Add the uxQueueSpacesAvailable() API function.

Move a configASSERT() call in timers.c to prevent a "condition is always true" compiler warning.

FreeRTOS/Source/include/queue.h

@@ -922,6 +922,23 @@ signed portBASE_TYPE xQueueGenericReceive( xQueueHandle xQueue, const void * con
  */
 unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle xQueue ) PRIVILEGED_FUNCTION;
 
+/**
+ * queue. h
+ * <pre>unsigned portBASE_TYPE uxQueueSpacesAvailable( const xQueueHandle xQueue );</pre>
+ *
+ * Return the number of free spaces available in a queue.  This is equal to the
+ * number of items that can be sent to the queue before the queue becomes full
+ * if no items are removed.
+ *
+ * @param xQueue A handle to the queue being queried.
+ *
+ * @return The number of spaces available in the queue.
+ *
+ * \defgroup uxQueueMessagesWaiting uxQueueMessagesWaiting
+ * \ingroup QueueManagement
+ */
+unsigned portBASE_TYPE uxQueueSpacesAvailable( const xQueueHandle xQueue ) PRIVILEGED_FUNCTION;
+
 /**
  * queue. h
  * <pre>void vQueueDelete( xQueueHandle xQueue );</pre>

FreeRTOS/Source/queue.c

@@ -1329,6 +1329,22 @@ unsigned portBASE_TYPE uxReturn;
 } /*lint !e818 Pointer cannot be declared const as xQueue is a typedef not pointer. */
 /*-----------------------------------------------------------*/
 
+unsigned portBASE_TYPE uxQueueSpacesAvailable( const xQueueHandle xQueue )
+{
+unsigned portBASE_TYPE uxReturn;
+xQUEUE *pxQueue;
+
+	pxQueue = ( xQUEUE * ) xQueue;
+	configASSERT( pxQueue );
+
+	taskENTER_CRITICAL();
+		uxReturn = pxQueue->uxLength - pxQueue->uxMessagesWaiting;
+	taskEXIT_CRITICAL();
+
+	return uxReturn;
+} /*lint !e818 Pointer cannot be declared const as xQueue is a typedef not pointer. */
+/*-----------------------------------------------------------*/
+
 unsigned portBASE_TYPE uxQueueMessagesWaitingFromISR( const xQueueHandle xQueue )
 {
 unsigned portBASE_TYPE uxReturn;

FreeRTOS/Source/timers.c

@@ -233,7 +233,6 @@ xTIMER *pxNewTimer;
 	if( xTimerPeriodInTicks == ( portTickType ) 0U )
 	{
 		pxNewTimer = NULL;
-		configASSERT( ( xTimerPeriodInTicks > 0 ) );
 	}
 	else
 	{
@@ -260,6 +259,9 @@ xTIMER *pxNewTimer;
 		}
 	}
 
+	/* 0 is not a valid value for xTimerPeriodInTicks. */
+	configASSERT( ( xTimerPeriodInTicks > 0 ) );
+
 	return ( xTimerHandle ) pxNewTimer;
 }
 /*-----------------------------------------------------------*/