Diff: FreeRTOS_V8_2_1/source/include/queue.h

Revision:

3:a8c249046181

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FreeRTOS_V8_2_1/source/include/queue.h	Thu Sep 03 14:02:37 2015 +0000
@@ -0,0 +1,1692 @@
+/*
+    FreeRTOS V8.2.1 - Copyright (C) 2015 Real Time Engineers Ltd.
+    All rights reserved
+
+    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.
+
+    ***************************************************************************
+    >>!   NOTE: The modification to the GPL is included to allow you to     !<<
+    >>!   distribute a combined work that includes FreeRTOS without being   !<<
+    >>!   obliged to provide the source code for proprietary components     !<<
+    >>!   outside of the FreeRTOS kernel.                                   !<<
+    ***************************************************************************
+
+    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
+    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+    FOR A PARTICULAR PURPOSE.  Full license text is available on the following
+    link: http://www.freertos.org/a00114.html
+
+    ***************************************************************************
+     *                                                                       *
+     *    FreeRTOS provides completely free yet professionally developed,    *
+     *    robust, strictly quality controlled, supported, and cross          *
+     *    platform software that is more than just the market leader, it     *
+     *    is the industry's de facto standard.                               *
+     *                                                                       *
+     *    Help yourself get started quickly while simultaneously helping     *
+     *    to support the FreeRTOS project by purchasing a FreeRTOS           *
+     *    tutorial book, reference manual, or both:                          *
+     *    http://www.FreeRTOS.org/Documentation                              *
+     *                                                                       *
+    ***************************************************************************
+
+    http://www.FreeRTOS.org/FAQHelp.html - Having a problem?  Start by reading
+    the FAQ page "My application does not run, what could be wrong?".  Have you
+    defined configASSERT()?
+
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+
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+
+    http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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+
+    http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
+    Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
+
+    http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
+    Integrity Systems ltd. to sell under the OpenRTOS brand.  Low cost OpenRTOS
+    licenses offer ticketed support, indemnification and commercial middleware.
+
+    http://www.SafeRTOS.com - High Integrity Systems also provide a safety
+    engineered and independently SIL3 certified version for use in safety and
+    mission critical applications that require provable dependability.
+
+    1 tab == 4 spaces!
+*/
+
+
+#ifndef QUEUE_H
+#define QUEUE_H
+
+#ifndef INC_FREERTOS_H
+	#error "include FreeRTOS.h" must appear in source files before "include queue.h"
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/**
+ * Type by which queues are referenced.  For example, a call to xQueueCreate()
+ * returns an QueueHandle_t variable that can then be used as a parameter to
+ * xQueueSend(), xQueueReceive(), etc.
+ */
+typedef void * QueueHandle_t;
+
+/**
+ * Type by which queue sets are referenced.  For example, a call to
+ * xQueueCreateSet() returns an xQueueSet variable that can then be used as a
+ * parameter to xQueueSelectFromSet(), xQueueAddToSet(), etc.
+ */
+typedef void * QueueSetHandle_t;
+
+/**
+ * Queue sets can contain both queues and semaphores, so the
+ * QueueSetMemberHandle_t is defined as a type to be used where a parameter or
+ * return value can be either an QueueHandle_t or an SemaphoreHandle_t.
+ */
+typedef void * 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 )
+
+/**
+ * queue. h
+ * <pre>
+ QueueHandle_t xQueueCreate(
+							  UBaseType_t uxQueueLength,
+							  UBaseType_t uxItemSize
+						  );
+ * </pre>
+ *
+ * Creates a new queue instance.  This allocates the storage required by the
+ * new queue and returns a handle for the queue.
+ *
+ * @param uxQueueLength The maximum number of items that the queue can contain.
+ *
+ * @param uxItemSize The number of bytes each item in the queue will require.
+ * Items are queued by copy, not by reference, so this is the number of bytes
+ * that will be copied for each posted item.  Each item on the queue must be
+ * the same size.
+ *
+ * @return If the queue is successfully create then a handle to the newly
+ * created queue is returned.  If the queue cannot be created then 0 is
+ * returned.
+ *
+ * Example usage:
+   <pre>
+ struct AMessage
+ {
+	char ucMessageID;
+	char ucData[ 20 ];
+ };
+
+ void vATask( void *pvParameters )
+ {
+ QueueHandle_t xQueue1, xQueue2;
+
+	// Create a queue capable of containing 10 uint32_t values.
+	xQueue1 = xQueueCreate( 10, sizeof( uint32_t ) );
+	if( xQueue1 == 0 )
+	{
+		// Queue was not created and must not be used.
+	}
+
+	// Create a queue capable of containing 10 pointers to AMessage structures.
+	// These should be passed by pointer as they contain a lot of data.
+	xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
+	if( xQueue2 == 0 )
+	{
+		// Queue was not created and must not be used.
+	}
+
+	// ... Rest of task code.
+ }
+ </pre>
+ * \defgroup xQueueCreate xQueueCreate
+ * \ingroup QueueManagement
+ */
+#define xQueueCreate( uxQueueLength, uxItemSize ) xQueueGenericCreate( uxQueueLength, uxItemSize, queueQUEUE_TYPE_BASE )
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueSendToToFront(
+								   QueueHandle_t	xQueue,
+								   const void		*pvItemToQueue,
+								   TickType_t		xTicksToWait
+							   );
+ * </pre>
+ *
+ * This is a macro that calls xQueueGenericSend().
+ *
+ * Post an item to the front of a queue.  The item is queued by copy, not by
+ * reference.  This function must not be called from an interrupt service
+ * routine.  See xQueueSendFromISR () for an alternative which may be used
+ * in an ISR.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param xTicksToWait The maximum amount of time the task should block
+ * waiting for space to become available on the queue, should it already
+ * be full.  The call will return immediately if this is set to 0 and the
+ * queue is full.  The time is defined in tick periods so the constant
+ * portTICK_PERIOD_MS should be used to convert to real time if this is required.
+ *
+ * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
+ *
+ * Example usage:
+   <pre>
+ struct AMessage
+ {
+	char ucMessageID;
+	char ucData[ 20 ];
+ } xMessage;
+
+ uint32_t ulVar = 10UL;
+
+ void vATask( void *pvParameters )
+ {
+ QueueHandle_t xQueue1, xQueue2;
+ struct AMessage *pxMessage;
+
+	// Create a queue capable of containing 10 uint32_t values.
+	xQueue1 = xQueueCreate( 10, sizeof( uint32_t ) );
+
+	// Create a queue capable of containing 10 pointers to AMessage structures.
+	// These should be passed by pointer as they contain a lot of data.
+	xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
+
+	// ...
+
+	if( xQueue1 != 0 )
+	{
+		// Send an uint32_t.  Wait for 10 ticks for space to become
+		// available if necessary.
+		if( xQueueSendToFront( xQueue1, ( void * ) &ulVar, ( TickType_t ) 10 ) != pdPASS )
+		{
+			// Failed to post the message, even after 10 ticks.
+		}
+	}
+
+	if( xQueue2 != 0 )
+	{
+		// Send a pointer to a struct AMessage object.  Don't block if the
+		// queue is already full.
+		pxMessage = & xMessage;
+		xQueueSendToFront( xQueue2, ( void * ) &pxMessage, ( TickType_t ) 0 );
+	}
+
+	// ... Rest of task code.
+ }
+ </pre>
+ * \defgroup xQueueSend xQueueSend
+ * \ingroup QueueManagement
+ */
+#define xQueueSendToFront( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_FRONT )
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueSendToBack(
+								   QueueHandle_t	xQueue,
+								   const void		*pvItemToQueue,
+								   TickType_t		xTicksToWait
+							   );
+ * </pre>
+ *
+ * This is a macro that calls xQueueGenericSend().
+ *
+ * Post an item to the back of a queue.  The item is queued by copy, not by
+ * reference.  This function must not be called from an interrupt service
+ * routine.  See xQueueSendFromISR () for an alternative which may be used
+ * in an ISR.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param xTicksToWait The maximum amount of time the task should block
+ * waiting for space to become available on the queue, should it already
+ * be full.  The call will return immediately if this is set to 0 and the queue
+ * is full.  The  time is defined in tick periods so the constant
+ * portTICK_PERIOD_MS should be used to convert to real time if this is required.
+ *
+ * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
+ *
+ * Example usage:
+   <pre>
+ struct AMessage
+ {
+	char ucMessageID;
+	char ucData[ 20 ];
+ } xMessage;
+
+ uint32_t ulVar = 10UL;
+
+ void vATask( void *pvParameters )
+ {
+ QueueHandle_t xQueue1, xQueue2;
+ struct AMessage *pxMessage;
+
+	// Create a queue capable of containing 10 uint32_t values.
+	xQueue1 = xQueueCreate( 10, sizeof( uint32_t ) );
+
+	// Create a queue capable of containing 10 pointers to AMessage structures.
+	// These should be passed by pointer as they contain a lot of data.
+	xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
+
+	// ...
+
+	if( xQueue1 != 0 )
+	{
+		// Send an uint32_t.  Wait for 10 ticks for space to become
+		// available if necessary.
+		if( xQueueSendToBack( xQueue1, ( void * ) &ulVar, ( TickType_t ) 10 ) != pdPASS )
+		{
+			// Failed to post the message, even after 10 ticks.
+		}
+	}
+
+	if( xQueue2 != 0 )
+	{
+		// Send a pointer to a struct AMessage object.  Don't block if the
+		// queue is already full.
+		pxMessage = & xMessage;
+		xQueueSendToBack( xQueue2, ( void * ) &pxMessage, ( TickType_t ) 0 );
+	}
+
+	// ... Rest of task code.
+ }
+ </pre>
+ * \defgroup xQueueSend xQueueSend
+ * \ingroup QueueManagement
+ */
+#define xQueueSendToBack( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueSend(
+							  QueueHandle_t xQueue,
+							  const void * pvItemToQueue,
+							  TickType_t xTicksToWait
+						 );
+ * </pre>
+ *
+ * This is a macro that calls xQueueGenericSend().  It is included for
+ * backward compatibility with versions of FreeRTOS.org that did not
+ * include the xQueueSendToFront() and xQueueSendToBack() macros.  It is
+ * equivalent to xQueueSendToBack().
+ *
+ * Post an item on a queue.  The item is queued by copy, not by reference.
+ * This function must not be called from an interrupt service routine.
+ * See xQueueSendFromISR () for an alternative which may be used in an ISR.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param xTicksToWait The maximum amount of time the task should block
+ * waiting for space to become available on the queue, should it already
+ * be full.  The call will return immediately if this is set to 0 and the
+ * queue is full.  The time is defined in tick periods so the constant
+ * portTICK_PERIOD_MS should be used to convert to real time if this is required.
+ *
+ * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
+ *
+ * Example usage:
+   <pre>
+ struct AMessage
+ {
+	char ucMessageID;
+	char ucData[ 20 ];
+ } xMessage;
+
+ uint32_t ulVar = 10UL;
+
+ void vATask( void *pvParameters )
+ {
+ QueueHandle_t xQueue1, xQueue2;
+ struct AMessage *pxMessage;
+
+	// Create a queue capable of containing 10 uint32_t values.
+	xQueue1 = xQueueCreate( 10, sizeof( uint32_t ) );
+
+	// Create a queue capable of containing 10 pointers to AMessage structures.
+	// These should be passed by pointer as they contain a lot of data.
+	xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
+
+	// ...
+
+	if( xQueue1 != 0 )
+	{
+		// Send an uint32_t.  Wait for 10 ticks for space to become
+		// available if necessary.
+		if( xQueueSend( xQueue1, ( void * ) &ulVar, ( TickType_t ) 10 ) != pdPASS )
+		{
+			// Failed to post the message, even after 10 ticks.
+		}
+	}
+
+	if( xQueue2 != 0 )
+	{
+		// Send a pointer to a struct AMessage object.  Don't block if the
+		// queue is already full.
+		pxMessage = & xMessage;
+		xQueueSend( xQueue2, ( void * ) &pxMessage, ( TickType_t ) 0 );
+	}
+
+	// ... Rest of task code.
+ }
+ </pre>
+ * \defgroup xQueueSend xQueueSend
+ * \ingroup QueueManagement
+ */
+#define xQueueSend( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueOverwrite(
+							  QueueHandle_t xQueue,
+							  const void * pvItemToQueue
+						 );
+ * </pre>
+ *
+ * Only for use with queues that have a length of one - so the queue is either
+ * empty or full.
+ *
+ * Post an item on a queue.  If the queue is already full then overwrite the
+ * value held in the queue.  The item is queued by copy, not by reference.
+ *
+ * This function must not be called from an interrupt service routine.
+ * See xQueueOverwriteFromISR () for an alternative which may be used in an ISR.
+ *
+ * @param xQueue The handle of the queue to which the data is being sent.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @return xQueueOverwrite() is a macro that calls xQueueGenericSend(), and
+ * therefore has the same return values as xQueueSendToFront().  However, pdPASS
+ * is the only value that can be returned because xQueueOverwrite() will write
+ * to the queue even when the queue is already full.
+ *
+ * Example usage:
+   <pre>
+
+ void vFunction( void *pvParameters )
+ {
+ QueueHandle_t xQueue;
+ uint32_t ulVarToSend, ulValReceived;
+
+	// Create a queue to hold one uint32_t value.  It is strongly
+	// recommended *not* to use xQueueOverwrite() on queues that can
+	// contain more than one value, and doing so will trigger an assertion
+	// if configASSERT() is defined.
+	xQueue = xQueueCreate( 1, sizeof( uint32_t ) );
+
+	// Write the value 10 to the queue using xQueueOverwrite().
+	ulVarToSend = 10;
+	xQueueOverwrite( xQueue, &ulVarToSend );
+
+	// Peeking the queue should now return 10, but leave the value 10 in
+	// the queue.  A block time of zero is used as it is known that the
+	// queue holds a value.
+	ulValReceived = 0;
+	xQueuePeek( xQueue, &ulValReceived, 0 );
+
+	if( ulValReceived != 10 )
+	{
+		// Error unless the item was removed by a different task.
+	}
+
+	// The queue is still full.  Use xQueueOverwrite() to overwrite the
+	// value held in the queue with 100.
+	ulVarToSend = 100;
+	xQueueOverwrite( xQueue, &ulVarToSend );
+
+	// This time read from the queue, leaving the queue empty once more.
+	// A block time of 0 is used again.
+	xQueueReceive( xQueue, &ulValReceived, 0 );
+
+	// The value read should be the last value written, even though the
+	// queue was already full when the value was written.
+	if( ulValReceived != 100 )
+	{
+		// Error!
+	}
+
+	// ...
+}
+ </pre>
+ * \defgroup xQueueOverwrite xQueueOverwrite
+ * \ingroup QueueManagement
+ */
+#define xQueueOverwrite( xQueue, pvItemToQueue ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), 0, queueOVERWRITE )
+
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueGenericSend(
+									QueueHandle_t xQueue,
+									const void * pvItemToQueue,
+									TickType_t xTicksToWait
+									BaseType_t xCopyPosition
+								);
+ * </pre>
+ *
+ * It is preferred that the macros xQueueSend(), xQueueSendToFront() and
+ * xQueueSendToBack() are used in place of calling this function directly.
+ *
+ * Post an item on a queue.  The item is queued by copy, not by reference.
+ * This function must not be called from an interrupt service routine.
+ * See xQueueSendFromISR () for an alternative which may be used in an ISR.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param xTicksToWait The maximum amount of time the task should block
+ * waiting for space to become available on the queue, should it already
+ * be full.  The call will return immediately if this is set to 0 and the
+ * queue is full.  The time is defined in tick periods so the constant
+ * portTICK_PERIOD_MS should be used to convert to real time if this is required.
+ *
+ * @param xCopyPosition Can take the value queueSEND_TO_BACK to place the
+ * item at the back of the queue, or queueSEND_TO_FRONT to place the item
+ * at the front of the queue (for high priority messages).
+ *
+ * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
+ *
+ * Example usage:
+   <pre>
+ struct AMessage
+ {
+	char ucMessageID;
+	char ucData[ 20 ];
+ } xMessage;
+
+ uint32_t ulVar = 10UL;
+
+ void vATask( void *pvParameters )
+ {
+ QueueHandle_t xQueue1, xQueue2;
+ struct AMessage *pxMessage;
+
+	// Create a queue capable of containing 10 uint32_t values.
+	xQueue1 = xQueueCreate( 10, sizeof( uint32_t ) );
+
+	// Create a queue capable of containing 10 pointers to AMessage structures.
+	// These should be passed by pointer as they contain a lot of data.
+	xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
+
+	// ...
+
+	if( xQueue1 != 0 )
+	{
+		// Send an uint32_t.  Wait for 10 ticks for space to become
+		// available if necessary.
+		if( xQueueGenericSend( xQueue1, ( void * ) &ulVar, ( TickType_t ) 10, queueSEND_TO_BACK ) != pdPASS )
+		{
+			// Failed to post the message, even after 10 ticks.
+		}
+	}
+
+	if( xQueue2 != 0 )
+	{
+		// Send a pointer to a struct AMessage object.  Don't block if the
+		// queue is already full.
+		pxMessage = & xMessage;
+		xQueueGenericSend( xQueue2, ( void * ) &pxMessage, ( TickType_t ) 0, queueSEND_TO_BACK );
+	}
+
+	// ... Rest of task code.
+ }
+ </pre>
+ * \defgroup xQueueSend xQueueSend
+ * \ingroup QueueManagement
+ */
+BaseType_t xQueueGenericSend( QueueHandle_t xQueue, const void * const pvItemToQueue, TickType_t xTicksToWait, const BaseType_t xCopyPosition ) PRIVILEGED_FUNCTION;
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueuePeek(
+							 QueueHandle_t xQueue,
+							 void *pvBuffer,
+							 TickType_t xTicksToWait
+						 );</pre>
+ *
+ * This is a macro that calls the xQueueGenericReceive() function.
+ *
+ * Receive an item from a queue without removing the item from the queue.
+ * The item is received by copy so a buffer of adequate size must be
+ * provided.  The number of bytes copied into the buffer was defined when
+ * the queue was created.
+ *
+ * Successfully received items remain on the queue so will be returned again
+ * by the next call, or a call to xQueueReceive().
+ *
+ * This macro must not be used in an interrupt service routine.  See
+ * xQueuePeekFromISR() for an alternative that can be called from an interrupt
+ * service routine.
+ *
+ * @param xQueue The handle to the queue from which the item is to be
+ * received.
+ *
+ * @param pvBuffer Pointer to the buffer into which the received item will
+ * be copied.
+ *
+ * @param xTicksToWait The maximum amount of time the task should block
+ * waiting for an item to receive should the queue be empty at the time
+ * of the call.	 The time is defined in tick periods so the constant
+ * portTICK_PERIOD_MS should be used to convert to real time if this is required.
+ * xQueuePeek() will return immediately if xTicksToWait is 0 and the queue
+ * is empty.
+ *
+ * @return pdTRUE if an item was successfully received from the queue,
+ * otherwise pdFALSE.
+ *
+ * Example usage:
+   <pre>
+ struct AMessage
+ {
+	char ucMessageID;
+	char ucData[ 20 ];
+ } xMessage;
+
+ QueueHandle_t xQueue;
+
+ // Task to create a queue and post a value.
+ void vATask( void *pvParameters )
+ {
+ struct AMessage *pxMessage;
+
+	// Create a queue capable of containing 10 pointers to AMessage structures.
+	// These should be passed by pointer as they contain a lot of data.
+	xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
+	if( xQueue == 0 )
+	{
+		// Failed to create the queue.
+	}
+
+	// ...
+
+	// Send a pointer to a struct AMessage object.  Don't block if the
+	// queue is already full.
+	pxMessage = & xMessage;
+	xQueueSend( xQueue, ( void * ) &pxMessage, ( TickType_t ) 0 );
+
+	// ... Rest of task code.
+ }
+
+ // Task to peek the data from the queue.
+ void vADifferentTask( void *pvParameters )
+ {
+ struct AMessage *pxRxedMessage;
+
+	if( xQueue != 0 )
+	{
+		// Peek a message on the created queue.  Block for 10 ticks if a
+		// message is not immediately available.
+		if( xQueuePeek( xQueue, &( pxRxedMessage ), ( TickType_t ) 10 ) )
+		{
+			// pcRxedMessage now points to the struct AMessage variable posted
+			// by vATask, but the item still remains on the queue.
+		}
+	}
+
+	// ... Rest of task code.
+ }
+ </pre>
+ * \defgroup xQueueReceive xQueueReceive
+ * \ingroup QueueManagement
+ */
+#define xQueuePeek( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdTRUE )
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueuePeekFromISR(
+									QueueHandle_t xQueue,
+									void *pvBuffer,
+								);</pre>
+ *
+ * A version of xQueuePeek() that can be called from an interrupt service
+ * routine (ISR).
+ *
+ * Receive an item from a queue without removing the item from the queue.
+ * The item is received by copy so a buffer of adequate size must be
+ * provided.  The number of bytes copied into the buffer was defined when
+ * the queue was created.
+ *
+ * Successfully received items remain on the queue so will be returned again
+ * by the next call, or a call to xQueueReceive().
+ *
+ * @param xQueue The handle to the queue from which the item is to be
+ * received.
+ *
+ * @param pvBuffer Pointer to the buffer into which the received item will
+ * be copied.
+ *
+ * @return pdTRUE if an item was successfully received from the queue,
+ * otherwise pdFALSE.
+ *
+ * \defgroup xQueuePeekFromISR xQueuePeekFromISR
+ * \ingroup QueueManagement
+ */
+BaseType_t xQueuePeekFromISR( QueueHandle_t xQueue, void * const pvBuffer ) PRIVILEGED_FUNCTION;
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueReceive(
+								 QueueHandle_t xQueue,
+								 void *pvBuffer,
+								 TickType_t xTicksToWait
+							);</pre>
+ *
+ * This is a macro that calls the xQueueGenericReceive() function.
+ *
+ * Receive an item from a queue.  The item is received by copy so a buffer of
+ * adequate size must be provided.  The number of bytes copied into the buffer
+ * was defined when the queue was created.
+ *
+ * Successfully received items are removed from the queue.
+ *
+ * This function must not be used in an interrupt service routine.  See
+ * xQueueReceiveFromISR for an alternative that can.
+ *
+ * @param xQueue The handle to the queue from which the item is to be
+ * received.
+ *
+ * @param pvBuffer Pointer to the buffer into which the received item will
+ * be copied.
+ *
+ * @param xTicksToWait The maximum amount of time the task should block
+ * waiting for an item to receive should the queue be empty at the time
+ * of the call.	 xQueueReceive() will return immediately if xTicksToWait
+ * is zero and the queue is empty.  The time is defined in tick periods so the
+ * constant portTICK_PERIOD_MS should be used to convert to real time if this is
+ * required.
+ *
+ * @return pdTRUE if an item was successfully received from the queue,
+ * otherwise pdFALSE.
+ *
+ * Example usage:
+   <pre>
+ struct AMessage
+ {
+	char ucMessageID;
+	char ucData[ 20 ];
+ } xMessage;
+
+ QueueHandle_t xQueue;
+
+ // Task to create a queue and post a value.
+ void vATask( void *pvParameters )
+ {
+ struct AMessage *pxMessage;
+
+	// Create a queue capable of containing 10 pointers to AMessage structures.
+	// These should be passed by pointer as they contain a lot of data.
+	xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
+	if( xQueue == 0 )
+	{
+		// Failed to create the queue.
+	}
+
+	// ...
+
+	// Send a pointer to a struct AMessage object.  Don't block if the
+	// queue is already full.
+	pxMessage = & xMessage;
+	xQueueSend( xQueue, ( void * ) &pxMessage, ( TickType_t ) 0 );
+
+	// ... Rest of task code.
+ }
+
+ // Task to receive from the queue.
+ void vADifferentTask( void *pvParameters )
+ {
+ struct AMessage *pxRxedMessage;
+
+	if( xQueue != 0 )
+	{
+		// Receive a message on the created queue.  Block for 10 ticks if a
+		// message is not immediately available.
+		if( xQueueReceive( xQueue, &( pxRxedMessage ), ( TickType_t ) 10 ) )
+		{
+			// pcRxedMessage now points to the struct AMessage variable posted
+			// by vATask.
+		}
+	}
+
+	// ... Rest of task code.
+ }
+ </pre>
+ * \defgroup xQueueReceive xQueueReceive
+ * \ingroup QueueManagement
+ */
+#define xQueueReceive( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdFALSE )
+
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueGenericReceive(
+									   QueueHandle_t	xQueue,
+									   void	*pvBuffer,
+									   TickType_t	xTicksToWait
+									   BaseType_t	xJustPeek
+									);</pre>
+ *
+ * It is preferred that the macro xQueueReceive() be used rather than calling
+ * this function directly.
+ *
+ * Receive an item from a queue.  The item is received by copy so a buffer of
+ * adequate size must be provided.  The number of bytes copied into the buffer
+ * was defined when the queue was created.
+ *
+ * This function must not be used in an interrupt service routine.  See
+ * xQueueReceiveFromISR for an alternative that can.
+ *
+ * @param xQueue The handle to the queue from which the item is to be
+ * received.
+ *
+ * @param pvBuffer Pointer to the buffer into which the received item will
+ * be copied.
+ *
+ * @param xTicksToWait The maximum amount of time the task should block
+ * waiting for an item to receive should the queue be empty at the time
+ * of the call.	 The time is defined in tick periods so the constant
+ * portTICK_PERIOD_MS should be used to convert to real time if this is required.
+ * xQueueGenericReceive() will return immediately if the queue is empty and
+ * xTicksToWait is 0.
+ *
+ * @param xJustPeek When set to true, the item received from the queue is not
+ * actually removed from the queue - meaning a subsequent call to
+ * xQueueReceive() will return the same item.  When set to false, the item
+ * being received from the queue is also removed from the queue.
+ *
+ * @return pdTRUE if an item was successfully received from the queue,
+ * otherwise pdFALSE.
+ *
+ * Example usage:
+   <pre>
+ struct AMessage
+ {
+	char ucMessageID;
+	char ucData[ 20 ];
+ } xMessage;
+
+ QueueHandle_t xQueue;
+
+ // Task to create a queue and post a value.
+ void vATask( void *pvParameters )
+ {
+ struct AMessage *pxMessage;
+
+	// Create a queue capable of containing 10 pointers to AMessage structures.
+	// These should be passed by pointer as they contain a lot of data.
+	xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
+	if( xQueue == 0 )
+	{
+		// Failed to create the queue.
+	}
+
+	// ...
+
+	// Send a pointer to a struct AMessage object.  Don't block if the
+	// queue is already full.
+	pxMessage = & xMessage;
+	xQueueSend( xQueue, ( void * ) &pxMessage, ( TickType_t ) 0 );
+
+	// ... Rest of task code.
+ }
+
+ // Task to receive from the queue.
+ void vADifferentTask( void *pvParameters )
+ {
+ struct AMessage *pxRxedMessage;
+
+	if( xQueue != 0 )
+	{
+		// Receive a message on the created queue.  Block for 10 ticks if a
+		// message is not immediately available.
+		if( xQueueGenericReceive( xQueue, &( pxRxedMessage ), ( TickType_t ) 10 ) )
+		{
+			// pcRxedMessage now points to the struct AMessage variable posted
+			// by vATask.
+		}
+	}
+
+	// ... Rest of task code.
+ }
+ </pre>
+ * \defgroup xQueueReceive xQueueReceive
+ * \ingroup QueueManagement
+ */
+BaseType_t xQueueGenericReceive( QueueHandle_t xQueue, void * const pvBuffer, TickType_t xTicksToWait, const BaseType_t xJustPeek ) PRIVILEGED_FUNCTION;
+
+/**
+ * queue. h
+ * <pre>UBaseType_t uxQueueMessagesWaiting( const QueueHandle_t xQueue );</pre>
+ *
+ * Return the number of messages stored in a queue.
+ *
+ * @param xQueue A handle to the queue being queried.
+ *
+ * @return The number of messages available in the queue.
+ *
+ * \defgroup uxQueueMessagesWaiting uxQueueMessagesWaiting
+ * \ingroup QueueManagement
+ */
+UBaseType_t uxQueueMessagesWaiting( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
+
+/**
+ * queue. h
+ * <pre>UBaseType_t uxQueueSpacesAvailable( const QueueHandle_t xQueue );</pre>
+ *
+ * Return the number of free spaces available in a queue.  This is equal to the
+ * number of items that can be sent to the queue before the queue becomes full
+ * if no items are removed.
+ *
+ * @param xQueue A handle to the queue being queried.
+ *
+ * @return The number of spaces available in the queue.
+ *
+ * \defgroup uxQueueMessagesWaiting uxQueueMessagesWaiting
+ * \ingroup QueueManagement
+ */
+UBaseType_t uxQueueSpacesAvailable( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
+
+/**
+ * queue. h
+ * <pre>void vQueueDelete( QueueHandle_t xQueue );</pre>
+ *
+ * Delete a queue - freeing all the memory allocated for storing of items
+ * placed on the queue.
+ *
+ * @param xQueue A handle to the queue to be deleted.
+ *
+ * \defgroup vQueueDelete vQueueDelete
+ * \ingroup QueueManagement
+ */
+void vQueueDelete( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueSendToFrontFromISR(
+										 QueueHandle_t xQueue,
+										 const void *pvItemToQueue,
+										 BaseType_t *pxHigherPriorityTaskWoken
+									  );
+ </pre>
+ *
+ * This is a macro that calls xQueueGenericSendFromISR().
+ *
+ * Post an item to the front of a queue.  It is safe to use this macro from
+ * within an interrupt service routine.
+ *
+ * Items are queued by copy not reference so it is preferable to only
+ * queue small items, especially when called from an ISR.  In most cases
+ * it would be preferable to store a pointer to the item being queued.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param pxHigherPriorityTaskWoken xQueueSendToFrontFromISR() will set
+ * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
+ * to unblock, and the unblocked task has a priority higher than the currently
+ * running task.  If xQueueSendToFromFromISR() sets this value to pdTRUE then
+ * a context switch should be requested before the interrupt is exited.
+ *
+ * @return pdTRUE if the data was successfully sent to the queue, otherwise
+ * errQUEUE_FULL.
+ *
+ * Example usage for buffered IO (where the ISR can obtain more than one value
+ * per call):
+   <pre>
+ void vBufferISR( void )
+ {
+ char cIn;
+ BaseType_t xHigherPrioritTaskWoken;
+
+	// We have not woken a task at the start of the ISR.
+	xHigherPriorityTaskWoken = pdFALSE;
+
+	// Loop until the buffer is empty.
+	do
+	{
+		// Obtain a byte from the buffer.
+		cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
+
+		// Post the byte.
+		xQueueSendToFrontFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWoken );
+
+	} while( portINPUT_BYTE( BUFFER_COUNT ) );
+
+	// Now the buffer is empty we can switch context if necessary.
+	if( xHigherPriorityTaskWoken )
+	{
+		taskYIELD ();
+	}
+ }
+ </pre>
+ *
+ * \defgroup xQueueSendFromISR xQueueSendFromISR
+ * \ingroup QueueManagement
+ */
+#define xQueueSendToFrontFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_FRONT )
+
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueSendToBackFromISR(
+										 QueueHandle_t xQueue,
+										 const void *pvItemToQueue,
+										 BaseType_t *pxHigherPriorityTaskWoken
+									  );
+ </pre>
+ *
+ * This is a macro that calls xQueueGenericSendFromISR().
+ *
+ * Post an item to the back of a queue.  It is safe to use this macro from
+ * within an interrupt service routine.
+ *
+ * Items are queued by copy not reference so it is preferable to only
+ * queue small items, especially when called from an ISR.  In most cases
+ * it would be preferable to store a pointer to the item being queued.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param pxHigherPriorityTaskWoken xQueueSendToBackFromISR() will set
+ * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
+ * to unblock, and the unblocked task has a priority higher than the currently
+ * running task.  If xQueueSendToBackFromISR() sets this value to pdTRUE then
+ * a context switch should be requested before the interrupt is exited.
+ *
+ * @return pdTRUE if the data was successfully sent to the queue, otherwise
+ * errQUEUE_FULL.
+ *
+ * Example usage for buffered IO (where the ISR can obtain more than one value
+ * per call):
+   <pre>
+ void vBufferISR( void )
+ {
+ char cIn;
+ BaseType_t xHigherPriorityTaskWoken;
+
+	// We have not woken a task at the start of the ISR.
+	xHigherPriorityTaskWoken = pdFALSE;
+
+	// Loop until the buffer is empty.
+	do
+	{
+		// Obtain a byte from the buffer.
+		cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
+
+		// Post the byte.
+		xQueueSendToBackFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWoken );
+
+	} while( portINPUT_BYTE( BUFFER_COUNT ) );
+
+	// Now the buffer is empty we can switch context if necessary.
+	if( xHigherPriorityTaskWoken )
+	{
+		taskYIELD ();
+	}
+ }
+ </pre>
+ *
+ * \defgroup xQueueSendFromISR xQueueSendFromISR
+ * \ingroup QueueManagement
+ */
+#define xQueueSendToBackFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_BACK )
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueOverwriteFromISR(
+							  QueueHandle_t xQueue,
+							  const void * pvItemToQueue,
+							  BaseType_t *pxHigherPriorityTaskWoken
+						 );
+ * </pre>
+ *
+ * A version of xQueueOverwrite() that can be used in an interrupt service
+ * routine (ISR).
+ *
+ * Only for use with queues that can hold a single item - so the queue is either
+ * empty or full.
+ *
+ * Post an item on a queue.  If the queue is already full then overwrite the
+ * value held in the queue.  The item is queued by copy, not by reference.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param pxHigherPriorityTaskWoken xQueueOverwriteFromISR() will set
+ * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
+ * to unblock, and the unblocked task has a priority higher than the currently
+ * running task.  If xQueueOverwriteFromISR() sets this value to pdTRUE then
+ * a context switch should be requested before the interrupt is exited.
+ *
+ * @return xQueueOverwriteFromISR() is a macro that calls
+ * xQueueGenericSendFromISR(), and therefore has the same return values as
+ * xQueueSendToFrontFromISR().  However, pdPASS is the only value that can be
+ * returned because xQueueOverwriteFromISR() will write to the queue even when
+ * the queue is already full.
+ *
+ * Example usage:
+   <pre>
+
+ QueueHandle_t xQueue;
+
+ void vFunction( void *pvParameters )
+ {
+ 	// Create a queue to hold one uint32_t value.  It is strongly
+	// recommended *not* to use xQueueOverwriteFromISR() on queues that can
+	// contain more than one value, and doing so will trigger an assertion
+	// if configASSERT() is defined.
+	xQueue = xQueueCreate( 1, sizeof( uint32_t ) );
+}
+
+void vAnInterruptHandler( void )
+{
+// xHigherPriorityTaskWoken must be set to pdFALSE before it is used.
+BaseType_t xHigherPriorityTaskWoken = pdFALSE;
+uint32_t ulVarToSend, ulValReceived;
+
+	// Write the value 10 to the queue using xQueueOverwriteFromISR().
+	ulVarToSend = 10;
+	xQueueOverwriteFromISR( xQueue, &ulVarToSend, &xHigherPriorityTaskWoken );
+
+	// The queue is full, but calling xQueueOverwriteFromISR() again will still
+	// pass because the value held in the queue will be overwritten with the
+	// new value.
+	ulVarToSend = 100;
+	xQueueOverwriteFromISR( xQueue, &ulVarToSend, &xHigherPriorityTaskWoken );
+
+	// Reading from the queue will now return 100.
+
+	// ...
+
+	if( xHigherPrioritytaskWoken == pdTRUE )
+	{
+		// Writing to the queue caused a task to unblock and the unblocked task
+		// has a priority higher than or equal to the priority of the currently
+		// executing task (the task this interrupt interrupted).  Perform a context
+		// switch so this interrupt returns directly to the unblocked task.
+		portYIELD_FROM_ISR(); // or portEND_SWITCHING_ISR() depending on the port.
+	}
+}
+ </pre>
+ * \defgroup xQueueOverwriteFromISR xQueueOverwriteFromISR
+ * \ingroup QueueManagement
+ */
+#define xQueueOverwriteFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueOVERWRITE )
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueSendFromISR(
+									 QueueHandle_t xQueue,
+									 const void *pvItemToQueue,
+									 BaseType_t *pxHigherPriorityTaskWoken
+								);
+ </pre>
+ *
+ * This is a macro that calls xQueueGenericSendFromISR().  It is included
+ * for backward compatibility with versions of FreeRTOS.org that did not
+ * include the xQueueSendToBackFromISR() and xQueueSendToFrontFromISR()
+ * macros.
+ *
+ * Post an item to the back of a queue.  It is safe to use this function from
+ * within an interrupt service routine.
+ *
+ * Items are queued by copy not reference so it is preferable to only
+ * queue small items, especially when called from an ISR.  In most cases
+ * it would be preferable to store a pointer to the item being queued.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param pxHigherPriorityTaskWoken xQueueSendFromISR() will set
+ * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
+ * to unblock, and the unblocked task has a priority higher than the currently
+ * running task.  If xQueueSendFromISR() sets this value to pdTRUE then
+ * a context switch should be requested before the interrupt is exited.
+ *
+ * @return pdTRUE if the data was successfully sent to the queue, otherwise
+ * errQUEUE_FULL.
+ *
+ * Example usage for buffered IO (where the ISR can obtain more than one value
+ * per call):
+   <pre>
+ void vBufferISR( void )
+ {
+ char cIn;
+ BaseType_t xHigherPriorityTaskWoken;
+
+	// We have not woken a task at the start of the ISR.
+	xHigherPriorityTaskWoken = pdFALSE;
+
+	// Loop until the buffer is empty.
+	do
+	{
+		// Obtain a byte from the buffer.
+		cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
+
+		// Post the byte.
+		xQueueSendFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWoken );
+
+	} while( portINPUT_BYTE( BUFFER_COUNT ) );
+
+	// Now the buffer is empty we can switch context if necessary.
+	if( xHigherPriorityTaskWoken )
+	{
+		// Actual macro used here is port specific.
+		portYIELD_FROM_ISR ();
+	}
+ }
+ </pre>
+ *
+ * \defgroup xQueueSendFromISR xQueueSendFromISR
+ * \ingroup QueueManagement
+ */
+#define xQueueSendFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_BACK )
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueGenericSendFromISR(
+										   QueueHandle_t		xQueue,
+										   const	void	*pvItemToQueue,
+										   BaseType_t	*pxHigherPriorityTaskWoken,
+										   BaseType_t	xCopyPosition
+									   );
+ </pre>
+ *
+ * It is preferred that the macros xQueueSendFromISR(),
+ * xQueueSendToFrontFromISR() and xQueueSendToBackFromISR() be used in place
+ * of calling this function directly.  xQueueGiveFromISR() is an
+ * equivalent for use by semaphores that don't actually copy any data.
+ *
+ * Post an item on a queue.  It is safe to use this function from within an
+ * interrupt service routine.
+ *
+ * Items are queued by copy not reference so it is preferable to only
+ * queue small items, especially when called from an ISR.  In most cases
+ * it would be preferable to store a pointer to the item being queued.
+ *
+ * @param xQueue The handle to the queue on which the item is to be posted.
+ *
+ * @param pvItemToQueue A pointer to the item that is to be placed on the
+ * queue.  The size of the items the queue will hold was defined when the
+ * queue was created, so this many bytes will be copied from pvItemToQueue
+ * into the queue storage area.
+ *
+ * @param pxHigherPriorityTaskWoken xQueueGenericSendFromISR() will set
+ * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
+ * to unblock, and the unblocked task has a priority higher than the currently
+ * running task.  If xQueueGenericSendFromISR() sets this value to pdTRUE then
+ * a context switch should be requested before the interrupt is exited.
+ *
+ * @param xCopyPosition Can take the value queueSEND_TO_BACK to place the
+ * item at the back of the queue, or queueSEND_TO_FRONT to place the item
+ * at the front of the queue (for high priority messages).
+ *
+ * @return pdTRUE if the data was successfully sent to the queue, otherwise
+ * errQUEUE_FULL.
+ *
+ * Example usage for buffered IO (where the ISR can obtain more than one value
+ * per call):
+   <pre>
+ void vBufferISR( void )
+ {
+ char cIn;
+ BaseType_t xHigherPriorityTaskWokenByPost;
+
+	// We have not woken a task at the start of the ISR.
+	xHigherPriorityTaskWokenByPost = pdFALSE;
+
+	// Loop until the buffer is empty.
+	do
+	{
+		// Obtain a byte from the buffer.
+		cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
+
+		// Post each byte.
+		xQueueGenericSendFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWokenByPost, queueSEND_TO_BACK );
+
+	} while( portINPUT_BYTE( BUFFER_COUNT ) );
+
+	// Now the buffer is empty we can switch context if necessary.  Note that the
+	// name of the yield function required is port specific.
+	if( xHigherPriorityTaskWokenByPost )
+	{
+		taskYIELD_YIELD_FROM_ISR();
+	}
+ }
+ </pre>
+ *
+ * \defgroup xQueueSendFromISR xQueueSendFromISR
+ * \ingroup QueueManagement
+ */
+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;
+
+/**
+ * queue. h
+ * <pre>
+ BaseType_t xQueueReceiveFromISR(
+									   QueueHandle_t	xQueue,
+									   void	*pvBuffer,
+									   BaseType_t *pxTaskWoken
+								   );
+ * </pre>
+ *
+ * Receive an item from a queue.  It is safe to use this function from within an
+ * interrupt service routine.
+ *
+ * @param xQueue The handle to the queue from which the item is to be
+ * received.
+ *
+ * @param pvBuffer Pointer to the buffer into which the received item will
+ * be copied.
+ *
+ * @param pxTaskWoken A task may be blocked waiting for space to become
+ * available on the queue.  If xQueueReceiveFromISR causes such a task to
+ * unblock *pxTaskWoken will get set to pdTRUE, otherwise *pxTaskWoken will
+ * remain unchanged.
+ *
+ * @return pdTRUE if an item was successfully received from the queue,
+ * otherwise pdFALSE.
+ *
+ * Example usage:
+   <pre>
+
+ QueueHandle_t xQueue;
+
+ // Function to create a queue and post some values.
+ void vAFunction( void *pvParameters )
+ {
+ char cValueToPost;
+ const TickType_t xTicksToWait = ( TickType_t )0xff;
+
+	// Create a queue capable of containing 10 characters.
+	xQueue = xQueueCreate( 10, sizeof( char ) );
+	if( xQueue == 0 )
+	{
+		// Failed to create the queue.
+	}
+
+	// ...
+
+	// Post some characters that will be used within an ISR.  If the queue
+	// is full then this task will block for xTicksToWait ticks.
+	cValueToPost = 'a';
+	xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait );
+	cValueToPost = 'b';
+	xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait );
+
+	// ... keep posting characters ... this task may block when the queue
+	// becomes full.
+
+	cValueToPost = 'c';
+	xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait );
+ }
+
+ // ISR that outputs all the characters received on the queue.
+ void vISR_Routine( void )
+ {
+ BaseType_t xTaskWokenByReceive = pdFALSE;
+ char cRxedChar;
+
+	while( xQueueReceiveFromISR( xQueue, ( void * ) &cRxedChar, &xTaskWokenByReceive) )
+	{
+		// A character was received.  Output the character now.
+		vOutputCharacter( cRxedChar );
+
+		// If removing the character from the queue woke the task that was
+		// posting onto the queue cTaskWokenByReceive will have been set to
+		// pdTRUE.  No matter how many times this loop iterates only one
+		// task will be woken.
+	}
+
+	if( cTaskWokenByPost != ( char ) pdFALSE;
+	{
+		taskYIELD ();
+	}
+ }
+ </pre>
+ * \defgroup xQueueReceiveFromISR xQueueReceiveFromISR
+ * \ingroup QueueManagement
+ */
+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 witin 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;
+
+
+/*
+ * xQueueAltGenericSend() is an alternative version of xQueueGenericSend().
+ * Likewise xQueueAltGenericReceive() is an alternative version of
+ * xQueueGenericReceive().
+ *
+ * The source code that implements the alternative (Alt) API is much
+ * simpler	because it executes everything from within a critical section.
+ * This is	the approach taken by many other RTOSes, but FreeRTOS.org has the
+ * preferred fully featured API too.  The fully featured API has more
+ * complex	code that takes longer to execute, but makes much less use of
+ * critical sections.  Therefore the alternative API sacrifices interrupt
+ * responsiveness to gain execution speed, whereas the fully featured API
+ * sacrifices execution speed to ensure better interrupt responsiveness.
+ */
+BaseType_t xQueueAltGenericSend( QueueHandle_t xQueue, const void * const pvItemToQueue, TickType_t xTicksToWait, BaseType_t xCopyPosition );
+BaseType_t xQueueAltGenericReceive( QueueHandle_t xQueue, void * const pvBuffer, TickType_t xTicksToWait, BaseType_t xJustPeeking );
+#define xQueueAltSendToFront( xQueue, pvItemToQueue, xTicksToWait ) xQueueAltGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_FRONT )
+#define xQueueAltSendToBack( xQueue, pvItemToQueue, xTicksToWait ) xQueueAltGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )
+#define xQueueAltReceive( xQueue, pvBuffer, xTicksToWait ) xQueueAltGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdFALSE )
+#define xQueueAltPeek( xQueue, pvBuffer, xTicksToWait ) xQueueAltGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdTRUE )
+
+/*
+ * 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 );
+
+/*
+ * For internal use only.  Use xSemaphoreCreateMutex(),
+ * xSemaphoreCreateCounting() or xSemaphoreGetMutexHolder() instead of calling
+ * these functions directly.
+ */
+QueueHandle_t xQueueCreateMutex( const uint8_t ucQueueType ) PRIVILEGED_FUNCTION;
+QueueHandle_t xQueueCreateCountingSemaphore( const UBaseType_t uxMaxCount, const UBaseType_t uxInitialCount ) PRIVILEGED_FUNCTION;
+void* xQueueGetMutexHolder( QueueHandle_t xSemaphore ) PRIVILEGED_FUNCTION;
+
+/*
+ * For internal use only.  Use xSemaphoreTakeMutexRecursive() or
+ * xSemaphoreGiveMutexRecursive() instead of calling these functions directly.
+ */
+BaseType_t xQueueTakeMutexRecursive( QueueHandle_t xMutex, TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
+BaseType_t xQueueGiveMutexRecursive( QueueHandle_t pxMutex ) 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 effect the number of queues, semaphores and mutexes that can be
+ * created - just the number that the registry can hold.
+ *
+ * @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 pcName 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 *pcName ) PRIVILEGED_FUNCTION; /*lint !e971 Unqualified char types are allowed for strings and single characters only. */
+#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
+
+/*
+ * Generic version of the queue creation function, which is in turn called by
+ * any queue, semaphore or mutex creation function or macro.
+ */
+QueueHandle_t xQueueGenericCreate( const UBaseType_t uxQueueLength, const UBaseType_t uxItemSize, const uint8_t ucQueueType ) PRIVILEGED_FUNCTION;
+
+/*
+ * 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 http://wwwFreeRTOS.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.
+ */
+QueueSetHandle_t xQueueCreateSet( const UBaseType_t uxEventQueueLength ) PRIVILEGED_FUNCTION;
+
+/*
+ * 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.
+ */
+BaseType_t xQueueAddToSet( QueueSetMemberHandle_t xQueueOrSemaphore, QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION;
+
+/*
+ * 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.
+ */
+BaseType_t xQueueRemoveFromSet( QueueSetMemberHandle_t xQueueOrSemaphore, QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION;
+
+/*
+ * 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 http://wwwFreeRTOS.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.
+ */
+QueueSetMemberHandle_t xQueueSelectFromSet( QueueSetHandle_t xQueueSet, const TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
+
+/*
+ * A version of xQueueSelectFromSet() that can be used from an ISR.
+ */
+QueueSetMemberHandle_t xQueueSelectFromSetFromISR( QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION;
+
+/* Not public API functions. */
+void vQueueWaitForMessageRestricted( QueueHandle_t xQueue, TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
+BaseType_t xQueueGenericReset( QueueHandle_t xQueue, BaseType_t xNewQueue ) PRIVILEGED_FUNCTION;
+void vQueueSetQueueNumber( QueueHandle_t xQueue, UBaseType_t uxQueueNumber ) PRIVILEGED_FUNCTION;
+UBaseType_t uxQueueGetQueueNumber( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
+uint8_t ucQueueGetQueueType( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION;
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* QUEUE_H */
+
+