]> git.sur5r.net Git - freertos/blobdiff - Source/queue.c
Update version numbers to V4.8.0
[freertos] / Source / queue.c
index 8eea22b6e4892fcf734078d6adead54fe04df34b..5b9cf69e335455ea68629dd4ac9a9b2788a5e4cf 100644 (file)
@@ -1,5 +1,5 @@
 /*\r
-       FreeRTOS.org V4.1.3 - Copyright (C) 2003-2006 Richard Barry.\r
+       FreeRTOS.org V4.8.0 - Copyright (C) 2003-2008 Richard Barry.\r
 \r
        This file is part of the FreeRTOS.org distribution.\r
 \r
        can be applied.\r
 \r
        ***************************************************************************\r
-       See http://www.FreeRTOS.org for documentation, latest information, license\r
-       and contact details.  Please ensure to read the configuration and relevant\r
-       port sections of the online documentation.\r
        ***************************************************************************\r
-*/\r
-\r
-/*\r
-Changes from V1.01\r
-\r
-       + More use of 8bit data types.\r
-       + Function name prefixes changed where the data type returned has changed.\r
-\r
-Changed from V2.0.0\r
-\r
-       + Added the queue locking mechanism and make more use of the scheduler\r
-         suspension feature to minimise the time interrupts have to be disabled\r
-         when accessing a queue.\r
-\r
-Changed from V2.2.0\r
-\r
-       + Explicit use of 'signed' qualifier on portCHAR types added.\r
-\r
-Changes from V3.0.0\r
-\r
-       + API changes as described on the FreeRTOS.org WEB site.\r
-\r
-Changes from V3.2.3\r
-\r
-       + Added the queue functions that can be used from co-routines.\r
+       *                                                                                                                                                 *\r
+       * SAVE TIME AND MONEY!  Why not get us to quote to get FreeRTOS.org               *\r
+       * running on your hardware - or even write all or part of your application*\r
+       * for you?  See http://www.OpenRTOS.com for details.                                      *\r
+       *                                                                                                                                                 *\r
+       ***************************************************************************\r
+       ***************************************************************************\r
 \r
-Changes from V4.0.5\r
+       Please ensure to read the configuration and relevant port sections of the\r
+       online documentation.\r
 \r
-       + Added a loop within xQueueSend() and xQueueReceive() to prevent the\r
-         functions exiting when a block time remains and the function has\r
-         not completed.\r
+       http://www.FreeRTOS.org - Documentation, latest information, license and \r
+       contact details.\r
 \r
-Changes from V4.1.2:\r
+       http://www.SafeRTOS.com - A version that is certified for use in safety \r
+       critical systems.\r
 \r
-       + BUG FIX:  Removed the call to prvIsQueueEmpty from within xQueueCRReceive\r
-         as it exited with interrupts enabled.  Thanks Paul Katz.\r
+       http://www.OpenRTOS.com - Commercial support, development, porting, \r
+       licensing and training services.\r
 */\r
 \r
 #include <stdlib.h>\r
@@ -80,6 +60,21 @@ Changes from V4.1.2:
 #define queueUNLOCKED  ( ( signed portBASE_TYPE ) -1 )\r
 #define queueERRONEOUS_UNBLOCK                                 ( -1 )\r
 \r
+/* For internal use only. */\r
+#define        queueSEND_TO_BACK       ( 0 )\r
+#define        queueSEND_TO_FRONT      ( 1 )\r
+\r
+/* Effectively make a union out of the xQUEUE structure. */\r
+#define pxMutexHolder                          pcTail\r
+#define uxQueueType                                    pcHead\r
+#define uxRecursiveCallCount           pcReadFrom\r
+#define queueQUEUE_IS_MUTEX                    NULL\r
+\r
+/* Semaphores do not actually store or copy data, so have an items size of\r
+zero. */\r
+#define queueSEMAPHORE_QUEUE_ITEM_LENGTH ( 0 )\r
+#define queueDONT_BLOCK                                         ( ( portTickType ) 0 )\r
+#define queueMUTEX_GIVE_BLOCK_TIME              ( ( portTickType ) 0 )\r
 /*\r
  * Definition of the queue used by the scheduler.\r
  * Items are queued by copy, not reference.\r
@@ -95,12 +90,12 @@ typedef struct QueueDefinition
        xList xTasksWaitingToSend;                              /*< List of tasks that are blocked waiting to post onto this queue.  Stored in priority order. */\r
        xList xTasksWaitingToReceive;                   /*< List of tasks that are blocked waiting to read from this queue.  Stored in priority order. */\r
 \r
-       unsigned portBASE_TYPE uxMessagesWaiting;/*< The number of items currently in the queue. */\r
+       volatile unsigned portBASE_TYPE uxMessagesWaiting;/*< The number of items currently in the queue. */\r
        unsigned portBASE_TYPE uxLength;                /*< The length of the queue defined as the number of items it will hold, not the number of bytes. */\r
        unsigned portBASE_TYPE uxItemSize;              /*< The size of each items that the queue will hold. */\r
 \r
-       signed portBASE_TYPE 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. */\r
-       signed portBASE_TYPE 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. */\r
+       signed portBASE_TYPE 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. */\r
+       signed portBASE_TYPE 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. */\r
 } xQUEUE;\r
 /*-----------------------------------------------------------*/\r
 \r
@@ -117,12 +112,22 @@ typedef xQUEUE * xQueueHandle;
  * functions are documented in the API header file.\r
  */\r
 xQueueHandle xQueueCreate( unsigned portBASE_TYPE uxQueueLength, unsigned portBASE_TYPE uxItemSize );\r
-signed portBASE_TYPE xQueueSend( xQueueHandle xQueue, const void * pvItemToQueue, portTickType xTicksToWait );\r
-unsigned portBASE_TYPE uxQueueMessagesWaiting( xQueueHandle pxQueue );\r
+signed portBASE_TYPE xQueueGenericSend( xQueueHandle xQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition );\r
+unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle const pxQueue );\r
 void vQueueDelete( xQueueHandle xQueue );\r
-signed portBASE_TYPE xQueueSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xTaskPreviouslyWoken );\r
-signed portBASE_TYPE xQueueReceive( xQueueHandle pxQueue, void *pvBuffer, portTickType xTicksToWait );\r
-signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, void *pvBuffer, signed portBASE_TYPE *pxTaskWoken );\r
+signed portBASE_TYPE xQueueGenericSendFromISR( xQueueHandle pxQueue, const void * const pvItemToQueue, signed portBASE_TYPE xTaskPreviouslyWoken, portBASE_TYPE xCopyPosition );\r
+signed portBASE_TYPE xQueueGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking );\r
+signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, const void * const pvBuffer, signed portBASE_TYPE *pxTaskWoken );\r
+xQueueHandle xQueueCreateMutex( void );\r
+xQueueHandle xQueueCreateCountingSemaphore( unsigned portBASE_TYPE uxCountValue, unsigned portBASE_TYPE uxInitialCount );\r
+portBASE_TYPE xQueueTakeMutexRecursive( xQueueHandle xMutex, portTickType xBlockTime );\r
+portBASE_TYPE xQueueGiveMutexRecursive( xQueueHandle xMutex );\r
+signed portBASE_TYPE xQueueAltGenericSend( xQueueHandle pxQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition );\r
+signed portBASE_TYPE xQueueAltGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking );\r
+portBASE_TYPE xQueueIsQueueEmptyFromISR( const xQueueHandle const pxQueue );\r
+portBASE_TYPE xQueueIsQueueFullFromISR( const xQueueHandle const pxQueue );\r
+unsigned portBASE_TYPE uxQueueMessagesWaitingFromISR( const xQueueHandle const pxQueue );\r
+\r
 \r
 #if configUSE_CO_ROUTINES == 1\r
        signed portBASE_TYPE xQueueCRSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xCoRoutinePreviouslyWoken );\r
@@ -146,30 +151,25 @@ static void prvUnlockQueue( xQueueHandle pxQueue );
  *\r
  * @return pdTRUE if the queue contains no items, otherwise pdFALSE.\r
  */\r
-static signed portBASE_TYPE prvIsQueueEmpty( const xQueueHandle pxQueue );\r
+static signed portBASE_TYPE prvIsQueueEmpty( const xQueueHandle const pxQueue );\r
 \r
 /*\r
  * Uses a critical section to determine if there is any space in a queue.\r
  *\r
  * @return pdTRUE if there is no space, otherwise pdFALSE;\r
  */\r
-static signed portBASE_TYPE prvIsQueueFull( const xQueueHandle pxQueue );\r
+static signed portBASE_TYPE prvIsQueueFull( const xQueueHandle const pxQueue );\r
 \r
 /*\r
- * Macro that copies an item into the queue.  This is done by copying the item\r
- * byte for byte, not by reference.  Updates the queue state to ensure it's\r
- * integrity after the copy.\r
+ * Copies an item into the queue, either at the front of the queue or the\r
+ * back of the queue.\r
  */\r
-#define prvCopyQueueData( pxQueue, pvItemToQueue )                                                                                             \\r
-{                                                                                                                                                                                              \\r
-       memcpy( ( void * ) pxQueue->pcWriteTo, pvItemToQueue, ( unsigned ) pxQueue->uxItemSize );       \\r
-       ++( pxQueue->uxMessagesWaiting );                                                                                                                       \\r
-       pxQueue->pcWriteTo += pxQueue->uxItemSize;                                                                                                      \\r
-       if( pxQueue->pcWriteTo >= pxQueue->pcTail )                                                                                                     \\r
-       {                                                                                                                                                                                       \\r
-               pxQueue->pcWriteTo = pxQueue->pcHead;                                                                                                   \\r
-       }                                                                                                                                                                                       \\r
-}\r
+static void prvCopyDataToQueue( xQUEUE *pxQueue, const void *pvItemToQueue, portBASE_TYPE xPosition );\r
+\r
+/*\r
+ * Copies an item out of a queue.\r
+ */\r
+static void prvCopyDataFromQueue( xQUEUE * const pxQueue, const void *pvBuffer );\r
 /*-----------------------------------------------------------*/\r
 \r
 /*\r
@@ -223,10 +223,13 @@ size_t xQueueSizeInBytes;
                                vListInitialise( &( pxNewQueue->xTasksWaitingToSend ) );\r
                                vListInitialise( &( pxNewQueue->xTasksWaitingToReceive ) );\r
 \r
+                               traceQUEUE_CREATE( pxNewQueue );\r
+\r
                                return  pxNewQueue;\r
                        }\r
                        else\r
                        {\r
+                               traceQUEUE_CREATE_FAILED();\r
                                vPortFree( pxNewQueue );\r
                        }\r
                }\r
@@ -238,193 +241,565 @@ size_t xQueueSizeInBytes;
 }\r
 /*-----------------------------------------------------------*/\r
 \r
-signed portBASE_TYPE xQueueSend( xQueueHandle pxQueue, const void *pvItemToQueue, portTickType xTicksToWait )\r
+#if ( configUSE_MUTEXES == 1 )\r
+\r
+       xQueueHandle xQueueCreateMutex( void )\r
+       {\r
+       xQUEUE *pxNewQueue;\r
+       \r
+               /* Allocate the new queue structure. */\r
+               pxNewQueue = ( xQUEUE * ) pvPortMalloc( sizeof( xQUEUE ) );\r
+               if( pxNewQueue != NULL )\r
+               {\r
+                       /* Information required for priority inheritance. */\r
+                       pxNewQueue->pxMutexHolder = NULL;\r
+                       pxNewQueue->uxQueueType = queueQUEUE_IS_MUTEX;\r
+       \r
+                       /* Queues used as a mutex no data is actually copied into or out\r
+                       of the queue. */\r
+                       pxNewQueue->pcWriteTo = NULL;\r
+                       pxNewQueue->pcReadFrom = NULL;\r
+                       \r
+                       /* Each mutex has a length of 1 (like a binary semaphore) and\r
+                       an item size of 0 as nothing is actually copied into or out\r
+                       of the mutex. */\r
+                       pxNewQueue->uxMessagesWaiting = 0;\r
+                       pxNewQueue->uxLength = 1;\r
+                       pxNewQueue->uxItemSize = 0;\r
+                       pxNewQueue->xRxLock = queueUNLOCKED;\r
+                       pxNewQueue->xTxLock = queueUNLOCKED;\r
+       \r
+                       /* Ensure the event queues start with the correct state. */\r
+                       vListInitialise( &( pxNewQueue->xTasksWaitingToSend ) );\r
+                       vListInitialise( &( pxNewQueue->xTasksWaitingToReceive ) );\r
+\r
+                       /* Start with the semaphore in the expected state. */\r
+                       xQueueGenericSend( pxNewQueue, NULL, 0, queueSEND_TO_BACK );\r
+\r
+                       traceCREATE_MUTEX( pxNewQueue );\r
+               }\r
+               else\r
+               {\r
+                       traceCREATE_MUTEX_FAILED();\r
+               }\r
+       \r
+               return pxNewQueue;\r
+       }\r
+\r
+#endif /* configUSE_MUTEXES */\r
+/*-----------------------------------------------------------*/\r
+\r
+#if configUSE_RECURSIVE_MUTEXES == 1\r
+\r
+       portBASE_TYPE xQueueGiveMutexRecursive( xQueueHandle pxMutex )\r
+       {\r
+       portBASE_TYPE xReturn;\r
+\r
+               /* If this is the task that holds the mutex then pxMutexHolder will not\r
+               change outside of this task.  If this task does not hold the mutex then\r
+               pxMutexHolder can never coincidentally equal the tasks handle, and as\r
+               this is the only condition we are interested in it does not matter if\r
+               pxMutexHolder is accessed simultaneously by another task.  Therefore no\r
+               mutual exclusion is required to test the pxMutexHolder variable. */\r
+               if( pxMutex->pxMutexHolder == xTaskGetCurrentTaskHandle() )\r
+               {\r
+                       /* uxRecursiveCallCount cannot be zero if pxMutexHolder is equal to\r
+                       the task handle, therefore no underflow check is required.  Also,\r
+                       uxRecursiveCallCount is only modified by the mutex holder, and as\r
+                       there can only be one, no mutual exclusion is required to modify the\r
+                       uxRecursiveCallCount member. */\r
+                       ( pxMutex->uxRecursiveCallCount )--;\r
+\r
+                       /* Have we unwound the call count? */\r
+                       if( pxMutex->uxRecursiveCallCount == 0 )\r
+                       {\r
+                               /* Return the mutex.  This will automatically unblock any other\r
+                               task that might be waiting to access the mutex. */\r
+                xQueueGenericSend( pxMutex, NULL, queueMUTEX_GIVE_BLOCK_TIME, queueSEND_TO_BACK );\r
+                       }\r
+\r
+                       xReturn = pdPASS;\r
+\r
+                       traceGIVE_MUTEX_RECURSIVE( pxMutex );\r
+               }\r
+               else\r
+               {\r
+                       /* We cannot give the mutex because we are not the holder. */\r
+                       xReturn = pdFAIL;\r
+\r
+                       traceGIVE_MUTEX_RECURSIVE_FAILED( pxMutex );\r
+               }\r
+\r
+               return xReturn;\r
+       }\r
+\r
+#endif /* configUSE_RECURSIVE_MUTEXES */\r
+/*-----------------------------------------------------------*/\r
+\r
+#if configUSE_RECURSIVE_MUTEXES == 1\r
+\r
+       portBASE_TYPE xQueueTakeMutexRecursive( xQueueHandle pxMutex, portTickType xBlockTime )\r
+       {\r
+       portBASE_TYPE xReturn;\r
+\r
+               /* Comments regarding mutual exclusion as per those within\r
+               xQueueGiveMutexRecursive(). */\r
+\r
+               if( pxMutex->pxMutexHolder == xTaskGetCurrentTaskHandle() )\r
+               {\r
+                       ( pxMutex->uxRecursiveCallCount )++;\r
+                       xReturn = pdPASS;\r
+               }\r
+               else\r
+               {\r
+            xReturn = xQueueGenericReceive( pxMutex, NULL, xBlockTime, pdFALSE );\r
+\r
+                       /* pdPASS will only be returned if we successfully obtained the mutex,\r
+                       we may have blocked to reach here. */\r
+                       if( xReturn == pdPASS )\r
+                       {\r
+                               ( pxMutex->uxRecursiveCallCount )++;\r
+                       }\r
+               }\r
+\r
+               traceTAKE_MUTEX_RECURSIVE( pxMutex );\r
+\r
+               return xReturn;\r
+       }\r
+\r
+#endif /* configUSE_RECURSIVE_MUTEXES */\r
+/*-----------------------------------------------------------*/\r
+\r
+#if configUSE_COUNTING_SEMAPHORES == 1\r
+\r
+       xQueueHandle xQueueCreateCountingSemaphore( unsigned portBASE_TYPE uxCountValue, unsigned portBASE_TYPE uxInitialCount )\r
+       {\r
+       xQueueHandle pxHandle;\r
+       \r
+               pxHandle = xQueueCreate( ( unsigned portBASE_TYPE ) uxCountValue, queueSEMAPHORE_QUEUE_ITEM_LENGTH );\r
+\r
+               if( pxHandle != NULL )\r
+               {\r
+                       pxHandle->uxMessagesWaiting = uxInitialCount;\r
+\r
+                       traceCREATE_COUNTING_SEMAPHORE();\r
+               }\r
+               else\r
+               {\r
+                       traceCREATE_COUNTING_SEMAPHORE_FAILED();\r
+               }\r
+\r
+               return pxHandle;\r
+       }\r
+\r
+#endif /* configUSE_COUNTING_SEMAPHORES */\r
+/*-----------------------------------------------------------*/\r
+\r
+signed portBASE_TYPE xQueueGenericSend( xQueueHandle pxQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition )\r
 {\r
-signed portBASE_TYPE xReturn = pdFAIL;\r
+signed portBASE_TYPE xReturn = pdTRUE;\r
 xTimeOutType xTimeOut;\r
 \r
-       /* Make sure other tasks do not access the queue. */\r
-       vTaskSuspendAll();\r
-\r
-       /* Capture the current time status for future reference. */\r
-       vTaskSetTimeOutState( &xTimeOut );\r
-\r
-       /* It is important that this is the only thread/ISR that modifies the\r
-       ready or delayed lists until xTaskResumeAll() is called.  Places where\r
-       the ready/delayed lists are modified include:\r
-\r
-               + vTaskDelay() -  Nothing can call vTaskDelay as the scheduler is\r
-                 suspended, vTaskDelay() cannot be called from an ISR.\r
-               + vTaskPrioritySet() - Has a critical section around the access.\r
-               + vTaskSwitchContext() - This will not get executed while the scheduler\r
-                 is suspended.\r
-               + prvCheckDelayedTasks() - This will not get executed while the\r
-                 scheduler is suspended.\r
-               + xTaskCreate() - Has a critical section around the access.\r
-               + vTaskResume() - Has a critical section around the access.\r
-               + xTaskResumeAll() - Has a critical section around the access.\r
-               + xTaskRemoveFromEventList - Checks to see if the scheduler is\r
-                 suspended.  If so then the TCB being removed from the event is\r
-                 removed from the event and added to the xPendingReadyList.\r
-       */\r
-\r
-       /* Make sure interrupts do not access the queue event list. */\r
-       prvLockQueue( pxQueue );\r
-\r
-       /* It is important that interrupts to not access the event list of the\r
-       queue being modified here.  Places where the event list is modified\r
-       include:\r
-\r
-               + xQueueSendFromISR().  This checks the lock on the queue to see if\r
-                 it has access.  If the queue is locked then the Tx lock count is\r
-                 incremented to signify that a task waiting for data can be made ready\r
-                 once the queue lock is removed.  If the queue is not locked then\r
-                 a task can be moved from the event list, but will not be removed\r
-                 from the delayed list or placed in the ready list until the scheduler\r
-                 is unlocked.\r
-\r
-               + xQueueReceiveFromISR().  As per xQueueSendFromISR().\r
-       */\r
-               \r
-       /* If the queue is already full we may have to block. */\r
        do\r
        {\r
-               if( prvIsQueueFull( pxQueue ) )\r
+       /* If xTicksToWait is zero then we are not going to block even\r
+       if there is no room in the queue to post. */\r
+               if( xTicksToWait > ( portTickType ) 0 )\r
                {\r
-                       /* The queue is full - do we want to block or just leave without\r
-                       posting? */\r
-                       if( xTicksToWait > ( portTickType ) 0 )\r
+                       vTaskSuspendAll();\r
+                       prvLockQueue( pxQueue );\r
+\r
+                       if( xReturn == pdTRUE )\r
                        {\r
-                               /* We are going to place ourselves on the xTasksWaitingToSend event\r
-                               list, and will get woken should the delay expire, or space become\r
-                               available on the queue.\r
-                               \r
-                               As detailed above we do not require mutual exclusion on the event\r
-                               list as nothing else can modify it or the ready lists while we\r
-                               have the scheduler suspended and queue locked.\r
-                               \r
-                               It is possible that an ISR has removed data from the queue since we\r
-                               checked if any was available.  If this is the case then the data\r
-                               will have been copied from the queue, and the queue variables\r
-                               updated, but the event list will not yet have been checked to see if\r
-                               anything is waiting as the queue is locked. */\r
-                               vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToSend ), xTicksToWait );\r
-       \r
-                               /* Force a context switch now as we are blocked.  We can do\r
-                               this from within a critical section as the task we are\r
-                               switching to has its own context.  When we return here (i.e. we\r
-                               unblock) we will leave the critical section as normal.\r
-                               \r
-                               It is possible that an ISR has caused an event on an unrelated and\r
-                               unlocked queue.  If this was the case then the event list for that\r
-                               queue will have been updated but the ready lists left unchanged -\r
-                               instead the readied task will have been added to the pending ready\r
-                               list. */\r
-                               taskENTER_CRITICAL();\r
+                               /* This is the first time through - we need to capture the\r
+                               time while the scheduler is locked to ensure we attempt to\r
+                               block at least once. */\r
+                               vTaskSetTimeOutState( &xTimeOut );\r
+                       }\r
+\r
+                       if( prvIsQueueFull( pxQueue ) )\r
+                       {\r
+                       /* Need to call xTaskCheckForTimeout again as time could\r
+                       have passed since it was last called if this is not the\r
+                       first time around this loop.  */\r
+                               if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )\r
                                {\r
-                                       /* We can safely unlock the queue and scheduler here as\r
-                                       interrupts are disabled.  We must not yield with anything\r
-                                       locked, but we can yield from within a critical section.\r
-                                       \r
-                                       Tasks that have been placed on the pending ready list cannot\r
-                                       be tasks that are waiting for events on this queue.  See\r
-                                       in comment xTaskRemoveFromEventList(). */\r
+                                       traceBLOCKING_ON_QUEUE_SEND( pxQueue );\r
+                                       vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToSend ), xTicksToWait );\r
+                                               \r
+                                       /* Unlocking the queue means queue events can effect the\r
+                                       event list.  It is possible     that interrupts occurring now\r
+                                       remove this task from the event list again - but as the\r
+                                       scheduler is suspended the task will go onto the pending\r
+                                       ready last instead of the actual ready list. */\r
                                        prvUnlockQueue( pxQueue );\r
-       \r
-                                       /* Resuming the scheduler may cause a yield.  If so then there\r
-                                       is no point yielding again here. */\r
+                                               \r
+                                       /* Resuming the scheduler will move tasks from the pending\r
+                                       ready list into the ready list - so it is feasible that this\r
+                                       task is already in a ready list before it yields - in which\r
+                                       case the yield will not cause a context switch unless there\r
+                                       is also a higher priority task in the pending ready list. */\r
                                        if( !xTaskResumeAll() )\r
                                        {\r
                                                taskYIELD();\r
                                        }\r
-\r
-                                       /* We want to check to see if the queue is still full\r
-                                       before leaving the critical section.  This is to prevent\r
-                                       this task placing an item into the queue due to an\r
-                                       interrupt making space on the queue between critical\r
-                                       sections (when there might be a higher priority task\r
-                                       blocked on the queue that cannot run yet because the\r
-                                       scheduler gets suspended). */\r
-                                       if( pxQueue->uxMessagesWaiting == pxQueue->uxLength )\r
+                               }\r
+                               else\r
+                               {\r
+                                       prvUnlockQueue( pxQueue );\r
+                                       ( void ) xTaskResumeAll();\r
+                               }\r
+                       }\r
+                       else\r
+                       {\r
+                       /* The queue was not full so we can just unlock the\r
+                       scheduler and queue again before carrying on. */\r
+                               prvUnlockQueue( pxQueue );\r
+                               ( void ) xTaskResumeAll();\r
+                       }\r
+               }\r
+                       \r
+               /* Higher priority tasks and interrupts can execute during\r
+               this time and could possible refill the queue - even if we\r
+               unblocked because space became available. */\r
+               \r
+               taskENTER_CRITICAL();\r
+               {\r
+                       /* Is there room on the queue now?  To be running we must be\r
+                       the highest priority task wanting to access the queue. */\r
+                       if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )\r
+                       {\r
+                               traceQUEUE_SEND( pxQueue );\r
+                               prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );\r
+                               xReturn = pdPASS;\r
+                                       \r
+                               /* If there was a task waiting for data to arrive on the\r
+                               queue then unblock it now. */\r
+                               if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )\r
+                               {\r
+                                       if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) == pdTRUE )\r
                                        {\r
-                                               /* We unblocked but there is no space in the queue,\r
-                                               we probably timed out. */\r
-                                               xReturn = errQUEUE_FULL;\r
+                                           /* The unblocked task has a priority higher than\r
+                                           our own so yield immediately. */\r
+                                           taskYIELD();\r
                                        }\r
-       \r
-                                       /* Before leaving the critical section we have to ensure\r
-                                       exclusive access again. */\r
-                                       vTaskSuspendAll();\r
-                                       prvLockQueue( pxQueue );                                \r
                                }\r
-                               taskEXIT_CRITICAL();\r
+                       }\r
+                       else\r
+                       {\r
+                               /* Setting xReturn to errQUEUE_FULL will force its timeout\r
+                               to be re-evaluated.  This is necessary in case interrupts\r
+                               and higher priority tasks accessed the queue between this\r
+                               task being unblocked and subsequently attempting to write\r
+                               to the queue. */\r
+                               xReturn = errQUEUE_FULL;\r
                        }\r
                }\r
-                       \r
-               /* If xReturn is errQUEUE_FULL then we unblocked when the queue\r
-               was still full.  Don't check it again now as it is possible that\r
-               an interrupt has removed an item from the queue since we left the\r
-               critical section and we don't want to write to the queue in case\r
-               there is a task of higher priority blocked waiting for space to\r
-               be available on the queue.  If this is the case the higher priority\r
-               task will execute when the scheduler is unsupended. */\r
-               if( xReturn != errQUEUE_FULL )\r
-               {\r
-                       /* When we are here it is possible that we unblocked as space became\r
-                       available on the queue.  It is also possible that an ISR posted to the\r
-                       queue since we left the critical section, so it may be that again there\r
-                       is no space.  This would only happen if a task and ISR post onto the\r
-                       same queue. */\r
+               taskEXIT_CRITICAL();\r
+\r
+               if( xReturn == errQUEUE_FULL )\r
+               {\r
+                       if( xTicksToWait > ( portTickType ) 0 )\r
+                       {\r
+                               if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )\r
+                               {\r
+                                       xReturn = queueERRONEOUS_UNBLOCK;\r
+                               }\r
+                               else\r
+                               {\r
+                                       traceQUEUE_SEND_FAILED( pxQueue );\r
+                               }\r
+                       }\r
+                       else\r
+                       {\r
+                               traceQUEUE_SEND_FAILED( pxQueue );\r
+                       }\r
+               }\r
+       }\r
+       while( xReturn == queueERRONEOUS_UNBLOCK );\r
+\r
+       return xReturn;\r
+}\r
+/*-----------------------------------------------------------*/\r
+\r
+#if configUSE_ALTERNATIVE_API == 1\r
+\r
+       signed portBASE_TYPE xQueueAltGenericSend( xQueueHandle pxQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition )\r
+       {\r
+       signed portBASE_TYPE xReturn = pdPASS;\r
+       xTimeOutType xTimeOut;\r
+\r
+               /* The source code that implements the alternative (Alt) API is\r
+               simpler because it makes more use of critical sections.  This is        \r
+               the approach taken by many other RTOSes, but FreeRTOS.org has the\r
+               preferred fully featured API too.  The fully featured API has more\r
+               complex code that takes longer to execute, but makes less use of\r
+               critical sections.  */\r
+\r
+               do\r
+               {\r
+               /* If xTicksToWait is zero then we are not going to block even\r
+               if there is no room in the queue to post. */\r
+                       if( xTicksToWait > ( portTickType ) 0 )\r
+                       {\r
+                               portENTER_CRITICAL();\r
+                               {\r
+                                       if( xReturn == pdPASS )\r
+                                       {\r
+                                               /* This is the first time through - capture the time\r
+                                               inside the critical section to ensure we attempt to\r
+                                               block at least once. */\r
+                                               vTaskSetTimeOutState( &xTimeOut );\r
+                                       }\r
+                                       \r
+                                       if( prvIsQueueFull( pxQueue ) )\r
+                                       {\r
+                                       /* Need to call xTaskCheckForTimeout again as time could\r
+                                       have passed since it was last called if this is not the\r
+                                       first time around this loop.  */\r
+                                               if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )\r
+                                               {\r
+                                                       traceBLOCKING_ON_QUEUE_SEND( pxQueue );\r
+                                                       vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToSend ), xTicksToWait );\r
+\r
+                                                       /* This will exit the critical section, then re-enter when\r
+                                                       the task next runs. */\r
+                                                       taskYIELD();\r
+                                               }\r
+                                       }\r
+                               }\r
+                               portEXIT_CRITICAL();\r
+                       }\r
+                               \r
+                       /* Higher priority tasks and interrupts can execute during\r
+                       this time and could possible refill the queue - even if we\r
+                       unblocked because space became available. */\r
+                       \r
                        taskENTER_CRITICAL();\r
                        {\r
+                               /* Is there room on the queue now?  To be running we must be\r
+                               the highest priority task wanting to access the queue. */\r
                                if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )\r
                                {\r
-                                       /* There is room in the queue, copy the data into the queue. */                 \r
-                                       prvCopyQueueData( pxQueue, pvItemToQueue );             \r
+                                       traceQUEUE_SEND( pxQueue );\r
+                                       prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );\r
                                        xReturn = pdPASS;\r
-               \r
-                                       /* Update the TxLock count so prvUnlockQueue knows to check for\r
-                                       tasks waiting for data to become available in the queue. */\r
-                                       ++( pxQueue->xTxLock );\r
+                                               \r
+                                       /* If there was a task waiting for data to arrive on the\r
+                                       queue then unblock it now. */\r
+                                       if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )\r
+                                       {\r
+                                               if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) == pdTRUE )\r
+                                               {\r
+                                                       /* The unblocked task has a priority higher than\r
+                                                       our own so yield immediately. */\r
+                                                       taskYIELD();\r
+                                               }\r
+                                       }\r
                                }\r
                                else\r
                                {\r
+                                       /* Setting xReturn to errQUEUE_FULL will force its timeout\r
+                                       to be re-evaluated.  This is necessary in case interrupts\r
+                                       and higher priority tasks accessed the queue between this\r
+                                       task being unblocked and subsequently attempting to write\r
+                                       to the queue. */\r
                                        xReturn = errQUEUE_FULL;\r
                                }\r
                        }\r
                        taskEXIT_CRITICAL();\r
+\r
+                       if( xReturn == errQUEUE_FULL )\r
+                       {\r
+                               if( xTicksToWait > ( portTickType ) 0 )\r
+                               {\r
+                                       if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )\r
+                                       {\r
+                                               xReturn = queueERRONEOUS_UNBLOCK;\r
+                                       }\r
+                                       else\r
+                                       {\r
+                                               traceQUEUE_SEND_FAILED( pxQueue );\r
+                                       }\r
+                               }\r
+                               else\r
+                               {\r
+                                       traceQUEUE_SEND_FAILED( pxQueue );\r
+                               }\r
+                       }\r
                }\r
+               while( xReturn == queueERRONEOUS_UNBLOCK );\r
 \r
-               if( xReturn == errQUEUE_FULL )\r
+               return xReturn;\r
+       }\r
+\r
+#endif /* configUSE_ALTERNATIVE_API */\r
+/*-----------------------------------------------------------*/\r
+\r
+#if configUSE_ALTERNATIVE_API == 1\r
+\r
+       signed portBASE_TYPE xQueueAltGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking )\r
+       {\r
+       signed portBASE_TYPE xReturn = pdTRUE;\r
+       xTimeOutType xTimeOut;\r
+       signed portCHAR *pcOriginalReadPosition;\r
+\r
+               /* The source code that implements the alternative (Alt) API is\r
+               simpler because it makes more use of critical sections.  This is        \r
+               the approach taken by many other RTOSes, but FreeRTOS.org has the\r
+               preferred fully featured API too.  The fully featured API has more\r
+               complex code that takes longer to execute, but makes less use of\r
+               critical sections.  */\r
+\r
+               do\r
                {\r
-                       if( xTicksToWait > 0 )\r
+                       /* If there are no messages in the queue we may have to block. */\r
+                       if( xTicksToWait > ( portTickType ) 0 )\r
                        {\r
-                               if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )\r
+                               portENTER_CRITICAL();\r
                                {\r
-                                       xReturn = queueERRONEOUS_UNBLOCK;\r
+                                       if( xReturn == pdPASS )\r
+                                       {\r
+                                               /* This is the first time through - capture the time\r
+                                               inside the critical section to ensure we attempt to\r
+                                               block at least once. */\r
+                                               vTaskSetTimeOutState( &xTimeOut );\r
+                                       }\r
+                                       \r
+                                       if( prvIsQueueEmpty( pxQueue ) )\r
+                                       {\r
+                                       /* Need to call xTaskCheckForTimeout again as time could\r
+                                       have passed since it was last called if this is not the\r
+                                       first time around this loop. */\r
+                                               if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )\r
+                                               {\r
+                                                       traceBLOCKING_ON_QUEUE_RECEIVE( pxQueue );\r
+\r
+                                                       #if ( configUSE_MUTEXES == 1 )\r
+                                                       {\r
+                                                               if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )\r
+                                                               {\r
+                                                                       portENTER_CRITICAL();\r
+                                                                               vTaskPriorityInherit( ( void * ) pxQueue->pxMutexHolder );\r
+                                                                       portEXIT_CRITICAL();\r
+                                                               }\r
+                                                       }\r
+                                                       #endif\r
+\r
+                                                       vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );\r
+                                                       taskYIELD();\r
+                                               }\r
+                                       }\r
                                }\r
+                               portEXIT_CRITICAL();\r
                        }\r
-               }\r
+               \r
+                       taskENTER_CRITICAL();\r
+                       {\r
+                               if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )\r
+                               {\r
+                                       /* Remember our read position in case we are just peeking. */\r
+                                       pcOriginalReadPosition = pxQueue->pcReadFrom;\r
+\r
+                                       prvCopyDataFromQueue( pxQueue, pvBuffer );\r
+\r
+                                       if( xJustPeeking == pdFALSE )\r
+                                       {\r
+                                               traceQUEUE_RECEIVE( pxQueue );\r
+\r
+                                               /* We are actually removing data. */\r
+                                               --( pxQueue->uxMessagesWaiting );\r
+\r
+                                               #if ( configUSE_MUTEXES == 1 )\r
+                                               {\r
+                                                       if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )\r
+                                                       {\r
+                                                               /* Record the information required to implement\r
+                                                               priority inheritance should it become necessary. */\r
+                                                               pxQueue->pxMutexHolder = xTaskGetCurrentTaskHandle();\r
+                                                       }\r
+                                               }\r
+                                               #endif\r
+                                                       \r
+                                               if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )\r
+                                               {\r
+                                                       if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) == pdTRUE )\r
+                                                       {\r
+                                                               taskYIELD();\r
+                                                       }\r
+                                               }\r
+                                       }\r
+                                       else\r
+                                       {\r
+                                               traceQUEUE_PEEK( pxQueue );\r
+\r
+                                               /* We are not removing the data, so reset our read\r
+                                               pointer. */\r
+                                               pxQueue->pcReadFrom = pcOriginalReadPosition;\r
+\r
+                                               /* The data is being left in the queue, so see if there are\r
+                                               any other tasks waiting for the data. */\r
+                                               if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )\r
+                                               {\r
+                                                       /* Tasks that are removed from the event list will get added to\r
+                                                       the pending ready list as the scheduler is still suspended. */\r
+                                                       if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )\r
+                                                       {\r
+                                                               /* The task waiting has a higher priority that this task. */\r
+                                                               taskYIELD();\r
+                                                       }\r
+                                               }                       \r
+\r
+                                       }\r
+                                       \r
+                                       xReturn = pdPASS;                                       \r
+                               }\r
+                               else\r
+                               {\r
+                                       xReturn = errQUEUE_EMPTY;\r
+                               }\r
+                       }\r
+                       taskEXIT_CRITICAL();\r
+\r
+                       if( xReturn == errQUEUE_EMPTY )\r
+                       {\r
+                               if( xTicksToWait > ( portTickType ) 0 )\r
+                               {\r
+                                       if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )\r
+                                       {\r
+                                               xReturn = queueERRONEOUS_UNBLOCK;\r
+                                       }\r
+                                       else\r
+                                       {\r
+                                               traceQUEUE_RECEIVE_FAILED( pxQueue );\r
+                                       }\r
+                               }\r
+                               else\r
+                               {\r
+                                       traceQUEUE_RECEIVE_FAILED( pxQueue );\r
+                               }\r
+                       }\r
+               } while( xReturn == queueERRONEOUS_UNBLOCK );\r
+\r
+               return xReturn;\r
        }\r
-       while( xReturn == queueERRONEOUS_UNBLOCK );\r
 \r
-       prvUnlockQueue( pxQueue );\r
-       xTaskResumeAll();\r
 \r
-       return xReturn;\r
-}\r
+#endif /* configUSE_ALTERNATIVE_API */\r
 /*-----------------------------------------------------------*/\r
 \r
-signed portBASE_TYPE xQueueSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xTaskPreviouslyWoken )\r
+signed portBASE_TYPE xQueueGenericSendFromISR( xQueueHandle pxQueue, const void * const pvItemToQueue, signed portBASE_TYPE xTaskPreviouslyWoken, portBASE_TYPE xCopyPosition )\r
 {\r
-       /* Similar to xQueueSend, except we don't block if there is no room in the\r
-       queue.  Also we don't directly wake a task that was blocked on a queue\r
-       read, instead we return a flag to say whether a context switch is required\r
-       or not (i.e. has a task with a higher priority than us been woken by this\r
-       post). */\r
+       /* Similar to xQueueGenericSend, except we don't block if there is no room\r
+       in the queue.  Also we don't directly wake a task that was blocked on a\r
+       queue read, instead we return a flag to say whether a context switch is\r
+       required or not (i.e. has a task with a higher priority than us been woken\r
+       by this post). */\r
        if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )\r
        {\r
-               prvCopyQueueData( pxQueue, pvItemToQueue );\r
+               traceQUEUE_SEND_FROM_ISR( pxQueue );\r
+\r
+               prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );\r
 \r
                /* If the queue is locked we do not alter the event list.  This will\r
                be done when the queue is unlocked later. */\r
@@ -452,86 +827,143 @@ signed portBASE_TYPE xQueueSendFromISR( xQueueHandle pxQueue, const void *pvItem
                        ++( pxQueue->xTxLock );\r
                }\r
        }\r
+       else\r
+       {\r
+               traceQUEUE_SEND_FROM_ISR_FAILED( pxQueue );\r
+       }\r
 \r
        return xTaskPreviouslyWoken;\r
 }\r
 /*-----------------------------------------------------------*/\r
 \r
-signed portBASE_TYPE xQueueReceive( xQueueHandle pxQueue, void *pvBuffer, portTickType xTicksToWait )\r
+signed portBASE_TYPE xQueueGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking )\r
 {\r
-signed portBASE_TYPE xReturn = pdFAIL;\r
+signed portBASE_TYPE xReturn = pdTRUE;\r
 xTimeOutType xTimeOut;\r
-\r
-       /* This function is very similar to xQueueSend().  See comments within\r
-       xQueueSend() for a more detailed explanation.\r
-\r
-       Make sure other tasks do not access the queue. */\r
-       vTaskSuspendAll();\r
-\r
-       /* Capture the current time status for future reference. */\r
-       vTaskSetTimeOutState( &xTimeOut );\r
-\r
-       /* Make sure interrupts do not access the queue. */\r
-       prvLockQueue( pxQueue );\r
+signed portCHAR *pcOriginalReadPosition;\r
 \r
        do\r
        {\r
                /* If there are no messages in the queue we may have to block. */\r
-               if( prvIsQueueEmpty( pxQueue ) )\r
+               if( xTicksToWait > ( portTickType ) 0 )\r
                {\r
-                       /* There are no messages in the queue, do we want to block or just\r
-                       leave with nothing? */                  \r
-                       if( xTicksToWait > ( portTickType ) 0 )\r
+                       vTaskSuspendAll();\r
+                       prvLockQueue( pxQueue );\r
+\r
+                       if( xReturn == pdTRUE )\r
                        {\r
-                               vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );\r
-                               taskENTER_CRITICAL();\r
+                               /* This is the first time through - we need to capture the\r
+                               time while the scheduler is locked to ensure we attempt to\r
+                               block at least once. */\r
+                               vTaskSetTimeOutState( &xTimeOut );\r
+                       }\r
+\r
+                       if( prvIsQueueEmpty( pxQueue ) )\r
+                       {\r
+                       /* Need to call xTaskCheckForTimeout again as time could\r
+                       have passed since it was last called if this is not the\r
+                       first time around this loop. */\r
+                               if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )\r
                                {\r
-                                       prvUnlockQueue( pxQueue );\r
-                                       if( !xTaskResumeAll() )\r
+                                       traceBLOCKING_ON_QUEUE_RECEIVE( pxQueue );\r
+\r
+                                       #if ( configUSE_MUTEXES == 1 )\r
                                        {\r
-                                               taskYIELD();\r
+                                               if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )\r
+                                               {\r
+                                                       portENTER_CRITICAL();\r
+                                                               vTaskPriorityInherit( ( void * ) pxQueue->pxMutexHolder );\r
+                                                       portEXIT_CRITICAL();\r
+                                               }\r
                                        }\r
+                                       #endif\r
 \r
-                                       if( pxQueue->uxMessagesWaiting == ( unsigned portBASE_TYPE ) 0 )\r
+                                       vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );\r
+                                       prvUnlockQueue( pxQueue );\r
+                                       if( !xTaskResumeAll() )\r
                                        {\r
-                                               /* We unblocked but the queue is empty.  We probably\r
-                                               timed out. */\r
-                                               xReturn = errQUEUE_EMPTY;\r
+                                               taskYIELD();\r
                                        }\r
-       \r
-                                       vTaskSuspendAll();\r
-                                       prvLockQueue( pxQueue );\r
                                }\r
-                               taskEXIT_CRITICAL();\r
+                               else\r
+                               {\r
+                                       prvUnlockQueue( pxQueue );\r
+                                       ( void ) xTaskResumeAll();\r
+                               }\r
+                       }\r
+                       else\r
+                       {\r
+                               prvUnlockQueue( pxQueue );\r
+                               ( void ) xTaskResumeAll();\r
                        }\r
                }\r
        \r
-               if( xReturn != errQUEUE_EMPTY )\r
+               taskENTER_CRITICAL();\r
                {\r
-                       taskENTER_CRITICAL();\r
+                       if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )\r
                        {\r
-                               if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )\r
+                               /* Remember our read position in case we are just peeking. */\r
+                               pcOriginalReadPosition = pxQueue->pcReadFrom;\r
+\r
+                               prvCopyDataFromQueue( pxQueue, pvBuffer );\r
+\r
+                               if( xJustPeeking == pdFALSE )\r
                                {\r
-                                       pxQueue->pcReadFrom += pxQueue->uxItemSize;\r
-                                       if( pxQueue->pcReadFrom >= pxQueue->pcTail )\r
+                                       traceQUEUE_RECEIVE( pxQueue );\r
+\r
+                                       /* We are actually removing data. */\r
+                                       --( pxQueue->uxMessagesWaiting );\r
+\r
+                                       #if ( configUSE_MUTEXES == 1 )\r
                                        {\r
-                                               pxQueue->pcReadFrom = pxQueue->pcHead;\r
+                                               if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )\r
+                                               {\r
+                                                       /* Record the information required to implement\r
+                                                       priority inheritance should it become necessary. */\r
+                                                       pxQueue->pxMutexHolder = xTaskGetCurrentTaskHandle();\r
+                                               }\r
+                                       }\r
+                                       #endif\r
+                                               \r
+                                       if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )\r
+                                       {\r
+                                               if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) == pdTRUE )\r
+                                               {\r
+                                                       taskYIELD();\r
+                                               }\r
                                        }\r
-                                       --( pxQueue->uxMessagesWaiting );\r
-                                       memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->pcReadFrom, ( unsigned ) pxQueue->uxItemSize );\r
-               \r
-                                       /* Increment the lock count so prvUnlockQueue knows to check for\r
-                                       tasks waiting for space to become available on the queue. */\r
-                                       ++( pxQueue->xRxLock );\r
-                                       xReturn = pdPASS;\r
                                }\r
                                else\r
                                {\r
-                                       xReturn = errQUEUE_EMPTY;\r
+                                       traceQUEUE_PEEK( pxQueue );\r
+\r
+                                       /* We are not removing the data, so reset our read\r
+                                       pointer. */\r
+                                       pxQueue->pcReadFrom = pcOriginalReadPosition;\r
+\r
+                                       /* The data is being left in the queue, so see if there are\r
+                                       any other tasks waiting for the data. */\r
+                                       if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )\r
+                                       {\r
+                                               /* Tasks that are removed from the event list will get added to\r
+                                               the pending ready list as the scheduler is still suspended. */\r
+                                               if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )\r
+                                               {\r
+                                                       /* The task waiting has a higher priority that this task. */\r
+                                                       taskYIELD();\r
+                                               }\r
+                                       }                       \r
+\r
                                }\r
+                               \r
+                               xReturn = pdPASS;                                       \r
+                       }\r
+                       else\r
+                       {\r
+                               xReturn = errQUEUE_EMPTY;\r
                        }\r
-                       taskEXIT_CRITICAL();\r
                }\r
+               taskEXIT_CRITICAL();\r
 \r
                if( xReturn == errQUEUE_EMPTY )\r
                {\r
@@ -541,33 +973,33 @@ xTimeOutType xTimeOut;
                                {\r
                                        xReturn = queueERRONEOUS_UNBLOCK;\r
                                }\r
+                               else\r
+                               {\r
+                                       traceQUEUE_RECEIVE_FAILED( pxQueue );\r
+                               }\r
+                       }\r
+                       else\r
+                       {\r
+                               traceQUEUE_RECEIVE_FAILED( pxQueue );\r
                        }\r
                }\r
        } while( xReturn == queueERRONEOUS_UNBLOCK );\r
 \r
-       /* We no longer require exclusive access to the queue. */\r
-       prvUnlockQueue( pxQueue );\r
-       xTaskResumeAll();\r
-\r
        return xReturn;\r
 }\r
 /*-----------------------------------------------------------*/\r
 \r
-signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, void *pvBuffer, signed portBASE_TYPE *pxTaskWoken )\r
+signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, const void * const pvBuffer, signed portBASE_TYPE *pxTaskWoken )\r
 {\r
 signed portBASE_TYPE xReturn;\r
 \r
        /* We cannot block from an ISR, so check there is data available. */\r
        if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )\r
        {\r
-               /* Copy the data from the queue. */\r
-               pxQueue->pcReadFrom += pxQueue->uxItemSize;\r
-               if( pxQueue->pcReadFrom >= pxQueue->pcTail )\r
-               {\r
-                       pxQueue->pcReadFrom = pxQueue->pcHead;\r
-               }\r
+               traceQUEUE_RECEIVE_FROM_ISR( pxQueue );\r
+\r
+               prvCopyDataFromQueue( pxQueue, pvBuffer );\r
                --( pxQueue->uxMessagesWaiting );\r
-               memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->pcReadFrom, ( unsigned ) pxQueue->uxItemSize );\r
 \r
                /* If the queue is locked we will not modify the event list.  Instead\r
                we update the lock count so the task that unlocks the queue will know\r
@@ -601,13 +1033,14 @@ signed portBASE_TYPE xReturn;
        else\r
        {\r
                xReturn = pdFAIL;\r
+               traceQUEUE_RECEIVE_FROM_ISR_FAILED( pxQueue );\r
        }\r
 \r
        return xReturn;\r
 }\r
 /*-----------------------------------------------------------*/\r
 \r
-unsigned portBASE_TYPE uxQueueMessagesWaiting( xQueueHandle pxQueue )\r
+unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle const pxQueue )\r
 {\r
 unsigned portBASE_TYPE uxReturn;\r
 \r
@@ -619,13 +1052,77 @@ unsigned portBASE_TYPE uxReturn;
 }\r
 /*-----------------------------------------------------------*/\r
 \r
+unsigned portBASE_TYPE uxQueueMessagesWaitingFromISR( const xQueueHandle pxQueue )\r
+{\r
+unsigned portBASE_TYPE uxReturn;\r
+\r
+       uxReturn = pxQueue->uxMessagesWaiting;\r
+\r
+       return uxReturn;\r
+}\r
+/*-----------------------------------------------------------*/\r
+\r
 void vQueueDelete( xQueueHandle pxQueue )\r
 {\r
+       traceQUEUE_DELETE( pxQueue );\r
+\r
        vPortFree( pxQueue->pcHead );\r
        vPortFree( pxQueue );\r
 }\r
 /*-----------------------------------------------------------*/\r
 \r
+static void prvCopyDataToQueue( xQUEUE *pxQueue, const void *pvItemToQueue, portBASE_TYPE xPosition )\r
+{\r
+       if( pxQueue->uxItemSize == 0 )\r
+       {\r
+               #if ( configUSE_MUTEXES == 1 )\r
+               {\r
+                       if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )\r
+                       {\r
+                               /* The mutex is no longer being held. */\r
+                               vTaskPriorityDisinherit( ( void * ) pxQueue->pxMutexHolder );\r
+                pxQueue->pxMutexHolder = NULL;\r
+                       }\r
+               }\r
+               #endif\r
+       }\r
+       else if( xPosition == queueSEND_TO_BACK )\r
+       {\r
+               memcpy( ( void * ) pxQueue->pcWriteTo, pvItemToQueue, ( unsigned ) pxQueue->uxItemSize );\r
+               pxQueue->pcWriteTo += pxQueue->uxItemSize;\r
+               if( pxQueue->pcWriteTo >= pxQueue->pcTail )\r
+               {\r
+                       pxQueue->pcWriteTo = pxQueue->pcHead;\r
+               }\r
+       }\r
+       else\r
+       {\r
+               memcpy( ( void * ) pxQueue->pcReadFrom, pvItemToQueue, ( unsigned ) pxQueue->uxItemSize );\r
+               pxQueue->pcReadFrom -= pxQueue->uxItemSize;\r
+               if( pxQueue->pcReadFrom < pxQueue->pcHead )\r
+               {\r
+                       pxQueue->pcReadFrom = ( pxQueue->pcTail - pxQueue->uxItemSize );\r
+               }               \r
+       }\r
+\r
+       ++( pxQueue->uxMessagesWaiting );\r
+}\r
+/*-----------------------------------------------------------*/\r
+\r
+static void prvCopyDataFromQueue( xQUEUE * const pxQueue, const void *pvBuffer )\r
+{\r
+       if( pxQueue->uxQueueType != queueQUEUE_IS_MUTEX )\r
+       {\r
+               pxQueue->pcReadFrom += pxQueue->uxItemSize;\r
+               if( pxQueue->pcReadFrom >= pxQueue->pcTail )\r
+               {\r
+                       pxQueue->pcReadFrom = pxQueue->pcHead;\r
+               }\r
+               memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->pcReadFrom, ( unsigned ) pxQueue->uxItemSize );\r
+       }       \r
+}\r
+/*-----------------------------------------------------------*/\r
+\r
 static void prvUnlockQueue( xQueueHandle pxQueue )\r
 {\r
        /* THIS FUNCTION MUST BE CALLED WITH THE SCHEDULER SUSPENDED. */\r
@@ -682,7 +1179,7 @@ static void prvUnlockQueue( xQueueHandle pxQueue )
 }\r
 /*-----------------------------------------------------------*/\r
 \r
-static signed portBASE_TYPE prvIsQueueEmpty( const xQueueHandle pxQueue )\r
+static signed portBASE_TYPE prvIsQueueEmpty( const xQueueHandle const pxQueue )\r
 {\r
 signed portBASE_TYPE xReturn;\r
 \r
@@ -694,7 +1191,17 @@ signed portBASE_TYPE xReturn;
 }\r
 /*-----------------------------------------------------------*/\r
 \r
-static signed portBASE_TYPE prvIsQueueFull( const xQueueHandle pxQueue )\r
+signed portBASE_TYPE xQueueIsQueueEmptyFromISR( const xQueueHandle pxQueue )\r
+{\r
+signed portBASE_TYPE xReturn;\r
+\r
+       xReturn = ( pxQueue->uxMessagesWaiting == ( unsigned portBASE_TYPE ) 0 );\r
+\r
+       return xReturn;\r
+}\r
+/*-----------------------------------------------------------*/\r
+\r
+static signed portBASE_TYPE prvIsQueueFull( const xQueueHandle const pxQueue )\r
 {\r
 signed portBASE_TYPE xReturn;\r
 \r
@@ -706,13 +1213,23 @@ signed portBASE_TYPE xReturn;
 }\r
 /*-----------------------------------------------------------*/\r
 \r
+signed portBASE_TYPE xQueueIsQueueFullFromISR( const xQueueHandle pxQueue )\r
+{\r
+signed portBASE_TYPE xReturn;\r
+\r
+       xReturn = ( pxQueue->uxMessagesWaiting == pxQueue->uxLength );\r
+\r
+       return xReturn;\r
+}\r
+/*-----------------------------------------------------------*/\r
+\r
 #if configUSE_CO_ROUTINES == 1\r
 signed portBASE_TYPE xQueueCRSend( xQueueHandle pxQueue, const void *pvItemToQueue, portTickType xTicksToWait )\r
 {\r
 signed portBASE_TYPE xReturn;\r
                \r
        /* If the queue is already full we may have to block.  A critical section\r
-       is required to prevent an interrupt removing something from the queue \r
+       is required to prevent an interrupt removing something from the queue\r
        between the check to see if the queue is full and blocking on the queue. */\r
        portDISABLE_INTERRUPTS();\r
        {\r
@@ -744,19 +1261,19 @@ signed portBASE_TYPE xReturn;
                if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )\r
                {\r
                        /* There is room in the queue, copy the data into the queue. */                 \r
-                       prvCopyQueueData( pxQueue, pvItemToQueue );             \r
+                       prvCopyDataToQueue( pxQueue, pvItemToQueue, queueSEND_TO_BACK );\r
                        xReturn = pdPASS;\r
 \r
                        /* Were any co-routines waiting for data to become available? */\r
                        if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )\r
                        {\r
-                               /* In this instance the co-routine could be placed directly \r
-                               into the ready list as we are within a critical section.  \r
-                               Instead the same pending ready list mechansim is used as if\r
+                               /* In this instance the co-routine could be placed directly\r
+                               into the ready list as we are within a critical section.\r
+                               Instead the same pending ready list mechanism is used as if\r
                                the event were caused from within an interrupt. */\r
                                if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )\r
                                {\r
-                                       /* The co-routine waiting has a higher priority so record \r
+                                       /* The co-routine waiting has a higher priority so record\r
                                        that a yield might be appropriate. */\r
                                        xReturn = errQUEUE_YIELD;\r
                                }\r
@@ -780,7 +1297,7 @@ signed portBASE_TYPE xQueueCRReceive( xQueueHandle pxQueue, void *pvBuffer, port
 signed portBASE_TYPE xReturn;\r
 \r
        /* If the queue is already empty we may have to block.  A critical section\r
-       is required to prevent an interrupt adding something to the queue \r
+       is required to prevent an interrupt adding something to the queue\r
        between the check to see if the queue is empty and blocking on the queue. */\r
        portDISABLE_INTERRUPTS();\r
        {\r
@@ -825,9 +1342,9 @@ signed portBASE_TYPE xReturn;
                        /* Were any co-routines waiting for space to become available? */\r
                        if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) )\r
                        {\r
-                               /* In this instance the co-routine could be placed directly \r
-                               into the ready list as we are within a critical section.  \r
-                               Instead the same pending ready list mechansim is used as if\r
+                               /* In this instance the co-routine could be placed directly\r
+                               into the ready list as we are within a critical section.\r
+                               Instead the same pending ready list mechanism is used as if\r
                                the event were caused from within an interrupt. */\r
                                if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )\r
                                {\r
@@ -856,9 +1373,9 @@ signed portBASE_TYPE xQueueCRSendFromISR( xQueueHandle pxQueue, const void *pvIt
        exit without doing anything. */\r
        if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )\r
        {\r
-               prvCopyQueueData( pxQueue, pvItemToQueue );\r
+               prvCopyDataToQueue( pxQueue, pvItemToQueue, queueSEND_TO_BACK );\r
 \r
-               /* We only want to wake one co-routine per ISR, so check that a \r
+               /* We only want to wake one co-routine per ISR, so check that a\r
                co-routine has not already been woken. */\r
                if( !xCoRoutinePreviouslyWoken )                \r
                {\r