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tasks.c
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tasks.c
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/*
FreeRTOS V7.1.0 - Copyright (C) 2011 Real Time Engineers Ltd.
***************************************************************************
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
***************************************************************************
This file is part of the FreeRTOS distribution.
FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
>>>NOTE<<< The modification to the GPL is included to allow you to
distribute a combined work that includes FreeRTOS without being obliged to
provide the source code for proprietary components outside of the FreeRTOS
kernel. FreeRTOS is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details. You should have received a copy of the GNU General Public
License and the FreeRTOS license exception along with FreeRTOS; if not it
can be viewed here: http://www.freertos.org/a00114.html and also obtained
by writing to Richard Barry, contact details for whom are available on the
FreeRTOS WEB site.
1 tab == 4 spaces!
http://www.FreeRTOS.org - Documentation, latest information, license and
contact details.
http://www.SafeRTOS.com - A version that is certified for use in safety
critical systems.
http://www.OpenRTOS.com - Commercial support, development, porting,
licensing and training services.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
all the API functions to use the MPU wrappers. That should only be done when
task.h is included from an application file. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
#include "FreeRTOS.h"
#include "task.h"
#include "timers.h"
#include "StackMacros.h"
#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE
/*
* Macro to define the amount of stack available to the idle task.
*/
#define tskIDLE_STACK_SIZE configMINIMAL_STACK_SIZE
/*
* Task control block. A task control block (TCB) is allocated to each task,
* and stores the context of the task.
*/
typedef struct tskTaskControlBlock
{
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. */
#if ( portUSING_MPU_WRAPPERS == 1 )
xMPU_SETTINGS xMPUSettings; /*< The MPU settings are defined as part of the port layer. THIS MUST BE THE SECOND MEMBER OF THE STRUCT. */
#endif
xListItem xGenericListItem; /*< List item used to place the TCB in ready and blocked queues. */
xListItem xEventListItem; /*< List item used to place the TCB in event lists. */
unsigned portBASE_TYPE uxPriority; /*< The priority of the task where 0 is the lowest priority. */
portSTACK_TYPE *pxStack; /*< Points to the start of the stack. */
signed char pcTaskName[ configMAX_TASK_NAME_LEN ];/*< Descriptive name given to the task when created. Facilitates debugging only. */
#if ( portSTACK_GROWTH > 0 )
portSTACK_TYPE *pxEndOfStack; /*< Used for stack overflow checking on architectures where the stack grows up from low memory. */
#endif
#if ( portCRITICAL_NESTING_IN_TCB == 1 )
unsigned portBASE_TYPE uxCriticalNesting;
#endif
#if ( configUSE_TRACE_FACILITY == 1 )
unsigned portBASE_TYPE uxTCBNumber; /*< This stores a number that increments each time a TCB is created. It allows debuggers to determine when a task has been deleted and then recreated. */
unsigned portBASE_TYPE uxTaskNumber; /*< This stores a number specifically for use by third party trace code. */
#endif
#if ( configUSE_MUTEXES == 1 )
unsigned portBASE_TYPE uxBasePriority; /*< The priority last assigned to the task - used by the priority inheritance mechanism. */
#endif
#if ( configUSE_APPLICATION_TASK_TAG == 1 )
pdTASK_HOOK_CODE pxTaskTag;
#endif
#if ( configGENERATE_RUN_TIME_STATS == 1 )
unsigned long ulRunTimeCounter; /*< Used for calculating how much CPU time each task is utilising. */
#endif
} tskTCB;
/*
* Some kernel aware debuggers require data to be viewed to be global, rather
* than file scope.
*/
#ifdef portREMOVE_STATIC_QUALIFIER
#define static
#endif
/*lint -e956 */
PRIVILEGED_DATA tskTCB * volatile pxCurrentTCB = NULL;
/* Lists for ready and blocked tasks. --------------------*/
PRIVILEGED_DATA static xList pxReadyTasksLists[ configMAX_PRIORITIES ]; /*< Prioritised ready tasks. */
PRIVILEGED_DATA static xList xDelayedTaskList1; /*< Delayed tasks. */
PRIVILEGED_DATA static xList xDelayedTaskList2; /*< Delayed tasks (two lists are used - one for delays that have overflowed the current tick count. */
PRIVILEGED_DATA static xList * volatile pxDelayedTaskList ; /*< Points to the delayed task list currently being used. */
PRIVILEGED_DATA static xList * volatile pxOverflowDelayedTaskList; /*< Points to the delayed task list currently being used to hold tasks that have overflowed the current tick count. */
PRIVILEGED_DATA 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. */
#if ( INCLUDE_vTaskDelete == 1 )
PRIVILEGED_DATA static xList xTasksWaitingTermination; /*< Tasks that have been deleted - but the their memory not yet freed. */
PRIVILEGED_DATA static volatile unsigned portBASE_TYPE uxTasksDeleted = ( unsigned portBASE_TYPE ) 0U;
#endif
#if ( INCLUDE_vTaskSuspend == 1 )
PRIVILEGED_DATA static xList xSuspendedTaskList; /*< Tasks that are currently suspended. */
#endif
#if ( INCLUDE_xTaskGetIdleTaskHandle == 1 )
PRIVILEGED_DATA static xTaskHandle xIdleTaskHandle = NULL;
#endif
/* File private variables. --------------------------------*/
PRIVILEGED_DATA static volatile unsigned portBASE_TYPE uxCurrentNumberOfTasks = ( unsigned portBASE_TYPE ) 0U;
PRIVILEGED_DATA static volatile portTickType xTickCount = ( portTickType ) 0U;
PRIVILEGED_DATA static unsigned portBASE_TYPE uxTopUsedPriority = tskIDLE_PRIORITY;
PRIVILEGED_DATA static volatile unsigned portBASE_TYPE uxTopReadyPriority = tskIDLE_PRIORITY;
PRIVILEGED_DATA static volatile signed portBASE_TYPE xSchedulerRunning = pdFALSE;
PRIVILEGED_DATA static volatile unsigned portBASE_TYPE uxSchedulerSuspended = ( unsigned portBASE_TYPE ) pdFALSE;
PRIVILEGED_DATA static volatile unsigned portBASE_TYPE uxMissedTicks = ( unsigned portBASE_TYPE ) 0U;
PRIVILEGED_DATA static volatile portBASE_TYPE xMissedYield = ( portBASE_TYPE ) pdFALSE;
PRIVILEGED_DATA static volatile portBASE_TYPE xNumOfOverflows = ( portBASE_TYPE ) 0;
PRIVILEGED_DATA static unsigned portBASE_TYPE uxTCBNumber = ( unsigned portBASE_TYPE ) 0U;
PRIVILEGED_DATA static portTickType xNextTaskUnblockTime = ( portTickType ) portMAX_DELAY;
#if ( configGENERATE_RUN_TIME_STATS == 1 )
PRIVILEGED_DATA static char pcStatsString[ 50 ] ;
PRIVILEGED_DATA static unsigned long ulTaskSwitchedInTime = 0UL; /*< Holds the value of a timer/counter the last time a task was switched in. */
static void prvGenerateRunTimeStatsForTasksInList( const signed char *pcWriteBuffer, xList *pxList, unsigned long ulTotalRunTime ) PRIVILEGED_FUNCTION;
#endif
/* Debugging and trace facilities private variables and macros. ------------*/
/*
* The value used to fill the stack of a task when the task is created. This
* is used purely for checking the high water mark for tasks.
*/
#define tskSTACK_FILL_BYTE ( 0xa5U )
/*
* Macros used by vListTask to indicate which state a task is in.
*/
#define tskBLOCKED_CHAR ( ( signed char ) 'B' )
#define tskREADY_CHAR ( ( signed char ) 'R' )
#define tskDELETED_CHAR ( ( signed char ) 'D' )
#define tskSUSPENDED_CHAR ( ( signed char ) 'S' )
/*-----------------------------------------------------------*/
/*
* Place the task represented by pxTCB into the appropriate ready queue for
* the task. It is inserted at the end of the list. One quirk of this is
* that if the task being inserted is at the same priority as the currently
* executing task, then it will only be rescheduled after the currently
* executing task has been rescheduled.
*/
#define prvAddTaskToReadyQueue( pxTCB ) \
if( ( pxTCB )->uxPriority > uxTopReadyPriority ) \
{ \
uxTopReadyPriority = ( pxTCB )->uxPriority; \
} \
vListInsertEnd( ( xList * ) &( pxReadyTasksLists[ ( pxTCB )->uxPriority ] ), &( ( pxTCB )->xGenericListItem ) )
/*-----------------------------------------------------------*/
/*
* Macro that looks at the list of tasks that are currently delayed to see if
* any require waking.
*
* Tasks are stored in the queue in the order of their wake time - meaning
* once one tasks has been found whose timer has not expired we need not look
* any further down the list.
*/
#define prvCheckDelayedTasks() \
{ \
portTickType xItemValue; \
\
/* Is the tick count greater than or equal to the wake time of the first \
task referenced from the delayed tasks list? */ \
if( xTickCount >= xNextTaskUnblockTime ) \
{ \
for( ;; ) \
{ \
if( listLIST_IS_EMPTY( pxDelayedTaskList ) != pdFALSE ) \
{ \
/* The delayed list is empty. Set xNextTaskUnblockTime to the \
maximum possible value so it is extremely unlikely that the \
if( xTickCount >= xNextTaskUnblockTime ) test will pass next \
time through. */ \
xNextTaskUnblockTime = portMAX_DELAY; \
break; \
} \
else \
{ \
/* The delayed list is not empty, get the value of the item at \
the head of the delayed list. This is the time at which the \
task at the head of the delayed list should be removed from \
the Blocked state. */ \
pxTCB = ( tskTCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxDelayedTaskList ); \
xItemValue = listGET_LIST_ITEM_VALUE( &( pxTCB->xGenericListItem ) ); \
\
if( xTickCount < xItemValue ) \
{ \
/* It is not time to unblock this item yet, but the item \
value is the time at which the task at the head of the \
blocked list should be removed from the Blocked state - \
so record the item value in xNextTaskUnblockTime. */ \
xNextTaskUnblockTime = xItemValue; \
break; \
} \
\
/* It is time to remove the item from the Blocked state. */ \
vListRemove( &( pxTCB->xGenericListItem ) ); \
\
/* Is the task waiting on an event also? */ \
if( pxTCB->xEventListItem.pvContainer != NULL ) \
{ \
vListRemove( &( pxTCB->xEventListItem ) ); \
} \
prvAddTaskToReadyQueue( pxTCB ); \
} \
} \
} \
}
/*-----------------------------------------------------------*/
/*
* Several functions take an xTaskHandle parameter that can optionally be NULL,
* where NULL is used to indicate that the handle of the currently executing
* task should be used in place of the parameter. This macro simply checks to
* see if the parameter is NULL and returns a pointer to the appropriate TCB.
*/
#define prvGetTCBFromHandle( pxHandle ) ( ( ( pxHandle ) == NULL ) ? ( tskTCB * ) pxCurrentTCB : ( tskTCB * ) ( pxHandle ) )
/* Callback function prototypes. --------------------------*/
extern void vApplicationStackOverflowHook( xTaskHandle *pxTask, signed char *pcTaskName );
extern void vApplicationTickHook( void );
/* File private functions. --------------------------------*/
/*
* Utility to ready a TCB for a given task. Mainly just copies the parameters
* into the TCB structure.
*/
static void prvInitialiseTCBVariables( tskTCB *pxTCB, const signed char * const pcName, unsigned portBASE_TYPE uxPriority, const xMemoryRegion * const xRegions, unsigned short usStackDepth ) PRIVILEGED_FUNCTION;
/*
* Utility to ready all the lists used by the scheduler. This is called
* automatically upon the creation of the first task.
*/
static void prvInitialiseTaskLists( void ) PRIVILEGED_FUNCTION;
/*
* The idle task, which as all tasks is implemented as a never ending loop.
* The idle task is automatically created and added to the ready lists upon
* creation of the first user task.
*
* The portTASK_FUNCTION_PROTO() macro is used to allow port/compiler specific
* language extensions. The equivalent prototype for this function is:
*
* void prvIdleTask( void *pvParameters );
*
*/
static portTASK_FUNCTION_PROTO( prvIdleTask, pvParameters );
/*
* Utility to free all memory allocated by the scheduler to hold a TCB,
* including the stack pointed to by the TCB.
*
* This does not free memory allocated by the task itself (i.e. memory
* allocated by calls to pvPortMalloc from within the tasks application code).
*/
#if ( INCLUDE_vTaskDelete == 1 )
static void prvDeleteTCB( tskTCB *pxTCB ) PRIVILEGED_FUNCTION;
#endif
/*
* Used only by the idle task. This checks to see if anything has been placed
* in the list of tasks waiting to be deleted. If so the task is cleaned up
* and its TCB deleted.
*/
static void prvCheckTasksWaitingTermination( void ) PRIVILEGED_FUNCTION;
/*
* The currently executing task is entering the Blocked state. Add the task to
* either the current or the overflow delayed task list.
*/
static void prvAddCurrentTaskToDelayedList( portTickType xTimeToWake ) PRIVILEGED_FUNCTION;
/*
* Allocates memory from the heap for a TCB and associated stack. Checks the
* allocation was successful.
*/
static tskTCB *prvAllocateTCBAndStack( unsigned short usStackDepth, portSTACK_TYPE *puxStackBuffer ) PRIVILEGED_FUNCTION;
/*
* Called from vTaskList. vListTasks details all the tasks currently under
* control of the scheduler. The tasks may be in one of a number of lists.
* prvListTaskWithinSingleList accepts a list and details the tasks from
* within just that list.
*
* THIS FUNCTION IS INTENDED FOR DEBUGGING ONLY, AND SHOULD NOT BE CALLED FROM
* NORMAL APPLICATION CODE.
*/
#if ( configUSE_TRACE_FACILITY == 1 )
static void prvListTaskWithinSingleList( const signed char *pcWriteBuffer, xList *pxList, signed char cStatus ) PRIVILEGED_FUNCTION;
#endif
/*
* When a task is created, the stack of the task is filled with a known value.
* This function determines the 'high water mark' of the task stack by
* determining how much of the stack remains at the original preset value.
*/
#if ( ( configUSE_TRACE_FACILITY == 1 ) || ( INCLUDE_uxTaskGetStackHighWaterMark == 1 ) )
static unsigned short usTaskCheckFreeStackSpace( const unsigned char * pucStackByte ) PRIVILEGED_FUNCTION;
#endif
/*lint +e956 */
/*-----------------------------------------------------------
* TASK CREATION API documented in task.h
*----------------------------------------------------------*/
signed portBASE_TYPE xTaskGenericCreate( pdTASK_CODE pxTaskCode, const signed char * const pcName, unsigned short usStackDepth, void *pvParameters, unsigned portBASE_TYPE uxPriority, xTaskHandle *pxCreatedTask, portSTACK_TYPE *puxStackBuffer, const xMemoryRegion * const xRegions )
{
signed portBASE_TYPE xReturn;
tskTCB * pxNewTCB;
configASSERT( pxTaskCode );
configASSERT( ( uxPriority < configMAX_PRIORITIES ) );
/* Allocate the memory required by the TCB and stack for the new task,
checking that the allocation was successful. */
pxNewTCB = prvAllocateTCBAndStack( usStackDepth, puxStackBuffer );
if( pxNewTCB != NULL )
{
portSTACK_TYPE *pxTopOfStack;
#if( portUSING_MPU_WRAPPERS == 1 )
/* Should the task be created in privileged mode? */
portBASE_TYPE xRunPrivileged;
if( ( uxPriority & portPRIVILEGE_BIT ) != 0U )
{
xRunPrivileged = pdTRUE;
}
else
{
xRunPrivileged = pdFALSE;
}
uxPriority &= ~portPRIVILEGE_BIT;
#endif /* portUSING_MPU_WRAPPERS == 1 */
/* Calculate the top of stack address. This depends on whether the
stack grows from high memory to low (as per the 80x86) or visa versa.
portSTACK_GROWTH is used to make the result positive or negative as
required by the port. */
#if( portSTACK_GROWTH < 0 )
{
pxTopOfStack = pxNewTCB->pxStack + ( usStackDepth - ( unsigned short ) 1 );
pxTopOfStack = ( portSTACK_TYPE * ) ( ( ( portPOINTER_SIZE_TYPE ) pxTopOfStack ) & ( ( portPOINTER_SIZE_TYPE ) ~portBYTE_ALIGNMENT_MASK ) );
/* Check the alignment of the calculated top of stack is correct. */
configASSERT( ( ( ( unsigned long ) pxTopOfStack & ( unsigned long ) portBYTE_ALIGNMENT_MASK ) == 0UL ) );
}
#else
{
pxTopOfStack = pxNewTCB->pxStack;
/* Check the alignment of the stack buffer is correct. */
configASSERT( ( ( ( unsigned long ) pxNewTCB->pxStack & ( unsigned long ) portBYTE_ALIGNMENT_MASK ) == 0UL ) );
/* If we want to use stack checking on architectures that use
a positive stack growth direction then we also need to store the
other extreme of the stack space. */
pxNewTCB->pxEndOfStack = pxNewTCB->pxStack + ( usStackDepth - 1 );
}
#endif
/* Setup the newly allocated TCB with the initial state of the task. */
prvInitialiseTCBVariables( pxNewTCB, pcName, uxPriority, xRegions, usStackDepth );
/* Initialize the TCB stack to look as if the task was already running,
but had been interrupted by the scheduler. The return address is set
to the start of the task function. Once the stack has been initialised
the top of stack variable is updated. */
#if( portUSING_MPU_WRAPPERS == 1 )
{
pxNewTCB->pxTopOfStack = pxPortInitialiseStack( pxTopOfStack, pxTaskCode, pvParameters, xRunPrivileged );
}
#else
{
pxNewTCB->pxTopOfStack = pxPortInitialiseStack( pxTopOfStack, pxTaskCode, pvParameters );
}
#endif
/* Check the alignment of the initialised stack. */
portALIGNMENT_ASSERT_pxCurrentTCB( ( ( ( unsigned long ) pxNewTCB->pxTopOfStack & ( unsigned long ) portBYTE_ALIGNMENT_MASK ) == 0UL ) );
if( ( void * ) pxCreatedTask != NULL )
{
/* Pass the TCB out - in an anonymous way. The calling function/
task can use this as a handle to delete the task later if
required.*/
*pxCreatedTask = ( xTaskHandle ) pxNewTCB;
}
/* We are going to manipulate the task queues to add this task to a
ready list, so must make sure no interrupts occur. */
taskENTER_CRITICAL();
{
uxCurrentNumberOfTasks++;
if( pxCurrentTCB == NULL )
{
/* There are no other tasks, or all the other tasks are in
the suspended state - make this the current task. */
pxCurrentTCB = pxNewTCB;
if( uxCurrentNumberOfTasks == ( unsigned portBASE_TYPE ) 1 )
{
/* This is the first task to be created so do the preliminary
initialisation required. We will not recover if this call
fails, but we will report the failure. */
prvInitialiseTaskLists();
}
}
else
{
/* If the scheduler is not already running, make this task the
current task if it is the highest priority task to be created
so far. */
if( xSchedulerRunning == pdFALSE )
{
if( pxCurrentTCB->uxPriority <= uxPriority )
{
pxCurrentTCB = pxNewTCB;
}
}
}
/* Remember the top priority to make context switching faster. Use
the priority in pxNewTCB as this has been capped to a valid value. */
if( pxNewTCB->uxPriority > uxTopUsedPriority )
{
uxTopUsedPriority = pxNewTCB->uxPriority;
}
#if ( configUSE_TRACE_FACILITY == 1 )
{
/* Add a counter into the TCB for tracing only. */
pxNewTCB->uxTCBNumber = uxTCBNumber;
}
#endif
uxTCBNumber++;
prvAddTaskToReadyQueue( pxNewTCB );
xReturn = pdPASS;
traceTASK_CREATE( pxNewTCB );
}
taskEXIT_CRITICAL();
}
else
{
xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;
traceTASK_CREATE_FAILED();
}
if( xReturn == pdPASS )
{
if( xSchedulerRunning != pdFALSE )
{
/* If the created task is of a higher priority than the current task
then it should run now. */
if( pxCurrentTCB->uxPriority < uxPriority )
{
portYIELD_WITHIN_API();
}
}
}
return xReturn;
}
/*-----------------------------------------------------------*/
#if ( INCLUDE_vTaskDelete == 1 )
void vTaskDelete( xTaskHandle pxTaskToDelete )
{
tskTCB *pxTCB;
taskENTER_CRITICAL();
{
/* Ensure a yield is performed if the current task is being
deleted. */
if( pxTaskToDelete == pxCurrentTCB )
{
pxTaskToDelete = NULL;
}
/* If null is passed in here then we are deleting ourselves. */
pxTCB = prvGetTCBFromHandle( pxTaskToDelete );
/* Remove task from the ready list and place in the termination list.
This will stop the task from be scheduled. The idle task will check
the termination list and free up any memory allocated by the
scheduler for the TCB and stack. */
vListRemove( &( pxTCB->xGenericListItem ) );
/* Is the task waiting on an event also? */
if( pxTCB->xEventListItem.pvContainer != NULL )
{
vListRemove( &( pxTCB->xEventListItem ) );
}
vListInsertEnd( ( xList * ) &xTasksWaitingTermination, &( pxTCB->xGenericListItem ) );
/* Increment the ucTasksDeleted variable so the idle task knows
there is a task that has been deleted and that it should therefore
check the xTasksWaitingTermination list. */
++uxTasksDeleted;
/* Increment the uxTaskNumberVariable also so kernel aware debuggers
can detect that the task lists need re-generating. */
uxTCBNumber++;
traceTASK_DELETE( pxTCB );
}
taskEXIT_CRITICAL();
/* Force a reschedule if we have just deleted the current task. */
if( xSchedulerRunning != pdFALSE )
{
if( ( void * ) pxTaskToDelete == NULL )
{
portYIELD_WITHIN_API();
}
}
}
#endif
/*-----------------------------------------------------------
* TASK CONTROL API documented in task.h
*----------------------------------------------------------*/
#if ( INCLUDE_vTaskDelayUntil == 1 )
void vTaskDelayUntil( portTickType * const pxPreviousWakeTime, portTickType xTimeIncrement )
{
portTickType xTimeToWake;
portBASE_TYPE xAlreadyYielded, xShouldDelay = pdFALSE;
configASSERT( pxPreviousWakeTime );
configASSERT( ( xTimeIncrement > 0U ) );
vTaskSuspendAll();
{
/* Generate the tick time at which the task wants to wake. */
xTimeToWake = *pxPreviousWakeTime + xTimeIncrement;
if( xTickCount < *pxPreviousWakeTime )
{
/* The tick count has overflowed since this function was
lasted called. In this case the only time we should ever
actually delay is if the wake time has also overflowed,
and the wake time is greater than the tick time. When this
is the case it is as if neither time had overflowed. */
if( ( xTimeToWake < *pxPreviousWakeTime ) && ( xTimeToWake > xTickCount ) )
{
xShouldDelay = pdTRUE;
}
}
else
{
/* The tick time has not overflowed. In this case we will
delay if either the wake time has overflowed, and/or the
tick time is less than the wake time. */
if( ( xTimeToWake < *pxPreviousWakeTime ) || ( xTimeToWake > xTickCount ) )
{
xShouldDelay = pdTRUE;
}
}
/* Update the wake time ready for the next call. */
*pxPreviousWakeTime = xTimeToWake;
if( xShouldDelay != pdFALSE )
{
traceTASK_DELAY_UNTIL();
/* We must remove ourselves from the ready list before adding
ourselves to the blocked list as the same list item is used for
both lists. */
vListRemove( ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
prvAddCurrentTaskToDelayedList( xTimeToWake );
}
}
xAlreadyYielded = xTaskResumeAll();
/* Force a reschedule if xTaskResumeAll has not already done so, we may
have put ourselves to sleep. */
if( xAlreadyYielded == pdFALSE )
{
portYIELD_WITHIN_API();
}
}
#endif
/*-----------------------------------------------------------*/
#if ( INCLUDE_vTaskDelay == 1 )
void vTaskDelay( portTickType xTicksToDelay )
{
portTickType xTimeToWake;
signed portBASE_TYPE xAlreadyYielded = pdFALSE;
/* A delay time of zero just forces a reschedule. */
if( xTicksToDelay > ( portTickType ) 0U )
{
vTaskSuspendAll();
{
traceTASK_DELAY();
/* A task that is removed from the event list while the
scheduler is suspended will not get placed in the ready
list or removed from the blocked list until the scheduler
is resumed.
This task cannot be in an event list as it is the currently
executing task. */
/* Calculate the time to wake - this may overflow but this is
not a problem. */
xTimeToWake = xTickCount + xTicksToDelay;
/* We must remove ourselves from the ready list before adding
ourselves to the blocked list as the same list item is used for
both lists. */
vListRemove( ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) );
prvAddCurrentTaskToDelayedList( xTimeToWake );
}
xAlreadyYielded = xTaskResumeAll();
}
/* Force a reschedule if xTaskResumeAll has not already done so, we may
have put ourselves to sleep. */
if( xAlreadyYielded == pdFALSE )
{
portYIELD_WITHIN_API();
}
}
#endif
/*-----------------------------------------------------------*/
#if ( INCLUDE_uxTaskPriorityGet == 1 )
unsigned portBASE_TYPE uxTaskPriorityGet( xTaskHandle pxTask )
{
tskTCB *pxTCB;
unsigned portBASE_TYPE uxReturn;
taskENTER_CRITICAL();
{
/* If null is passed in here then we are changing the
priority of the calling function. */
pxTCB = prvGetTCBFromHandle( pxTask );
uxReturn = pxTCB->uxPriority;
}
taskEXIT_CRITICAL();
return uxReturn;
}
#endif
/*-----------------------------------------------------------*/
#if ( INCLUDE_vTaskPrioritySet == 1 )
void vTaskPrioritySet( xTaskHandle pxTask, unsigned portBASE_TYPE uxNewPriority )
{
tskTCB *pxTCB;
unsigned portBASE_TYPE uxCurrentPriority;
portBASE_TYPE xYieldRequired = pdFALSE;
configASSERT( ( uxNewPriority < configMAX_PRIORITIES ) );
/* Ensure the new priority is valid. */
if( uxNewPriority >= configMAX_PRIORITIES )
{
uxNewPriority = configMAX_PRIORITIES - ( unsigned portBASE_TYPE ) 1U;
}
taskENTER_CRITICAL();
{
if( pxTask == pxCurrentTCB )
{
pxTask = NULL;
}
/* If null is passed in here then we are changing the
priority of the calling function. */
pxTCB = prvGetTCBFromHandle( pxTask );
traceTASK_PRIORITY_SET( pxTCB, uxNewPriority );
#if ( configUSE_MUTEXES == 1 )
{
uxCurrentPriority = pxTCB->uxBasePriority;
}
#else
{
uxCurrentPriority = pxTCB->uxPriority;
}
#endif
if( uxCurrentPriority != uxNewPriority )
{
/* The priority change may have readied a task of higher
priority than the calling task. */
if( uxNewPriority > uxCurrentPriority )
{
if( pxTask != NULL )
{
/* The priority of another task is being raised. If we
were raising the priority of the currently running task
there would be no need to switch as it must have already
been the highest priority task. */
xYieldRequired = pdTRUE;
}
}
else if( pxTask == NULL )
{
/* Setting our own priority down means there may now be another
task of higher priority that is ready to execute. */
xYieldRequired = pdTRUE;
}
#if ( configUSE_MUTEXES == 1 )
{
/* Only change the priority being used if the task is not
currently using an inherited priority. */
if( pxTCB->uxBasePriority == pxTCB->uxPriority )
{
pxTCB->uxPriority = uxNewPriority;
}
/* The base priority gets set whatever. */
pxTCB->uxBasePriority = uxNewPriority;
}
#else
{
pxTCB->uxPriority = uxNewPriority;
}
#endif
listSET_LIST_ITEM_VALUE( &( pxTCB->xEventListItem ), ( configMAX_PRIORITIES - ( portTickType ) uxNewPriority ) );
/* If the task is in the blocked or suspended list we need do
nothing more than change it's priority variable. However, if
the task is in a ready list it needs to be removed and placed
in the queue appropriate to its new priority. */
if( listIS_CONTAINED_WITHIN( &( pxReadyTasksLists[ uxCurrentPriority ] ), &( pxTCB->xGenericListItem ) ) )
{
/* The task is currently in its ready list - remove before adding
it to it's new ready list. As we are in a critical section we
can do this even if the scheduler is suspended. */
vListRemove( &( pxTCB->xGenericListItem ) );
prvAddTaskToReadyQueue( pxTCB );
}
if( xYieldRequired == pdTRUE )
{
portYIELD_WITHIN_API();
}
}
}
taskEXIT_CRITICAL();
}
#endif
/*-----------------------------------------------------------*/
#if ( INCLUDE_vTaskSuspend == 1 )
void vTaskSuspend( xTaskHandle pxTaskToSuspend )
{
tskTCB *pxTCB;
taskENTER_CRITICAL();
{
/* Ensure a yield is performed if the current task is being
suspended. */
if( pxTaskToSuspend == pxCurrentTCB )
{
pxTaskToSuspend = NULL;
}
/* If null is passed in here then we are suspending ourselves. */
pxTCB = prvGetTCBFromHandle( pxTaskToSuspend );
traceTASK_SUSPEND( pxTCB );
/* Remove task from the ready/delayed list and place in the suspended list. */
vListRemove( &( pxTCB->xGenericListItem ) );
/* Is the task waiting on an event also? */
if( pxTCB->xEventListItem.pvContainer != NULL )
{
vListRemove( &( pxTCB->xEventListItem ) );
}
vListInsertEnd( ( xList * ) &xSuspendedTaskList, &( pxTCB->xGenericListItem ) );
}
taskEXIT_CRITICAL();
if( ( void * ) pxTaskToSuspend == NULL )
{
if( xSchedulerRunning != pdFALSE )
{
/* We have just suspended the current task. */
portYIELD_WITHIN_API();
}
else
{
/* The scheduler is not running, but the task that was pointed
to by pxCurrentTCB has just been suspended and pxCurrentTCB
must be adjusted to point to a different task. */
if( listCURRENT_LIST_LENGTH( &xSuspendedTaskList ) == uxCurrentNumberOfTasks )
{
/* No other tasks are ready, so set pxCurrentTCB back to
NULL so when the next task is created pxCurrentTCB will
be set to point to it no matter what its relative priority
is. */
pxCurrentTCB = NULL;
}
else
{
vTaskSwitchContext();
}
}
}
}
#endif
/*-----------------------------------------------------------*/
#if ( INCLUDE_vTaskSuspend == 1 )
signed portBASE_TYPE xTaskIsTaskSuspended( xTaskHandle xTask )
{
portBASE_TYPE xReturn = pdFALSE;
const tskTCB * const pxTCB = ( tskTCB * ) xTask;
/* It does not make sense to check if the calling task is suspended. */
configASSERT( xTask );
/* Is the task we are attempting to resume actually in the
suspended list? */
if( listIS_CONTAINED_WITHIN( &xSuspendedTaskList, &( pxTCB->xGenericListItem ) ) != pdFALSE )
{
/* Has the task already been resumed from within an ISR? */
if( listIS_CONTAINED_WITHIN( &xPendingReadyList, &( pxTCB->xEventListItem ) ) != pdTRUE )
{
/* Is it in the suspended list because it is in the
Suspended state? It is possible to be in the suspended
list because it is blocked on a task with no timeout
specified. */
if( listIS_CONTAINED_WITHIN( NULL, &( pxTCB->xEventListItem ) ) == pdTRUE )
{
xReturn = pdTRUE;
}
}
}
return xReturn;
}
#endif
/*-----------------------------------------------------------*/
#if ( INCLUDE_vTaskSuspend == 1 )
void vTaskResume( xTaskHandle pxTaskToResume )
{
tskTCB *pxTCB;
/* It does not make sense to resume the calling task. */
configASSERT( pxTaskToResume );
/* Remove the task from whichever list it is currently in, and place
it in the ready list. */
pxTCB = ( tskTCB * ) pxTaskToResume;
/* The parameter cannot be NULL as it is impossible to resume the
currently executing task. */
if( ( pxTCB != NULL ) && ( pxTCB != pxCurrentTCB ) )
{
taskENTER_CRITICAL();
{
if( xTaskIsTaskSuspended( pxTCB ) == pdTRUE )
{
traceTASK_RESUME( pxTCB );
/* As we are in a critical section we can access the ready
lists even if the scheduler is suspended. */
vListRemove( &( pxTCB->xGenericListItem ) );
prvAddTaskToReadyQueue( pxTCB );
/* We may have just resumed a higher priority task. */
if( pxTCB->uxPriority >= pxCurrentTCB->uxPriority )
{
/* This yield may not cause the task just resumed to run, but
will leave the lists in the correct state for the next yield. */
portYIELD_WITHIN_API();
}
}
}
taskEXIT_CRITICAL();
}
}
#endif
/*-----------------------------------------------------------*/
#if ( ( INCLUDE_xTaskResumeFromISR == 1 ) && ( INCLUDE_vTaskSuspend == 1 ) )
portBASE_TYPE xTaskResumeFromISR( xTaskHandle pxTaskToResume )
{
portBASE_TYPE xYieldRequired = pdFALSE;
tskTCB *pxTCB;
unsigned portBASE_TYPE uxSavedInterruptStatus;