xEntryTimeSet = pdFALSE;
    TimeOut_t xTimeOut;
    Queue_t * const pxQueue = ( Queue_t * ) xQueue;

        configASSERT( pxQueue );
        configASSERT( !( ( pvItemToQueue == NULL ) && ( pxQueue->uxItemSize != ( UBaseType_t ) 0U ) ) );

        for( ;; )
        {
            taskENTER_CRITICAL();
            {
                /* Is there room on the queue now?  To be running we must be
                the highest priority task wanting to access the queue. */
                if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
                {
                    traceQUEUE_SEND( pxQueue );
                    prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );

                    /* If there was a task waiting for data to arrive on the
                    queue then unblock it now. */
                    if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                    {
                        if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) == pdTRUE )
                        {
                            /* The unblocked task has a priority higher than
                            our own so yield immediately. */
                            portYIELD_WITHIN_API();
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }

                    taskEXIT_CRITICAL();
                    return pdPASS;
                }
                else
                {
                    if( xTicksToWait == ( TickType_t ) 0 )
                    {
                        taskEXIT_CRITICAL();
                        return errQUEUE_FULL;
                    }
                    else if( xEntryTimeSet == pdFALSE )
                    {
                        vTaskSetTimeOutState( &xTimeOut );
                        xEntryTimeSet = pdTRUE;
                    }
                }
            }
            taskEXIT_CRITICAL();

            taskENTER_CRITICAL();
            {
                if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
                {
                    if( prvIsQueueFull( pxQueue ) != pdFALSE )
                    {
                        traceBLOCKING_ON_QUEUE_SEND( pxQueue );
                        vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToSend ), xTicksToWait );
                        portYIELD_WITHIN_API();
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    taskEXIT_CRITICAL();
                    traceQUEUE_SEND_FAILED( pxQueue );
                    return errQUEUE_FULL;
                }
            }
            taskEXIT_CRITICAL();
        }
    }

#endif /* configUSE_ALTERNATIVE_API */
/*-----------------------------------------------------------*/

#if ( configUSE_ALTERNATIVE_API == 1 )

    BaseType_t xQueueAltGenericReceive( QueueHandle_t xQueue, void * const pvBuffer, TickType_t xTicksToWait, BaseType_t xJustPeeking )
    {
    BaseType_t xEntryTimeSet = pdFALSE;
    TimeOut_t xTimeOut;
    int8_t *pcOriginalReadPosition;
    Queue_t * const pxQueue = ( Queue_t * ) xQueue;

        configASSERT( pxQueue );
        configASSERT( !( ( pvBuffer == NULL ) && ( pxQueue->uxItemSize != ( UBaseType_t ) 0U ) ) );

        for( ;; )
        {
            taskENTER_CRITICAL();
            {
                if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
                {
                    /* Remember our read position in case we are just peeking. */
                    pcOriginalReadPosition = pxQueue->u.pcReadFrom;

                    prvCopyDataFromQueue( pxQueue, pvBuffer );

                    if( xJustPeeking == pdFALSE )
                    {
                        traceQUEUE_RECEIVE( pxQueue );

                        /* Data is actually being removed (not just peeked). */
                        --( pxQueue->uxMessagesWaiting );

                        #if ( configUSE_MUTEXES == 1 )
                        {
                            if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
                            {
                                /* Record the information required to implement
                                priority inheritance should it become necessary. */
                                pxQueue->pxMutexHolder = ( int8_t * ) xTaskGetCurrentTaskHandle();
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        #endif

                        if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
                        {
                            if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) == pdTRUE )
                            {
                                portYIELD_WITHIN_API();
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                    }
                    else
                    {
                        traceQUEUE_PEEK( pxQueue );

                        /* The data is not being removed, so reset our read
                        pointer. */
                        pxQueue->u.pcReadFrom = pcOriginalReadPosition;

                        /* The data is being left in the queue, so see if there are
                        any other tasks waiting for the data. */
                        if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                        {
                            /* Tasks that are removed from the event list will get added to
                            the pending ready list as the scheduler is still suspended. */
                            if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                            {
                                /* The task waiting has a higher priority than this task. */
                                portYIELD_WITHIN_API();
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }

                    taskEXIT_CRITICAL();
                    return pdPASS;
                }
                else
                {
                    if( xTicksToWait == ( TickType_t ) 0 )
                    {
                        taskEXIT_CRITICAL();
                        traceQUEUE_RECEIVE_FAILED( pxQueue );
                        return errQUEUE_EMPTY;
                    }
                    else if( xEntryTimeSet == pdFALSE )
                    {
                        vTaskSetTimeOutState( &xTimeOut );
                        xEntryTimeSet = pdTRUE;
                    }
                }
            }
            taskEXIT_CRITICAL();

            taskENTER_CRITICAL();
            {
                if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
                {
                    if( prvIsQueueEmpty( pxQueue ) != pdFALSE )
                    {
                        traceBLOCKING_ON_QUEUE_RECEIVE( pxQueue );

                        #if ( configUSE_MUTEXES == 1 )
                        {
                            if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
                            {
                                taskENTER_CRITICAL();
                                {
                                    vTaskPriorityInherit( ( void * ) pxQueue->pxMutexHolder );
                                }
                                taskEXIT_CRITICAL();
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        #endif

                        vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );
                        portYIELD_WITHIN_API();
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    taskEXIT_CRITICAL();
                    traceQUEUE_RECEIVE_FAILED( pxQueue );
                    return errQUEUE_EMPTY;
                }
            }
            taskEXIT_CRITICAL();
        }
    }


#endif /* configUSE_ALTERNATIVE_API */
/*-----------------------------------------------------------*/

BaseType_t xQueueGenericSendFromISR( QueueHandle_t xQueue, const void * const pvItemToQueue, BaseType_t * const pxHigherPriorityTaskWoken, const BaseType_t xCopyPosition )
{
BaseType_t xReturn;
UBaseType_t uxSavedInterruptStatus;
Queue_t * const pxQueue = ( Queue_t * ) xQueue;

    configASSERT( pxQueue );
    configASSERT( !( ( pvItemToQueue == NULL ) && ( pxQueue->uxItemSize != ( UBaseType_t ) 0U ) ) );
    configASSERT( !( ( xCopyPosition == queueOVERWRITE ) && ( pxQueue->uxLength != 1 ) ) );

    /* RTOS ports that support interrupt nesting have the concept of a maximum
    system call (or maximum API call) interrupt priority.  Interrupts that are
    above the maximum system call priority are kept permanently enabled, even
    when the RTOS kernel is in a critical section, but cannot make any calls to
    FreeRTOS API functions.  If configASSERT() is defined in FreeRTOSConfig.h
    then portASSERT_IF_INTERRUPT_PRIORITY_INVALID() will result in an assertion
    failure if a FreeRTOS API function is called from an interrupt that has been
    assigned a priority above the configured maximum system call priority.
    Only FreeRTOS functions that end in FromISR can be called from interrupts
    that have been assigned a priority at or (logically) below the maximum
    system call interrupt priority.  FreeRTOS maintains a separate interrupt
    safe API to ensure interrupt entry is as fast and as simple as possible.
    More information (albeit Cortex-M specific) is provided on the following
    link: http://www.freertos.org/RTOS-Cortex-M3-M4.html */
    portASSERT_IF_INTERRUPT_PRIORITY_INVALID();

    /* Similar to xQueueGenericSend, except without blocking if there is no room
    in the queue.  Also don't directly wake a task that was blocked on a queue
    read, instead return a flag to say whether a context switch is required or
    not (i.e. has a task with a higher priority than us been woken by this
    post). */
    uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
    {
        if( ( pxQueue->uxMessagesWaiting < pxQueue->uxLength ) || ( xCopyPosition == queueOVERWRITE ) )
        {
            traceQUEUE_SEND_FROM_ISR( pxQueue );

            /* Semaphores use xQueueGiveFromISR(), so pxQueue will not be a
            semaphore or mutex.  That means prvCopyDataToQueue() cannot result
            in a task disinheriting a priority and prvCopyDataToQueue() can be
            called here even though the disinherit function does not check if
            the scheduler is suspended before accessing the ready lists. */
            ( void ) prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );

            /* The event list is not altered if the queue is locked.  This will
            be done when the queue is unlocked later. */
            if( pxQueue->xTxLock == queueUNLOCKED )
            {
                #if ( configUSE_QUEUE_SETS == 1 )
                {
                    if( pxQueue->pxQueueSetContainer != NULL )
                    {
                        if( prvNotifyQueueSetContainer( pxQueue, xCopyPosition ) == pdTRUE )
                        {
                            /* The queue is a member of a queue set, and posting
                            to the queue set caused a higher priority task to
                            unblock.  A context switch is required. */
                            if( pxHigherPriorityTaskWoken != NULL )
                            {
                                *pxHigherPriorityTaskWoken = pdTRUE;
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                        {
                            if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                            {
                                /* The task waiting has a higher priority so
                                record that a context switch is required. */
                                if( pxHigherPriorityTaskWoken != NULL )
                                {
                                    *pxHigherPriorityTaskWoken = pdTRUE;
                                }
                                else
                                {
                                    mtCOVERAGE_TEST_MARKER();
                                }
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                }
                #else /* configUSE_QUEUE_SETS */
                {
                    if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                    {
                        if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                        {
                            /* The task waiting has a higher priority so record that a
                            context switch is required. */
                            if( pxHigherPriorityTaskWoken != NULL )
                            {
                                *pxHigherPriorityTaskWoken = pdTRUE;
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                #endif /* configUSE_QUEUE_SETS */
            }
            else
            {
                /* Increment the lock count so the task that unlocks the queue
                knows that data was posted while it was locked. */
                ++( pxQueue->xTxLock );
            }

            xReturn = pdPASS;
        }
        else
        {
            traceQUEUE_SEND_FROM_ISR_FAILED( pxQueue );
            xReturn = errQUEUE_FULL;
        }
    }
    portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );

    return xReturn;
}
/*-----------------------------------------------------------*/

BaseType_t xQueueGiveFromISR( QueueHandle_t xQueue, BaseType_t * const pxHigherPriorityTaskWoken )
{
BaseType_t xReturn;
UBaseType_t uxSavedInterruptStatus;
Queue_t * const pxQueue = ( Queue_t * ) xQueue;

    /* Similar to xQueueGenericSendFromISR() but used with semaphores where the
    item size is 0.  Don't directly wake a task that was blocked on a queue
    read, instead return a flag to say whether a context switch is required or
    not (i.e. has a task with a higher priority than us been woken by this
    post). */

    configASSERT( pxQueue );

    /* xQueueGenericSendFromISR() should be used instead of xQueueGiveFromISR()
    if the item size is not 0. */
    configASSERT( pxQueue->uxItemSize == 0 );

    /* Normally a mutex would not be given from an interrupt, especially if
    there is a mutex holder, as priority inheritance makes no sense for an
    interrupts, only tasks. */
    configASSERT( !( ( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX ) && ( pxQueue->pxMutexHolder != NULL ) ) );

    /* RTOS ports that support interrupt nesting have the concept of a maximum
    system call (or maximum API call) interrupt priority.  Interrupts that are
    above the maximum system call priority are kept permanently enabled, even
    when the RTOS kernel is in a critical section, but cannot make any calls to
    FreeRTOS API functions.  If configASSERT() is defined in FreeRTOSConfig.h
    then portASSERT_IF_INTERRUPT_PRIORITY_INVALID() will result in an assertion
    failure if a FreeRTOS API function is called from an interrupt that has been
    assigned a priority above the configured maximum system call priority.
    Only FreeRTOS functions that end in FromISR can be called from interrupts
    that have been assigned a priority at or (logically) below the maximum
    system call interrupt priority.  FreeRTOS maintains a separate interrupt
    safe API to ensure interrupt entry is as fast and as simple as possible.
    More information (albeit Cortex-M specific) is provided on the following
    link: http://www.freertos.org/RTOS-Cortex-M3-M4.html */
    portASSERT_IF_INTERRUPT_PRIORITY_INVALID();

    uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
    {
        /* When the queue is used to implement a semaphore no data is ever
        moved through the queue but it is still valid to see if the queue 'has
        space'. */
        if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
        {
            traceQUEUE_SEND_FROM_ISR( pxQueue );

            /* A task can only have an inherited priority if it is a mutex
            holder - and if there is a mutex holder then the mutex cannot be
            given from an ISR.  As this is the ISR version of the function it
            can be assumed there is no mutex holder and no need to determine if
            priority disinheritance is needed.  Simply increase the count of
            messages (semaphores) available. */
            ++( pxQueue->uxMessagesWaiting );

            /* The event list is not altered if the queue is locked.  This will
            be done when the queue is unlocked later. */
            if( pxQueue->xTxLock == queueUNLOCKED )
            {
                #if ( configUSE_QUEUE_SETS == 1 )
                {
                    if( pxQueue->pxQueueSetContainer != NULL )
                    {
                        if( prvNotifyQueueSetContainer( pxQueue, queueSEND_TO_BACK ) == pdTRUE )
                        {
                            /* The semaphore is a member of a queue set, and
                            posting to the queue set caused a higher priority
                            task to unblock.  A context switch is required. */
                            if( pxHigherPriorityTaskWoken != NULL )
                            {
                                *pxHigherPriorityTaskWoken = pdTRUE;
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                        {
                            if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                            {
                                /* The task waiting has a higher priority so
                                record that a context switch is required. */
                                if( pxHigherPriorityTaskWoken != NULL )
                                {
                                    *pxHigherPriorityTaskWoken = pdTRUE;
                                }
                                else
                                {
                                    mtCOVERAGE_TEST_MARKER();
                                }
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                }
                #else /* configUSE_QUEUE_SETS */
                {
                    if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                    {
                        if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                        {
                            /* The task waiting has a higher priority so record that a
                            context switch is required. */
                            if( pxHigherPriorityTaskWoken != NULL )
                            {
                                *pxHigherPriorityTaskWoken = pdTRUE;
                            }
                            else
                            {
                                mtCOVERAGE_TEST_MARKER();
                            }
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                #endif /* configUSE_QUEUE_SETS */
            }
            else
            {
                /* Increment the lock count so the task that unlocks the queue
                knows that data was posted while it was locked. */
                ++( pxQueue->xTxLock );
            }

            xReturn = pdPASS;
        }
        else
        {
            traceQUEUE_SEND_FROM_ISR_FAILED( pxQueue );
            xReturn = errQUEUE_FULL;
        }
    }
    portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );

    return xReturn;
}
/*-----------------------------------------------------------*/

BaseType_t xQueueGenericReceive( QueueHandle_t xQueue, void * const pvBuffer, TickType_t xTicksToWait, const BaseType_t xJustPeeking )
{
BaseType_t xEntryTimeSet = pdFALSE;
TimeOut_t xTimeOut;
int8_t *pcOriginalReadPosition;
Queue_t * const pxQueue = ( Queue_t * ) xQueue;

    configASSERT( pxQueue );
    configASSERT( !( ( pvBuffer == NULL ) && ( pxQueue->uxItemSize != ( UBaseType_t ) 0U ) ) );
    #if ( ( INCLUDE_xTaskGetSchedulerState == 1 ) || ( configUSE_TIMERS == 1 ) )
    {
        configASSERT( !( ( xTaskGetSchedulerState() == taskSCHEDULER_SUSPENDED ) && ( xTicksToWait != 0 ) ) );
    }
    #endif

    /* This function relaxes the coding standard somewhat to allow return
    statements within the function itself.  This is done in the interest
    of execution time efficiency. */

    for( ;; )
    {
        taskENTER_CRITICAL();
        {
            /* Is there data in the queue now?  To be running the calling task
            must be the highest priority task wanting to access the queue. */
            if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
            {
                /* Remember the read position in case the queue is only being
                peeked. */
                pcOriginalReadPosition = pxQueue->u.pcReadFrom;

                prvCopyDataFromQueue( pxQueue, pvBuffer );

                if( xJustPeeking == pdFALSE )
                {
                    traceQUEUE_RECEIVE( pxQueue );

                    /* Actually removing data, not just peeking. */
                    --( pxQueue->uxMessagesWaiting );

                    #if ( configUSE_MUTEXES == 1 )
                    {
                        if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
                        {
                            /* Record the information required to implement
                            priority inheritance should it become necessary. */
                            pxQueue->pxMutexHolder = ( int8_t * ) pvTaskIncrementMutexHeldCount(); /*lint !e961 Cast is not redundant as TaskHandle_t is a typedef. */
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    #endif /* configUSE_MUTEXES */

                    if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
                    {
                        if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) == pdTRUE )
                        {
                            queueYIELD_IF_USING_PREEMPTION();
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    traceQUEUE_PEEK( pxQueue );

                    /* The data is not being removed, so reset the read
                    pointer. */
                    pxQueue->u.pcReadFrom = pcOriginalReadPosition;

                    /* The data is being left in the queue, so see if there are
                    any other tasks waiting for the data. */
                    if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                    {
                        if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                        {
                            /* The task waiting has a higher priority than this task. */
                            queueYIELD_IF_USING_PREEMPTION();
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }

                taskEXIT_CRITICAL();
                return pdPASS;
            }
            else
            {
                if( xTicksToWait == ( TickType_t ) 0 )
                {
                    /* The queue was empty and no block time is specified (or
                    the block time has expired) so leave now. */
                    taskEXIT_CRITICAL();
                    traceQUEUE_RECEIVE_FAILED( pxQueue );
                    return errQUEUE_EMPTY;
                }
                else if( xEntryTimeSet == pdFALSE )
                {
                    /* The queue was empty and a block time was specified so
                    configure the timeout structure. */
                    vTaskSetTimeOutState( &xTimeOut );
                    xEntryTimeSet = pdTRUE;
                }
                else
                {
                    /* Entry time was already set. */
                    mtCOVERAGE_TEST_MARKER();
                }
            }
        }
        taskEXIT_CRITICAL();

        /* Interrupts and other tasks can send to and receive from the queue
        now the critical section has been exited. */

        vTaskSuspendAll();
        prvLockQueue( pxQueue );

        /* Update the timeout state to see if it has expired yet. */
        if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
        {
            if( prvIsQueueEmpty( pxQueue ) != pdFALSE )
            {
                traceBLOCKING_ON_QUEUE_RECEIVE( pxQueue );

                #if ( configUSE_MUTEXES == 1 )
                {
                    if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
                    {
                        taskENTER_CRITICAL();
                        {
                            vTaskPriorityInherit( ( void * ) pxQueue->pxMutexHolder );
                        }
                        taskEXIT_CRITICAL();
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                #endif

                vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );
                prvUnlockQueue( pxQueue );
                if( xTaskResumeAll() == pdFALSE )
                {
                    portYIELD_WITHIN_API();
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                /* Try again. */
                prvUnlockQueue( pxQueue );
                ( void ) xTaskResumeAll();
            }
        }
        else
        {
            prvUnlockQueue( pxQueue );
            ( void ) xTaskResumeAll();
            traceQUEUE_RECEIVE_FAILED( pxQueue );
            return errQUEUE_EMPTY;
        }
    }
}
/*-----------------------------------------------------------*/

BaseType_t xQueueReceiveFromISR( QueueHandle_t xQueue, void * const pvBuffer, BaseType_t * const pxHigherPriorityTaskWoken )
{
BaseType_t xReturn;
UBaseType_t uxSavedInterruptStatus;
Queue_t * const pxQueue = ( Queue_t * ) xQueue;

    configASSERT( pxQueue );
    configASSERT( !( ( pvBuffer == NULL ) && ( pxQueue->uxItemSize != ( UBaseType_t ) 0U ) ) );

    /* RTOS ports that support interrupt nesting have the concept of a maximum
    system call (or maximum API call) interrupt priority.  Interrupts that are
    above the maximum system call priority are kept permanently enabled, even
    when the RTOS kernel is in a critical section, but cannot make any calls to
    FreeRTOS API functions.  If configASSERT() is defined in FreeRTOSConfig.h
    then portASSERT_IF_INTERRUPT_PRIORITY_INVALID() will result in an assertion
    failure if a FreeRTOS API function is called from an interrupt that has been
    assigned a priority above the configured maximum system call priority.
    Only FreeRTOS functions that end in FromISR can be called from interrupts
    that have been assigned a priority at or (logically) below the maximum
    system call interrupt priority.  FreeRTOS maintains a separate interrupt
    safe API to ensure interrupt entry is as fast and as simple as possible.
    More information (albeit Cortex-M specific) is provided on the following
    link: http://www.freertos.org/RTOS-Cortex-M3-M4.html */
    portASSERT_IF_INTERRUPT_PRIORITY_INVALID();

    uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
    {
        /* Cannot block in an ISR, so check there is data available. */
        if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
        {
            traceQUEUE_RECEIVE_FROM_ISR( pxQueue );

            prvCopyDataFromQueue( pxQueue, pvBuffer );
            --( pxQueue->uxMessagesWaiting );

            /* If the queue is locked the event list will not be modified.
            Instead update the lock count so the task that unlocks the queue
            will know that an ISR has removed data while the queue was
            locked. */
            if( pxQueue->xRxLock == queueUNLOCKED )
            {
                if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
                {
                    if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
                    {
                        /* The task waiting has a higher priority than us so
                        force a context switch. */
                        if( pxHigherPriorityTaskWoken != NULL )
                        {
                            *pxHigherPriorityTaskWoken = pdTRUE;
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                /* Increment the lock count so the task that unlocks the queue
                knows that data was removed while it was locked. */
                ++( pxQueue->xRxLock );
            }

            xReturn = pdPASS;
        }
        else
        {
            xReturn = pdFAIL;
            traceQUEUE_RECEIVE_FROM_ISR_FAILED( pxQueue );
        }
    }
    portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );

    return xReturn;
}
/*-----------------------------------------------------------*/

BaseType_t xQueuePeekFromISR( QueueHandle_t xQueue,  void * const pvBuffer )
{
BaseType_t xReturn;
UBaseType_t uxSavedInterruptStatus;
int8_t *pcOriginalReadPosition;
Queue_t * const pxQueue = ( Queue_t * ) xQueue;

    configASSERT( pxQueue );
    configASSERT( !( ( pvBuffer == NULL ) && ( pxQueue->uxItemSize != ( UBaseType_t ) 0U ) ) );
    configASSERT( pxQueue->uxItemSize != 0 ); /* Can't peek a semaphore. */

    /* RTOS ports that support interrupt nesting have the concept of a maximum
    system call (or maximum API call) interrupt priority.  Interrupts that are
    above the maximum system call priority are kept permanently enabled, even
    when the RTOS kernel is in a critical section, but cannot make any calls to
    FreeRTOS API functions.  If configASSERT() is defined in FreeRTOSConfig.h
    then portASSERT_IF_INTERRUPT_PRIORITY_INVALID() will result in an assertion
    failure if a FreeRTOS API function is called from an interrupt that has been
    assigned a priority above the configured maximum system call priority.
    Only FreeRTOS functions that end in FromISR can be called from interrupts
    that have been assigned a priority at or (logically) below the maximum
    system call interrupt priority.  FreeRTOS maintains a separate interrupt
    safe API to ensure interrupt entry is as fast and as simple as possible.
    More information (albeit Cortex-M specific) is provided on the following
    link: http://www.freertos.org/RTOS-Cortex-M3-M4.html */
    portASSERT_IF_INTERRUPT_PRIORITY_INVALID();

    uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
    {
        /* Cannot block in an ISR, so check there is data available. */
        if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
        {
            traceQUEUE_PEEK_FROM_ISR( pxQueue );

            /* Remember the read position so it can be reset as nothing is
            actually being removed from the queue. */
            pcOriginalReadPosition = pxQueue->u.pcReadFrom;
            prvCopyDataFromQueue( pxQueue, pvBuffer );
            pxQueue->u.pcReadFrom = pcOriginalReadPosition;

            xReturn = pdPASS;
        }
        else
        {
            xReturn = pdFAIL;
            traceQUEUE_PEEK_FROM_ISR_FAILED( pxQueue );
        }
    }
    portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );

    return xReturn;
}
/*-----------------------------------------------------------*/

UBaseType_t uxQueueMessagesWaiting( const QueueHandle_t xQueue )
{
UBaseType_t uxReturn;

    configASSERT( xQueue );

    taskENTER_CRITICAL();
    {
        uxReturn = ( ( Queue_t * ) xQueue )->uxMessagesWaiting;
    }
    taskEXIT_CRITICAL();

    return uxReturn;
} /*lint !e818 Pointer cannot be declared const as xQueue is a typedef not pointer. */
/*-----------------------------------------------------------*/

UBaseType_t uxQueueSpacesAvailable( const QueueHandle_t xQueue )
{
UBaseType_t uxReturn;
Queue_t *pxQueue;

    pxQueue = ( Queue_t * ) xQueue;
    configASSERT( pxQueue );

    taskENTER_CRITICAL();
    {
        uxReturn = pxQueue->uxLength - pxQueue->uxMessagesWaiting;
    }
    taskEXIT_CRITICAL();

    return uxReturn;
} /*lint !e818 Pointer cannot be declared const as xQueue is a typedef not pointer. */
/*-----------------------------------------------------------*/

UBaseType_t uxQueueMessagesWaitingFromISR( const QueueHandle_t xQueue )
{
UBaseType_t uxReturn;

    configASSERT( xQueue );

    uxReturn = ( ( Queue_t * ) xQueue )->uxMessagesWaiting;

    return uxReturn;
} /*lint !e818 Pointer cannot be declared const as xQueue is a typedef not pointer. */
/*-----------------------------------------------------------*/

void vQueueDelete( QueueHandle_t xQueue )
{
Queue_t * const pxQueue = ( Queue_t * ) xQueue;

    configASSERT( pxQueue );

    traceQUEUE_DELETE( pxQueue );
    #if ( configQUEUE_REGISTRY_SIZE > 0 )
    {
        vQueueUnregisterQueue( pxQueue );
    }
    #endif
    vPortFree( pxQueue );
}
/*-----------------------------------------------------------*/

#if ( configUSE_TRACE_FACILITY == 1 )

    UBaseType_t uxQueueGetQueueNumber( QueueHandle_t xQueue )
    {
        return ( ( Queue_t * ) xQueue )->uxQueueNumber;
    }

#endif /* configUSE_TRACE_FACILITY */
/*-----------------------------------------------------------*/

#if ( configUSE_TRACE_FACILITY == 1 )

    void vQueueSetQueueNumber( QueueHandle_t xQueue, UBaseType_t uxQueueNumber )
    {
        ( ( Queue_t * ) xQueue )->uxQueueNumber = uxQueueNumber;
    }

#endif /* configUSE_TRACE_FACILITY */
/*-----------------------------------------------------------*/

#if ( configUSE_TRACE_FACILITY == 1 )

    uint8_t ucQueueGetQueueType( QueueHandle_t xQueue )
    {
        return ( ( Queue_t * ) xQueue )->ucQueueType;
    }

#endif /* configUSE_TRACE_FACILITY */
/*-----------------------------------------------------------*/

static BaseType_t prvCopyDataToQueue( Queue_t * const pxQueue, const void *pvItemToQueue, const BaseType_t xPosition )
{
BaseType_t xReturn = pdFALSE;

    if( pxQueue->uxItemSize == ( UBaseType_t ) 0 )
    {
        #if ( configUSE_MUTEXES == 1 )
        {
            if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
            {
                /* The mutex is no longer being held. */
                xReturn = xTaskPriorityDisinherit( ( void * ) pxQueue->pxMutexHolder );
                pxQueue->pxMutexHolder = NULL;
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
        #endif /* configUSE_MUTEXES */
    }
    else if( xPosition == queueSEND_TO_BACK )
    {
        ( void ) memcpy( ( void * ) pxQueue->pcWriteTo, pvItemToQueue, ( size_t ) pxQueue->uxItemSize ); /*lint !e961 !e418 MISRA exception as the casts are only redundant for some ports, plus previous logic ensures a null pointer can only be passed to memcpy() if the copy size is 0. */
        pxQueue->pcWriteTo += pxQueue->uxItemSize;
        if( pxQueue->pcWriteTo >= pxQueue->pcTail ) /*lint !e946 MISRA exception justified as comparison of pointers is the cleanest solution. */
        {
            pxQueue->pcWriteTo = pxQueue->pcHead;
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }
    }
    else
    {
        ( void ) memcpy( ( void * ) pxQueue->u.pcReadFrom, pvItemToQueue, ( size_t ) pxQueue->uxItemSize ); /*lint !e961 MISRA exception as the casts are only redundant for some ports. */
        pxQueue->u.pcReadFrom -= pxQueue->uxItemSize;
        if( pxQueue->u.pcReadFrom < pxQueue->pcHead ) /*lint !e946 MISRA exception justified as comparison of pointers is the cleanest solution. */
        {
            pxQueue->u.pcReadFrom = ( pxQueue->pcTail - pxQueue->uxItemSize );
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }

        if( xPosition == queueOVERWRITE )
        {
            if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
            {
                /* An item is not being added but overwritten, so subtract
                one from the recorded number of items in the queue so when
                one is added again below the number of recorded items remains
                correct. */
                --( pxQueue->uxMessagesWaiting );
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }
    }

    ++( pxQueue->uxMessagesWaiting );

    return xReturn;
}
/*-----------------------------------------------------------*/

static void prvCopyDataFromQueue( Queue_t * const pxQueue, void * const pvBuffer )
{
    if( pxQueue->uxItemSize != ( UBaseType_t ) 0 )
    {
        pxQueue->u.pcReadFrom += pxQueue->uxItemSize;
        if( pxQueue->u.pcReadFrom >= pxQueue->pcTail ) /*lint !e946 MISRA exception justified as use of the relational operator is the cleanest solutions. */
        {
            pxQueue->u.pcReadFrom = pxQueue->pcHead;
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }
        ( void ) memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->u.pcReadFrom, ( size_t ) pxQueue->uxItemSize ); /*lint !e961 !e418 MISRA exception as the casts are only redundant for some ports.  Also previous logic ensures a null pointer can only be passed to memcpy() when the count is 0. */
    }
}
/*-----------------------------------------------------------*/

static void prvUnlockQueue( Queue_t * const pxQueue )
{
    /* THIS FUNCTION MUST BE CALLED WITH THE SCHEDULER SUSPENDED. */

    /* The lock counts contains the number of extra data items placed or
    removed from the queue while the queue was locked.  When a queue is
    locked items can be added or removed, but the event lists cannot be
    updated. */
    taskENTER_CRITICAL();
    {
        /* See if data was added to the queue while it was locked. */
        while( pxQueue->xTxLock > queueLOCKED_UNMODIFIED )
        {
            /* Data was posted while the queue was locked.  Are any tasks
            blocked waiting for data to become available? */
            #if ( configUSE_QUEUE_SETS == 1 )
            {
                if( pxQueue->pxQueueSetContainer != NULL )
                {
                    if( prvNotifyQueueSetContainer( pxQueue, queueSEND_TO_BACK ) == pdTRUE )
                    {
                        /* The queue is a member of a queue set, and posting to
                        the queue set caused a higher priority task to unblock.
                        A context switch is required. */
                        vTaskMissedYield();
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    /* Tasks that are removed from the event list will get added to
                    the pending ready list as the scheduler is still suspended. */
                    if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                    {
                        if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                        {
                            /* The task waiting has a higher priority so record that a
                            context switch is required. */
                            vTaskMissedYield();
                        }
                        else
                        {
                            mtCOVERAGE_TEST_MARKER();
                        }
                    }
                    else
                    {
                        break;
                    }
                }
            }
            #else /* configUSE_QUEUE_SETS */
            {
                /* Tasks that are removed from the event list will get added to
                the pending ready list as the scheduler is still suspended. */
                if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                {
                    if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                    {
                        /* The task waiting has a higher priority so record that a
                        context switch is required. */
                        vTaskMissedYield();
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    break;
                }
            }
            #endif /* configUSE_QUEUE_SETS */

            --( pxQueue->xTxLock );
        }

        pxQueue->xTxLock = queueUNLOCKED;
    }
    taskEXIT_CRITICAL();

    /* Do the same for the Rx lock. */
    taskENTER_CRITICAL();
    {
        while( pxQueue->xRxLock > queueLOCKED_UNMODIFIED )
        {
            if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
            {
                if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
                {
                    vTaskMissedYield();
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }

                --( pxQueue->xRxLock );
            }
            else
            {
                break;
            }
        }

        pxQueue->xRxLock = queueUNLOCKED;
    }
    taskEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/

static BaseType_t prvIsQueueEmpty( const Queue_t *pxQueue )
{
BaseType_t xReturn;

    taskENTER_CRITICAL();
    {
        if( pxQueue->uxMessagesWaiting == ( UBaseType_t )  0 )
        {
            xReturn = pdTRUE;
        }
        else
        {
            xReturn = pdFALSE;
        }
    }
    taskEXIT_CRITICAL();

    return xReturn;
}
/*-----------------------------------------------------------*/

BaseType_t xQueueIsQueueEmptyFromISR( const QueueHandle_t xQueue )
{
BaseType_t xReturn;

    configASSERT( xQueue );
    if( ( ( Queue_t * ) xQueue )->uxMessagesWaiting == ( UBaseType_t ) 0 )
    {
        xReturn = pdTRUE;
    }
    else
    {
        xReturn = pdFALSE;
    }

    return xReturn;
} /*lint !e818 xQueue could not be pointer to const because it is a typedef. */
/*-----------------------------------------------------------*/

static BaseType_t prvIsQueueFull( const Queue_t *pxQueue )
{
BaseType_t xReturn;

    taskENTER_CRITICAL();
    {
        if( pxQueue->uxMessagesWaiting == pxQueue->uxLength )
        {
            xReturn = pdTRUE;
        }
        else
        {
            xReturn = pdFALSE;
        }
    }
    taskEXIT_CRITICAL();

    return xReturn;
}
/*-----------------------------------------------------------*/

BaseType_t xQueueIsQueueFullFromISR( const QueueHandle_t xQueue )
{
BaseType_t xReturn;

    configASSERT( xQueue );
    if( ( ( Queue_t * ) xQueue )->uxMessagesWaiting == ( ( Queue_t * ) xQueue )->uxLength )
    {
        xReturn = pdTRUE;
    }
    else
    {
        xReturn = pdFALSE;
    }

    return xReturn;
} /*lint !e818 xQueue could not be pointer to const because it is a typedef. */
/*-----------------------------------------------------------*/

#if ( configUSE_CO_ROUTINES == 1 )

    BaseType_t xQueueCRSend( QueueHandle_t xQueue, const void *pvItemToQueue, TickType_t xTicksToWait )
    {
    BaseType_t xReturn;
    Queue_t * const pxQueue = ( Queue_t * ) xQueue;

        /* If the queue is already full we may have to block.  A critical section
        is required to prevent an interrupt removing something from the queue
        between the check to see if the queue is full and blocking on the queue. */
        portDISABLE_INTERRUPTS();
        {
            if( prvIsQueueFull( pxQueue ) != pdFALSE )
            {
                /* The queue is full - do we want to block or just leave without
                posting? */
                if( xTicksToWait > ( TickType_t ) 0 )
                {
                    /* As this is called from a coroutine we cannot block directly, but
                    return indicating that we need to block. */
                    vCoRoutineAddToDelayedList( xTicksToWait, &( pxQueue->xTasksWaitingToSend ) );
                    portENABLE_INTERRUPTS();
                    return errQUEUE_BLOCKED;
                }
                else
                {
                    portENABLE_INTERRUPTS();
                    return errQUEUE_FULL;
                }
            }
        }
        portENABLE_INTERRUPTS();

        portDISABLE_INTERRUPTS();
        {
            if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
            {
                /* There is room in the queue, copy the data into the queue. */
                prvCopyDataToQueue( pxQueue, pvItemToQueue, queueSEND_TO_BACK );
                xReturn = pdPASS;

                /* Were any co-routines waiting for data to become available? */
                if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                {
                    /* In this instance the co-routine could be placed directly
                    into the ready list as we are within a critical section.
                    Instead the same pending ready list mechanism is used as if
                    the event were caused from within an interrupt. */
                    if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                    {
                        /* The co-routine waiting has a higher priority so record
                        that a yield might be appropriate. */
                        xReturn = errQUEUE_YIELD;
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                xReturn = errQUEUE_FULL;
            }
        }
        portENABLE_INTERRUPTS();

        return xReturn;
    }

#endif /* configUSE_CO_ROUTINES */
/*-----------------------------------------------------------*/

#if ( configUSE_CO_ROUTINES == 1 )

    BaseType_t xQueueCRReceive( QueueHandle_t xQueue, void *pvBuffer, TickType_t xTicksToWait )
    {
    BaseType_t xReturn;
    Queue_t * const pxQueue = ( Queue_t * ) xQueue;

        /* If the queue is already empty we may have to block.  A critical section
        is required to prevent an interrupt adding something to the queue
        between the check to see if the queue is empty and blocking on the queue. */
        portDISABLE_INTERRUPTS();
        {
            if( pxQueue->uxMessagesWaiting == ( UBaseType_t ) 0 )
            {
                /* There are no messages in the queue, do we want to block or just
                leave with nothing? */
                if( xTicksToWait > ( TickType_t ) 0 )
                {
                    /* As this is a co-routine we cannot block directly, but return
                    indicating that we need to block. */
                    vCoRoutineAddToDelayedList( xTicksToWait, &( pxQueue->xTasksWaitingToReceive ) );
                    portENABLE_INTERRUPTS();
                    return errQUEUE_BLOCKED;
                }
                else
                {
                    portENABLE_INTERRUPTS();
                    return errQUEUE_FULL;
                }
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
        portENABLE_INTERRUPTS();

        portDISABLE_INTERRUPTS();
        {
            if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
            {
                /* Data is available from the queue. */
                pxQueue->u.pcReadFrom += pxQueue->uxItemSize;
                if( pxQueue->u.pcReadFrom >= pxQueue->pcTail )
                {
                    pxQueue->u.pcReadFrom = pxQueue->pcHead;
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
                --( pxQueue->uxMessagesWaiting );
                ( void ) memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->u.pcReadFrom, ( unsigned ) pxQueue->uxItemSize );

                xReturn = pdPASS;

                /* Were any co-routines waiting for space to become available? */
                if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
                {
                    /* In this instance the co-routine could be placed directly
                    into the ready list as we are within a critical section.
                    Instead the same pending ready list mechanism is used as if
                    the event were caused from within an interrupt. */
                    if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
                    {
                        xReturn = errQUEUE_YIELD;
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                xReturn = pdFAIL;
            }
        }
        portENABLE_INTERRUPTS();

        return xReturn;
    }

#endif /* configUSE_CO_ROUTINES */
/*-----------------------------------------------------------*/

#if ( configUSE_CO_ROUTINES == 1 )

    BaseType_t xQueueCRSendFromISR( QueueHandle_t xQueue, const void *pvItemToQueue, BaseType_t xCoRoutinePreviouslyWoken )
    {
    Queue_t * const pxQueue = ( Queue_t * ) xQueue;

        /* Cannot block within an ISR so if there is no space on the queue then
        exit without doing anything. */
        if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
        {
            prvCopyDataToQueue( pxQueue, pvItemToQueue, queueSEND_TO_BACK );

            /* We only want to wake one co-routine per ISR, so check that a
            co-routine has not already been woken. */
            if( xCoRoutinePreviouslyWoken == pdFALSE )
            {
                if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
                {
                    if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
                    {
                        return pdTRUE;
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }

        return xCoRoutinePreviouslyWoken;
    }

#endif /* configUSE_CO_ROUTINES */
/*-----------------------------------------------------------*/

#if ( configUSE_CO_ROUTINES == 1 )

    BaseType_t xQueueCRReceiveFromISR( QueueHandle_t xQueue, void *pvBuffer, BaseType_t *pxCoRoutineWoken )
    {
    BaseType_t xReturn;
    Queue_t * const pxQueue = ( Queue_t * ) xQueue;

        /* We cannot block from an ISR, so check there is data available. If
        not then just leave without doing anything. */
        if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
        {
            /* Copy the data from the queue. */
            pxQueue->u.pcReadFrom += pxQueue->uxItemSize;
            if( pxQueue->u.pcReadFrom >= pxQueue->pcTail )
            {
                pxQueue->u.pcReadFrom = pxQueue->pcHead;
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
            --( pxQueue->uxMessagesWaiting );
            ( void ) memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->u.pcReadFrom, ( unsigned ) pxQueue->uxItemSize );

            if( ( *pxCoRoutineWoken ) == pdFALSE )
            {
                if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
                {
                    if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
                    {
                        *pxCoRoutineWoken = pdTRUE;
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }

            xReturn = pdPASS;
        }
        else
        {
            xReturn = pdFAIL;
        }

        return xReturn;
    }

#endif /* configUSE_CO_ROUTINES */
/*-----------------------------------------------------------*/

#if ( configQUEUE_REGISTRY_SIZE > 0 )

    void vQueueAddToRegistry( QueueHandle_t xQueue, const char *pcQueueName ) /*lint !e971 Unqualified char types are allowed for strings and single characters only. */
    {
    UBaseType_t ux;

        /* See if there is an empty space in the registry.  A NULL name denotes
        a free slot. */
        for( ux = ( UBaseType_t ) 0U; ux < ( UBaseType_t ) configQUEUE_REGISTRY_SIZE; ux++ )
        {
            if( xQueueRegistry[ ux ].pcQueueName == NULL )
            {
                /* Store the information on this queue. */
                xQueueRegistry[ ux ].pcQueueName = pcQueueName;
                xQueueRegistry[ ux ].xHandle = xQueue;

                traceQUEUE_REGISTRY_ADD( xQueue, pcQueueName );
                break;
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
    }

#endif /* configQUEUE_REGISTRY_SIZE */
/*-----------------------------------------------------------*/

#if ( configQUEUE_REGISTRY_SIZE > 0 )

    void vQueueUnregisterQueue( QueueHandle_t xQueue )
    {
    UBaseType_t ux;

        /* See if the handle of the queue being unregistered in actually in the
        registry. */
        for( ux = ( UBaseType_t ) 0U; ux < ( UBaseType_t ) configQUEUE_REGISTRY_SIZE; ux++ )
        {
            if( xQueueRegistry[ ux ].xHandle == xQueue )
            {
                /* Set the name to NULL to show that this slot if free again. */
                xQueueRegistry[ ux ].pcQueueName = NULL;
                break;
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }

    } /*lint !e818 xQueue could not be pointer to const because it is a typedef. */

#endif /* configQUEUE_REGISTRY_SIZE */
/*-----------------------------------------------------------*/

#if ( configUSE_TIMERS == 1 )

    void vQueueWaitForMessageRestricted( QueueHandle_t xQueue, TickType_t xTicksToWait, const BaseType_t xWaitIndefinitely )
    {
    Queue_t * const pxQueue = ( Queue_t * ) xQueue;

        /* This function should not be called by application code hence the
        'Restricted' in its name.  It is not part of the public API.  It is
        designed for use by kernel code, and has special calling requirements.
        It can result in vListInsert() being called on a list that can only
        possibly ever have one item in it, so the list will be fast, but even
        so it should be called with the scheduler locked and not from a critical
        section. */

        /* Only do anything if there are no messages in the queue.  This function
        will not actually cause the task to block, just place it on a blocked
        list.  It will not block until the scheduler is unlocked - at which
        time a yield will be performed.  If an item is added to the queue while
        the queue is locked, and the calling task blocks on the queue, then the
        calling task will be immediately unblocked when the queue is unlocked. */
        prvLockQueue( pxQueue );
        if( pxQueue->uxMessagesWaiting == ( UBaseType_t ) 0U )
        {
            /* There is nothing in the queue, block for the specified period. */
            vTaskPlaceOnEventListRestricted( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait, xWaitIndefinitely );
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }
        prvUnlockQueue( pxQueue );
    }

#endif /* configUSE_TIMERS */
/*-----------------------------------------------------------*/

#if ( configUSE_QUEUE_SETS == 1 )

    QueueSetHandle_t xQueueCreateSet( const UBaseType_t uxEventQueueLength )
    {
    QueueSetHandle_t pxQueue;

        pxQueue = xQueueGenericCreate( uxEventQueueLength, sizeof( Queue_t * ), queueQUEUE_TYPE_SET );

        return pxQueue;
    }

#endif /* configUSE_QUEUE_SETS */
/*-----------------------------------------------------------*/

#if ( configUSE_QUEUE_SETS == 1 )

    BaseType_t xQueueAddToSet( QueueSetMemberHandle_t xQueueOrSemaphore, QueueSetHandle_t xQueueSet )
    {
    BaseType_t xReturn;

        taskENTER_CRITICAL();
        {
            if( ( ( Queue_t * ) xQueueOrSemaphore )->pxQueueSetContainer != NULL )
            {
                /* Cannot add a queue/semaphore to more than one queue set. */
                xReturn = pdFAIL;
            }
            else if( ( ( Queue_t * ) xQueueOrSemaphore )->uxMessagesWaiting != ( UBaseType_t ) 0 )
            {
                /* Cannot add a queue/semaphore to a queue set if there are already
                items in the queue/semaphore. */
                xReturn = pdFAIL;
            }
            else
            {
                ( ( Queue_t * ) xQueueOrSemaphore )->pxQueueSetContainer = xQueueSet;
                xReturn = pdPASS;
            }
        }
        taskEXIT_CRITICAL();

        return xReturn;
    }

#endif /* configUSE_QUEUE_SETS */
/*-----------------------------------------------------------*/

#if ( configUSE_QUEUE_SETS == 1 )

    BaseType_t xQueueRemoveFromSet( QueueSetMemberHandle_t xQueueOrSemaphore, QueueSetHandle_t xQueueSet )
    {
    BaseType_t xReturn;
    Queue_t * const pxQueueOrSemaphore = ( Queue_t * ) xQueueOrSemaphore;

        if( pxQueueOrSemaphore->pxQueueSetContainer != xQueueSet )
        {
            /* The queue was not a member of the set. */
            xReturn = pdFAIL;
        }
        else if( pxQueueOrSemaphore->uxMessagesWaiting != ( UBaseType_t ) 0 )
        {
            /* It is dangerous to remove a queue from a set when the queue is
            not empty because the queue set will still hold pending events for
            the queue. */
            xReturn = pdFAIL;
        }
        else
        {
            taskENTER_CRITICAL();
            {
                /* The queue is no longer contained in the set. */
                pxQueueOrSemaphore->pxQueueSetContainer = NULL;
            }
            taskEXIT_CRITICAL();
            xReturn = pdPASS;
        }

        return xReturn;
    } /*lint !e818 xQueueSet could not be declared as pointing to const as it is a typedef. */

#endif /* configUSE_QUEUE_SETS */
/*-----------------------------------------------------------*/

#if ( configUSE_QUEUE_SETS == 1 )

    QueueSetMemberHandle_t xQueueSelectFromSet( QueueSetHandle_t xQueueSet, TickType_t const xTicksToWait )
    {
    QueueSetMemberHandle_t xReturn = NULL;

        ( void ) xQueueGenericReceive( ( QueueHandle_t ) xQueueSet, &xReturn, xTicksToWait, pdFALSE ); /*lint !e961 Casting from one typedef to another is not redundant. */
        return xReturn;
    }

#endif /* configUSE_QUEUE_SETS */
/*-----------------------------------------------------------*/

#if ( configUSE_QUEUE_SETS == 1 )

    QueueSetMemberHandle_t xQueueSelectFromSetFromISR( QueueSetHandle_t xQueueSet )
    {
    QueueSetMemberHandle_t xReturn = NULL;

        ( void ) xQueueReceiveFromISR( ( QueueHandle_t ) xQueueSet, &xReturn, NULL ); /*lint !e961 Casting from one typedef to another is not redundant. */
        return xReturn;
    }

#endif /* configUSE_QUEUE_SETS */
/*-----------------------------------------------------------*/

#if ( configUSE_QUEUE_SETS == 1 )

    static BaseType_t prvNotifyQueueSetContainer( const Queue_t * const pxQueue, const BaseType_t xCopyPosition )
    {
    Queue_t *pxQueueSetContainer = pxQueue->pxQueueSetContainer;
    BaseType_t xReturn = pdFALSE;

        /* This function must be called form a critical section. */

        configASSERT( pxQueueSetContainer );
        configASSERT( pxQueueSetContainer->uxMessagesWaiting < pxQueueSetContainer->uxLength );

        if( pxQueueSetContainer->uxMessagesWaiting < pxQueueSetContainer->uxLength )
        {
            traceQUEUE_SEND( pxQueueSetContainer );

            /* The data copied is the handle of the queue that contains data. */
            xReturn = prvCopyDataToQueue( pxQueueSetContainer, &pxQueue, xCopyPosition );

            if( pxQueueSetContainer->xTxLock == queueUNLOCKED )
            {
                if( listLIST_IS_EMPTY( &( pxQueueSetContainer->xTasksWaitingToReceive ) ) == pdFALSE )
                {
                    if( xTaskRemoveFromEventList( &( pxQueueSetContainer->xTasksWaitingToReceive ) ) != pdFALSE )
                    {
                        /* The task waiting has a higher priority. */
                        xReturn = pdTRUE;
                    }
                    else
                    {
                        mtCOVERAGE_TEST_MARKER();
                    }
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                ( pxQueueSetContainer->xTxLock )++;
            }
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }

        return xReturn;
    }

#endif /* configUSE_QUEUE_SETS */