uxQueueMessagesWaiting() function

{c} struct AMessage { char ucMessageID; char ucData[ 20 ]; } xMessage; uint32_t ulVar = 10UL; void vATask( void *pvParameters ) { QueueHandle_t xQueue1, xQueue2; struct AMessage *pxMessage; // Create a queue capable of containing 10 uint32_t values. xQueue1 = xQueueCreate( 10, sizeof( uint32_t ) ); // Create a queue capable of containing 10 pointers to AMessage structures. // These should be passed by pointer as they contain a lot of data. xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) ); // ... if( xQueue1 != 0 ) { // Send an uint32_t. Wait for 10 ticks for space to become // available if necessary. if( xQueueGenericSend( xQueue1, ( void * ) &ulVar, ( TickType_t ) 10, queueSEND_TO_BACK ) != pdPASS ) { // Failed to post the message, even after 10 ticks. } } if( xQueue2 != 0 ) { // Send a pointer to a struct AMessage object. Don't block if the // queue is already full. pxMessage = & xMessage; xQueueGenericSend( xQueue2, ( void * ) &pxMessage, ( TickType_t ) 0, queueSEND_TO_BACK ); } // ... Rest of task code. }

{c} struct AMessage { char ucMessageID; char ucData[ 20 ]; } xMessage; QueueHandle_t xQueue; // Task to create a queue and post a value. void vATask( void *pvParameters ) { struct AMessage *pxMessage; // Create a queue capable of containing 10 pointers to AMessage structures. // These should be passed by pointer as they contain a lot of data. xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) ); if( xQueue == 0 ) { // Failed to create the queue. } // ... // Send a pointer to a struct AMessage object. Don't block if the // queue is already full. pxMessage = & xMessage; xQueueSend( xQueue, ( void * ) &pxMessage, ( TickType_t ) 0 ); // ... Rest of task code. } // Task to receive from the queue. void vADifferentTask( void *pvParameters ) { struct AMessage *pxRxedMessage; if( xQueue != 0 ) { // Receive a message on the created queue. Block for 10 ticks if a // message is not immediately available. if( xQueueReceive( xQueue, &( pxRxedMessage ), ( TickType_t ) 10 ) ) { // pcRxedMessage now points to the struct AMessage variable posted // by vATask. } } // ... Rest of task code. }

{c} void vBufferISR( void ) { char cIn; BaseType_t xHigherPriorityTaskWokenByPost; // We have not woken a task at the start of the ISR. xHigherPriorityTaskWokenByPost = pdFALSE; // Loop until the buffer is empty. do { // Obtain a byte from the buffer. cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS ); // Post each byte. xQueueGenericSendFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWokenByPost, queueSEND_TO_BACK ); } while( portINPUT_BYTE( BUFFER_COUNT ) ); // Now the buffer is empty we can switch context if necessary. Note that the // name of the yield function required is port specific. if( xHigherPriorityTaskWokenByPost ) { portYIELD_FROM_ISR(); } }

{c} QueueHandle_t xQueue; // Function to create a queue and post some values. void vAFunction( void *pvParameters ) { char cValueToPost; const TickType_t xTicksToWait = ( TickType_t )0xff; // Create a queue capable of containing 10 characters. xQueue = xQueueCreate( 10, sizeof( char ) ); if( xQueue == 0 ) { // Failed to create the queue. } // ... // Post some characters that will be used within an ISR. If the queue // is full then this task will block for xTicksToWait ticks. cValueToPost = 'a'; xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait ); cValueToPost = 'b'; xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait ); // ... keep posting characters ... this task may block when the queue // becomes full. cValueToPost = 'c'; xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait ); } // ISR that outputs all the characters received on the queue. void vISR_Routine( void ) { BaseType_t xTaskWokenByReceive = pdFALSE; char cRxedChar; while( xQueueReceiveFromISR( xQueue, ( void * ) &cRxedChar, &xTaskWokenByReceive) ) { // A character was received. Output the character now. vOutputCharacter( cRxedChar ); // If removing the character from the queue woke the task that was // posting onto the queue xTaskWokenByReceive will have been set to // pdTRUE. No matter how many times this loop iterates only one // task will be woken. } if( xTaskWokenByReceive != ( char ) pdFALSE; { taskYIELD (); } }

{c} struct AMessage { char ucMessageID; char ucData[ 20 ]; } xMessage; QueueHandle_t xQueue; // Task to create a queue and post a value. void vATask( void *pvParameters ) { struct AMessage *pxMessage; // Create a queue capable of containing 10 pointers to AMessage structures. // These should be passed by pointer as they contain a lot of data. xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) ); if( xQueue == 0 ) { // Failed to create the queue. } // ... // Send a pointer to a struct AMessage object. Don't block if the // queue is already full. pxMessage = & xMessage; xQueueSend( xQueue, ( void * ) &pxMessage, ( TickType_t ) 0 ); // ... Rest of task code. } // Task to peek the data from the queue. void vADifferentTask( void *pvParameters ) { struct AMessage *pxRxedMessage; if( xQueue != 0 ) { // Peek a message on the created queue. Block for 10 ticks if a // message is not immediately available. if( xQueuePeek( xQueue, &( pxRxedMessage ), ( TickType_t ) 10 ) ) { // pcRxedMessage now points to the struct AMessage variable posted // by vATask, but the item still remains on the queue. } } // ... Rest of task code. }