diff --git a/FreeRTOS/Demo/Common/Minimal/QueueOverwrite.c b/FreeRTOS/Demo/Common/Minimal/QueueOverwrite.c
index e33dcdbff..b20f903a9 100644
--- a/FreeRTOS/Demo/Common/Minimal/QueueOverwrite.c
+++ b/FreeRTOS/Demo/Common/Minimal/QueueOverwrite.c
@@ -233,12 +233,19 @@ unsigned long ulRx;
last parameter is not used because there are no tasks blocked on
this queue. */
xQueueOverwriteFromISR( xISRQueue, &ulTx1, NULL );
+
+ /* Peek the queue to check it holds the expected value. */
+ xQueuePeekFromISR( xISRQueue, &ulRx );
+ if( ulRx != ulTx1 )
+ {
+ xISRTestStatus = pdFAIL;
+ }
break;
case 1:
/* The queue already holds ulTx1. Overwrite the value in the queue
with ulTx2. */
- xQueueOverwriteFromISR( xISRQueue, &ulTx2, NULL );
+ xQueueOverwriteFromISR( xISRQueue, &ulTx2, NULL );
break;
case 2:
diff --git a/FreeRTOS/Source/include/FreeRTOS.h b/FreeRTOS/Source/include/FreeRTOS.h
index 060523fee..fbd75e3d0 100644
--- a/FreeRTOS/Source/include/FreeRTOS.h
+++ b/FreeRTOS/Source/include/FreeRTOS.h
@@ -410,6 +410,10 @@ typedef portBASE_TYPE (*pdTASK_HOOK_CODE)( void * );
#define traceQUEUE_PEEK( pxQueue )
#endif
+#ifndef traceQUEUE_PEEK_FROM_ISR
+ #define traceQUEUE_PEEK_FROM_ISR( pxQueue )
+#endif
+
#ifndef traceQUEUE_RECEIVE_FAILED
#define traceQUEUE_RECEIVE_FAILED( pxQueue )
#endif
@@ -430,6 +434,10 @@ typedef portBASE_TYPE (*pdTASK_HOOK_CODE)( void * );
#define traceQUEUE_RECEIVE_FROM_ISR_FAILED( pxQueue )
#endif
+#ifndef traceQUEUE_PEEK_FROM_ISR_FAILED
+ #define traceQUEUE_PEEK_FROM_ISR_FAILED( pxQueue )
+#endif
+
#ifndef traceQUEUE_DELETE
#define traceQUEUE_DELETE( pxQueue )
#endif
diff --git a/FreeRTOS/Source/include/queue.h b/FreeRTOS/Source/include/queue.h
index 915e2ab99..315b67e25 100644
--- a/FreeRTOS/Source/include/queue.h
+++ b/FreeRTOS/Source/include/queue.h
@@ -616,7 +616,9 @@ signed portBASE_TYPE xQueueGenericSend( xQueueHandle xQueue, const void * const
* 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.
+ * 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.
@@ -691,6 +693,39 @@ signed portBASE_TYPE xQueueGenericSend( xQueueHandle xQueue, const void * const
*/
#define xQueuePeek( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdTRUE )
+/**
+ * queue. h
+ *
+ portBASE_TYPE xQueuePeekFromISR(
+ xQueueHandle xQueue,
+ void *pvBuffer,
+ );
+ *
+ * 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
+ */
+signed portBASE_TYPE xQueuePeekFromISR( xQueueHandle xQueue, void * const pvBuffer );
+
/**
* queue. h
*
diff --git a/FreeRTOS/Source/queue.c b/FreeRTOS/Source/queue.c
index 4488169ea..b9024d535 100644
--- a/FreeRTOS/Source/queue.c
+++ b/FreeRTOS/Source/queue.c
@@ -1060,7 +1060,7 @@ xQUEUE *pxQueue;
{
traceQUEUE_RECEIVE( pxQueue );
- /* We are actually removing data. */
+ /* Actually removing data, not just peeking. */
--( pxQueue->uxMessagesWaiting );
#if ( configUSE_MUTEXES == 1 )
@@ -1191,7 +1191,7 @@ xQUEUE *pxQueue;
uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
{
- /* We cannot block from an ISR, so check there is data available. */
+ /* Cannot block in an ISR, so check there is data available. */
if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
{
traceQUEUE_RECEIVE_FROM_ISR( pxQueue );
@@ -1199,9 +1199,10 @@ xQUEUE *pxQueue;
prvCopyDataFromQueue( pxQueue, pvBuffer );
--( pxQueue->uxMessagesWaiting );
- /* If the queue is locked we will not modify the event list. Instead
- we update the lock count so the task that unlocks the queue will know
- that an ISR has removed data while the queue was locked. */
+ /* If the queue is locked the event list will not be modified.
+ Instead update the lock count so the task that unlocks the queue
+ will know that an ISR has removed data while the queue was
+ locked. */
if( pxQueue->xRxLock == queueUNLOCKED )
{
if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
@@ -1238,6 +1239,44 @@ xQUEUE *pxQueue;
}
/*-----------------------------------------------------------*/
+signed portBASE_TYPE xQueuePeekFromISR( xQueueHandle xQueue, void * const pvBuffer )
+{
+signed portBASE_TYPE xReturn;
+unsigned portBASE_TYPE uxSavedInterruptStatus;
+signed char *pcOriginalReadPosition;
+xQUEUE *pxQueue;
+
+ pxQueue = ( xQUEUE * ) xQueue;
+ configASSERT( pxQueue );
+ configASSERT( !( ( pvBuffer == NULL ) && ( pxQueue->uxItemSize != ( unsigned portBASE_TYPE ) 0U ) ) );
+
+ uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
+ {
+ /* Cannot block in an ISR, so check there is data available. */
+ if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
+ {
+ traceQUEUE_PEEK_FROM_ISR( pxQueue );
+
+ /* Remember the read position so it can be reset as nothing is
+ actually being removed from the queue. */
+ pcOriginalReadPosition = pxQueue->u.pcReadFrom;
+ prvCopyDataFromQueue( pxQueue, pvBuffer );
+ pxQueue->u.pcReadFrom = pcOriginalReadPosition;
+
+ xReturn = pdPASS;
+ }
+ else
+ {
+ xReturn = pdFAIL;
+ traceQUEUE_PEEK_FROM_ISR_FAILED( pxQueue );
+ }
+ }
+ portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );
+
+ return xReturn;
+}
+/*-----------------------------------------------------------*/
+
unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle xQueue )
{
unsigned portBASE_TYPE uxReturn;