queue.h

Go to the documentation of this file.

/*
 * FreeRTOS Kernel V11.1.0
 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 *
 */
 
 
#ifndef QUEUE_H
#define QUEUE_H
 
#ifndef INC_FREERTOS_H
    #error "include FreeRTOS.h" must appear in source files before "include queue.h"
#endif
 
/* *INDENT-OFF* */
#ifdef __cplusplus
    extern "C" {
#endif
/* *INDENT-ON* */
 
#include "task.h"

struct QueueDefinition; /* Using old naming convention so as not to break kernel aware debuggers. */
typedef struct QueueDefinition   * QueueHandle_t;

typedef struct QueueDefinition   * QueueSetHandle_t;

typedef struct QueueDefinition   * QueueSetMemberHandle_t;
 
/* For internal use only. */
#define queueSEND_TO_BACK                     ( ( BaseType_t ) 0 )
#define queueSEND_TO_FRONT                    ( ( BaseType_t ) 1 )
#define queueOVERWRITE                        ( ( BaseType_t ) 2 )
 
/* For internal use only.  These definitions *must* match those in queue.c. */
#define queueQUEUE_TYPE_BASE                  ( ( uint8_t ) 0U )
#define queueQUEUE_TYPE_SET                   ( ( uint8_t ) 0U )
#define queueQUEUE_TYPE_MUTEX                 ( ( uint8_t ) 1U )
#define queueQUEUE_TYPE_COUNTING_SEMAPHORE    ( ( uint8_t ) 2U )
#define queueQUEUE_TYPE_BINARY_SEMAPHORE      ( ( uint8_t ) 3U )
#define queueQUEUE_TYPE_RECURSIVE_MUTEX       ( ( uint8_t ) 4U )

#if ( configSUPPORT_DYNAMIC_ALLOCATION == 1 )
    #define xQueueCreate( uxQueueLength, uxItemSize )    xQueueGenericCreate( ( uxQueueLength ), ( uxItemSize ), ( queueQUEUE_TYPE_BASE ) )
#endif

#if ( configSUPPORT_STATIC_ALLOCATION == 1 )
    #define xQueueCreateStatic( uxQueueLength, uxItemSize, pucQueueStorage, pxQueueBuffer )    xQueueGenericCreateStatic( ( uxQueueLength ), ( uxItemSize ), ( pucQueueStorage ), ( pxQueueBuffer ), ( queueQUEUE_TYPE_BASE ) )
#endif /* configSUPPORT_STATIC_ALLOCATION */

#if ( configSUPPORT_STATIC_ALLOCATION == 1 )
    #define xQueueGetStaticBuffers( xQueue, ppucQueueStorage, ppxStaticQueue )    xQueueGenericGetStaticBuffers( ( xQueue ), ( ppucQueueStorage ), ( ppxStaticQueue ) )
#endif /* configSUPPORT_STATIC_ALLOCATION */

#define xQueueSendToFront( xQueue, pvItemToQueue, xTicksToWait ) \
    xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_FRONT )

#define xQueueSendToBack( xQueue, pvItemToQueue, xTicksToWait ) \
    xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )

#define xQueueSend( xQueue, pvItemToQueue, xTicksToWait ) \
    xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )

#define xQueueOverwrite( xQueue, pvItemToQueue ) \
    xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), 0, queueOVERWRITE )
 

BaseType_t xQueueGenericSend( QueueHandle_t xQueue,
                              const void * const pvItemToQueue,
                              TickType_t xTicksToWait,
                              const BaseType_t xCopyPosition ) PRIVILEGED_FUNCTION;

BaseType_t xQueuePeek( QueueHandle_t xQueue,
                       void * const pvBuffer,
                       TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;

BaseType_t xQueuePeekFromISR( QueueHandle_t xQueue,
                              void * const pvBuffer ) PRIVILEGED_FUNCTION;

BaseType_t xQueueReceive( QueueHandle_t xQueue,
                          void * const pvBuffer,
                          TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;

UBaseType_t uxQueueMessagesWaiting( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;

UBaseType_t uxQueueSpacesAvailable( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;

void vQueueDelete( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;

#define xQueueSendToFrontFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) \
    xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_FRONT )
 

#define xQueueSendToBackFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) \
    xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_BACK )

#define xQueueOverwriteFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) \
    xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueOVERWRITE )

#define xQueueSendFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) \
    xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_BACK )

BaseType_t xQueueGenericSendFromISR( QueueHandle_t xQueue,
                                     const void * const pvItemToQueue,
                                     BaseType_t * const pxHigherPriorityTaskWoken,
                                     const BaseType_t xCopyPosition ) PRIVILEGED_FUNCTION;
BaseType_t xQueueGiveFromISR( QueueHandle_t xQueue,
                              BaseType_t * const pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION;

BaseType_t xQueueReceiveFromISR( QueueHandle_t xQueue,
                                 void * const pvBuffer,
                                 BaseType_t * const pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION;
 
/*
 * Utilities to query queues that are safe to use from an ISR.  These utilities
 * should be used only from within an ISR, or within a critical section.
 */
BaseType_t xQueueIsQueueEmptyFromISR( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
BaseType_t xQueueIsQueueFullFromISR( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
UBaseType_t uxQueueMessagesWaitingFromISR( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
 
#if ( configUSE_CO_ROUTINES == 1 )
 
/*
 * The functions defined above are for passing data to and from tasks.  The
 * functions below are the equivalents for passing data to and from
 * co-routines.
 *
 * These functions are called from the co-routine macro implementation and
 * should not be called directly from application code.  Instead use the macro
 * wrappers defined within croutine.h.
 */
    BaseType_t xQueueCRSendFromISR( QueueHandle_t xQueue,
                                    const void * pvItemToQueue,
                                    BaseType_t xCoRoutinePreviouslyWoken );
    BaseType_t xQueueCRReceiveFromISR( QueueHandle_t xQueue,
                                       void * pvBuffer,
                                       BaseType_t * pxTaskWoken );
    BaseType_t xQueueCRSend( QueueHandle_t xQueue,
                             const void * pvItemToQueue,
                             TickType_t xTicksToWait );
    BaseType_t xQueueCRReceive( QueueHandle_t xQueue,
                                void * pvBuffer,
                                TickType_t xTicksToWait );
 
#endif /* if ( configUSE_CO_ROUTINES == 1 ) */
 
/*
 * For internal use only.  Use xSemaphoreCreateMutex(),
 * xSemaphoreCreateCounting() or xSemaphoreGetMutexHolder() instead of calling
 * these functions directly.
 */
QueueHandle_t xQueueCreateMutex( const uint8_t ucQueueType ) PRIVILEGED_FUNCTION;
 
#if ( configSUPPORT_STATIC_ALLOCATION == 1 )
    QueueHandle_t xQueueCreateMutexStatic( const uint8_t ucQueueType,
                                           StaticQueue_t * pxStaticQueue ) PRIVILEGED_FUNCTION;
#endif
 
#if ( configUSE_COUNTING_SEMAPHORES == 1 )
    QueueHandle_t xQueueCreateCountingSemaphore( const UBaseType_t uxMaxCount,
                                                 const UBaseType_t uxInitialCount ) PRIVILEGED_FUNCTION;
#endif
 
#if ( ( configUSE_COUNTING_SEMAPHORES == 1 ) && ( configSUPPORT_STATIC_ALLOCATION == 1 ) )
    QueueHandle_t xQueueCreateCountingSemaphoreStatic( const UBaseType_t uxMaxCount,
                                                       const UBaseType_t uxInitialCount,
                                                       StaticQueue_t * pxStaticQueue ) PRIVILEGED_FUNCTION;
#endif
 
BaseType_t xQueueSemaphoreTake( QueueHandle_t xQueue,
                                TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
 
#if ( ( configUSE_MUTEXES == 1 ) && ( INCLUDE_xSemaphoreGetMutexHolder == 1 ) )
    TaskHandle_t xQueueGetMutexHolder( QueueHandle_t xSemaphore ) PRIVILEGED_FUNCTION;
    TaskHandle_t xQueueGetMutexHolderFromISR( QueueHandle_t xSemaphore ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * For internal use only.  Use xSemaphoreTakeRecursive() or
 * xSemaphoreGiveRecursive() instead of calling these functions directly.
 */
BaseType_t xQueueTakeMutexRecursive( QueueHandle_t xMutex,
                                     TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
BaseType_t xQueueGiveMutexRecursive( QueueHandle_t xMutex ) PRIVILEGED_FUNCTION;
 
/*
 * Reset a queue back to its original empty state.  The return value is now
 * obsolete and is always set to pdPASS.
 */
#define xQueueReset( xQueue )    xQueueGenericReset( ( xQueue ), pdFALSE )
 
/*
 * The registry is provided as a means for kernel aware debuggers to
 * locate queues, semaphores and mutexes.  Call vQueueAddToRegistry() add
 * a queue, semaphore or mutex handle to the registry if you want the handle
 * to be available to a kernel aware debugger.  If you are not using a kernel
 * aware debugger then this function can be ignored.
 *
 * configQUEUE_REGISTRY_SIZE defines the maximum number of handles the
 * registry can hold.  configQUEUE_REGISTRY_SIZE must be greater than 0
 * within FreeRTOSConfig.h for the registry to be available.  Its value
 * does not affect the number of queues, semaphores and mutexes that can be
 * created - just the number that the registry can hold.
 *
 * If vQueueAddToRegistry is called more than once with the same xQueue
 * parameter, the registry will store the pcQueueName parameter from the
 * most recent call to vQueueAddToRegistry.
 *
 * @param xQueue The handle of the queue being added to the registry.  This
 * is the handle returned by a call to xQueueCreate().  Semaphore and mutex
 * handles can also be passed in here.
 *
 * @param pcQueueName The name to be associated with the handle.  This is the
 * name that the kernel aware debugger will display.  The queue registry only
 * stores a pointer to the string - so the string must be persistent (global or
 * preferably in ROM/Flash), not on the stack.
 */
#if ( configQUEUE_REGISTRY_SIZE > 0 )
    void vQueueAddToRegistry( QueueHandle_t xQueue,
                              const char * pcQueueName ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * The registry is provided as a means for kernel aware debuggers to
 * locate queues, semaphores and mutexes.  Call vQueueAddToRegistry() add
 * a queue, semaphore or mutex handle to the registry if you want the handle
 * to be available to a kernel aware debugger, and vQueueUnregisterQueue() to
 * remove the queue, semaphore or mutex from the register.  If you are not using
 * a kernel aware debugger then this function can be ignored.
 *
 * @param xQueue The handle of the queue being removed from the registry.
 */
#if ( configQUEUE_REGISTRY_SIZE > 0 )
    void vQueueUnregisterQueue( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * The queue registry is provided as a means for kernel aware debuggers to
 * locate queues, semaphores and mutexes.  Call pcQueueGetName() to look
 * up and return the name of a queue in the queue registry from the queue's
 * handle.
 *
 * @param xQueue The handle of the queue the name of which will be returned.
 * @return If the queue is in the registry then a pointer to the name of the
 * queue is returned.  If the queue is not in the registry then NULL is
 * returned.
 */
#if ( configQUEUE_REGISTRY_SIZE > 0 )
    const char * pcQueueGetName( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * Generic version of the function used to create a queue using dynamic memory
 * allocation.  This is called by other functions and macros that create other
 * RTOS objects that use the queue structure as their base.
 */
#if ( configSUPPORT_DYNAMIC_ALLOCATION == 1 )
    QueueHandle_t xQueueGenericCreate( const UBaseType_t uxQueueLength,
                                       const UBaseType_t uxItemSize,
                                       const uint8_t ucQueueType ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * Generic version of the function used to create a queue using dynamic memory
 * allocation.  This is called by other functions and macros that create other
 * RTOS objects that use the queue structure as their base.
 */
#if ( configSUPPORT_STATIC_ALLOCATION == 1 )
    QueueHandle_t xQueueGenericCreateStatic( const UBaseType_t uxQueueLength,
                                             const UBaseType_t uxItemSize,
                                             uint8_t * pucQueueStorage,
                                             StaticQueue_t * pxStaticQueue,
                                             const uint8_t ucQueueType ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * Generic version of the function used to retrieve the buffers of statically
 * created queues. This is called by other functions and macros that retrieve
 * the buffers of other statically created RTOS objects that use the queue
 * structure as their base.
 */
#if ( configSUPPORT_STATIC_ALLOCATION == 1 )
    BaseType_t xQueueGenericGetStaticBuffers( QueueHandle_t xQueue,
                                              uint8_t ** ppucQueueStorage,
                                              StaticQueue_t ** ppxStaticQueue ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * Queue sets provide a mechanism to allow a task to block (pend) on a read
 * operation from multiple queues or semaphores simultaneously.
 *
 * See FreeRTOS/Source/Demo/Common/Minimal/QueueSet.c for an example using this
 * function.
 *
 * A queue set must be explicitly created using a call to xQueueCreateSet()
 * before it can be used.  Once created, standard FreeRTOS queues and semaphores
 * can be added to the set using calls to xQueueAddToSet().
 * xQueueSelectFromSet() is then used to determine which, if any, of the queues
 * or semaphores contained in the set is in a state where a queue read or
 * semaphore take operation would be successful.
 *
 * Note 1:  See the documentation on https://www.FreeRTOS.org/RTOS-queue-sets.html
 * for reasons why queue sets are very rarely needed in practice as there are
 * simpler methods of blocking on multiple objects.
 *
 * Note 2:  Blocking on a queue set that contains a mutex will not cause the
 * mutex holder to inherit the priority of the blocked task.
 *
 * Note 3:  An additional 4 bytes of RAM is required for each space in a every
 * queue added to a queue set.  Therefore counting semaphores that have a high
 * maximum count value should not be added to a queue set.
 *
 * Note 4:  A receive (in the case of a queue) or take (in the case of a
 * semaphore) operation must not be performed on a member of a queue set unless
 * a call to xQueueSelectFromSet() has first returned a handle to that set member.
 *
 * @param uxEventQueueLength Queue sets store events that occur on
 * the queues and semaphores contained in the set.  uxEventQueueLength specifies
 * the maximum number of events that can be queued at once.  To be absolutely
 * certain that events are not lost uxEventQueueLength should be set to the
 * total sum of the length of the queues added to the set, where binary
 * semaphores and mutexes have a length of 1, and counting semaphores have a
 * length set by their maximum count value.  Examples:
 *  + If a queue set is to hold a queue of length 5, another queue of length 12,
 *    and a binary semaphore, then uxEventQueueLength should be set to
 *    (5 + 12 + 1), or 18.
 *  + If a queue set is to hold three binary semaphores then uxEventQueueLength
 *    should be set to (1 + 1 + 1 ), or 3.
 *  + If a queue set is to hold a counting semaphore that has a maximum count of
 *    5, and a counting semaphore that has a maximum count of 3, then
 *    uxEventQueueLength should be set to (5 + 3), or 8.
 *
 * @return If the queue set is created successfully then a handle to the created
 * queue set is returned.  Otherwise NULL is returned.
 */
#if ( ( configUSE_QUEUE_SETS == 1 ) && ( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) )
    QueueSetHandle_t xQueueCreateSet( const UBaseType_t uxEventQueueLength ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * Adds a queue or semaphore to a queue set that was previously created by a
 * call to xQueueCreateSet().
 *
 * See FreeRTOS/Source/Demo/Common/Minimal/QueueSet.c for an example using this
 * function.
 *
 * Note 1:  A receive (in the case of a queue) or take (in the case of a
 * semaphore) operation must not be performed on a member of a queue set unless
 * a call to xQueueSelectFromSet() has first returned a handle to that set member.
 *
 * @param xQueueOrSemaphore The handle of the queue or semaphore being added to
 * the queue set (cast to an QueueSetMemberHandle_t type).
 *
 * @param xQueueSet The handle of the queue set to which the queue or semaphore
 * is being added.
 *
 * @return If the queue or semaphore was successfully added to the queue set
 * then pdPASS is returned.  If the queue could not be successfully added to the
 * queue set because it is already a member of a different queue set then pdFAIL
 * is returned.
 */
#if ( configUSE_QUEUE_SETS == 1 )
    BaseType_t xQueueAddToSet( QueueSetMemberHandle_t xQueueOrSemaphore,
                               QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * Removes a queue or semaphore from a queue set.  A queue or semaphore can only
 * be removed from a set if the queue or semaphore is empty.
 *
 * See FreeRTOS/Source/Demo/Common/Minimal/QueueSet.c for an example using this
 * function.
 *
 * @param xQueueOrSemaphore The handle of the queue or semaphore being removed
 * from the queue set (cast to an QueueSetMemberHandle_t type).
 *
 * @param xQueueSet The handle of the queue set in which the queue or semaphore
 * is included.
 *
 * @return If the queue or semaphore was successfully removed from the queue set
 * then pdPASS is returned.  If the queue was not in the queue set, or the
 * queue (or semaphore) was not empty, then pdFAIL is returned.
 */
#if ( configUSE_QUEUE_SETS == 1 )
    BaseType_t xQueueRemoveFromSet( QueueSetMemberHandle_t xQueueOrSemaphore,
                                    QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * xQueueSelectFromSet() selects from the members of a queue set a queue or
 * semaphore that either contains data (in the case of a queue) or is available
 * to take (in the case of a semaphore).  xQueueSelectFromSet() effectively
 * allows a task to block (pend) on a read operation on all the queues and
 * semaphores in a queue set simultaneously.
 *
 * See FreeRTOS/Source/Demo/Common/Minimal/QueueSet.c for an example using this
 * function.
 *
 * Note 1:  See the documentation on https://www.FreeRTOS.org/RTOS-queue-sets.html
 * for reasons why queue sets are very rarely needed in practice as there are
 * simpler methods of blocking on multiple objects.
 *
 * Note 2:  Blocking on a queue set that contains a mutex will not cause the
 * mutex holder to inherit the priority of the blocked task.
 *
 * Note 3:  A receive (in the case of a queue) or take (in the case of a
 * semaphore) operation must not be performed on a member of a queue set unless
 * a call to xQueueSelectFromSet() has first returned a handle to that set member.
 *
 * @param xQueueSet The queue set on which the task will (potentially) block.
 *
 * @param xTicksToWait The maximum time, in ticks, that the calling task will
 * remain in the Blocked state (with other tasks executing) to wait for a member
 * of the queue set to be ready for a successful queue read or semaphore take
 * operation.
 *
 * @return xQueueSelectFromSet() will return the handle of a queue (cast to
 * a QueueSetMemberHandle_t type) contained in the queue set that contains data,
 * or the handle of a semaphore (cast to a QueueSetMemberHandle_t type) contained
 * in the queue set that is available, or NULL if no such queue or semaphore
 * exists before before the specified block time expires.
 */
#if ( configUSE_QUEUE_SETS == 1 )
    QueueSetMemberHandle_t xQueueSelectFromSet( QueueSetHandle_t xQueueSet,
                                                const TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
#endif
 
/*
 * A version of xQueueSelectFromSet() that can be used from an ISR.
 */
#if ( configUSE_QUEUE_SETS == 1 )
    QueueSetMemberHandle_t xQueueSelectFromSetFromISR( QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION;
#endif
 
/* Not public API functions. */
void vQueueWaitForMessageRestricted( QueueHandle_t xQueue,
                                     TickType_t xTicksToWait,
                                     const BaseType_t xWaitIndefinitely ) PRIVILEGED_FUNCTION;
BaseType_t xQueueGenericReset( QueueHandle_t xQueue,
                               BaseType_t xNewQueue ) PRIVILEGED_FUNCTION;
 
#if ( configUSE_TRACE_FACILITY == 1 )
    void vQueueSetQueueNumber( QueueHandle_t xQueue,
                               UBaseType_t uxQueueNumber ) PRIVILEGED_FUNCTION;
#endif
 
#if ( configUSE_TRACE_FACILITY == 1 )
    UBaseType_t uxQueueGetQueueNumber( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
#endif
 
#if ( configUSE_TRACE_FACILITY == 1 )
    uint8_t ucQueueGetQueueType( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
#endif
 
UBaseType_t uxQueueGetQueueItemSize( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
UBaseType_t uxQueueGetQueueLength( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
 
/* *INDENT-OFF* */
#ifdef __cplusplus
    }
#endif
/* *INDENT-ON* */
 
#endif /* QUEUE_H */