2 FreeRTOS.org V4.4.0 - Copyright (C) 2003-2007 Richard Barry.
4 This file is part of the FreeRTOS.org distribution.
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26 ***************************************************************************
27 See http://www.FreeRTOS.org for documentation, latest information, license
28 and contact details. Please ensure to read the configuration and relevant
29 port sections of the online documentation.
31 Also see http://www.SafeRTOS.com for an IEC 61508 compliant version, along
32 with development and support options.
33 ***************************************************************************
39 + Call to portRESTORE_CONTEXT has been removed. The first context
40 switch is now performed within sPortStartScheduler().
44 + More use of 8bit data types.
45 + Function name prefixes changed where the data type returned has changed.
46 + configUSE_TRACE_FACILITY is no longer defined by default.
50 + Introduced ucTopReadyPriority. This tracks the highest priority ready
51 queue that contains a valid TCB and thus makes the context switch
54 + prvAddTaskToReadyQueue() has been made a macro.
58 + Added conditional compilation directives.
60 + Rearranged function order.
61 + Creating a task now causes a context switch if the task being created
62 has a higher priority than the calling task - assuming the kernel is
64 + vTaskDelete() now only causes a context switch if the calling task is
65 the task being deleted.
69 + Allow the type of the tick count to be 16 or 32 bits.
70 + Introduce xPendingReadyList feature to allow the time interrupts have to
71 be disabled to be minimised.
72 + Remove the #if( INCLUDE_vTaskSuspendAll ) statements. vTaskSuspendAll()
73 is now always included as it is used by the scheduler itself.
77 + Bug fix - pxCurrentTCB is now initialised before the call to
78 prvInitializeTaskLists(). Previously pxCurrentTCB could be accessed
83 + Change to where lStackSize is declared within sTaskCreate() to prevent
84 compiler warnings with 8051 port.
88 + Explicit use of 'signed' qualifier on portCHAR types added.
89 + Changed odd calculation of initial pxTopOfStack value when
91 + Removed pcVersionNumber definition.
95 + cTaskResumeAll() modified to ensure it can be called prior to the task
96 lists being initialised.
100 + Added API function vTaskDelayUntil().
101 + Added INCLUDE_vTaskDelay conditional compilation.
105 + Updated the vWriteTraceToBuffer macro to always be 4 byte aligned so it
106 can be used on ARM architectures.
107 + tskMAX_TASK_NAME_LEN definition replaced with the port specific
108 configMAX_TASK_NAME_LEN definition.
109 + Removed the call to strcpy when copying across the task name into the
111 + Added ucTasksDeleted variable to prevent vTaskSuspendAll() being called
112 too often in the idle task.
114 Changes between V3.0.0 and V2.6.1
116 + When resuming the scheduler a yield is performed if either a tick has
117 been missed, or a task is moved from the pending ready list into a ready
118 list. Previously a yield was not performed on this second condition.
119 + Introduced the type portBASE_TYPE. This necessitates several API
121 + Removed the sUsingPreemption variable. The constant defined in
122 portmacro.h is now used directly.
123 + The idle task can now include an optional hook function - and no longer
124 completes its time slice if other tasks with equal priority to it are
126 + See the FreeRTOS.org documentation for more information on V2.x.x to
127 V3.x.x modifications.
131 + Modified vTaskPrioritySet() and vTaskResume() to allow these functions to
132 be called while the scheduler is suspended.
133 + Corrected the task ordering within event lists.
137 + Added function xTaskGetCurrentTaskHandle().
141 + Changed the volatile declarations on some variables to reflect the
142 changes to the list definitions.
143 + Changed the order of the TCB definition so there is commonality between
144 the task control block and a co-routine control block.
145 + Allow the scheduler to be started even if no tasks other than the idle
146 task has been created. This allows co-routines to run even when no tasks
148 + The need for a context switch is now signalled if a task woken by an
149 event has a priority greater or equal to the currently running task.
150 Previously this was only greater than.
154 + Added the xMissedYield handling.
158 + The function vTaskList() now suspends the scheduler rather than disabling
159 interrupts during the creation of the task list.
160 + Allow a task to delete itself by passing in its own handle. Previously
161 this could only be done by passing in NULL.
162 + The tick hook function is now called only within a tick isr. Previously
163 it was also called when the tick function was called during the scheduler
168 + Extra checks have been placed in vTaskPrioritySet() to avoid unnecessary
173 + Bug fix: The 'value' of the event list item is updated when the priority
174 of a task is changed. Previously only the priority of the TCB itself was
176 + When resuming a task a check is first made to see if the task is actually
178 + vTaskPrioritySet() and vTaskResume() no longer use the event list item.
179 This has not been necessary since V4.0.1 when the xMissedYield handling
181 + Implement xTaskResumeFromISR().
185 + Added utility functions and xOverflowCount variable to facilitate the
190 + Tasks that block on events with a timeout of portMAX_DELAY are now
191 blocked indefinitely if configINCLUDE_vTaskSuspend is defined.
192 Previously portMAX_DELAY was just the longest block time possible.
196 + Very small change made to xTaskCheckForTimeout() as a result of the
197 SafeRTOS testing. This corrects the case where the function can return an
198 invalid value - but only in an extremely unlikely scenario.
200 Changes since V4.3.1:
202 + Added xTaskGetSchedulerState() function.
203 + Added prvIsTaskSuspended() to take into account the Occurrence of
204 vTaskResume() or vTaskResumeFromISR() being called passing in the
205 handle of a task that appears in the Suspended list only because it
206 is blocked on an event without a timeout being specified.
207 + Updated xTaskCheckForTimeout() to take into account that tasks blocked
208 using the Suspended list should never time out.
215 #include "FreeRTOS.h"
219 * Macro to define the amount of stack available to the idle task.
221 #define tskIDLE_STACK_SIZE configMINIMAL_STACK_SIZE
225 * Default a definitions for backwards compatibility with old
228 #ifndef configMAX_TASK_NAME_LEN
229 #define configMAX_TASK_NAME_LEN 16
232 #ifndef INCLUDE_xTaskGetCurrentTaskHandle
233 #define INCLUDE_xTaskGetCurrentTaskHandle 0
236 #ifndef configIDLE_SHOULD_YIELD
237 #define configIDLE_SHOULD_YIELD 1
240 #if configMAX_TASK_NAME_LEN < 1
241 #undef configMAX_TASK_NAME_LEN
242 #define configMAX_TASK_NAME_LEN 1
245 #ifndef INCLUDE_xTaskResumeFromISR
246 #define INCLUDE_xTaskResumeFromISR 1
249 #ifndef INCLUDE_xTaskGetSchedulerState
250 #define INCLUDE_xTaskGetSchedulerState 0
254 * Task control block. A task control block (TCB) is allocated to each task,
255 * and stores the context of the task.
257 typedef struct tskTaskControlBlock
259 volatile portSTACK_TYPE *pxTopOfStack; /*< Points to the location of the last item placed on the tasks stack. THIS MUST BE THE FIRST MEMBER OF THE STRUCT. */
260 xListItem xGenericListItem; /*< List item used to place the TCB in ready and blocked queues. */
261 xListItem xEventListItem; /*< List item used to place the TCB in event lists. */
262 unsigned portBASE_TYPE uxPriority; /*< The priority of the task where 0 is the lowest priority. */
263 portSTACK_TYPE *pxStack; /*< Points to the start of the stack. */
264 unsigned portBASE_TYPE uxTCBNumber; /*< This is used for tracing the scheduler and making debugging easier only. */
265 signed portCHAR pcTaskName[ configMAX_TASK_NAME_LEN ];/*< Descriptive name given to the task when created. Facilitates debugging only. */
266 unsigned portSHORT usStackDepth; /*< Total depth of the stack (when empty). This is defined as the number of variables the stack can hold, not the number of bytes. */
271 tskTCB * volatile pxCurrentTCB = NULL;
273 /* Lists for ready and blocked tasks. --------------------*/
275 static xList pxReadyTasksLists[ configMAX_PRIORITIES ]; /*< Prioritised ready tasks. */
276 static xList xDelayedTaskList1; /*< Delayed tasks. */
277 static xList xDelayedTaskList2; /*< Delayed tasks (two lists are used - one for delays that have overflowed the current tick count. */
278 static xList * volatile pxDelayedTaskList; /*< Points to the delayed task list currently being used. */
279 static xList * volatile pxOverflowDelayedTaskList; /*< Points to the delayed task list currently being used to hold tasks that have overflowed the current tick count. */
280 static xList xPendingReadyList; /*< Tasks that have been readied while the scheduler was suspended. They will be moved to the ready queue when the scheduler is resumed. */
282 #if ( INCLUDE_vTaskDelete == 1 )
284 static volatile xList xTasksWaitingTermination; /*< Tasks that have been deleted - but the their memory not yet freed. */
285 static volatile unsigned portBASE_TYPE uxTasksDeleted = ( unsigned portBASE_TYPE ) 0;
289 #if ( INCLUDE_vTaskSuspend == 1 )
291 static xList xSuspendedTaskList; /*< Tasks that are currently suspended. */
295 /* File private variables. --------------------------------*/
296 static volatile unsigned portBASE_TYPE uxCurrentNumberOfTasks = ( unsigned portBASE_TYPE ) 0;
297 static volatile portTickType xTickCount = ( portTickType ) 0;
298 static unsigned portBASE_TYPE uxTopUsedPriority = tskIDLE_PRIORITY;
299 static volatile unsigned portBASE_TYPE uxTopReadyPriority = tskIDLE_PRIORITY;
300 static volatile signed portBASE_TYPE xSchedulerRunning = pdFALSE;
301 static volatile unsigned portBASE_TYPE uxSchedulerSuspended = ( unsigned portBASE_TYPE ) pdFALSE;
302 static volatile unsigned portBASE_TYPE uxMissedTicks = ( unsigned portBASE_TYPE ) 0;
303 static volatile portBASE_TYPE xMissedYield = ( portBASE_TYPE ) pdFALSE;
304 static volatile portBASE_TYPE xNumOfOverflows = ( portBASE_TYPE ) 0;
305 /* Debugging and trace facilities private variables and macros. ------------*/
308 * The value used to fill the stack of a task when the task is created. This
309 * is used purely for checking the high water mark for tasks.
311 #define tskSTACK_FILL_BYTE ( 0xa5 )
314 * Macros used by vListTask to indicate which state a task is in.
316 #define tskBLOCKED_CHAR ( ( signed portCHAR ) 'B' )
317 #define tskREADY_CHAR ( ( signed portCHAR ) 'R' )
318 #define tskDELETED_CHAR ( ( signed portCHAR ) 'D' )
319 #define tskSUSPENDED_CHAR ( ( signed portCHAR ) 'S' )
322 * Macros and private variables used by the trace facility.
324 #if ( configUSE_TRACE_FACILITY == 1 )
326 #define tskSIZE_OF_EACH_TRACE_LINE ( ( unsigned portLONG ) ( sizeof( unsigned portLONG ) + sizeof( unsigned portLONG ) ) )
327 static volatile signed portCHAR * volatile pcTraceBuffer;
328 static signed portCHAR *pcTraceBufferStart;
329 static signed portCHAR *pcTraceBufferEnd;
330 static signed portBASE_TYPE xTracing = pdFALSE;
335 * Macro that writes a trace of scheduler activity to a buffer. This trace
336 * shows which task is running when and is very useful as a debugging tool.
337 * As this macro is called each context switch it is a good idea to undefine
338 * it if not using the facility.
340 #if ( configUSE_TRACE_FACILITY == 1 )
342 #define vWriteTraceToBuffer() \
346 static unsigned portBASE_TYPE uxPreviousTask = 255; \
348 if( uxPreviousTask != pxCurrentTCB->uxTCBNumber ) \
350 if( ( pcTraceBuffer + tskSIZE_OF_EACH_TRACE_LINE ) < pcTraceBufferEnd ) \
352 uxPreviousTask = pxCurrentTCB->uxTCBNumber; \
353 *( unsigned portLONG * ) pcTraceBuffer = ( unsigned portLONG ) xTickCount; \
354 pcTraceBuffer += sizeof( unsigned portLONG ); \
355 *( unsigned portLONG * ) pcTraceBuffer = ( unsigned portLONG ) uxPreviousTask; \
356 pcTraceBuffer += sizeof( unsigned portLONG ); \
360 xTracing = pdFALSE; \
368 #define vWriteTraceToBuffer()
374 * Place the task represented by pxTCB into the appropriate ready queue for
375 * the task. It is inserted at the end of the list. One quirk of this is
376 * that if the task being inserted is at the same priority as the currently
377 * executing task, then it will only be rescheduled after the currently
378 * executing task has been rescheduled.
380 #define prvAddTaskToReadyQueue( pxTCB ) \
382 if( pxTCB->uxPriority > uxTopReadyPriority ) \
384 uxTopReadyPriority = pxTCB->uxPriority; \
386 vListInsertEnd( ( xList * ) &( pxReadyTasksLists[ pxTCB->uxPriority ] ), &( pxTCB->xGenericListItem ) ); \
390 * Macro that looks at the list of tasks that are currently delayed to see if
391 * any require waking.
393 * Tasks are stored in the queue in the order of their wake time - meaning
394 * once one tasks has been found whose timer has not expired we need not look
395 * any further down the list.
397 #define prvCheckDelayedTasks() \
399 register tskTCB *pxTCB; \
401 while( ( pxTCB = ( tskTCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxDelayedTaskList ) ) != NULL ) \
403 if( xTickCount < listGET_LIST_ITEM_VALUE( &( pxTCB->xGenericListItem ) ) ) \
407 vListRemove( &( pxTCB->xGenericListItem ) ); \
408 /* Is the task waiting on an event also? */ \
409 if( pxTCB->xEventListItem.pvContainer ) \
411 vListRemove( &( pxTCB->xEventListItem ) ); \
413 prvAddTaskToReadyQueue( pxTCB ); \
418 * Several functions take an xTaskHandle parameter that can optionally be NULL,
419 * where NULL is used to indicate that the handle of the currently executing
420 * task should be used in place of the parameter. This macro simply checks to
421 * see if the parameter is NULL and returns a pointer to the appropriate TCB.
423 #define prvGetTCBFromHandle( pxHandle ) ( ( pxHandle == NULL ) ? ( tskTCB * ) pxCurrentTCB : ( tskTCB * ) pxHandle )
426 /* File private functions. --------------------------------*/
429 * Utility to ready a TCB for a given task. Mainly just copies the parameters
430 * into the TCB structure.
432 static void prvInitialiseTCBVariables( tskTCB *pxTCB, unsigned portSHORT usStackDepth, const signed portCHAR * const pcName, unsigned portBASE_TYPE uxPriority );
435 * Utility to ready all the lists used by the scheduler. This is called
436 * automatically upon the creation of the first task.
438 static void prvInitialiseTaskLists( void );
441 * The idle task, which as all tasks is implemented as a never ending loop.
442 * The idle task is automatically created and added to the ready lists upon
443 * creation of the first user task.
445 * The portTASK_FUNCTION_PROTO() macro is used to allow port/compiler specific
446 * language extensions. The equivalent prototype for this function is:
448 * void prvIdleTask( void *pvParameters );
451 static portTASK_FUNCTION_PROTO( prvIdleTask, pvParameters );
454 * Utility to free all memory allocated by the scheduler to hold a TCB,
455 * including the stack pointed to by the TCB.
457 * This does not free memory allocated by the task itself (i.e. memory
458 * allocated by calls to pvPortMalloc from within the tasks application code).
460 #if ( ( INCLUDE_vTaskDelete == 1 ) || ( INCLUDE_vTaskCleanUpResources == 1 ) )
461 static void prvDeleteTCB( tskTCB *pxTCB );
465 * Used only by the idle task. This checks to see if anything has been placed
466 * in the list of tasks waiting to be deleted. If so the task is cleaned up
467 * and its TCB deleted.
469 static void prvCheckTasksWaitingTermination( void );
472 * Allocates memory from the heap for a TCB and associated stack. Checks the
473 * allocation was successful.
475 static tskTCB *prvAllocateTCBAndStack( unsigned portSHORT usStackDepth );
478 * Called from vTaskList. vListTasks details all the tasks currently under
479 * control of the scheduler. The tasks may be in one of a number of lists.
480 * prvListTaskWithinSingleList accepts a list and details the tasks from
481 * within just that list.
483 * THIS FUNCTION IS INTENDED FOR DEBUGGING ONLY, AND SHOULD NOT BE CALLED FROM
484 * NORMAL APPLICATION CODE.
486 #if ( configUSE_TRACE_FACILITY == 1 )
488 static void prvListTaskWithinSingleList( signed portCHAR *pcWriteBuffer, xList *pxList, signed portCHAR cStatus );
493 * When a task is created, the stack of the task is filled with a known value.
494 * This function determines the 'high water mark' of the task stack by
495 * determining how much of the stack remains at the original preset value.
497 #if ( configUSE_TRACE_FACILITY == 1 )
499 unsigned portSHORT usTaskCheckFreeStackSpace( const unsigned portCHAR *pucStackByte );
504 * Checks that a task being resumed (unsuspended) is actually in the Suspended
507 #if ( INCLUDE_vTaskSuspend == 1 )
509 static portBASE_TYPE prvIsTaskSuspended( const tskTCB * const pxTCB );
519 /*-----------------------------------------------------------
520 * TASK CREATION API documented in task.h
521 *----------------------------------------------------------*/
523 signed portBASE_TYPE xTaskCreate( pdTASK_CODE pvTaskCode, const signed portCHAR * const pcName, unsigned portSHORT usStackDepth, void *pvParameters, unsigned portBASE_TYPE uxPriority, xTaskHandle *pxCreatedTask )
525 signed portBASE_TYPE xReturn;
527 static unsigned portBASE_TYPE uxTaskNumber = 0; /*lint !e956 Static is deliberate - this is guarded before use. */
529 /* Allocate the memory required by the TCB and stack for the new task.
530 checking that the allocation was successful. */
531 pxNewTCB = prvAllocateTCBAndStack( usStackDepth );
533 if( pxNewTCB != NULL )
535 portSTACK_TYPE *pxTopOfStack;
537 /* Setup the newly allocated TCB with the initial state of the task. */
538 prvInitialiseTCBVariables( pxNewTCB, usStackDepth, pcName, uxPriority );
540 /* Calculate the top of stack address. This depends on whether the
541 stack grows from high memory to low (as per the 80x86) or visa versa.
542 portSTACK_GROWTH is used to make the result positive or negative as
543 required by the port. */
544 #if portSTACK_GROWTH < 0
546 pxTopOfStack = pxNewTCB->pxStack + ( pxNewTCB->usStackDepth - 1 );
550 pxTopOfStack = pxNewTCB->pxStack;
554 /* Initialize the TCB stack to look as if the task was already running,
555 but had been interrupted by the scheduler. The return address is set
556 to the start of the task function. Once the stack has been initialised
557 the top of stack variable is updated. */
558 pxNewTCB->pxTopOfStack = pxPortInitialiseStack( pxTopOfStack, pvTaskCode, pvParameters );
560 /* We are going to manipulate the task queues to add this task to a
561 ready list, so must make sure no interrupts occur. */
562 portENTER_CRITICAL();
564 uxCurrentNumberOfTasks++;
565 if( uxCurrentNumberOfTasks == ( unsigned portBASE_TYPE ) 1 )
567 /* As this is the first task it must also be the current task. */
568 pxCurrentTCB = pxNewTCB;
570 /* This is the first task to be created so do the preliminary
571 initialisation required. We will not recover if this call
572 fails, but we will report the failure. */
573 prvInitialiseTaskLists();
577 /* If the scheduler is not already running, make this task the
578 current task if it is the highest priority task to be created
580 if( xSchedulerRunning == pdFALSE )
582 if( pxCurrentTCB->uxPriority <= uxPriority )
584 pxCurrentTCB = pxNewTCB;
589 /* Remember the top priority to make context switching faster. Use
590 the priority in pxNewTCB as this has been capped to a valid value. */
591 if( pxNewTCB->uxPriority > uxTopUsedPriority )
593 uxTopUsedPriority = pxNewTCB->uxPriority;
596 /* Add a counter into the TCB for tracing only. */
597 pxNewTCB->uxTCBNumber = uxTaskNumber;
600 prvAddTaskToReadyQueue( pxNewTCB );
608 xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;
611 if( xReturn == pdPASS )
613 if( ( void * ) pxCreatedTask != NULL )
615 /* Pass the TCB out - in an anonymous way. The calling function/
616 task can use this as a handle to delete the task later if
618 *pxCreatedTask = ( xTaskHandle ) pxNewTCB;
621 if( xSchedulerRunning != pdFALSE )
623 /* If the created task is of a higher priority than the current task
624 then it should run now. */
625 if( pxCurrentTCB->uxPriority < uxPriority )
634 /*-----------------------------------------------------------*/
636 #if ( INCLUDE_vTaskDelete == 1 )
638 void vTaskDelete( xTaskHandle pxTaskToDelete )
642 taskENTER_CRITICAL();
644 /* Ensure a yield is performed if the current task is being
646 if( pxTaskToDelete == pxCurrentTCB )
648 pxTaskToDelete = NULL;
651 /* If null is passed in here then we are deleting ourselves. */
652 pxTCB = prvGetTCBFromHandle( pxTaskToDelete );
654 /* Remove task from the ready list and place in the termination list.
655 This will stop the task from be scheduled. The idle task will check
656 the termination list and free up any memory allocated by the
657 scheduler for the TCB and stack. */
658 vListRemove( &( pxTCB->xGenericListItem ) );
660 /* Is the task waiting on an event also? */
661 if( pxTCB->xEventListItem.pvContainer )
663 vListRemove( &( pxTCB->xEventListItem ) );
666 vListInsertEnd( ( xList * ) &xTasksWaitingTermination, &( pxTCB->xGenericListItem ) );
668 /* Increment the ucTasksDeleted variable so the idle task knows
669 there is a task that has been deleted and that it should therefore
670 check the xTasksWaitingTermination list. */
675 /* Force a reschedule if we have just deleted the current task. */
676 if( xSchedulerRunning != pdFALSE )
678 if( ( void * ) pxTaskToDelete == NULL )
692 /*-----------------------------------------------------------
693 * TASK CONTROL API documented in task.h
694 *----------------------------------------------------------*/
696 #if ( INCLUDE_vTaskDelayUntil == 1 )
698 void vTaskDelayUntil( portTickType *pxPreviousWakeTime, portTickType xTimeIncrement )
700 portTickType xTimeToWake;
701 portBASE_TYPE xAlreadyYielded, xShouldDelay = pdFALSE;
705 /* Generate the tick time at which the task wants to wake. */
706 xTimeToWake = *pxPreviousWakeTime + xTimeIncrement;
708 if( xTickCount < *pxPreviousWakeTime )
710 /* The tick count has overflowed since this function was
711 lasted called. In this case the only time we should ever
712 actually delay is if the wake time has also overflowed,
713 and the wake time is greater than the tick time. When this
714 is the case it is as if neither time had overflowed. */
715 if( ( xTimeToWake < *pxPreviousWakeTime ) && ( xTimeToWake > xTickCount ) )
717 xShouldDelay = pdTRUE;
722 /* The tick time has not overflowed. In this case we will
723 delay if either the wake time has overflowed, and/or the
724 tick time is less than the wake time. */
725 if( ( xTimeToWake < *pxPreviousWakeTime ) || ( xTimeToWake > xTickCount ) )
727 xShouldDelay = pdTRUE;
731 /* Update the wake time ready for the next call. */
732 *pxPreviousWakeTime = xTimeToWake;
736 /* We must remove ourselves from the ready list before adding
737 ourselves to the blocked list as the same list item is used for
739 vListRemove( ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
741 /* The list item will be inserted in wake time order. */
742 listSET_LIST_ITEM_VALUE( &( pxCurrentTCB->xGenericListItem ), xTimeToWake );
744 if( xTimeToWake < xTickCount )
746 /* Wake time has overflowed. Place this item in the
748 vListInsert( ( xList * ) pxOverflowDelayedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
752 /* The wake time has not overflowed, so we can use the
753 current block list. */
754 vListInsert( ( xList * ) pxDelayedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
758 xAlreadyYielded = xTaskResumeAll();
760 /* Force a reschedule if xTaskResumeAll has not already done so, we may
761 have put ourselves to sleep. */
762 if( !xAlreadyYielded )
769 /*-----------------------------------------------------------*/
771 #if ( INCLUDE_vTaskDelay == 1 )
773 void vTaskDelay( portTickType xTicksToDelay )
775 portTickType xTimeToWake;
776 signed portBASE_TYPE xAlreadyYielded = pdFALSE;
778 /* A delay time of zero just forces a reschedule. */
779 if( xTicksToDelay > ( portTickType ) 0 )
783 /* A task that is removed from the event list while the
784 scheduler is suspended will not get placed in the ready
785 list or removed from the blocked list until the scheduler
788 This task cannot be in an event list as it is the currently
791 /* Calculate the time to wake - this may overflow but this is
793 xTimeToWake = xTickCount + xTicksToDelay;
795 /* We must remove ourselves from the ready list before adding
796 ourselves to the blocked list as the same list item is used for
798 vListRemove( ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
800 /* The list item will be inserted in wake time order. */
801 listSET_LIST_ITEM_VALUE( &( pxCurrentTCB->xGenericListItem ), xTimeToWake );
803 if( xTimeToWake < xTickCount )
805 /* Wake time has overflowed. Place this item in the
807 vListInsert( ( xList * ) pxOverflowDelayedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
811 /* The wake time has not overflowed, so we can use the
812 current block list. */
813 vListInsert( ( xList * ) pxDelayedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
816 xAlreadyYielded = xTaskResumeAll();
819 /* Force a reschedule if xTaskResumeAll has not already done so, we may
820 have put ourselves to sleep. */
821 if( !xAlreadyYielded )
828 /*-----------------------------------------------------------*/
830 #if ( INCLUDE_uxTaskPriorityGet == 1 )
832 unsigned portBASE_TYPE uxTaskPriorityGet( xTaskHandle pxTask )
835 unsigned portBASE_TYPE uxReturn;
837 taskENTER_CRITICAL();
839 /* If null is passed in here then we are changing the
840 priority of the calling function. */
841 pxTCB = prvGetTCBFromHandle( pxTask );
842 uxReturn = pxTCB->uxPriority;
850 /*-----------------------------------------------------------*/
852 #if ( INCLUDE_vTaskPrioritySet == 1 )
854 void vTaskPrioritySet( xTaskHandle pxTask, unsigned portBASE_TYPE uxNewPriority )
857 unsigned portBASE_TYPE uxCurrentPriority, xYieldRequired = pdFALSE;
859 /* Ensure the new priority is valid. */
860 if( uxNewPriority >= configMAX_PRIORITIES )
862 uxNewPriority = configMAX_PRIORITIES - 1;
865 taskENTER_CRITICAL();
867 /* If null is passed in here then we are changing the
868 priority of the calling function. */
869 pxTCB = prvGetTCBFromHandle( pxTask );
870 uxCurrentPriority = pxTCB->uxPriority;
872 if( uxCurrentPriority != uxNewPriority )
874 /* The priority change may have readied a task of higher
875 priority than the calling task. */
876 if( uxNewPriority > pxCurrentTCB->uxPriority )
880 /* The priority of another task is being raised. If we
881 were raising the priority of the currently running task
882 there would be no need to switch as it must have already
883 been the highest priority task. */
884 xYieldRequired = pdTRUE;
887 else if( pxTask == NULL )
889 /* Setting our own priority down means there may now be another
890 task of higher priority that is ready to execute. */
891 xYieldRequired = pdTRUE;
894 pxTCB->uxPriority = uxNewPriority;
895 listSET_LIST_ITEM_VALUE( &( pxTCB->xEventListItem ), configMAX_PRIORITIES - ( portTickType ) uxNewPriority );
897 /* If the task is in the blocked or suspended list we need do
898 nothing more than change it's priority variable. However, if
899 the task is in a ready list it needs to be removed and placed
900 in the queue appropriate to its new priority. */
901 if( listIS_CONTAINED_WITHIN( &( pxReadyTasksLists[ uxCurrentPriority ] ), &( pxTCB->xGenericListItem ) ) )
903 /* The task is currently in its ready list - remove before adding
904 it to it's new ready list. As we are in a critical section we
905 can do this even if the scheduler is suspended. */
906 vListRemove( &( pxTCB->xGenericListItem ) );
907 prvAddTaskToReadyQueue( pxTCB );
910 if( xYieldRequired == pdTRUE )
920 /*-----------------------------------------------------------*/
922 #if ( INCLUDE_vTaskSuspend == 1 )
924 void vTaskSuspend( xTaskHandle pxTaskToSuspend )
928 taskENTER_CRITICAL();
930 /* Ensure a yield is performed if the current task is being
932 if( pxTaskToSuspend == pxCurrentTCB )
934 pxTaskToSuspend = NULL;
937 /* If null is passed in here then we are suspending ourselves. */
938 pxTCB = prvGetTCBFromHandle( pxTaskToSuspend );
940 /* Remove task from the ready/delayed list and place in the suspended list. */
941 vListRemove( &( pxTCB->xGenericListItem ) );
943 /* Is the task waiting on an event also? */
944 if( pxTCB->xEventListItem.pvContainer )
946 vListRemove( &( pxTCB->xEventListItem ) );
949 vListInsertEnd( ( xList * ) &xSuspendedTaskList, &( pxTCB->xGenericListItem ) );
953 /* We may have just suspended the current task. */
954 if( ( void * ) pxTaskToSuspend == NULL )
961 /*-----------------------------------------------------------*/
963 #if ( INCLUDE_vTaskSuspend == 1 )
965 static portBASE_TYPE prvIsTaskSuspended( const tskTCB * const pxTCB )
967 portBASE_TYPE xReturn = pdFALSE;
969 /* Is the task we are attempting to resume actually in the
971 if( listIS_CONTAINED_WITHIN( &xSuspendedTaskList, &( pxTCB->xGenericListItem ) ) != pdFALSE )
973 /* Has the task already been resumed from within an ISR? */
974 if( listIS_CONTAINED_WITHIN( &xPendingReadyList, &( pxTCB->xEventListItem ) ) != pdTRUE )
976 /* Is it in the suspended list because it is in the
977 Suspended state? It is possible to be in the suspended
978 list because it is blocked on a task with no timeout
980 if( listIS_CONTAINED_WITHIN( NULL, &( pxTCB->xEventListItem ) ) == pdTRUE )
991 /*-----------------------------------------------------------*/
993 #if ( INCLUDE_vTaskSuspend == 1 )
995 void vTaskResume( xTaskHandle pxTaskToResume )
999 /* Remove the task from whichever list it is currently in, and place
1000 it in the ready list. */
1001 pxTCB = ( tskTCB * ) pxTaskToResume;
1003 /* The parameter cannot be NULL as it is impossible to resume the
1004 currently executing task. */
1007 taskENTER_CRITICAL();
1009 if( prvIsTaskSuspended( pxTCB ) == pdTRUE )
1011 /* As we are in a critical section we can access the ready
1012 lists even if the scheduler is suspended. */
1013 vListRemove( &( pxTCB->xGenericListItem ) );
1014 prvAddTaskToReadyQueue( pxTCB );
1016 /* We may have just resumed a higher priority task. */
1017 if( pxTCB->uxPriority >= pxCurrentTCB->uxPriority )
1019 /* This yield may not cause the task just resumed to run, but
1020 will leave the lists in the correct state for the next yield. */
1025 taskEXIT_CRITICAL();
1031 /*-----------------------------------------------------------*/
1033 #if ( ( INCLUDE_xTaskResumeFromISR == 1 ) && ( INCLUDE_vTaskSuspend == 1 ) )
1035 portBASE_TYPE xTaskResumeFromISR( xTaskHandle pxTaskToResume )
1037 portBASE_TYPE xYieldRequired = pdFALSE;
1040 pxTCB = ( tskTCB * ) pxTaskToResume;
1042 if( prvIsTaskSuspended( pxTCB ) == pdTRUE )
1044 if( uxSchedulerSuspended == ( unsigned portBASE_TYPE ) pdFALSE )
1046 xYieldRequired = ( pxTCB->uxPriority >= pxCurrentTCB->uxPriority );
1047 vListRemove( &( pxTCB->xGenericListItem ) );
1048 prvAddTaskToReadyQueue( pxTCB );
1052 /* We cannot access the delayed or ready lists, so will hold this
1053 task pending until the scheduler is resumed, at which point a
1054 yield will be preformed if necessary. */
1055 vListInsertEnd( ( xList * ) &( xPendingReadyList ), &( pxTCB->xEventListItem ) );
1059 return xYieldRequired;
1067 /*-----------------------------------------------------------
1068 * PUBLIC SCHEDULER CONTROL documented in task.h
1069 *----------------------------------------------------------*/
1072 void vTaskStartScheduler( void )
1074 portBASE_TYPE xReturn;
1076 /* Add the idle task at the lowest priority. */
1077 xReturn = xTaskCreate( prvIdleTask, ( signed portCHAR * ) "IDLE", tskIDLE_STACK_SIZE, ( void * ) NULL, tskIDLE_PRIORITY, ( xTaskHandle * ) NULL );
1079 if( xReturn == pdPASS )
1081 /* Interrupts are turned off here, to ensure a tick does not occur
1082 before or during the call to xPortStartScheduler(). The stacks of
1083 the created tasks contain a status word with interrupts switched on
1084 so interrupts will automatically get re-enabled when the first task
1087 STEPPING THROUGH HERE USING A DEBUGGER CAN CAUSE BIG PROBLEMS IF THE
1088 DEBUGGER ALLOWS INTERRUPTS TO BE PROCESSED. */
1089 portDISABLE_INTERRUPTS();
1091 xSchedulerRunning = pdTRUE;
1092 xTickCount = ( portTickType ) 0;
1094 /* Setting up the timer tick is hardware specific and thus in the
1095 portable interface. */
1096 if( xPortStartScheduler() )
1098 /* Should not reach here as if the scheduler is running the
1099 function will not return. */
1103 /* Should only reach here if a task calls xTaskEndScheduler(). */
1107 /*-----------------------------------------------------------*/
1109 void vTaskEndScheduler( void )
1111 /* Stop the scheduler interrupts and call the portable scheduler end
1112 routine so the original ISRs can be restored if necessary. The port
1113 layer must ensure interrupts enable bit is left in the correct state. */
1114 portDISABLE_INTERRUPTS();
1115 xSchedulerRunning = pdFALSE;
1116 vPortEndScheduler();
1118 /*----------------------------------------------------------*/
1120 void vTaskSuspendAll( void )
1122 portENTER_CRITICAL();
1123 ++uxSchedulerSuspended;
1124 portEXIT_CRITICAL();
1126 /*----------------------------------------------------------*/
1128 signed portBASE_TYPE xTaskResumeAll( void )
1130 register tskTCB *pxTCB;
1131 signed portBASE_TYPE xAlreadyYielded = pdFALSE;
1133 /* It is possible that an ISR caused a task to be removed from an event
1134 list while the scheduler was suspended. If this was the case then the
1135 removed task will have been added to the xPendingReadyList. Once the
1136 scheduler has been resumed it is safe to move all the pending ready
1137 tasks from this list into their appropriate ready list. */
1138 portENTER_CRITICAL();
1140 --uxSchedulerSuspended;
1142 if( uxSchedulerSuspended == ( unsigned portBASE_TYPE ) pdFALSE )
1144 if( uxCurrentNumberOfTasks > ( unsigned portBASE_TYPE ) 0 )
1146 portBASE_TYPE xYieldRequired = pdFALSE;
1148 /* Move any readied tasks from the pending list into the
1149 appropriate ready list. */
1150 while( ( pxTCB = ( tskTCB * ) listGET_OWNER_OF_HEAD_ENTRY( ( ( xList * ) &xPendingReadyList ) ) ) != NULL )
1152 vListRemove( &( pxTCB->xEventListItem ) );
1153 vListRemove( &( pxTCB->xGenericListItem ) );
1154 prvAddTaskToReadyQueue( pxTCB );
1156 /* If we have moved a task that has a priority higher than
1157 the current task then we should yield. */
1158 if( pxTCB->uxPriority >= pxCurrentTCB->uxPriority )
1160 xYieldRequired = pdTRUE;
1164 /* If any ticks occurred while the scheduler was suspended then
1165 they should be processed now. This ensures the tick count does not
1166 slip, and that any delayed tasks are resumed at the correct time. */
1167 if( uxMissedTicks > ( unsigned portBASE_TYPE ) 0 )
1169 while( uxMissedTicks > ( unsigned portBASE_TYPE ) 0 )
1171 vTaskIncrementTick();
1175 /* As we have processed some ticks it is appropriate to yield
1176 to ensure the highest priority task that is ready to run is
1177 the task actually running. */
1178 xYieldRequired = pdTRUE;
1181 if( ( xYieldRequired == pdTRUE ) || ( xMissedYield == pdTRUE ) )
1183 xAlreadyYielded = pdTRUE;
1184 xMissedYield = pdFALSE;
1190 portEXIT_CRITICAL();
1192 return xAlreadyYielded;
1200 /*-----------------------------------------------------------
1201 * PUBLIC TASK UTILITIES documented in task.h
1202 *----------------------------------------------------------*/
1206 portTickType xTaskGetTickCount( void )
1208 portTickType xTicks;
1210 /* Critical section required if running on a 16 bit processor. */
1211 taskENTER_CRITICAL();
1213 xTicks = xTickCount;
1215 taskEXIT_CRITICAL();
1219 /*-----------------------------------------------------------*/
1221 unsigned portBASE_TYPE uxTaskGetNumberOfTasks( void )
1223 unsigned portBASE_TYPE uxNumberOfTasks;
1225 taskENTER_CRITICAL();
1226 uxNumberOfTasks = uxCurrentNumberOfTasks;
1227 taskEXIT_CRITICAL();
1229 return uxNumberOfTasks;
1231 /*-----------------------------------------------------------*/
1233 #if ( ( configUSE_TRACE_FACILITY == 1 ) && ( INCLUDE_vTaskDelete == 1 ) && ( INCLUDE_vTaskSuspend == 1 ) )
1235 void vTaskList( signed portCHAR *pcWriteBuffer )
1237 unsigned portBASE_TYPE uxQueue;
1239 /* This is a VERY costly function that should be used for debug only.
1240 It leaves interrupts disabled for a LONG time. */
1244 /* Run through all the lists that could potentially contain a TCB and
1245 report the task name, state and stack high water mark. */
1247 pcWriteBuffer[ 0 ] = ( signed portCHAR ) 0x00;
1248 strcat( ( portCHAR * ) pcWriteBuffer, ( const portCHAR * ) "\r\n" );
1250 uxQueue = uxTopUsedPriority + 1;
1256 if( !listLIST_IS_EMPTY( &( pxReadyTasksLists[ uxQueue ] ) ) )
1258 prvListTaskWithinSingleList( pcWriteBuffer, ( xList * ) &( pxReadyTasksLists[ uxQueue ] ), tskREADY_CHAR );
1260 }while( uxQueue > ( unsigned portSHORT ) tskIDLE_PRIORITY );
1262 if( !listLIST_IS_EMPTY( pxDelayedTaskList ) )
1264 prvListTaskWithinSingleList( pcWriteBuffer, ( xList * ) pxDelayedTaskList, tskBLOCKED_CHAR );
1267 if( !listLIST_IS_EMPTY( pxOverflowDelayedTaskList ) )
1269 prvListTaskWithinSingleList( pcWriteBuffer, ( xList * ) pxOverflowDelayedTaskList, tskBLOCKED_CHAR );
1272 if( !listLIST_IS_EMPTY( &xTasksWaitingTermination ) )
1274 prvListTaskWithinSingleList( pcWriteBuffer, ( xList * ) &xTasksWaitingTermination, tskDELETED_CHAR );
1277 if( !listLIST_IS_EMPTY( &xSuspendedTaskList ) )
1279 prvListTaskWithinSingleList( pcWriteBuffer, ( xList * ) &xSuspendedTaskList, tskSUSPENDED_CHAR );
1286 /*----------------------------------------------------------*/
1288 #if ( configUSE_TRACE_FACILITY == 1 )
1290 void vTaskStartTrace( signed portCHAR * pcBuffer, unsigned portLONG ulBufferSize )
1292 portENTER_CRITICAL();
1294 pcTraceBuffer = ( volatile signed portCHAR * volatile )pcBuffer;
1295 pcTraceBufferStart = pcBuffer;
1296 pcTraceBufferEnd = pcBuffer + ( ulBufferSize - tskSIZE_OF_EACH_TRACE_LINE );
1299 portEXIT_CRITICAL();
1303 /*----------------------------------------------------------*/
1305 #if ( configUSE_TRACE_FACILITY == 1 )
1307 unsigned portLONG ulTaskEndTrace( void )
1309 unsigned portLONG ulBufferLength;
1311 portENTER_CRITICAL();
1313 portEXIT_CRITICAL();
1315 ulBufferLength = ( unsigned portLONG ) ( pcTraceBuffer - pcTraceBufferStart );
1317 return ulBufferLength;
1324 /*-----------------------------------------------------------
1325 * SCHEDULER INTERNALS AVAILABLE FOR PORTING PURPOSES
1326 * documented in task.h
1327 *----------------------------------------------------------*/
1330 inline void vTaskIncrementTick( void )
1332 /* Called by the portable layer each time a tick interrupt occurs.
1333 Increments the tick then checks to see if the new tick value will cause any
1334 tasks to be unblocked. */
1335 if( uxSchedulerSuspended == ( unsigned portBASE_TYPE ) pdFALSE )
1338 if( xTickCount == ( portTickType ) 0 )
1342 /* Tick count has overflowed so we need to swap the delay lists.
1343 If there are any items in pxDelayedTaskList here then there is
1345 pxTemp = pxDelayedTaskList;
1346 pxDelayedTaskList = pxOverflowDelayedTaskList;
1347 pxOverflowDelayedTaskList = pxTemp;
1351 /* See if this tick has made a timeout expire. */
1352 prvCheckDelayedTasks();
1358 /* The tick hook gets called at regular intervals, even if the
1359 scheduler is locked. */
1360 #if ( configUSE_TICK_HOOK == 1 )
1362 extern void vApplicationTickHook( void );
1364 vApplicationTickHook();
1369 #if ( configUSE_TICK_HOOK == 1 )
1371 extern void vApplicationTickHook( void );
1373 /* Guard against the tick hook being called when the missed tick
1374 count is being unwound (when the scheduler is being unlocked. */
1375 if( uxMissedTicks == 0 )
1377 vApplicationTickHook();
1382 /*-----------------------------------------------------------*/
1384 #if ( ( INCLUDE_vTaskCleanUpResources == 1 ) && ( INCLUDE_vTaskSuspend == 1 ) )
1386 void vTaskCleanUpResources( void )
1388 unsigned portSHORT usQueue;
1389 volatile tskTCB *pxTCB;
1391 usQueue = ( unsigned portSHORT ) uxTopUsedPriority + ( unsigned portSHORT ) 1;
1393 /* Remove any TCB's from the ready queues. */
1398 while( !listLIST_IS_EMPTY( &( pxReadyTasksLists[ usQueue ] ) ) )
1400 listGET_OWNER_OF_NEXT_ENTRY( pxTCB, &( pxReadyTasksLists[ usQueue ] ) );
1401 vListRemove( ( xListItem * ) &( pxTCB->xGenericListItem ) );
1403 prvDeleteTCB( ( tskTCB * ) pxTCB );
1405 }while( usQueue > ( unsigned portSHORT ) tskIDLE_PRIORITY );
1407 /* Remove any TCB's from the delayed queue. */
1408 while( !listLIST_IS_EMPTY( &xDelayedTaskList1 ) )
1410 listGET_OWNER_OF_NEXT_ENTRY( pxTCB, &xDelayedTaskList1 );
1411 vListRemove( ( xListItem * ) &( pxTCB->xGenericListItem ) );
1413 prvDeleteTCB( ( tskTCB * ) pxTCB );
1416 /* Remove any TCB's from the overflow delayed queue. */
1417 while( !listLIST_IS_EMPTY( &xDelayedTaskList2 ) )
1419 listGET_OWNER_OF_NEXT_ENTRY( pxTCB, &xDelayedTaskList2 );
1420 vListRemove( ( xListItem * ) &( pxTCB->xGenericListItem ) );
1422 prvDeleteTCB( ( tskTCB * ) pxTCB );
1425 while( !listLIST_IS_EMPTY( &xSuspendedTaskList ) )
1427 listGET_OWNER_OF_NEXT_ENTRY( pxTCB, &xSuspendedTaskList );
1428 vListRemove( ( xListItem * ) &( pxTCB->xGenericListItem ) );
1430 prvDeleteTCB( ( tskTCB * ) pxTCB );
1435 /*-----------------------------------------------------------*/
1437 void vTaskSwitchContext( void )
1439 if( uxSchedulerSuspended != ( unsigned portBASE_TYPE ) pdFALSE )
1441 /* The scheduler is currently suspended - do not allow a context
1443 xMissedYield = pdTRUE;
1447 /* Find the highest priority queue that contains ready tasks. */
1448 while( listLIST_IS_EMPTY( &( pxReadyTasksLists[ uxTopReadyPriority ] ) ) )
1450 --uxTopReadyPriority;
1453 /* listGET_OWNER_OF_NEXT_ENTRY walks through the list, so the tasks of the
1454 same priority get an equal share of the processor time. */
1455 listGET_OWNER_OF_NEXT_ENTRY( pxCurrentTCB, &( pxReadyTasksLists[ uxTopReadyPriority ] ) );
1456 vWriteTraceToBuffer();
1458 /*-----------------------------------------------------------*/
1460 void vTaskPlaceOnEventList( xList *pxEventList, portTickType xTicksToWait )
1462 portTickType xTimeToWake;
1464 /* THIS FUNCTION MUST BE CALLED WITH INTERRUPTS DISABLED OR THE
1465 SCHEDULER SUSPENDED. */
1467 /* Place the event list item of the TCB in the appropriate event list.
1468 This is placed in the list in priority order so the highest priority task
1469 is the first to be woken by the event. */
1470 vListInsert( ( xList * ) pxEventList, ( xListItem * ) &( pxCurrentTCB->xEventListItem ) );
1472 /* We must remove ourselves from the ready list before adding ourselves
1473 to the blocked list as the same list item is used for both lists. We have
1474 exclusive access to the ready lists as the scheduler is locked. */
1475 vListRemove( ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
1478 #if ( INCLUDE_vTaskSuspend == 1 )
1480 if( xTicksToWait == portMAX_DELAY )
1482 /* Add ourselves to the suspended task list instead of a delayed task
1483 list to ensure we are not woken by a timing event. We will block
1485 vListInsertEnd( ( xList * ) &xSuspendedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
1489 /* Calculate the time at which the task should be woken if the event does
1490 not occur. This may overflow but this doesn't matter. */
1491 xTimeToWake = xTickCount + xTicksToWait;
1493 listSET_LIST_ITEM_VALUE( &( pxCurrentTCB->xGenericListItem ), xTimeToWake );
1495 if( xTimeToWake < xTickCount )
1497 /* Wake time has overflowed. Place this item in the overflow list. */
1498 vListInsert( ( xList * ) pxOverflowDelayedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
1502 /* The wake time has not overflowed, so we can use the current block list. */
1503 vListInsert( ( xList * ) pxDelayedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
1509 /* Calculate the time at which the task should be woken if the event does
1510 not occur. This may overflow but this doesn't matter. */
1511 xTimeToWake = xTickCount + xTicksToWait;
1513 listSET_LIST_ITEM_VALUE( &( pxCurrentTCB->xGenericListItem ), xTimeToWake );
1515 if( xTimeToWake < xTickCount )
1517 /* Wake time has overflowed. Place this item in the overflow list. */
1518 vListInsert( ( xList * ) pxOverflowDelayedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
1522 /* The wake time has not overflowed, so we can use the current block list. */
1523 vListInsert( ( xList * ) pxDelayedTaskList, ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
1528 /*-----------------------------------------------------------*/
1530 signed portBASE_TYPE xTaskRemoveFromEventList( const xList *pxEventList )
1532 tskTCB *pxUnblockedTCB;
1533 portBASE_TYPE xReturn;
1535 /* THIS FUNCTION MUST BE CALLED WITH INTERRUPTS DISABLED OR THE
1536 SCHEDULER SUSPENDED. It can also be called from within an ISR. */
1538 /* The event list is sorted in priority order, so we can remove the
1539 first in the list, remove the TCB from the delayed list, and add
1540 it to the ready list.
1542 If an event is for a queue that is locked then this function will never
1543 get called - the lock count on the queue will get modified instead. This
1544 means we can always expect exclusive access to the event list here. */
1545 pxUnblockedTCB = ( tskTCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxEventList );
1546 vListRemove( &( pxUnblockedTCB->xEventListItem ) );
1548 if( uxSchedulerSuspended == ( unsigned portBASE_TYPE ) pdFALSE )
1550 vListRemove( &( pxUnblockedTCB->xGenericListItem ) );
1551 prvAddTaskToReadyQueue( pxUnblockedTCB );
1555 /* We cannot access the delayed or ready lists, so will hold this
1556 task pending until the scheduler is resumed. */
1557 vListInsertEnd( ( xList * ) &( xPendingReadyList ), &( pxUnblockedTCB->xEventListItem ) );
1560 if( pxUnblockedTCB->uxPriority >= pxCurrentTCB->uxPriority )
1562 /* Return true if the task removed from the event list has
1563 a higher priority than the calling task. This allows
1564 the calling task to know if it should force a context
1575 /*-----------------------------------------------------------*/
1577 void vTaskSetTimeOutState( xTimeOutType *pxTimeOut )
1579 pxTimeOut->xOverflowCount = xNumOfOverflows;
1580 pxTimeOut->xTimeOnEntering = xTickCount;
1582 /*-----------------------------------------------------------*/
1584 portBASE_TYPE xTaskCheckForTimeOut( xTimeOutType *pxTimeOut, portTickType * const pxTicksToWait )
1586 portBASE_TYPE xReturn;
1588 #if ( INCLUDE_vTaskSuspend == 1 )
1589 /* If INCLUDE_vTaskSuspend is set to 1 and the block time specified is
1590 the maximum block time then the task should block indefinitely, and
1591 therefore never time out. */
1592 if( *pxTicksToWait == portMAX_DELAY )
1596 else /* We are not blocking indefinitely, perform the checks below. */
1599 if( ( xNumOfOverflows != pxTimeOut->xOverflowCount ) && ( xTickCount >= pxTimeOut->xTimeOnEntering ) )
1601 /* The tick count is greater than the time at which vTaskSetTimeout()
1602 was called, but has also overflowed since vTaskSetTimeOut() was called.
1603 It must have wrapped all the way around and gone past us again. This
1604 passed since vTaskSetTimeout() was called. */
1607 else if( ( xTickCount - pxTimeOut->xTimeOnEntering ) < *pxTicksToWait )
1609 /* Not a genuine timeout. Adjust parameters for time remaining. */
1610 *pxTicksToWait -= ( xTickCount - pxTimeOut->xTimeOnEntering );
1611 vTaskSetTimeOutState( pxTimeOut );
1621 /*-----------------------------------------------------------*/
1623 void vTaskMissedYield( void )
1625 xMissedYield = pdTRUE;
1629 * -----------------------------------------------------------
1631 * ----------------------------------------------------------
1633 * The portTASK_FUNCTION() macro is used to allow port/compiler specific
1634 * language extensions. The equivalent prototype for this function is:
1636 * void prvIdleTask( void *pvParameters );
1639 static portTASK_FUNCTION( prvIdleTask, pvParameters )
1641 /* Stop warnings. */
1642 ( void ) pvParameters;
1646 /* See if any tasks have been deleted. */
1647 prvCheckTasksWaitingTermination();
1649 #if ( configUSE_PREEMPTION == 0 )
1651 /* If we are not using preemption we keep forcing a task switch to
1652 see if any other task has become available. If we are using
1653 preemption we don't need to do this as any task becoming available
1654 will automatically get the processor anyway. */
1659 #if ( ( configUSE_PREEMPTION == 1 ) && ( configIDLE_SHOULD_YIELD == 1 ) )
1661 /* When using preemption tasks of equal priority will be
1662 timesliced. If a task that is sharing the idle priority is ready
1663 to run then the idle task should yield before the end of the
1666 A critical region is not required here as we are just reading from
1667 the list, and an occasional incorrect value will not matter. If
1668 the ready list at the idle priority contains more than one task
1669 then a task other than the idle task is ready to execute. */
1670 if( listCURRENT_LIST_LENGTH( &( pxReadyTasksLists[ tskIDLE_PRIORITY ] ) ) > ( unsigned portBASE_TYPE ) 1 )
1677 #if ( configUSE_IDLE_HOOK == 1 )
1679 extern void vApplicationIdleHook( void );
1681 /* Call the user defined function from within the idle task. This
1682 allows the application designer to add background functionality
1683 without the overhead of a separate task.
1684 NOTE: vApplicationIdleHook() MUST NOT, UNDER ANY CIRCUMSTANCES,
1685 CALL A FUNCTION THAT MIGHT BLOCK. */
1686 vApplicationIdleHook();
1690 } /*lint !e715 pvParameters is not accessed but all task functions require the same prototype. */
1698 /*-----------------------------------------------------------
1699 * File private functions documented at the top of the file.
1700 *----------------------------------------------------------*/
1704 static void prvInitialiseTCBVariables( tskTCB *pxTCB, unsigned portSHORT usStackDepth, const signed portCHAR * const pcName, unsigned portBASE_TYPE uxPriority )
1706 pxTCB->usStackDepth = usStackDepth;
1708 /* Store the function name in the TCB. */
1709 strncpy( ( char * ) pxTCB->pcTaskName, ( const char * ) pcName, ( unsigned portSHORT ) configMAX_TASK_NAME_LEN );
1710 pxTCB->pcTaskName[ ( unsigned portSHORT ) configMAX_TASK_NAME_LEN - ( unsigned portSHORT ) 1 ] = '\0';
1712 /* This is used as an array index so must ensure it's not too large. */
1713 if( uxPriority >= configMAX_PRIORITIES )
1715 uxPriority = configMAX_PRIORITIES - 1;
1718 pxTCB->uxPriority = uxPriority;
1720 vListInitialiseItem( &( pxTCB->xGenericListItem ) );
1721 vListInitialiseItem( &( pxTCB->xEventListItem ) );
1723 /* Set the pxTCB as a link back from the xListItem. This is so we can get
1724 back to the containing TCB from a generic item in a list. */
1725 listSET_LIST_ITEM_OWNER( &( pxTCB->xGenericListItem ), pxTCB );
1727 /* Event lists are always in priority order. */
1728 listSET_LIST_ITEM_VALUE( &( pxTCB->xEventListItem ), configMAX_PRIORITIES - ( portTickType ) uxPriority );
1729 listSET_LIST_ITEM_OWNER( &( pxTCB->xEventListItem ), pxTCB );
1731 /*-----------------------------------------------------------*/
1733 static void prvInitialiseTaskLists( void )
1735 unsigned portBASE_TYPE uxPriority;
1737 for( uxPriority = 0; uxPriority < configMAX_PRIORITIES; uxPriority++ )
1739 vListInitialise( ( xList * ) &( pxReadyTasksLists[ uxPriority ] ) );
1742 vListInitialise( ( xList * ) &xDelayedTaskList1 );
1743 vListInitialise( ( xList * ) &xDelayedTaskList2 );
1744 vListInitialise( ( xList * ) &xPendingReadyList );
1746 #if ( INCLUDE_vTaskDelete == 1 )
1748 vListInitialise( ( xList * ) &xTasksWaitingTermination );
1752 #if ( INCLUDE_vTaskSuspend == 1 )
1754 vListInitialise( ( xList * ) &xSuspendedTaskList );
1758 /* Start with pxDelayedTaskList using list1 and the pxOverflowDelayedTaskList
1760 pxDelayedTaskList = &xDelayedTaskList1;
1761 pxOverflowDelayedTaskList = &xDelayedTaskList2;
1763 /*-----------------------------------------------------------*/
1765 static void prvCheckTasksWaitingTermination( void )
1767 #if ( INCLUDE_vTaskDelete == 1 )
1769 portBASE_TYPE xListIsEmpty;
1771 /* ucTasksDeleted is used to prevent vTaskSuspendAll() being called
1772 too often in the idle task. */
1773 if( uxTasksDeleted > ( unsigned portBASE_TYPE ) 0 )
1776 xListIsEmpty = listLIST_IS_EMPTY( &xTasksWaitingTermination );
1783 portENTER_CRITICAL();
1785 pxTCB = ( tskTCB * ) listGET_OWNER_OF_HEAD_ENTRY( ( ( xList * ) &xTasksWaitingTermination ) );
1786 vListRemove( &( pxTCB->xGenericListItem ) );
1787 --uxCurrentNumberOfTasks;
1790 portEXIT_CRITICAL();
1792 prvDeleteTCB( pxTCB );
1798 /*-----------------------------------------------------------*/
1800 static tskTCB *prvAllocateTCBAndStack( unsigned portSHORT usStackDepth )
1804 /* Allocate space for the TCB. Where the memory comes from depends on
1805 the implementation of the port malloc function. */
1806 pxNewTCB = ( tskTCB * ) pvPortMalloc( sizeof( tskTCB ) );
1808 if( pxNewTCB != NULL )
1810 /* Allocate space for the stack used by the task being created.
1811 The base of the stack memory stored in the TCB so the task can
1812 be deleted later if required. */
1813 pxNewTCB->pxStack = ( portSTACK_TYPE * ) pvPortMalloc( ( ( size_t )usStackDepth ) * sizeof( portSTACK_TYPE ) );
1815 if( pxNewTCB->pxStack == NULL )
1817 /* Could not allocate the stack. Delete the allocated TCB. */
1818 vPortFree( pxNewTCB );
1823 /* Just to help debugging. */
1824 memset( pxNewTCB->pxStack, tskSTACK_FILL_BYTE, usStackDepth * sizeof( portSTACK_TYPE ) );
1830 /*-----------------------------------------------------------*/
1832 #if ( configUSE_TRACE_FACILITY == 1 )
1834 static void prvListTaskWithinSingleList( signed portCHAR *pcWriteBuffer, xList *pxList, signed portCHAR cStatus )
1836 volatile tskTCB *pxNextTCB, *pxFirstTCB;
1837 static portCHAR pcStatusString[ 50 ];
1838 unsigned portSHORT usStackRemaining;
1840 /* Write the details of all the TCB's in pxList into the buffer. */
1841 listGET_OWNER_OF_NEXT_ENTRY( pxFirstTCB, pxList );
1844 listGET_OWNER_OF_NEXT_ENTRY( pxNextTCB, pxList );
1845 usStackRemaining = usTaskCheckFreeStackSpace( ( unsigned portCHAR * ) pxNextTCB->pxStack );
1846 sprintf( pcStatusString, ( portCHAR * ) "%s\t\t%c\t%u\t%u\t%u\r\n", pxNextTCB->pcTaskName, cStatus, ( unsigned int ) pxNextTCB->uxPriority, usStackRemaining, ( unsigned int ) pxNextTCB->uxTCBNumber );
1847 strcat( ( portCHAR * ) pcWriteBuffer, ( portCHAR * ) pcStatusString );
1849 } while( pxNextTCB != pxFirstTCB );
1853 /*-----------------------------------------------------------*/
1855 #if ( configUSE_TRACE_FACILITY == 1 )
1856 unsigned portSHORT usTaskCheckFreeStackSpace( const unsigned portCHAR *pucStackByte )
1858 register unsigned portSHORT usCount = 0;
1860 while( *pucStackByte == tskSTACK_FILL_BYTE )
1862 pucStackByte -= portSTACK_GROWTH;
1866 usCount /= sizeof( portSTACK_TYPE );
1871 /*-----------------------------------------------------------*/
1875 #if ( ( INCLUDE_vTaskDelete == 1 ) || ( INCLUDE_vTaskCleanUpResources == 1 ) )
1877 static void prvDeleteTCB( tskTCB *pxTCB )
1879 /* Free up the memory allocated by the scheduler for the task. It is up to
1880 the task to free any memory allocated at the application level. */
1881 vPortFree( pxTCB->pxStack );
1888 /*-----------------------------------------------------------*/
1890 #if ( INCLUDE_xTaskGetCurrentTaskHandle == 1 )
1892 xTaskHandle xTaskGetCurrentTaskHandle( void )
1894 xTaskHandle xReturn;
1896 portENTER_CRITICAL();
1898 xReturn = ( xTaskHandle ) pxCurrentTCB;
1900 portEXIT_CRITICAL();
1907 /*-----------------------------------------------------------*/
1909 #if ( INCLUDE_xTaskGetSchedulerState == 1 )
1911 portBASE_TYPE xTaskGetSchedulerState( void )
1913 portBASE_TYPE xReturn;
1915 if( xSchedulerRunning == pdFALSE )
1917 xReturn = taskSCHEDULER_NOT_STARTED;
1921 if( uxSchedulerSuspended == ( unsigned portBASE_TYPE ) pdFALSE )
1923 xReturn = taskSCHEDULER_RUNNING;
1927 xReturn = taskSCHEDULER_SUSPENDED;