source: S-port/trunk/Middlewares/Third_Party/FreeRTOS/Source/include/croutine.h

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1/*
2 * FreeRTOS Kernel V10.3.1
3 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
6 * this software and associated documentation files (the "Software"), to deal in
7 * the Software without restriction, including without limitation the rights to
8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
9 * the Software, and to permit persons to whom the Software is furnished to do so,
10 * subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be included in all
13 * copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
21 *
22 * http://www.FreeRTOS.org
23 * http://aws.amazon.com/freertos
24 *
25 * 1 tab == 4 spaces!
26 */
27
28#ifndef CO_ROUTINE_H
29#define CO_ROUTINE_H
30
31#ifndef INC_FREERTOS_H
32 #error "include FreeRTOS.h must appear in source files before include croutine.h"
33#endif
34
35#include "list.h"
36
37#ifdef __cplusplus
38extern "C" {
39#endif
40
41/* Used to hide the implementation of the co-routine control block. The
42control block structure however has to be included in the header due to
43the macro implementation of the co-routine functionality. */
44typedef void * CoRoutineHandle_t;
45
46/* Defines the prototype to which co-routine functions must conform. */
47typedef void (*crCOROUTINE_CODE)( CoRoutineHandle_t, UBaseType_t );
48
49typedef struct corCoRoutineControlBlock
50{
51 crCOROUTINE_CODE pxCoRoutineFunction;
52 ListItem_t xGenericListItem; /*< List item used to place the CRCB in ready and blocked queues. */
53 ListItem_t xEventListItem; /*< List item used to place the CRCB in event lists. */
54 UBaseType_t uxPriority; /*< The priority of the co-routine in relation to other co-routines. */
55 UBaseType_t uxIndex; /*< Used to distinguish between co-routines when multiple co-routines use the same co-routine function. */
56 uint16_t uxState; /*< Used internally by the co-routine implementation. */
57} CRCB_t; /* Co-routine control block. Note must be identical in size down to uxPriority with TCB_t. */
58
59/**
60 * croutine. h
61 *<pre>
62 BaseType_t xCoRoutineCreate(
63 crCOROUTINE_CODE pxCoRoutineCode,
64 UBaseType_t uxPriority,
65 UBaseType_t uxIndex
66 );</pre>
67 *
68 * Create a new co-routine and add it to the list of co-routines that are
69 * ready to run.
70 *
71 * @param pxCoRoutineCode Pointer to the co-routine function. Co-routine
72 * functions require special syntax - see the co-routine section of the WEB
73 * documentation for more information.
74 *
75 * @param uxPriority The priority with respect to other co-routines at which
76 * the co-routine will run.
77 *
78 * @param uxIndex Used to distinguish between different co-routines that
79 * execute the same function. See the example below and the co-routine section
80 * of the WEB documentation for further information.
81 *
82 * @return pdPASS if the co-routine was successfully created and added to a ready
83 * list, otherwise an error code defined with ProjDefs.h.
84 *
85 * Example usage:
86 <pre>
87 // Co-routine to be created.
88 void vFlashCoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
89 {
90 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
91 // This may not be necessary for const variables.
92 static const char cLedToFlash[ 2 ] = { 5, 6 };
93 static const TickType_t uxFlashRates[ 2 ] = { 200, 400 };
94
95 // Must start every co-routine with a call to crSTART();
96 crSTART( xHandle );
97
98 for( ;; )
99 {
100 // This co-routine just delays for a fixed period, then toggles
101 // an LED. Two co-routines are created using this function, so
102 // the uxIndex parameter is used to tell the co-routine which
103 // LED to flash and how int32_t to delay. This assumes xQueue has
104 // already been created.
105 vParTestToggleLED( cLedToFlash[ uxIndex ] );
106 crDELAY( xHandle, uxFlashRates[ uxIndex ] );
107 }
108
109 // Must end every co-routine with a call to crEND();
110 crEND();
111 }
112
113 // Function that creates two co-routines.
114 void vOtherFunction( void )
115 {
116 uint8_t ucParameterToPass;
117 TaskHandle_t xHandle;
118
119 // Create two co-routines at priority 0. The first is given index 0
120 // so (from the code above) toggles LED 5 every 200 ticks. The second
121 // is given index 1 so toggles LED 6 every 400 ticks.
122 for( uxIndex = 0; uxIndex < 2; uxIndex++ )
123 {
124 xCoRoutineCreate( vFlashCoRoutine, 0, uxIndex );
125 }
126 }
127 </pre>
128 * \defgroup xCoRoutineCreate xCoRoutineCreate
129 * \ingroup Tasks
130 */
131BaseType_t xCoRoutineCreate( crCOROUTINE_CODE pxCoRoutineCode, UBaseType_t uxPriority, UBaseType_t uxIndex );
132
133
134/**
135 * croutine. h
136 *<pre>
137 void vCoRoutineSchedule( void );</pre>
138 *
139 * Run a co-routine.
140 *
141 * vCoRoutineSchedule() executes the highest priority co-routine that is able
142 * to run. The co-routine will execute until it either blocks, yields or is
143 * preempted by a task. Co-routines execute cooperatively so one
144 * co-routine cannot be preempted by another, but can be preempted by a task.
145 *
146 * If an application comprises of both tasks and co-routines then
147 * vCoRoutineSchedule should be called from the idle task (in an idle task
148 * hook).
149 *
150 * Example usage:
151 <pre>
152 // This idle task hook will schedule a co-routine each time it is called.
153 // The rest of the idle task will execute between co-routine calls.
154 void vApplicationIdleHook( void )
155 {
156 vCoRoutineSchedule();
157 }
158
159 // Alternatively, if you do not require any other part of the idle task to
160 // execute, the idle task hook can call vCoRoutineSchedule() within an
161 // infinite loop.
162 void vApplicationIdleHook( void )
163 {
164 for( ;; )
165 {
166 vCoRoutineSchedule();
167 }
168 }
169 </pre>
170 * \defgroup vCoRoutineSchedule vCoRoutineSchedule
171 * \ingroup Tasks
172 */
173void vCoRoutineSchedule( void );
174
175/**
176 * croutine. h
177 * <pre>
178 crSTART( CoRoutineHandle_t xHandle );</pre>
179 *
180 * This macro MUST always be called at the start of a co-routine function.
181 *
182 * Example usage:
183 <pre>
184 // Co-routine to be created.
185 void vACoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
186 {
187 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
188 static int32_t ulAVariable;
189
190 // Must start every co-routine with a call to crSTART();
191 crSTART( xHandle );
192
193 for( ;; )
194 {
195 // Co-routine functionality goes here.
196 }
197
198 // Must end every co-routine with a call to crEND();
199 crEND();
200 }</pre>
201 * \defgroup crSTART crSTART
202 * \ingroup Tasks
203 */
204#define crSTART( pxCRCB ) switch( ( ( CRCB_t * )( pxCRCB ) )->uxState ) { case 0:
205
206/**
207 * croutine. h
208 * <pre>
209 crEND();</pre>
210 *
211 * This macro MUST always be called at the end of a co-routine function.
212 *
213 * Example usage:
214 <pre>
215 // Co-routine to be created.
216 void vACoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
217 {
218 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
219 static int32_t ulAVariable;
220
221 // Must start every co-routine with a call to crSTART();
222 crSTART( xHandle );
223
224 for( ;; )
225 {
226 // Co-routine functionality goes here.
227 }
228
229 // Must end every co-routine with a call to crEND();
230 crEND();
231 }</pre>
232 * \defgroup crSTART crSTART
233 * \ingroup Tasks
234 */
235#define crEND() }
236
237/*
238 * These macros are intended for internal use by the co-routine implementation
239 * only. The macros should not be used directly by application writers.
240 */
241#define crSET_STATE0( xHandle ) ( ( CRCB_t * )( xHandle ) )->uxState = (__LINE__ * 2); return; case (__LINE__ * 2):
242#define crSET_STATE1( xHandle ) ( ( CRCB_t * )( xHandle ) )->uxState = ((__LINE__ * 2)+1); return; case ((__LINE__ * 2)+1):
243
244/**
245 * croutine. h
246 *<pre>
247 crDELAY( CoRoutineHandle_t xHandle, TickType_t xTicksToDelay );</pre>
248 *
249 * Delay a co-routine for a fixed period of time.
250 *
251 * crDELAY can only be called from the co-routine function itself - not
252 * from within a function called by the co-routine function. This is because
253 * co-routines do not maintain their own stack.
254 *
255 * @param xHandle The handle of the co-routine to delay. This is the xHandle
256 * parameter of the co-routine function.
257 *
258 * @param xTickToDelay The number of ticks that the co-routine should delay
259 * for. The actual amount of time this equates to is defined by
260 * configTICK_RATE_HZ (set in FreeRTOSConfig.h). The constant portTICK_PERIOD_MS
261 * can be used to convert ticks to milliseconds.
262 *
263 * Example usage:
264 <pre>
265 // Co-routine to be created.
266 void vACoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
267 {
268 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
269 // This may not be necessary for const variables.
270 // We are to delay for 200ms.
271 static const xTickType xDelayTime = 200 / portTICK_PERIOD_MS;
272
273 // Must start every co-routine with a call to crSTART();
274 crSTART( xHandle );
275
276 for( ;; )
277 {
278 // Delay for 200ms.
279 crDELAY( xHandle, xDelayTime );
280
281 // Do something here.
282 }
283
284 // Must end every co-routine with a call to crEND();
285 crEND();
286 }</pre>
287 * \defgroup crDELAY crDELAY
288 * \ingroup Tasks
289 */
290#define crDELAY( xHandle, xTicksToDelay ) \
291 if( ( xTicksToDelay ) > 0 ) \
292 { \
293 vCoRoutineAddToDelayedList( ( xTicksToDelay ), NULL ); \
294 } \
295 crSET_STATE0( ( xHandle ) );
296
297/**
298 * <pre>
299 crQUEUE_SEND(
300 CoRoutineHandle_t xHandle,
301 QueueHandle_t pxQueue,
302 void *pvItemToQueue,
303 TickType_t xTicksToWait,
304 BaseType_t *pxResult
305 )</pre>
306 *
307 * The macro's crQUEUE_SEND() and crQUEUE_RECEIVE() are the co-routine
308 * equivalent to the xQueueSend() and xQueueReceive() functions used by tasks.
309 *
310 * crQUEUE_SEND and crQUEUE_RECEIVE can only be used from a co-routine whereas
311 * xQueueSend() and xQueueReceive() can only be used from tasks.
312 *
313 * crQUEUE_SEND can only be called from the co-routine function itself - not
314 * from within a function called by the co-routine function. This is because
315 * co-routines do not maintain their own stack.
316 *
317 * See the co-routine section of the WEB documentation for information on
318 * passing data between tasks and co-routines and between ISR's and
319 * co-routines.
320 *
321 * @param xHandle The handle of the calling co-routine. This is the xHandle
322 * parameter of the co-routine function.
323 *
324 * @param pxQueue The handle of the queue on which the data will be posted.
325 * The handle is obtained as the return value when the queue is created using
326 * the xQueueCreate() API function.
327 *
328 * @param pvItemToQueue A pointer to the data being posted onto the queue.
329 * The number of bytes of each queued item is specified when the queue is
330 * created. This number of bytes is copied from pvItemToQueue into the queue
331 * itself.
332 *
333 * @param xTickToDelay The number of ticks that the co-routine should block
334 * to wait for space to become available on the queue, should space not be
335 * available immediately. The actual amount of time this equates to is defined
336 * by configTICK_RATE_HZ (set in FreeRTOSConfig.h). The constant
337 * portTICK_PERIOD_MS can be used to convert ticks to milliseconds (see example
338 * below).
339 *
340 * @param pxResult The variable pointed to by pxResult will be set to pdPASS if
341 * data was successfully posted onto the queue, otherwise it will be set to an
342 * error defined within ProjDefs.h.
343 *
344 * Example usage:
345 <pre>
346 // Co-routine function that blocks for a fixed period then posts a number onto
347 // a queue.
348 static void prvCoRoutineFlashTask( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
349 {
350 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
351 static BaseType_t xNumberToPost = 0;
352 static BaseType_t xResult;
353
354 // Co-routines must begin with a call to crSTART().
355 crSTART( xHandle );
356
357 for( ;; )
358 {
359 // This assumes the queue has already been created.
360 crQUEUE_SEND( xHandle, xCoRoutineQueue, &xNumberToPost, NO_DELAY, &xResult );
361
362 if( xResult != pdPASS )
363 {
364 // The message was not posted!
365 }
366
367 // Increment the number to be posted onto the queue.
368 xNumberToPost++;
369
370 // Delay for 100 ticks.
371 crDELAY( xHandle, 100 );
372 }
373
374 // Co-routines must end with a call to crEND().
375 crEND();
376 }</pre>
377 * \defgroup crQUEUE_SEND crQUEUE_SEND
378 * \ingroup Tasks
379 */
380#define crQUEUE_SEND( xHandle, pxQueue, pvItemToQueue, xTicksToWait, pxResult ) \
381{ \
382 *( pxResult ) = xQueueCRSend( ( pxQueue) , ( pvItemToQueue) , ( xTicksToWait ) ); \
383 if( *( pxResult ) == errQUEUE_BLOCKED ) \
384 { \
385 crSET_STATE0( ( xHandle ) ); \
386 *pxResult = xQueueCRSend( ( pxQueue ), ( pvItemToQueue ), 0 ); \
387 } \
388 if( *pxResult == errQUEUE_YIELD ) \
389 { \
390 crSET_STATE1( ( xHandle ) ); \
391 *pxResult = pdPASS; \
392 } \
393}
394
395/**
396 * croutine. h
397 * <pre>
398 crQUEUE_RECEIVE(
399 CoRoutineHandle_t xHandle,
400 QueueHandle_t pxQueue,
401 void *pvBuffer,
402 TickType_t xTicksToWait,
403 BaseType_t *pxResult
404 )</pre>
405 *
406 * The macro's crQUEUE_SEND() and crQUEUE_RECEIVE() are the co-routine
407 * equivalent to the xQueueSend() and xQueueReceive() functions used by tasks.
408 *
409 * crQUEUE_SEND and crQUEUE_RECEIVE can only be used from a co-routine whereas
410 * xQueueSend() and xQueueReceive() can only be used from tasks.
411 *
412 * crQUEUE_RECEIVE can only be called from the co-routine function itself - not
413 * from within a function called by the co-routine function. This is because
414 * co-routines do not maintain their own stack.
415 *
416 * See the co-routine section of the WEB documentation for information on
417 * passing data between tasks and co-routines and between ISR's and
418 * co-routines.
419 *
420 * @param xHandle The handle of the calling co-routine. This is the xHandle
421 * parameter of the co-routine function.
422 *
423 * @param pxQueue The handle of the queue from which the data will be received.
424 * The handle is obtained as the return value when the queue is created using
425 * the xQueueCreate() API function.
426 *
427 * @param pvBuffer The buffer into which the received item is to be copied.
428 * The number of bytes of each queued item is specified when the queue is
429 * created. This number of bytes is copied into pvBuffer.
430 *
431 * @param xTickToDelay The number of ticks that the co-routine should block
432 * to wait for data to become available from the queue, should data not be
433 * available immediately. The actual amount of time this equates to is defined
434 * by configTICK_RATE_HZ (set in FreeRTOSConfig.h). The constant
435 * portTICK_PERIOD_MS can be used to convert ticks to milliseconds (see the
436 * crQUEUE_SEND example).
437 *
438 * @param pxResult The variable pointed to by pxResult will be set to pdPASS if
439 * data was successfully retrieved from the queue, otherwise it will be set to
440 * an error code as defined within ProjDefs.h.
441 *
442 * Example usage:
443 <pre>
444 // A co-routine receives the number of an LED to flash from a queue. It
445 // blocks on the queue until the number is received.
446 static void prvCoRoutineFlashWorkTask( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
447 {
448 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
449 static BaseType_t xResult;
450 static UBaseType_t uxLEDToFlash;
451
452 // All co-routines must start with a call to crSTART().
453 crSTART( xHandle );
454
455 for( ;; )
456 {
457 // Wait for data to become available on the queue.
458 crQUEUE_RECEIVE( xHandle, xCoRoutineQueue, &uxLEDToFlash, portMAX_DELAY, &xResult );
459
460 if( xResult == pdPASS )
461 {
462 // We received the LED to flash - flash it!
463 vParTestToggleLED( uxLEDToFlash );
464 }
465 }
466
467 crEND();
468 }</pre>
469 * \defgroup crQUEUE_RECEIVE crQUEUE_RECEIVE
470 * \ingroup Tasks
471 */
472#define crQUEUE_RECEIVE( xHandle, pxQueue, pvBuffer, xTicksToWait, pxResult ) \
473{ \
474 *( pxResult ) = xQueueCRReceive( ( pxQueue) , ( pvBuffer ), ( xTicksToWait ) ); \
475 if( *( pxResult ) == errQUEUE_BLOCKED ) \
476 { \
477 crSET_STATE0( ( xHandle ) ); \
478 *( pxResult ) = xQueueCRReceive( ( pxQueue) , ( pvBuffer ), 0 ); \
479 } \
480 if( *( pxResult ) == errQUEUE_YIELD ) \
481 { \
482 crSET_STATE1( ( xHandle ) ); \
483 *( pxResult ) = pdPASS; \
484 } \
485}
486
487/**
488 * croutine. h
489 * <pre>
490 crQUEUE_SEND_FROM_ISR(
491 QueueHandle_t pxQueue,
492 void *pvItemToQueue,
493 BaseType_t xCoRoutinePreviouslyWoken
494 )</pre>
495 *
496 * The macro's crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() are the
497 * co-routine equivalent to the xQueueSendFromISR() and xQueueReceiveFromISR()
498 * functions used by tasks.
499 *
500 * crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() can only be used to
501 * pass data between a co-routine and and ISR, whereas xQueueSendFromISR() and
502 * xQueueReceiveFromISR() can only be used to pass data between a task and and
503 * ISR.
504 *
505 * crQUEUE_SEND_FROM_ISR can only be called from an ISR to send data to a queue
506 * that is being used from within a co-routine.
507 *
508 * See the co-routine section of the WEB documentation for information on
509 * passing data between tasks and co-routines and between ISR's and
510 * co-routines.
511 *
512 * @param xQueue The handle to the queue on which the item is to be posted.
513 *
514 * @param pvItemToQueue A pointer to the item that is to be placed on the
515 * queue. The size of the items the queue will hold was defined when the
516 * queue was created, so this many bytes will be copied from pvItemToQueue
517 * into the queue storage area.
518 *
519 * @param xCoRoutinePreviouslyWoken This is included so an ISR can post onto
520 * the same queue multiple times from a single interrupt. The first call
521 * should always pass in pdFALSE. Subsequent calls should pass in
522 * the value returned from the previous call.
523 *
524 * @return pdTRUE if a co-routine was woken by posting onto the queue. This is
525 * used by the ISR to determine if a context switch may be required following
526 * the ISR.
527 *
528 * Example usage:
529 <pre>
530 // A co-routine that blocks on a queue waiting for characters to be received.
531 static void vReceivingCoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
532 {
533 char cRxedChar;
534 BaseType_t xResult;
535
536 // All co-routines must start with a call to crSTART().
537 crSTART( xHandle );
538
539 for( ;; )
540 {
541 // Wait for data to become available on the queue. This assumes the
542 // queue xCommsRxQueue has already been created!
543 crQUEUE_RECEIVE( xHandle, xCommsRxQueue, &uxLEDToFlash, portMAX_DELAY, &xResult );
544
545 // Was a character received?
546 if( xResult == pdPASS )
547 {
548 // Process the character here.
549 }
550 }
551
552 // All co-routines must end with a call to crEND().
553 crEND();
554 }
555
556 // An ISR that uses a queue to send characters received on a serial port to
557 // a co-routine.
558 void vUART_ISR( void )
559 {
560 char cRxedChar;
561 BaseType_t xCRWokenByPost = pdFALSE;
562
563 // We loop around reading characters until there are none left in the UART.
564 while( UART_RX_REG_NOT_EMPTY() )
565 {
566 // Obtain the character from the UART.
567 cRxedChar = UART_RX_REG;
568
569 // Post the character onto a queue. xCRWokenByPost will be pdFALSE
570 // the first time around the loop. If the post causes a co-routine
571 // to be woken (unblocked) then xCRWokenByPost will be set to pdTRUE.
572 // In this manner we can ensure that if more than one co-routine is
573 // blocked on the queue only one is woken by this ISR no matter how
574 // many characters are posted to the queue.
575 xCRWokenByPost = crQUEUE_SEND_FROM_ISR( xCommsRxQueue, &cRxedChar, xCRWokenByPost );
576 }
577 }</pre>
578 * \defgroup crQUEUE_SEND_FROM_ISR crQUEUE_SEND_FROM_ISR
579 * \ingroup Tasks
580 */
581#define crQUEUE_SEND_FROM_ISR( pxQueue, pvItemToQueue, xCoRoutinePreviouslyWoken ) xQueueCRSendFromISR( ( pxQueue ), ( pvItemToQueue ), ( xCoRoutinePreviouslyWoken ) )
582
583
584/**
585 * croutine. h
586 * <pre>
587 crQUEUE_SEND_FROM_ISR(
588 QueueHandle_t pxQueue,
589 void *pvBuffer,
590 BaseType_t * pxCoRoutineWoken
591 )</pre>
592 *
593 * The macro's crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() are the
594 * co-routine equivalent to the xQueueSendFromISR() and xQueueReceiveFromISR()
595 * functions used by tasks.
596 *
597 * crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() can only be used to
598 * pass data between a co-routine and and ISR, whereas xQueueSendFromISR() and
599 * xQueueReceiveFromISR() can only be used to pass data between a task and and
600 * ISR.
601 *
602 * crQUEUE_RECEIVE_FROM_ISR can only be called from an ISR to receive data
603 * from a queue that is being used from within a co-routine (a co-routine
604 * posted to the queue).
605 *
606 * See the co-routine section of the WEB documentation for information on
607 * passing data between tasks and co-routines and between ISR's and
608 * co-routines.
609 *
610 * @param xQueue The handle to the queue on which the item is to be posted.
611 *
612 * @param pvBuffer A pointer to a buffer into which the received item will be
613 * placed. The size of the items the queue will hold was defined when the
614 * queue was created, so this many bytes will be copied from the queue into
615 * pvBuffer.
616 *
617 * @param pxCoRoutineWoken A co-routine may be blocked waiting for space to become
618 * available on the queue. If crQUEUE_RECEIVE_FROM_ISR causes such a
619 * co-routine to unblock *pxCoRoutineWoken will get set to pdTRUE, otherwise
620 * *pxCoRoutineWoken will remain unchanged.
621 *
622 * @return pdTRUE an item was successfully received from the queue, otherwise
623 * pdFALSE.
624 *
625 * Example usage:
626 <pre>
627 // A co-routine that posts a character to a queue then blocks for a fixed
628 // period. The character is incremented each time.
629 static void vSendingCoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
630 {
631 // cChar holds its value while this co-routine is blocked and must therefore
632 // be declared static.
633 static char cCharToTx = 'a';
634 BaseType_t xResult;
635
636 // All co-routines must start with a call to crSTART().
637 crSTART( xHandle );
638
639 for( ;; )
640 {
641 // Send the next character to the queue.
642 crQUEUE_SEND( xHandle, xCoRoutineQueue, &cCharToTx, NO_DELAY, &xResult );
643
644 if( xResult == pdPASS )
645 {
646 // The character was successfully posted to the queue.
647 }
648 else
649 {
650 // Could not post the character to the queue.
651 }
652
653 // Enable the UART Tx interrupt to cause an interrupt in this
654 // hypothetical UART. The interrupt will obtain the character
655 // from the queue and send it.
656 ENABLE_RX_INTERRUPT();
657
658 // Increment to the next character then block for a fixed period.
659 // cCharToTx will maintain its value across the delay as it is
660 // declared static.
661 cCharToTx++;
662 if( cCharToTx > 'x' )
663 {
664 cCharToTx = 'a';
665 }
666 crDELAY( 100 );
667 }
668
669 // All co-routines must end with a call to crEND().
670 crEND();
671 }
672
673 // An ISR that uses a queue to receive characters to send on a UART.
674 void vUART_ISR( void )
675 {
676 char cCharToTx;
677 BaseType_t xCRWokenByPost = pdFALSE;
678
679 while( UART_TX_REG_EMPTY() )
680 {
681 // Are there any characters in the queue waiting to be sent?
682 // xCRWokenByPost will automatically be set to pdTRUE if a co-routine
683 // is woken by the post - ensuring that only a single co-routine is
684 // woken no matter how many times we go around this loop.
685 if( crQUEUE_RECEIVE_FROM_ISR( pxQueue, &cCharToTx, &xCRWokenByPost ) )
686 {
687 SEND_CHARACTER( cCharToTx );
688 }
689 }
690 }</pre>
691 * \defgroup crQUEUE_RECEIVE_FROM_ISR crQUEUE_RECEIVE_FROM_ISR
692 * \ingroup Tasks
693 */
694#define crQUEUE_RECEIVE_FROM_ISR( pxQueue, pvBuffer, pxCoRoutineWoken ) xQueueCRReceiveFromISR( ( pxQueue ), ( pvBuffer ), ( pxCoRoutineWoken ) )
695
696/*
697 * This function is intended for internal use by the co-routine macros only.
698 * The macro nature of the co-routine implementation requires that the
699 * prototype appears here. The function should not be used by application
700 * writers.
701 *
702 * Removes the current co-routine from its ready list and places it in the
703 * appropriate delayed list.
704 */
705void vCoRoutineAddToDelayedList( TickType_t xTicksToDelay, List_t *pxEventList );
706
707/*
708 * This function is intended for internal use by the queue implementation only.
709 * The function should not be used by application writers.
710 *
711 * Removes the highest priority co-routine from the event list and places it in
712 * the pending ready list.
713 */
714BaseType_t xCoRoutineRemoveFromEventList( const List_t *pxEventList );
715
716#ifdef __cplusplus
717}
718#endif
719
720#endif /* CO_ROUTINE_H */
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