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Add xQueueOverwrite() and a common demo task to demonstrate its use.
Update MSVC Win32 demo to include the xQueueOverwrite() common demo tasks.
This commit is contained in:
Richard Barry
parent
59f75a12f6
commit
671949ad78
8 changed files with 491 additions and 74 deletions
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@ -109,8 +109,9 @@ typedef void * xQueueSetHandle;
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typedef void * xQueueSetMemberHandle;
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/* For internal use only. */
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#define queueSEND_TO_BACK ( 0 )
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#define queueSEND_TO_FRONT ( 1 )
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#define queueSEND_TO_BACK ( 0 )
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#define queueSEND_TO_FRONT ( 1 )
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#define queueOVERWRITE ( 2 )
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/* For internal use only. These definitions *must* match those in queue.c. */
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#define queueQUEUE_TYPE_BASE ( 0U )
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@ -426,6 +427,88 @@ typedef void * xQueueSetMemberHandle;
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*/
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#define xQueueSend( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )
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/**
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* queue. h
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* <pre>
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portBASE_TYPE xQueueOverwrite(
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xQueueHandle xQueue,
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const void * pvItemToQueue,
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);
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* </pre>
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*
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* Only for use with queues that can hold a single item - so the queue is either
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* empty or full.
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*
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* Post an item on a queue. If the queue is already full then overwrite the
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* value held in the queue. The item is queued by copy, not by reference.
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* This function must not be called from an interrupt service routine.
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* See xQueueOverwriteFromISR () for an alternative which may be used in an ISR.
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*
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* @param xQueue The handle to the queue on which the item is to be posted.
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*
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* @param pvItemToQueue A pointer to the item that is to be placed on the
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* queue. The size of the items the queue will hold was defined when the
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* queue was created, so this many bytes will be copied from pvItemToQueue
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* into the queue storage area.
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*
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* @return xQueueOverwrite() is a macro that calls xQueueGenericSend(), and
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* therefore has the same return values as xQueueSendToFront(). However, as
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* xQueueOverwrite() will write to the queue even when the queue is full pdPASS
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* will be returned in all cases (errQUEUE_FULL will never be returned).
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*
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* Example usage:
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<pre>
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void vFunction( void *pvParameters )
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{
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xQueueHandle xQueue;
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unsigned long ulVarToSend, ulValReceived;
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// Create a queue to hold one unsigned long value. It is strongly
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// recommended *not* to use xQueueOverwrite() on queues that can
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// contain more than one value, and doing so will trigger an assertion
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// if configASSERT() is defined.
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xQueue = xQueueCreate( 1, sizeof( unsigned long ) );
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// Write the value 10 to the queue using xQueueOverwrite().
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ulVarToSend = 10;
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xQueueOverwrite( xQueue, &ulVarToSend );
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// Peeking the queue should now return 10, but leave the value 10 in
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// the queue. A block time of zero is used as it is known that the
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// queue holds a value.
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ulValReceived = 0;
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xQueuePeek( xQueue, &ulValReceived, 0 );
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if( ulValReceived != 10 )
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{
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// Error!
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}
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// The queue is still full. Use xQueueOverwrite() to overwrite the
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// value held in the queue with 100.
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ulVarToSend = 100;
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xQueueOverwrite( xQueue, &ulVarToSend );
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// This time read from the queue, leaving the queue empty once more.
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// A block time of 0 is used again.
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xQueueReceive( xQueue, &ulValReceived, 0 );
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// The value read should be the last value written, even though the
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// queue was already full when the value was written.
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if( ulValReceived != 100 )
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{
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// Error!
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}
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// ...
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}
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</pre>
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* \defgroup xQueueOverwrite xQueueOverwrite
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* \ingroup QueueManagement
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*/
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#define xQueueOverwrite( xQueue, pvItemToQueue ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), 0, queueOVERWRITE )
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/**
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* queue. h
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@ -570,6 +570,7 @@ xQUEUE *pxQueue;
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pxQueue = ( xQUEUE * ) xQueue;
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configASSERT( pxQueue );
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configASSERT( !( ( pvItemToQueue == NULL ) && ( pxQueue->uxItemSize != ( unsigned portBASE_TYPE ) 0U ) ) );
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configASSERT( !( ( xCopyPosition == queueOVERWRITE ) && ( pxQueue->uxLength != 1 ) ) );
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/* This function relaxes the coding standard somewhat to allow return
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statements within the function itself. This is done in the interest
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@ -578,9 +579,11 @@ xQUEUE *pxQueue;
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{
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taskENTER_CRITICAL();
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{
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/* Is there room on the queue now? To be running we must be
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the highest priority task wanting to access the queue. */
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if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
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/* Is there room on the queue now? The running task must be
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the highest priority task wanting to access the queue. If
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the head item in the queue is to be overwritten then it does
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not matter if the queue is full. */
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if( ( pxQueue->uxMessagesWaiting < pxQueue->uxLength ) || ( xCopyPosition == queueOVERWRITE ) )
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{
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traceQUEUE_SEND( pxQueue );
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prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );
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@ -1046,7 +1049,8 @@ xQUEUE *pxQueue;
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the highest priority task wanting to access the queue. */
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if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
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{
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/* Remember our read position in case we are just peeking. */
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/* Remember the read position in case the queue is only being
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peeked. */
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pcOriginalReadPosition = pxQueue->u.pcReadFrom;
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prvCopyDataFromQueue( pxQueue, pvBuffer );
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@ -1320,7 +1324,7 @@ static void prvCopyDataToQueue( xQUEUE *pxQueue, const void *pvItemToQueue, port
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pxQueue->pxMutexHolder = NULL;
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}
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}
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#endif
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#endif /* configUSE_MUTEXES */
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}
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else if( xPosition == queueSEND_TO_BACK )
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{
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@ -1339,6 +1343,18 @@ static void prvCopyDataToQueue( xQUEUE *pxQueue, const void *pvItemToQueue, port
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{
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pxQueue->u.pcReadFrom = ( pxQueue->pcTail - pxQueue->uxItemSize );
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}
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if( xPosition == queueOVERWRITE )
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{
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if( pxQueue->uxMessagesWaiting > 0 )
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{
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/* An item is not being added but overwritten, so subtract
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one from the recorded number of items in the queue so when
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one is added again below the number of recorded items remains
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correct. */
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--( pxQueue->uxMessagesWaiting );
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}
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}
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}
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++( pxQueue->uxMessagesWaiting );
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@ -115,7 +115,7 @@ typedef struct tskTaskControlBlock
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xMPU_SETTINGS xMPUSettings; /*< The MPU settings are defined as part of the port layer. THIS MUST BE THE SECOND MEMBER OF THE TCB STRUCT. */
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#endif
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xListItem xGenericListItem; /*< The list that the state list item of a task is reference from denotes the state of that task (Ready, Blocked, Suspended ). */
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xListItem xGenericListItem; /*< The list that the state list item of a task is reference from denotes the state of that task (Ready, Blocked, Suspended ). */
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xListItem xEventListItem; /*< Used to reference a task from an event list. */
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unsigned portBASE_TYPE uxPriority; /*< The priority of the task. 0 is the lowest priority. */
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portSTACK_TYPE *pxStack; /*< Points to the start of the stack. */
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@ -149,8 +149,11 @@ typedef struct tskTaskControlBlock
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#if ( configUSE_NEWLIB_REENTRANT == 1 )
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/* Allocate a Newlib reent structure that is specific to this task.
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Note Newlib support has been included by popular demand, but is not
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used by the FreeRTOS maintainers themselves, and therefore receives
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less rigorous testing than the rest of the FreeRTOS code. */
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used by the FreeRTOS maintainers themselves. FreeRTOS is not
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responsible for resulting newlib operation. User must be familiar with
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newlib and must provide system-wide implementations of the necessary
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stubs. Be warned that (at the time of writing) the current newlib design
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implements a system-wide malloc() that must be provided with locks. */
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struct _reent xNewLib_reent;
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#endif
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