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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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54 #ifndef INC_FREERTOS_H
55 #error "#include FreeRTOS.h" must appear in source files before "#include queue.h"
69 #include "mpu_wrappers.h"
72 typedef void * xQueueHandle
;
75 /* For internal use only. */
76 #define queueSEND_TO_BACK ( 0 )
77 #define queueSEND_TO_FRONT ( 1 )
83 xQueueHandle xQueueCreate(
84 unsigned portBASE_TYPE uxQueueLength,
85 unsigned portBASE_TYPE uxItemSize
89 * Creates a new queue instance. This allocates the storage required by the
90 * new queue and returns a handle for the queue.
92 * @param uxQueueLength The maximum number of items that the queue can contain.
94 * @param uxItemSize The number of bytes each item in the queue will require.
95 * Items are queued by copy, not by reference, so this is the number of bytes
96 * that will be copied for each posted item. Each item on the queue must be
99 * @return If the queue is successfully create then a handle to the newly
100 * created queue is returned. If the queue cannot be created then 0 is
111 void vATask( void *pvParameters )
113 xQueueHandle xQueue1, xQueue2;
115 // Create a queue capable of containing 10 unsigned long values.
116 xQueue1 = xQueueCreate( 10, sizeof( unsigned long ) );
119 // Queue was not created and must not be used.
122 // Create a queue capable of containing 10 pointers to AMessage structures.
123 // These should be passed by pointer as they contain a lot of data.
124 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
127 // Queue was not created and must not be used.
130 // ... Rest of task code.
133 * \defgroup xQueueCreate xQueueCreate
134 * \ingroup QueueManagement
136 xQueueHandle
xQueueCreate( unsigned portBASE_TYPE uxQueueLength
, unsigned portBASE_TYPE uxItemSize
);
141 portBASE_TYPE xQueueSendToToFront(
143 const void * pvItemToQueue,
144 portTickType xTicksToWait
148 * This is a macro that calls xQueueGenericSend().
150 * Post an item to the front of a queue. The item is queued by copy, not by
151 * reference. This function must not be called from an interrupt service
152 * routine. See xQueueSendFromISR () for an alternative which may be used
155 * @param xQueue The handle to the queue on which the item is to be posted.
157 * @param pvItemToQueue A pointer to the item that is to be placed on the
158 * queue. The size of the items the queue will hold was defined when the
159 * queue was created, so this many bytes will be copied from pvItemToQueue
160 * into the queue storage area.
162 * @param xTicksToWait The maximum amount of time the task should block
163 * waiting for space to become available on the queue, should it already
164 * be full. The call will return immediately if this is set to 0 and the
165 * queue is full. The time is defined in tick periods so the constant
166 * portTICK_RATE_MS should be used to convert to real time if this is required.
168 * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
178 unsigned long ulVar = 10UL;
180 void vATask( void *pvParameters )
182 xQueueHandle xQueue1, xQueue2;
183 struct AMessage *pxMessage;
185 // Create a queue capable of containing 10 unsigned long values.
186 xQueue1 = xQueueCreate( 10, sizeof( unsigned long ) );
188 // Create a queue capable of containing 10 pointers to AMessage structures.
189 // These should be passed by pointer as they contain a lot of data.
190 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
196 // Send an unsigned long. Wait for 10 ticks for space to become
197 // available if necessary.
198 if( xQueueSendToFront( xQueue1, ( void * ) &ulVar, ( portTickType ) 10 ) != pdPASS )
200 // Failed to post the message, even after 10 ticks.
206 // Send a pointer to a struct AMessage object. Don't block if the
207 // queue is already full.
208 pxMessage = & xMessage;
209 xQueueSendToFront( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0 );
212 // ... Rest of task code.
215 * \defgroup xQueueSend xQueueSend
216 * \ingroup QueueManagement
218 #define xQueueSendToFront( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( xQueue, pvItemToQueue, xTicksToWait, queueSEND_TO_FRONT )
223 portBASE_TYPE xQueueSendToBack(
225 const void * pvItemToQueue,
226 portTickType xTicksToWait
230 * This is a macro that calls xQueueGenericSend().
232 * Post an item to the back of a queue. The item is queued by copy, not by
233 * reference. This function must not be called from an interrupt service
234 * routine. See xQueueSendFromISR () for an alternative which may be used
237 * @param xQueue The handle to the queue on which the item is to be posted.
239 * @param pvItemToQueue A pointer to the item that is to be placed on the
240 * queue. The size of the items the queue will hold was defined when the
241 * queue was created, so this many bytes will be copied from pvItemToQueue
242 * into the queue storage area.
244 * @param xTicksToWait The maximum amount of time the task should block
245 * waiting for space to become available on the queue, should it already
246 * be full. The call will return immediately if this is set to 0 and the queue
247 * is full. The time is defined in tick periods so the constant
248 * portTICK_RATE_MS should be used to convert to real time if this is required.
250 * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
260 unsigned long ulVar = 10UL;
262 void vATask( void *pvParameters )
264 xQueueHandle xQueue1, xQueue2;
265 struct AMessage *pxMessage;
267 // Create a queue capable of containing 10 unsigned long values.
268 xQueue1 = xQueueCreate( 10, sizeof( unsigned long ) );
270 // Create a queue capable of containing 10 pointers to AMessage structures.
271 // These should be passed by pointer as they contain a lot of data.
272 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
278 // Send an unsigned long. Wait for 10 ticks for space to become
279 // available if necessary.
280 if( xQueueSendToBack( xQueue1, ( void * ) &ulVar, ( portTickType ) 10 ) != pdPASS )
282 // Failed to post the message, even after 10 ticks.
288 // Send a pointer to a struct AMessage object. Don't block if the
289 // queue is already full.
290 pxMessage = & xMessage;
291 xQueueSendToBack( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0 );
294 // ... Rest of task code.
297 * \defgroup xQueueSend xQueueSend
298 * \ingroup QueueManagement
300 #define xQueueSendToBack( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( xQueue, pvItemToQueue, xTicksToWait, queueSEND_TO_BACK )
305 portBASE_TYPE xQueueSend(
307 const void * pvItemToQueue,
308 portTickType xTicksToWait
312 * This is a macro that calls xQueueGenericSend(). It is included for
313 * backward compatibility with versions of FreeRTOS.org that did not
314 * include the xQueueSendToFront() and xQueueSendToBack() macros. It is
315 * equivalent to xQueueSendToBack().
317 * Post an item on a queue. The item is queued by copy, not by reference.
318 * This function must not be called from an interrupt service routine.
319 * See xQueueSendFromISR () for an alternative which may be used in an ISR.
321 * @param xQueue The handle to the queue on which the item is to be posted.
323 * @param pvItemToQueue A pointer to the item that is to be placed on the
324 * queue. The size of the items the queue will hold was defined when the
325 * queue was created, so this many bytes will be copied from pvItemToQueue
326 * into the queue storage area.
328 * @param xTicksToWait The maximum amount of time the task should block
329 * waiting for space to become available on the queue, should it already
330 * be full. The call will return immediately if this is set to 0 and the
331 * queue is full. The time is defined in tick periods so the constant
332 * portTICK_RATE_MS should be used to convert to real time if this is required.
334 * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
344 unsigned long ulVar = 10UL;
346 void vATask( void *pvParameters )
348 xQueueHandle xQueue1, xQueue2;
349 struct AMessage *pxMessage;
351 // Create a queue capable of containing 10 unsigned long values.
352 xQueue1 = xQueueCreate( 10, sizeof( unsigned long ) );
354 // Create a queue capable of containing 10 pointers to AMessage structures.
355 // These should be passed by pointer as they contain a lot of data.
356 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
362 // Send an unsigned long. Wait for 10 ticks for space to become
363 // available if necessary.
364 if( xQueueSend( xQueue1, ( void * ) &ulVar, ( portTickType ) 10 ) != pdPASS )
366 // Failed to post the message, even after 10 ticks.
372 // Send a pointer to a struct AMessage object. Don't block if the
373 // queue is already full.
374 pxMessage = & xMessage;
375 xQueueSend( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0 );
378 // ... Rest of task code.
381 * \defgroup xQueueSend xQueueSend
382 * \ingroup QueueManagement
384 #define xQueueSend( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( xQueue, pvItemToQueue, xTicksToWait, queueSEND_TO_BACK )
390 portBASE_TYPE xQueueGenericSend(
392 const void * pvItemToQueue,
393 portTickType xTicksToWait
394 portBASE_TYPE xCopyPosition
398 * It is preferred that the macros xQueueSend(), xQueueSendToFront() and
399 * xQueueSendToBack() are used in place of calling this function directly.
401 * Post an item on a queue. The item is queued by copy, not by reference.
402 * This function must not be called from an interrupt service routine.
403 * See xQueueSendFromISR () for an alternative which may be used in an ISR.
405 * @param xQueue The handle to the queue on which the item is to be posted.
407 * @param pvItemToQueue A pointer to the item that is to be placed on the
408 * queue. The size of the items the queue will hold was defined when the
409 * queue was created, so this many bytes will be copied from pvItemToQueue
410 * into the queue storage area.
412 * @param xTicksToWait The maximum amount of time the task should block
413 * waiting for space to become available on the queue, should it already
414 * be full. The call will return immediately if this is set to 0 and the
415 * queue is full. The time is defined in tick periods so the constant
416 * portTICK_RATE_MS should be used to convert to real time if this is required.
418 * @param xCopyPosition Can take the value queueSEND_TO_BACK to place the
419 * item at the back of the queue, or queueSEND_TO_FRONT to place the item
420 * at the front of the queue (for high priority messages).
422 * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
432 unsigned long ulVar = 10UL;
434 void vATask( void *pvParameters )
436 xQueueHandle xQueue1, xQueue2;
437 struct AMessage *pxMessage;
439 // Create a queue capable of containing 10 unsigned long values.
440 xQueue1 = xQueueCreate( 10, sizeof( unsigned long ) );
442 // Create a queue capable of containing 10 pointers to AMessage structures.
443 // These should be passed by pointer as they contain a lot of data.
444 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
450 // Send an unsigned long. Wait for 10 ticks for space to become
451 // available if necessary.
452 if( xQueueGenericSend( xQueue1, ( void * ) &ulVar, ( portTickType ) 10, queueSEND_TO_BACK ) != pdPASS )
454 // Failed to post the message, even after 10 ticks.
460 // Send a pointer to a struct AMessage object. Don't block if the
461 // queue is already full.
462 pxMessage = & xMessage;
463 xQueueGenericSend( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0, queueSEND_TO_BACK );
466 // ... Rest of task code.
469 * \defgroup xQueueSend xQueueSend
470 * \ingroup QueueManagement
472 signed portBASE_TYPE
xQueueGenericSend( xQueueHandle xQueue
, const void * const pvItemToQueue
, portTickType xTicksToWait
, portBASE_TYPE xCopyPosition
);
477 portBASE_TYPE xQueuePeek(
480 portTickType xTicksToWait
483 * This is a macro that calls the xQueueGenericReceive() function.
485 * Receive an item from a queue without removing the item from the queue.
486 * The item is received by copy so a buffer of adequate size must be
487 * provided. The number of bytes copied into the buffer was defined when
488 * the queue was created.
490 * Successfully received items remain on the queue so will be returned again
491 * by the next call, or a call to xQueueReceive().
493 * This macro must not be used in an interrupt service routine.
495 * @param pxQueue The handle to the queue from which the item is to be
498 * @param pvBuffer Pointer to the buffer into which the received item will
501 * @param xTicksToWait The maximum amount of time the task should block
502 * waiting for an item to receive should the queue be empty at the time
503 * of the call. The time is defined in tick periods so the constant
504 * portTICK_RATE_MS should be used to convert to real time if this is required.
505 * xQueuePeek() will return immediately if xTicksToWait is 0 and the queue
508 * @return pdTRUE if an item was successfully received from the queue,
521 // Task to create a queue and post a value.
522 void vATask( void *pvParameters )
524 struct AMessage *pxMessage;
526 // Create a queue capable of containing 10 pointers to AMessage structures.
527 // These should be passed by pointer as they contain a lot of data.
528 xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
531 // Failed to create the queue.
536 // Send a pointer to a struct AMessage object. Don't block if the
537 // queue is already full.
538 pxMessage = & xMessage;
539 xQueueSend( xQueue, ( void * ) &pxMessage, ( portTickType ) 0 );
541 // ... Rest of task code.
544 // Task to peek the data from the queue.
545 void vADifferentTask( void *pvParameters )
547 struct AMessage *pxRxedMessage;
551 // Peek a message on the created queue. Block for 10 ticks if a
552 // message is not immediately available.
553 if( xQueuePeek( xQueue, &( pxRxedMessage ), ( portTickType ) 10 ) )
555 // pcRxedMessage now points to the struct AMessage variable posted
556 // by vATask, but the item still remains on the queue.
560 // ... Rest of task code.
563 * \defgroup xQueueReceive xQueueReceive
564 * \ingroup QueueManagement
566 #define xQueuePeek( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( xQueue, pvBuffer, xTicksToWait, pdTRUE )
571 portBASE_TYPE xQueueReceive(
574 portTickType xTicksToWait
577 * This is a macro that calls the xQueueGenericReceive() function.
579 * Receive an item from a queue. The item is received by copy so a buffer of
580 * adequate size must be provided. The number of bytes copied into the buffer
581 * was defined when the queue was created.
583 * Successfully received items are removed from the queue.
585 * This function must not be used in an interrupt service routine. See
586 * xQueueReceiveFromISR for an alternative that can.
588 * @param pxQueue The handle to the queue from which the item is to be
591 * @param pvBuffer Pointer to the buffer into which the received item will
594 * @param xTicksToWait The maximum amount of time the task should block
595 * waiting for an item to receive should the queue be empty at the time
596 * of the call. xQueueReceive() will return immediately if xTicksToWait
597 * is zero and the queue is empty. The time is defined in tick periods so the
598 * constant portTICK_RATE_MS should be used to convert to real time if this is
601 * @return pdTRUE if an item was successfully received from the queue,
614 // Task to create a queue and post a value.
615 void vATask( void *pvParameters )
617 struct AMessage *pxMessage;
619 // Create a queue capable of containing 10 pointers to AMessage structures.
620 // These should be passed by pointer as they contain a lot of data.
621 xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
624 // Failed to create the queue.
629 // Send a pointer to a struct AMessage object. Don't block if the
630 // queue is already full.
631 pxMessage = & xMessage;
632 xQueueSend( xQueue, ( void * ) &pxMessage, ( portTickType ) 0 );
634 // ... Rest of task code.
637 // Task to receive from the queue.
638 void vADifferentTask( void *pvParameters )
640 struct AMessage *pxRxedMessage;
644 // Receive a message on the created queue. Block for 10 ticks if a
645 // message is not immediately available.
646 if( xQueueReceive( xQueue, &( pxRxedMessage ), ( portTickType ) 10 ) )
648 // pcRxedMessage now points to the struct AMessage variable posted
653 // ... Rest of task code.
656 * \defgroup xQueueReceive xQueueReceive
657 * \ingroup QueueManagement
659 #define xQueueReceive( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( xQueue, pvBuffer, xTicksToWait, pdFALSE )
665 portBASE_TYPE xQueueGenericReceive(
668 portTickType xTicksToWait
669 portBASE_TYPE xJustPeek
672 * It is preferred that the macro xQueueReceive() be used rather than calling
673 * this function directly.
675 * Receive an item from a queue. The item is received by copy so a buffer of
676 * adequate size must be provided. The number of bytes copied into the buffer
677 * was defined when the queue was created.
679 * This function must not be used in an interrupt service routine. See
680 * xQueueReceiveFromISR for an alternative that can.
682 * @param pxQueue The handle to the queue from which the item is to be
685 * @param pvBuffer Pointer to the buffer into which the received item will
688 * @param xTicksToWait The maximum amount of time the task should block
689 * waiting for an item to receive should the queue be empty at the time
690 * of the call. The time is defined in tick periods so the constant
691 * portTICK_RATE_MS should be used to convert to real time if this is required.
692 * xQueueGenericReceive() will return immediately if the queue is empty and
695 * @param xJustPeek When set to true, the item received from the queue is not
696 * actually removed from the queue - meaning a subsequent call to
697 * xQueueReceive() will return the same item. When set to false, the item
698 * being received from the queue is also removed from the queue.
700 * @return pdTRUE if an item was successfully received from the queue,
713 // Task to create a queue and post a value.
714 void vATask( void *pvParameters )
716 struct AMessage *pxMessage;
718 // Create a queue capable of containing 10 pointers to AMessage structures.
719 // These should be passed by pointer as they contain a lot of data.
720 xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
723 // Failed to create the queue.
728 // Send a pointer to a struct AMessage object. Don't block if the
729 // queue is already full.
730 pxMessage = & xMessage;
731 xQueueSend( xQueue, ( void * ) &pxMessage, ( portTickType ) 0 );
733 // ... Rest of task code.
736 // Task to receive from the queue.
737 void vADifferentTask( void *pvParameters )
739 struct AMessage *pxRxedMessage;
743 // Receive a message on the created queue. Block for 10 ticks if a
744 // message is not immediately available.
745 if( xQueueGenericReceive( xQueue, &( pxRxedMessage ), ( portTickType ) 10 ) )
747 // pcRxedMessage now points to the struct AMessage variable posted
752 // ... Rest of task code.
755 * \defgroup xQueueReceive xQueueReceive
756 * \ingroup QueueManagement
758 signed portBASE_TYPE
xQueueGenericReceive( xQueueHandle xQueue
, void * const pvBuffer
, portTickType xTicksToWait
, portBASE_TYPE xJustPeek
);
762 * <pre>unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle xQueue );</pre>
764 * Return the number of messages stored in a queue.
766 * @param xQueue A handle to the queue being queried.
768 * @return The number of messages available in the queue.
770 * \page uxQueueMessagesWaiting uxQueueMessagesWaiting
771 * \ingroup QueueManagement
773 unsigned portBASE_TYPE
uxQueueMessagesWaiting( const xQueueHandle xQueue
);
777 * <pre>void vQueueDelete( xQueueHandle xQueue );</pre>
779 * Delete a queue - freeing all the memory allocated for storing of items
780 * placed on the queue.
782 * @param xQueue A handle to the queue to be deleted.
784 * \page vQueueDelete vQueueDelete
785 * \ingroup QueueManagement
787 void vQueueDelete( xQueueHandle xQueue
);
792 portBASE_TYPE xQueueSendToFrontFromISR(
793 xQueueHandle pxQueue,
794 const void *pvItemToQueue,
795 portBASE_TYPE *pxHigherPriorityTaskWoken
799 * This is a macro that calls xQueueGenericSendFromISR().
801 * Post an item to the front of a queue. It is safe to use this macro from
802 * within an interrupt service routine.
804 * Items are queued by copy not reference so it is preferable to only
805 * queue small items, especially when called from an ISR. In most cases
806 * it would be preferable to store a pointer to the item being queued.
808 * @param xQueue The handle to the queue on which the item is to be posted.
810 * @param pvItemToQueue A pointer to the item that is to be placed on the
811 * queue. The size of the items the queue will hold was defined when the
812 * queue was created, so this many bytes will be copied from pvItemToQueue
813 * into the queue storage area.
815 * @param pxHigherPriorityTaskWoken xQueueSendToFrontFromISR() will set
816 * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
817 * to unblock, and the unblocked task has a priority higher than the currently
818 * running task. If xQueueSendToFromFromISR() sets this value to pdTRUE then
819 * a context switch should be requested before the interrupt is exited.
821 * @return pdTRUE if the data was successfully sent to the queue, otherwise
824 * Example usage for buffered IO (where the ISR can obtain more than one value
827 void vBufferISR( void )
830 portBASE_TYPE xHigherPrioritTaskWoken;
832 // We have not woken a task at the start of the ISR.
833 xHigherPriorityTaskWoken = pdFALSE;
835 // Loop until the buffer is empty.
838 // Obtain a byte from the buffer.
839 cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
842 xQueueSendToFrontFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWoken );
844 } while( portINPUT_BYTE( BUFFER_COUNT ) );
846 // Now the buffer is empty we can switch context if necessary.
847 if( xHigherPriorityTaskWoken )
854 * \defgroup xQueueSendFromISR xQueueSendFromISR
855 * \ingroup QueueManagement
857 #define xQueueSendToFrontFromISR( pxQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( pxQueue, pvItemToQueue, pxHigherPriorityTaskWoken, queueSEND_TO_FRONT )
863 portBASE_TYPE xQueueSendToBackFromISR(
864 xQueueHandle pxQueue,
865 const void *pvItemToQueue,
866 portBASE_TYPE *pxHigherPriorityTaskWoken
870 * This is a macro that calls xQueueGenericSendFromISR().
872 * Post an item to the back of a queue. It is safe to use this macro from
873 * within an interrupt service routine.
875 * Items are queued by copy not reference so it is preferable to only
876 * queue small items, especially when called from an ISR. In most cases
877 * it would be preferable to store a pointer to the item being queued.
879 * @param xQueue The handle to the queue on which the item is to be posted.
881 * @param pvItemToQueue A pointer to the item that is to be placed on the
882 * queue. The size of the items the queue will hold was defined when the
883 * queue was created, so this many bytes will be copied from pvItemToQueue
884 * into the queue storage area.
886 * @param pxHigherPriorityTaskWoken xQueueSendToBackFromISR() will set
887 * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
888 * to unblock, and the unblocked task has a priority higher than the currently
889 * running task. If xQueueSendToBackFromISR() sets this value to pdTRUE then
890 * a context switch should be requested before the interrupt is exited.
892 * @return pdTRUE if the data was successfully sent to the queue, otherwise
895 * Example usage for buffered IO (where the ISR can obtain more than one value
898 void vBufferISR( void )
901 portBASE_TYPE xHigherPriorityTaskWoken;
903 // We have not woken a task at the start of the ISR.
904 xHigherPriorityTaskWoken = pdFALSE;
906 // Loop until the buffer is empty.
909 // Obtain a byte from the buffer.
910 cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
913 xQueueSendToBackFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWoken );
915 } while( portINPUT_BYTE( BUFFER_COUNT ) );
917 // Now the buffer is empty we can switch context if necessary.
918 if( xHigherPriorityTaskWoken )
925 * \defgroup xQueueSendFromISR xQueueSendFromISR
926 * \ingroup QueueManagement
928 #define xQueueSendToBackFromISR( pxQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( pxQueue, pvItemToQueue, pxHigherPriorityTaskWoken, queueSEND_TO_BACK )
933 portBASE_TYPE xQueueSendFromISR(
934 xQueueHandle pxQueue,
935 const void *pvItemToQueue,
936 portBASE_TYPE *pxHigherPriorityTaskWoken
940 * This is a macro that calls xQueueGenericSendFromISR(). It is included
941 * for backward compatibility with versions of FreeRTOS.org that did not
942 * include the xQueueSendToBackFromISR() and xQueueSendToFrontFromISR()
945 * Post an item to the back of a queue. It is safe to use this function from
946 * within an interrupt service routine.
948 * Items are queued by copy not reference so it is preferable to only
949 * queue small items, especially when called from an ISR. In most cases
950 * it would be preferable to store a pointer to the item being queued.
952 * @param xQueue The handle to the queue on which the item is to be posted.
954 * @param pvItemToQueue A pointer to the item that is to be placed on the
955 * queue. The size of the items the queue will hold was defined when the
956 * queue was created, so this many bytes will be copied from pvItemToQueue
957 * into the queue storage area.
959 * @param pxHigherPriorityTaskWoken xQueueSendFromISR() will set
960 * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
961 * to unblock, and the unblocked task has a priority higher than the currently
962 * running task. If xQueueSendFromISR() sets this value to pdTRUE then
963 * a context switch should be requested before the interrupt is exited.
965 * @return pdTRUE if the data was successfully sent to the queue, otherwise
968 * Example usage for buffered IO (where the ISR can obtain more than one value
971 void vBufferISR( void )
974 portBASE_TYPE xHigherPriorityTaskWoken;
976 // We have not woken a task at the start of the ISR.
977 xHigherPriorityTaskWoken = pdFALSE;
979 // Loop until the buffer is empty.
982 // Obtain a byte from the buffer.
983 cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
986 xQueueSendFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWoken );
988 } while( portINPUT_BYTE( BUFFER_COUNT ) );
990 // Now the buffer is empty we can switch context if necessary.
991 if( xHigherPriorityTaskWoken )
993 // Actual macro used here is port specific.
994 taskYIELD_FROM_ISR ();
999 * \defgroup xQueueSendFromISR xQueueSendFromISR
1000 * \ingroup QueueManagement
1002 #define xQueueSendFromISR( pxQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( pxQueue, pvItemToQueue, pxHigherPriorityTaskWoken, queueSEND_TO_BACK )
1007 portBASE_TYPE xQueueGenericSendFromISR(
1008 xQueueHandle pxQueue,
1009 const void *pvItemToQueue,
1010 portBASE_TYPE *pxHigherPriorityTaskWoken,
1011 portBASE_TYPE xCopyPosition
1015 * It is preferred that the macros xQueueSendFromISR(),
1016 * xQueueSendToFrontFromISR() and xQueueSendToBackFromISR() be used in place
1017 * of calling this function directly.
1019 * Post an item on a queue. It is safe to use this function from within an
1020 * interrupt service routine.
1022 * Items are queued by copy not reference so it is preferable to only
1023 * queue small items, especially when called from an ISR. In most cases
1024 * it would be preferable to store a pointer to the item being queued.
1026 * @param xQueue The handle to the queue on which the item is to be posted.
1028 * @param pvItemToQueue A pointer to the item that is to be placed on the
1029 * queue. The size of the items the queue will hold was defined when the
1030 * queue was created, so this many bytes will be copied from pvItemToQueue
1031 * into the queue storage area.
1033 * @param pxHigherPriorityTaskWoken xQueueGenericSendFromISR() will set
1034 * *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
1035 * to unblock, and the unblocked task has a priority higher than the currently
1036 * running task. If xQueueGenericSendFromISR() sets this value to pdTRUE then
1037 * a context switch should be requested before the interrupt is exited.
1039 * @param xCopyPosition Can take the value queueSEND_TO_BACK to place the
1040 * item at the back of the queue, or queueSEND_TO_FRONT to place the item
1041 * at the front of the queue (for high priority messages).
1043 * @return pdTRUE if the data was successfully sent to the queue, otherwise
1046 * Example usage for buffered IO (where the ISR can obtain more than one value
1049 void vBufferISR( void )
1052 portBASE_TYPE xHigherPriorityTaskWokenByPost;
1054 // We have not woken a task at the start of the ISR.
1055 xHigherPriorityTaskWokenByPost = pdFALSE;
1057 // Loop until the buffer is empty.
1060 // Obtain a byte from the buffer.
1061 cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
1064 xQueueGenericSendFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWokenByPost, queueSEND_TO_BACK );
1066 } while( portINPUT_BYTE( BUFFER_COUNT ) );
1068 // Now the buffer is empty we can switch context if necessary. Note that the
1069 // name of the yield function required is port specific.
1070 if( xHigherPriorityTaskWokenByPost )
1072 taskYIELD_YIELD_FROM_ISR();
1077 * \defgroup xQueueSendFromISR xQueueSendFromISR
1078 * \ingroup QueueManagement
1080 signed portBASE_TYPE
xQueueGenericSendFromISR( xQueueHandle pxQueue
, const void * const pvItemToQueue
, signed portBASE_TYPE
*pxHigherPriorityTaskWoken
, portBASE_TYPE xCopyPosition
);
1085 portBASE_TYPE xQueueReceiveFromISR(
1086 xQueueHandle pxQueue,
1088 portBASE_TYPE *pxTaskWoken
1092 * Receive an item from a queue. It is safe to use this function from within an
1093 * interrupt service routine.
1095 * @param pxQueue The handle to the queue from which the item is to be
1098 * @param pvBuffer Pointer to the buffer into which the received item will
1101 * @param pxTaskWoken A task may be blocked waiting for space to become
1102 * available on the queue. If xQueueReceiveFromISR causes such a task to
1103 * unblock *pxTaskWoken will get set to pdTRUE, otherwise *pxTaskWoken will
1106 * @return pdTRUE if an item was successfully received from the queue,
1107 * otherwise pdFALSE.
1112 xQueueHandle xQueue;
1114 // Function to create a queue and post some values.
1115 void vAFunction( void *pvParameters )
1118 const portTickType xBlockTime = ( portTickType )0xff;
1120 // Create a queue capable of containing 10 characters.
1121 xQueue = xQueueCreate( 10, sizeof( char ) );
1124 // Failed to create the queue.
1129 // Post some characters that will be used within an ISR. If the queue
1130 // is full then this task will block for xBlockTime ticks.
1132 xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
1134 xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
1136 // ... keep posting characters ... this task may block when the queue
1140 xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
1143 // ISR that outputs all the characters received on the queue.
1144 void vISR_Routine( void )
1146 portBASE_TYPE xTaskWokenByReceive = pdFALSE;
1149 while( xQueueReceiveFromISR( xQueue, ( void * ) &cRxedChar, &xTaskWokenByReceive) )
1151 // A character was received. Output the character now.
1152 vOutputCharacter( cRxedChar );
1154 // If removing the character from the queue woke the task that was
1155 // posting onto the queue cTaskWokenByReceive will have been set to
1156 // pdTRUE. No matter how many times this loop iterates only one
1157 // task will be woken.
1160 if( cTaskWokenByPost != ( char ) pdFALSE;
1166 * \defgroup xQueueReceiveFromISR xQueueReceiveFromISR
1167 * \ingroup QueueManagement
1169 signed portBASE_TYPE
xQueueReceiveFromISR( xQueueHandle pxQueue
, void * const pvBuffer
, signed portBASE_TYPE
*pxTaskWoken
);
1172 * Utilities to query queue that are safe to use from an ISR. These utilities
1173 * should be used only from witin an ISR, or within a critical section.
1175 signed portBASE_TYPE
xQueueIsQueueEmptyFromISR( const xQueueHandle pxQueue
);
1176 signed portBASE_TYPE
xQueueIsQueueFullFromISR( const xQueueHandle pxQueue
);
1177 unsigned portBASE_TYPE
uxQueueMessagesWaitingFromISR( const xQueueHandle pxQueue
);
1181 * xQueueAltGenericSend() is an alternative version of xQueueGenericSend().
1182 * Likewise xQueueAltGenericReceive() is an alternative version of
1183 * xQueueGenericReceive().
1185 * The source code that implements the alternative (Alt) API is much
1186 * simpler because it executes everything from within a critical section.
1187 * This is the approach taken by many other RTOSes, but FreeRTOS.org has the
1188 * preferred fully featured API too. The fully featured API has more
1189 * complex code that takes longer to execute, but makes much less use of
1190 * critical sections. Therefore the alternative API sacrifices interrupt
1191 * responsiveness to gain execution speed, whereas the fully featured API
1192 * sacrifices execution speed to ensure better interrupt responsiveness.
1194 signed portBASE_TYPE
xQueueAltGenericSend( xQueueHandle pxQueue
, const void * const pvItemToQueue
, portTickType xTicksToWait
, portBASE_TYPE xCopyPosition
);
1195 signed portBASE_TYPE
xQueueAltGenericReceive( xQueueHandle pxQueue
, void * const pvBuffer
, portTickType xTicksToWait
, portBASE_TYPE xJustPeeking
);
1196 #define xQueueAltSendToFront( xQueue, pvItemToQueue, xTicksToWait ) xQueueAltGenericSend( xQueue, pvItemToQueue, xTicksToWait, queueSEND_TO_FRONT )
1197 #define xQueueAltSendToBack( xQueue, pvItemToQueue, xTicksToWait ) xQueueAltGenericSend( xQueue, pvItemToQueue, xTicksToWait, queueSEND_TO_BACK )
1198 #define xQueueAltReceive( xQueue, pvBuffer, xTicksToWait ) xQueueAltGenericReceive( xQueue, pvBuffer, xTicksToWait, pdFALSE )
1199 #define xQueueAltPeek( xQueue, pvBuffer, xTicksToWait ) xQueueAltGenericReceive( xQueue, pvBuffer, xTicksToWait, pdTRUE )
1202 * The functions defined above are for passing data to and from tasks. The
1203 * functions below are the equivalents for passing data to and from
1206 * These functions are called from the co-routine macro implementation and
1207 * should not be called directly from application code. Instead use the macro
1208 * wrappers defined within croutine.h.
1210 signed portBASE_TYPE
xQueueCRSendFromISR( xQueueHandle pxQueue
, const void *pvItemToQueue
, signed portBASE_TYPE xCoRoutinePreviouslyWoken
);
1211 signed portBASE_TYPE
xQueueCRReceiveFromISR( xQueueHandle pxQueue
, void *pvBuffer
, signed portBASE_TYPE
*pxTaskWoken
);
1212 signed portBASE_TYPE
xQueueCRSend( xQueueHandle pxQueue
, const void *pvItemToQueue
, portTickType xTicksToWait
);
1213 signed portBASE_TYPE
xQueueCRReceive( xQueueHandle pxQueue
, void *pvBuffer
, portTickType xTicksToWait
);
1216 * For internal use only. Use xSemaphoreCreateMutex() or
1217 * xSemaphoreCreateCounting() instead of calling these functions directly.
1219 xQueueHandle
xQueueCreateMutex( void );
1220 xQueueHandle
xQueueCreateCountingSemaphore( unsigned portBASE_TYPE uxCountValue
, unsigned portBASE_TYPE uxInitialCount
);
1223 * For internal use only. Use xSemaphoreTakeMutexRecursive() or
1224 * xSemaphoreGiveMutexRecursive() instead of calling these functions directly.
1226 portBASE_TYPE
xQueueTakeMutexRecursive( xQueueHandle xMutex
, portTickType xBlockTime
);
1227 portBASE_TYPE
xQueueGiveMutexRecursive( xQueueHandle xMutex
);
1230 * The registry is provided as a means for kernel aware debuggers to
1231 * locate queues, semaphores and mutexes. Call vQueueAddToRegistry() add
1232 * a queue, semaphore or mutex handle to the registry if you want the handle
1233 * to be available to a kernel aware debugger. If you are not using a kernel
1234 * aware debugger then this function can be ignored.
1236 * configQUEUE_REGISTRY_SIZE defines the maximum number of handles the
1237 * registry can hold. configQUEUE_REGISTRY_SIZE must be greater than 0
1238 * within FreeRTOSConfig.h for the registry to be available. Its value
1239 * does not effect the number of queues, semaphores and mutexes that can be
1240 * created - just the number that the registry can hold.
1242 * @param xQueue The handle of the queue being added to the registry. This
1243 * is the handle returned by a call to xQueueCreate(). Semaphore and mutex
1244 * handles can also be passed in here.
1246 * @param pcName The name to be associated with the handle. This is the
1247 * name that the kernel aware debugger will display.
1249 #if configQUEUE_REGISTRY_SIZE > 0
1250 void vQueueAddToRegistry( xQueueHandle xQueue
, signed char *pcName
);
1260 #endif /* QUEUE_H */