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*/
#ifndef TASK_H
#define TASK_H
#ifndef INC_FREERTOS_H
#error "include FreeRTOS.h must appear in source files before include task.h"
#endif
#include "portable.h"
#include "list.h"
#ifdef __cplusplus
extern "C" {
#endif
/*-----------------------------------------------------------
* MACROS AND DEFINITIONS
*----------------------------------------------------------*/
#define tskKERNEL_VERSION_NUMBER "V7.4.1"
/**
* task. h
*
* Type by which tasks are referenced. For example, a call to xTaskCreate
* returns (via a pointer parameter) an xTaskHandle variable that can then
* be used as a parameter to vTaskDelete to delete the task.
*
* \page xTaskHandle xTaskHandle
* \ingroup Tasks
*/
typedef void * xTaskHandle;
/*
* Used internally only.
*/
typedef struct xTIME_OUT
{
portBASE_TYPE xOverflowCount;
portTickType xTimeOnEntering;
} xTimeOutType;
/*
* Defines the memory ranges allocated to the task when an MPU is used.
*/
typedef struct xMEMORY_REGION
{
void *pvBaseAddress;
unsigned long ulLengthInBytes;
unsigned long ulParameters;
} xMemoryRegion;
/*
* Parameters required to create an MPU protected task.
*/
typedef struct xTASK_PARAMTERS
{
pdTASK_CODE pvTaskCode;
const signed char * const pcName;
unsigned short usStackDepth;
void *pvParameters;
unsigned portBASE_TYPE uxPriority;
portSTACK_TYPE *puxStackBuffer;
xMemoryRegion xRegions[ portNUM_CONFIGURABLE_REGIONS ];
} xTaskParameters;
/* Task states returned by eTaskGetState. */
typedef enum
{
eRunning = 0, /* A task is querying the state of itself, so must be running. */
eReady, /* The task being queried is in a read or pending ready list. */
eBlocked, /* The task being queried is in the Blocked state. */
eSuspended, /* The task being queried is in the Suspended state, or is in the Blocked state with an infinite time out. */
eDeleted /* The task being queried has been deleted, but its TCB has not yet been freed. */
} eTaskState;
/* Possible return values for eTaskConfirmSleepModeStatus(). */
typedef enum
{
eAbortSleep = 0, /* A task has been made ready or a context switch pended since portSUPPORESS_TICKS_AND_SLEEP() was called - abort entering a sleep mode. */
eStandardSleep, /* Enter a sleep mode that will not last any longer than the expected idle time. */
eNoTasksWaitingTimeout /* No tasks are waiting for a timeout so it is safe to enter a sleep mode that can only be exited by an external interrupt. */
} eSleepModeStatus;
/*
* Defines the priority used by the idle task. This must not be modified.
*
* \ingroup TaskUtils
*/
#define tskIDLE_PRIORITY ( ( unsigned portBASE_TYPE ) 0U )
/**
* task. h
*
* Macro for forcing a context switch.
*
* \page taskYIELD taskYIELD
* \ingroup SchedulerControl
*/
#define taskYIELD() portYIELD()
/**
* task. h
*
* Macro to mark the start of a critical code region. Preemptive context
* switches cannot occur when in a critical region.
*
* NOTE: This may alter the stack (depending on the portable implementation)
* so must be used with care!
*
* \page taskENTER_CRITICAL taskENTER_CRITICAL
* \ingroup SchedulerControl
*/
#define taskENTER_CRITICAL() portENTER_CRITICAL()
/**
* task. h
*
* Macro to mark the end of a critical code region. Preemptive context
* switches cannot occur when in a critical region.
*
* NOTE: This may alter the stack (depending on the portable implementation)
* so must be used with care!
*
* \page taskEXIT_CRITICAL taskEXIT_CRITICAL
* \ingroup SchedulerControl
*/
#define taskEXIT_CRITICAL() portEXIT_CRITICAL()
/**
* task. h
*
* Macro to disable all maskable interrupts.
*
* \page taskDISABLE_INTERRUPTS taskDISABLE_INTERRUPTS
* \ingroup SchedulerControl
*/
#define taskDISABLE_INTERRUPTS() portDISABLE_INTERRUPTS()
/**
* task. h
*
* Macro to enable microcontroller interrupts.
*
* \page taskENABLE_INTERRUPTS taskENABLE_INTERRUPTS
* \ingroup SchedulerControl
*/
#define taskENABLE_INTERRUPTS() portENABLE_INTERRUPTS()
/* Definitions returned by xTaskGetSchedulerState(). */
#define taskSCHEDULER_NOT_STARTED 0
#define taskSCHEDULER_RUNNING 1
#define taskSCHEDULER_SUSPENDED 2
/*-----------------------------------------------------------
* TASK CREATION API
*----------------------------------------------------------*/
/**
* task. h
*<pre>
portBASE_TYPE xTaskCreate(
pdTASK_CODE pvTaskCode,
const char * const pcName,
unsigned short usStackDepth,
void *pvParameters,
unsigned portBASE_TYPE uxPriority,
xTaskHandle *pvCreatedTask
);</pre>
*
* Create a new task and add it to the list of tasks that are ready to run.
*
* xTaskCreate() can only be used to create a task that has unrestricted
* access to the entire microcontroller memory map. Systems that include MPU
* support can alternatively create an MPU constrained task using
* xTaskCreateRestricted().
*
* @param pvTaskCode Pointer to the task entry function. Tasks
* must be implemented to never return (i.e. continuous loop).
*
* @param pcName A descriptive name for the task. This is mainly used to
* facilitate debugging. Max length defined by tskMAX_TASK_NAME_LEN - default
* is 16.
*
* @param usStackDepth The size of the task stack specified as the number of
* variables the stack can hold - not the number of bytes. For example, if
* the stack is 16 bits wide and usStackDepth is defined as 100, 200 bytes
* will be allocated for stack storage.
*
* @param pvParameters Pointer that will be used as the parameter for the task
* being created.
*
* @param uxPriority The priority at which the task should run. Systems that
* include MPU support can optionally create tasks in a privileged (system)
* mode by setting bit portPRIVILEGE_BIT of the priority parameter. For
* example, to create a privileged task at priority 2 the uxPriority parameter
* should be set to ( 2 | portPRIVILEGE_BIT ).
*
* @param pvCreatedTask Used to pass back a handle by which the created task
* can be referenced.
*
* @return pdPASS if the task was successfully created and added to a ready
* list, otherwise an error code defined in the file errors. h
*
* Example usage:
<pre>
// Task to be created.
void vTaskCode( void * pvParameters )
{
for( ;; )
{
// Task code goes here.
}
}
// Function that creates a task.
void vOtherFunction( void )
{
static unsigned char ucParameterToPass;
xTaskHandle xHandle;
// Create the task, storing the handle. Note that the passed parameter ucParameterToPass
// must exist for the lifetime of the task, so in this case is declared static. If it was just an
// an automatic stack variable it might no longer exist, or at least have been corrupted, by the time
// the new task attempts to access it.
xTaskCreate( vTaskCode, "NAME", STACK_SIZE, &ucParameterToPass, tskIDLE_PRIORITY, &xHandle );
// Use the handle to delete the task.
vTaskDelete( xHandle );
}
</pre>
* \defgroup xTaskCreate xTaskCreate
* \ingroup Tasks
*/
#define xTaskCreate( pvTaskCode, pcName, usStackDepth, pvParameters, uxPriority, pxCreatedTask ) xTaskGenericCreate( ( pvTaskCode ), ( pcName ), ( usStackDepth ), ( pvParameters ), ( uxPriority ), ( pxCreatedTask ), ( NULL ), ( NULL ) )
/**
* task. h
*<pre>
portBASE_TYPE xTaskCreateRestricted( xTaskParameters *pxTaskDefinition, xTaskHandle *pxCreatedTask );</pre>
*
* xTaskCreateRestricted() should only be used in systems that include an MPU
* implementation.
*
* Create a new task and add it to the list of tasks that are ready to run.
* The function parameters define the memory regions and associated access
* permissions allocated to the task.
*
* @param pxTaskDefinition Pointer to a structure that contains a member
* for each of the normal xTaskCreate() parameters (see the xTaskCreate() API
* documentation) plus an optional stack buffer and the memory region
* definitions.
*
* @param pxCreatedTask Used to pass back a handle by which the created task
* can be referenced.
*
* @return pdPASS if the task was successfully created and added to a ready
* list, otherwise an error code defined in the file errors. h
*
* Example usage:
<pre>
// Create an xTaskParameters structure that defines the task to be created.
static const xTaskParameters xCheckTaskParameters =
{
vATask, // pvTaskCode - the function that implements the task.
"ATask", // pcName - just a text name for the task to assist debugging.
100, // usStackDepth - the stack size DEFINED IN WORDS.
NULL, // pvParameters - passed into the task function as the function parameters.
( 1UL | portPRIVILEGE_BIT ),// uxPriority - task priority, set the portPRIVILEGE_BIT if the task should run in a privileged state.
cStackBuffer,// puxStackBuffer - the buffer to be used as the task stack.
// xRegions - Allocate up to three separate memory regions for access by
// the task, with appropriate access permissions. Different processors have
// different memory alignment requirements - refer to the FreeRTOS documentation
// for full information.
{
// Base address Length Parameters
{ cReadWriteArray, 32, portMPU_REGION_READ_WRITE },
{ cReadOnlyArray, 32, portMPU_REGION_READ_ONLY },
{ cPrivilegedOnlyAccessArray, 128, portMPU_REGION_PRIVILEGED_READ_WRITE }
}
};
int main( void )
{
xTaskHandle xHandle;
// Create a task from the const structure defined above. The task handle
// is requested (the second parameter is not NULL) but in this case just for
// demonstration purposes as its not actually used.
xTaskCreateRestricted( &xRegTest1Parameters, &xHandle );
// Start the scheduler.
vTaskStartScheduler();
// Will only get here if there was insufficient memory to create the idle
// task.
for( ;; );
}
</pre>
* \defgroup xTaskCreateRestricted xTaskCreateRestricted
* \ingroup Tasks
*/
#define xTaskCreateRestricted( x, pxCreatedTask ) xTaskGenericCreate( ((x)->pvTaskCode), ((x)->pcName), ((x)->usStackDepth), ((x)->pvParameters), ((x)->uxPriority), (pxCreatedTask), ((x)->puxStackBuffer), ((x)->xRegions) )
/**
* task. h
*<pre>
void vTaskAllocateMPURegions( xTaskHandle xTask, const xMemoryRegion * const pxRegions );</pre>
*
* Memory regions are assigned to a restricted task when the task is created by
* a call to xTaskCreateRestricted(). These regions can be redefined using
* vTaskAllocateMPURegions().
*
* @param xTask The handle of the task being updated.
*
* @param xRegions A pointer to an xMemoryRegion structure that contains the
* new memory region definitions.
*
* Example usage:
<pre>
// Define an array of xMemoryRegion structures that configures an MPU region
// allowing read/write access for 1024 bytes starting at the beginning of the
// ucOneKByte array. The other two of the maximum 3 definable regions are
// unused so set to zero.
static const xMemoryRegion xAltRegions[ portNUM_CONFIGURABLE_REGIONS ] =
{
// Base address Length Parameters
{ ucOneKByte, 1024, portMPU_REGION_READ_WRITE },
{ 0, 0, 0 },
{ 0, 0, 0 }
};
void vATask( void *pvParameters )
{
// This task was created such that it has access to certain regions of
// memory as defined by the MPU configuration. At some point it is
// desired that these MPU regions are replaced with that defined in the
// xAltRegions const struct above. Use a call to vTaskAllocateMPURegions()
// for this purpose. NULL is used as the task handle to indicate that this
// function should modify the MPU regions of the calling task.
vTaskAllocateMPURegions( NULL, xAltRegions );
// Now the task can continue its function, but from this point on can only
// access its stack and the ucOneKByte array (unless any other statically
// defined or shared regions have been declared elsewhere).
}
</pre>
* \defgroup xTaskCreateRestricted xTaskCreateRestricted
* \ingroup Tasks
*/
void vTaskAllocateMPURegions( xTaskHandle xTask, const xMemoryRegion * const pxRegions ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>void vTaskDelete( xTaskHandle xTask );</pre>
*
* INCLUDE_vTaskDelete must be defined as 1 for this function to be available.
* See the configuration section for more information.
*
* Remove a task from the RTOS real time kernels management. The task being
* deleted will be removed from all ready, blocked, suspended and event lists.
*
* NOTE: The idle task is responsible for freeing the kernel allocated
* memory from tasks that have been deleted. It is therefore important that
* the idle task is not starved of microcontroller processing time if your
* application makes any calls to vTaskDelete (). Memory allocated by the
* task code is not automatically freed, and should be freed before the task
* is deleted.
*
* See the demo application file death.c for sample code that utilises
* vTaskDelete ().
*
* @param xTask The handle of the task to be deleted. Passing NULL will
* cause the calling task to be deleted.
*
* Example usage:
<pre>
void vOtherFunction( void )
{
xTaskHandle xHandle;
// Create the task, storing the handle.
xTaskCreate( vTaskCode, "NAME", STACK_SIZE, NULL, tskIDLE_PRIORITY, &xHandle );
// Use the handle to delete the task.
vTaskDelete( xHandle );
}
</pre>
* \defgroup vTaskDelete vTaskDelete
* \ingroup Tasks
*/
void vTaskDelete( xTaskHandle xTaskToDelete ) PRIVILEGED_FUNCTION;
/*-----------------------------------------------------------
* TASK CONTROL API
*----------------------------------------------------------*/
/**
* task. h
* <pre>void vTaskDelay( portTickType xTicksToDelay );</pre>
*
* Delay a task for a given number of ticks. The actual time that the
* task remains blocked depends on the tick rate. The constant
* portTICK_RATE_MS can be used to calculate real time from the tick
* rate - with the resolution of one tick period.
*
* INCLUDE_vTaskDelay must be defined as 1 for this function to be available.
* See the configuration section for more information.
*
*
* vTaskDelay() specifies a time at which the task wishes to unblock relative to
* the time at which vTaskDelay() is called. For example, specifying a block
* period of 100 ticks will cause the task to unblock 100 ticks after
* vTaskDelay() is called. vTaskDelay() does not therefore provide a good method
* of controlling the frequency of a cyclical task as the path taken through the
* code, as well as other task and interrupt activity, will effect the frequency
* at which vTaskDelay() gets called and therefore the time at which the task
* next executes. See vTaskDelayUntil() for an alternative API function designed
* to facilitate fixed frequency execution. It does this by specifying an
* absolute time (rather than a relative time) at which the calling task should
* unblock.
*
* @param xTicksToDelay The amount of time, in tick periods, that
* the calling task should block.
*
* Example usage:
void vTaskFunction( void * pvParameters )
{
void vTaskFunction( void * pvParameters )
{
// Block for 500ms.
const portTickType xDelay = 500 / portTICK_RATE_MS;
for( ;; )
{
// Simply toggle the LED every 500ms, blocking between each toggle.
vToggleLED();
vTaskDelay( xDelay );
}
}
* \defgroup vTaskDelay vTaskDelay
* \ingroup TaskCtrl
*/
void vTaskDelay( portTickType xTicksToDelay ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>void vTaskDelayUntil( portTickType *pxPreviousWakeTime, portTickType xTimeIncrement );</pre>
*
* INCLUDE_vTaskDelayUntil must be defined as 1 for this function to be available.
* See the configuration section for more information.
*
* Delay a task until a specified time. This function can be used by cyclical
* tasks to ensure a constant execution frequency.
*
* This function differs from vTaskDelay () in one important aspect: vTaskDelay () will
* cause a task to block for the specified number of ticks from the time vTaskDelay () is
* called. It is therefore difficult to use vTaskDelay () by itself to generate a fixed
* execution frequency as the time between a task starting to execute and that task
* calling vTaskDelay () may not be fixed [the task may take a different path though the
* code between calls, or may get interrupted or preempted a different number of times
* each time it executes].
*
* Whereas vTaskDelay () specifies a wake time relative to the time at which the function
* is called, vTaskDelayUntil () specifies the absolute (exact) time at which it wishes to
* unblock.
*
* The constant portTICK_RATE_MS can be used to calculate real time from the tick
* rate - with the resolution of one tick period.
*
* @param pxPreviousWakeTime Pointer to a variable that holds the time at which the
* task was last unblocked. The variable must be initialised with the current time
* prior to its first use (see the example below). Following this the variable is
* automatically updated within vTaskDelayUntil ().
*
* @param xTimeIncrement The cycle time period. The task will be unblocked at
* time *pxPreviousWakeTime + xTimeIncrement. Calling vTaskDelayUntil with the
* same xTimeIncrement parameter value will cause the task to execute with
* a fixed interface period.
*
* Example usage:
<pre>
// Perform an action every 10 ticks.
void vTaskFunction( void * pvParameters )
{
portTickType xLastWakeTime;
const portTickType xFrequency = 10;
// Initialise the xLastWakeTime variable with the current time.
xLastWakeTime = xTaskGetTickCount ();
for( ;; )
{
// Wait for the next cycle.
vTaskDelayUntil( &xLastWakeTime, xFrequency );
// Perform action here.
}
}
</pre>
* \defgroup vTaskDelayUntil vTaskDelayUntil
* \ingroup TaskCtrl
*/
void vTaskDelayUntil( portTickType * const pxPreviousWakeTime, portTickType xTimeIncrement ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>unsigned portBASE_TYPE uxTaskPriorityGet( xTaskHandle xTask );</pre>
*
* INCLUDE_xTaskPriorityGet must be defined as 1 for this function to be available.
* See the configuration section for more information.
*
* Obtain the priority of any task.
*
* @param xTask Handle of the task to be queried. Passing a NULL
* handle results in the priority of the calling task being returned.
*
* @return The priority of xTask.
*
* Example usage:
<pre>
void vAFunction( void )
{
xTaskHandle xHandle;
// Create a task, storing the handle.
xTaskCreate( vTaskCode, "NAME", STACK_SIZE, NULL, tskIDLE_PRIORITY, &xHandle );
// ...
// Use the handle to obtain the priority of the created task.
// It was created with tskIDLE_PRIORITY, but may have changed
// it itself.
if( uxTaskPriorityGet( xHandle ) != tskIDLE_PRIORITY )
{
// The task has changed it's priority.
}
// ...
// Is our priority higher than the created task?
if( uxTaskPriorityGet( xHandle ) < uxTaskPriorityGet( NULL ) )
{
// Our priority (obtained using NULL handle) is higher.
}
}
</pre>
* \defgroup uxTaskPriorityGet uxTaskPriorityGet
* \ingroup TaskCtrl
*/
unsigned portBASE_TYPE uxTaskPriorityGet( xTaskHandle xTask ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>eTaskState eTaskGetState( xTaskHandle xTask );</pre>
*
* INCLUDE_eTaskGetState must be defined as 1 for this function to be available.
* See the configuration section for more information.
*
* Obtain the state of any task. States are encoded by the eTaskState
* enumerated type.
*
* @param xTask Handle of the task to be queried.
*
* @return The state of xTask at the time the function was called. Note the
* state of the task might change between the function being called, and the
* functions return value being tested by the calling task.
*/
eTaskState eTaskGetState( xTaskHandle xTask ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>void vTaskPrioritySet( xTaskHandle xTask, unsigned portBASE_TYPE uxNewPriority );</pre>
*
* INCLUDE_vTaskPrioritySet must be defined as 1 for this function to be available.
* See the configuration section for more information.
*
* Set the priority of any task.
*
* A context switch will occur before the function returns if the priority
* being set is higher than the currently executing task.
*
* @param xTask Handle to the task for which the priority is being set.
* Passing a NULL handle results in the priority of the calling task being set.
*
* @param uxNewPriority The priority to which the task will be set.
*
* Example usage:
<pre>
void vAFunction( void )
{
xTaskHandle xHandle;
// Create a task, storing the handle.
xTaskCreate( vTaskCode, "NAME", STACK_SIZE, NULL, tskIDLE_PRIORITY, &xHandle );
// ...
// Use the handle to raise the priority of the created task.
vTaskPrioritySet( xHandle, tskIDLE_PRIORITY + 1 );
// ...
// Use a NULL handle to raise our priority to the same value.
vTaskPrioritySet( NULL, tskIDLE_PRIORITY + 1 );
}
</pre>
* \defgroup vTaskPrioritySet vTaskPrioritySet
* \ingroup TaskCtrl
*/
void vTaskPrioritySet( xTaskHandle xTask, unsigned portBASE_TYPE uxNewPriority ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>void vTaskSuspend( xTaskHandle xTaskToSuspend );</pre>
*
* INCLUDE_vTaskSuspend must be defined as 1 for this function to be available.
* See the configuration section for more information.
*
* Suspend any task. When suspended a task will never get any microcontroller
* processing time, no matter what its priority.
*
* Calls to vTaskSuspend are not accumulative -
* i.e. calling vTaskSuspend () twice on the same task still only requires one
* call to vTaskResume () to ready the suspended task.
*
* @param xTaskToSuspend Handle to the task being suspended. Passing a NULL
* handle will cause the calling task to be suspended.
*
* Example usage:
<pre>
void vAFunction( void )
{
xTaskHandle xHandle;
// Create a task, storing the handle.
xTaskCreate( vTaskCode, "NAME", STACK_SIZE, NULL, tskIDLE_PRIORITY, &xHandle );
// ...
// Use the handle to suspend the created task.
vTaskSuspend( xHandle );
// ...
// The created task will not run during this period, unless
// another task calls vTaskResume( xHandle ).
//...
// Suspend ourselves.
vTaskSuspend( NULL );
// We cannot get here unless another task calls vTaskResume
// with our handle as the parameter.
}
</pre>
* \defgroup vTaskSuspend vTaskSuspend
* \ingroup TaskCtrl
*/
void vTaskSuspend( xTaskHandle xTaskToSuspend ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>void vTaskResume( xTaskHandle xTaskToResume );</pre>
*
* INCLUDE_vTaskSuspend must be defined as 1 for this function to be available.
* See the configuration section for more information.
*
* Resumes a suspended task.
*
* A task that has been suspended by one of more calls to vTaskSuspend ()
* will be made available for running again by a single call to
* vTaskResume ().
*
* @param xTaskToResume Handle to the task being readied.
*
* Example usage:
<pre>
void vAFunction( void )
{
xTaskHandle xHandle;
// Create a task, storing the handle.
xTaskCreate( vTaskCode, "NAME", STACK_SIZE, NULL, tskIDLE_PRIORITY, &xHandle );
// ...
// Use the handle to suspend the created task.
vTaskSuspend( xHandle );
// ...
// The created task will not run during this period, unless
// another task calls vTaskResume( xHandle ).
//...
// Resume the suspended task ourselves.
vTaskResume( xHandle );
// The created task will once again get microcontroller processing
// time in accordance with it priority within the system.
}
</pre>
* \defgroup vTaskResume vTaskResume
* \ingroup TaskCtrl
*/
void vTaskResume( xTaskHandle xTaskToResume ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>void xTaskResumeFromISR( xTaskHandle xTaskToResume );</pre>
*
* INCLUDE_xTaskResumeFromISR must be defined as 1 for this function to be
* available. See the configuration section for more information.
*
* An implementation of vTaskResume() that can be called from within an ISR.
*
* A task that has been suspended by one of more calls to vTaskSuspend ()
* will be made available for running again by a single call to
* xTaskResumeFromISR ().
*
* @param xTaskToResume Handle to the task being readied.
*
* \defgroup vTaskResumeFromISR vTaskResumeFromISR
* \ingroup TaskCtrl
*/
portBASE_TYPE xTaskResumeFromISR( xTaskHandle xTaskToResume ) PRIVILEGED_FUNCTION;
/*-----------------------------------------------------------
* SCHEDULER CONTROL
*----------------------------------------------------------*/
/**
* task. h
* <pre>void vTaskStartScheduler( void );</pre>
*
* Starts the real time kernel tick processing. After calling the kernel
* has control over which tasks are executed and when. This function
* does not return until an executing task calls vTaskEndScheduler ().
*
* At least one task should be created via a call to xTaskCreate ()
* before calling vTaskStartScheduler (). The idle task is created
* automatically when the first application task is created.
*
* See the demo application file main.c for an example of creating
* tasks and starting the kernel.
*
* Example usage:
<pre>
void vAFunction( void )
{
// Create at least one task before starting the kernel.
xTaskCreate( vTaskCode, "NAME", STACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
// Start the real time kernel with preemption.
vTaskStartScheduler ();
// Will not get here unless a task calls vTaskEndScheduler ()
}
</pre>
*
* \defgroup vTaskStartScheduler vTaskStartScheduler
* \ingroup SchedulerControl
*/
void vTaskStartScheduler( void ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>void vTaskEndScheduler( void );</pre>
*
* Stops the real time kernel tick. All created tasks will be automatically
* deleted and multitasking (either preemptive or cooperative) will
* stop. Execution then resumes from the point where vTaskStartScheduler ()
* was called, as if vTaskStartScheduler () had just returned.
*
* See the demo application file main. c in the demo/PC directory for an
* example that uses vTaskEndScheduler ().
*
* vTaskEndScheduler () requires an exit function to be defined within the
* portable layer (see vPortEndScheduler () in port. c for the PC port). This
* performs hardware specific operations such as stopping the kernel tick.
*
* vTaskEndScheduler () will cause all of the resources allocated by the
* kernel to be freed - but will not free resources allocated by application
* tasks.
*
* Example usage:
<pre>
void vTaskCode( void * pvParameters )
{
for( ;; )
{
// Task code goes here.
// At some point we want to end the real time kernel processing
// so call ...
vTaskEndScheduler ();
}
}
void vAFunction( void )
{
// Create at least one task before starting the kernel.
xTaskCreate( vTaskCode, "NAME", STACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
// Start the real time kernel with preemption.
vTaskStartScheduler ();
// Will only get here when the vTaskCode () task has called
// vTaskEndScheduler (). When we get here we are back to single task
// execution.
}
</pre>
*
* \defgroup vTaskEndScheduler vTaskEndScheduler
* \ingroup SchedulerControl
*/
void vTaskEndScheduler( void ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>void vTaskSuspendAll( void );</pre>
*
* Suspends all real time kernel activity while keeping interrupts (including the
* kernel tick) enabled.
*
* After calling vTaskSuspendAll () the calling task will continue to execute
* without risk of being swapped out until a call to xTaskResumeAll () has been
* made.
*
* API functions that have the potential to cause a context switch (for example,
* vTaskDelayUntil(), xQueueSend(), etc.) must not be called while the scheduler
* is suspended.
*
* Example usage:
<pre>
void vTask1( void * pvParameters )
{
for( ;; )
{
// Task code goes here.
// ...
// At some point the task wants to perform a long operation during
// which it does not want to get swapped out. It cannot use
// taskENTER_CRITICAL ()/taskEXIT_CRITICAL () as the length of the
// operation may cause interrupts to be missed - including the
// ticks.
// Prevent the real time kernel swapping out the task.
vTaskSuspendAll ();
// Perform the operation here. There is no need to use critical
// sections as we have all the microcontroller processing time.
// During this time interrupts will still operate and the kernel
// tick count will be maintained.
// ...
// The operation is complete. Restart the kernel.
xTaskResumeAll ();
}
}
</pre>
* \defgroup vTaskSuspendAll vTaskSuspendAll
* \ingroup SchedulerControl
*/
void vTaskSuspendAll( void ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>char xTaskResumeAll( void );</pre>
*
* Resumes real time kernel activity following a call to vTaskSuspendAll ().
* After a call to vTaskSuspendAll () the kernel will take control of which
* task is executing at any time.
*
* @return If resuming the scheduler caused a context switch then pdTRUE is
* returned, otherwise pdFALSE is returned.
*
* Example usage:
<pre>
void vTask1( void * pvParameters )
{
for( ;; )
{
// Task code goes here.
// ...
// At some point the task wants to perform a long operation during
// which it does not want to get swapped out. It cannot use
// taskENTER_CRITICAL ()/taskEXIT_CRITICAL () as the length of the
// operation may cause interrupts to be missed - including the
// ticks.
// Prevent the real time kernel swapping out the task.
vTaskSuspendAll ();
// Perform the operation here. There is no need to use critical
// sections as we have all the microcontroller processing time.
// During this time interrupts will still operate and the real
// time kernel tick count will be maintained.
// ...
// The operation is complete. Restart the kernel. We want to force
// a context switch - but there is no point if resuming the scheduler
// caused a context switch already.
if( !xTaskResumeAll () )
{
taskYIELD ();
}
}
}
</pre>
* \defgroup xTaskResumeAll xTaskResumeAll
* \ingroup SchedulerControl
*/
signed portBASE_TYPE xTaskResumeAll( void ) PRIVILEGED_FUNCTION;
/**
* task. h
* <pre>signed portBASE_TYPE xTaskIsTaskSuspended( xTaskHandle xTask );</pre>
*
* Utility task that simply returns pdTRUE if the task referenced by xTask is
* currently in the Suspended state, or pdFALSE if the task referenced by xTask
* is in any other state.
*
*/
signed portBASE_TYPE xTaskIsTaskSuspended( xTaskHandle xTask ) PRIVILEGED_FUNCTION;
/*-----------------------------------------------------------
* TASK UTILITIES
*----------------------------------------------------------*/
/**
* task. h
* <PRE>portTickType xTaskGetTickCount( void );</PRE>
*
* @return The count of ticks since vTaskStartScheduler was called.
*
* \page xTaskGetTickCount xTaskGetTickCount
* \ingroup TaskUtils
*/
portTickType xTaskGetTickCount( void ) PRIVILEGED_FUNCTION;
/**
* task. h
* <PRE>portTickType xTaskGetTickCountFromISR( void );</PRE>
*
* @return The count of ticks since vTaskStartScheduler was called.
*
* This is a version of xTaskGetTickCount() that is safe to be called from an
* ISR - provided that portTickType is the natural word size of the
* microcontroller being used or interrupt nesting is either not supported or
* not being used.
*
* \page xTaskGetTickCount xTaskGetTickCount
* \ingroup TaskUtils
*/
portTickType xTaskGetTickCountFromISR( void ) PRIVILEGED_FUNCTION;
/**
* task. h
* <PRE>unsigned short uxTaskGetNumberOfTasks( void );</PRE>
*
* @return The number of tasks that the real time kernel is currently managing.
* This includes all ready, blocked and suspended tasks. A task that
* has been deleted but not yet freed by the idle task will also be
* included in the count.
*
* \page uxTaskGetNumberOfTasks uxTaskGetNumberOfTasks
* \ingroup TaskUtils
*/
unsigned portBASE_TYPE uxTaskGetNumberOfTasks( void ) PRIVILEGED_FUNCTION;
/**
* task. h
* <PRE>signed char *pcTaskGetTaskName( xTaskHandle xTaskToQuery );</PRE>
*
* @return The text (human readable) name of the task referenced by the handle
* xTaskToQueury. A task can query its own name by either passing in its own
* handle, or by setting xTaskToQuery to NULL. INCLUDE_pcTaskGetTaskName must be
* set to 1 in FreeRTOSConfig.h for pcTaskGetTaskName() to be available.
*
* \page pcTaskGetTaskName pcTaskGetTaskName
* \ingroup TaskUtils
*/
signed char *pcTaskGetTaskName( xTaskHandle xTaskToQuery );
/**
* task. h
* <PRE>void vTaskList( char *pcWriteBuffer );</PRE>
*
* configUSE_TRACE_FACILITY must be defined as 1 for this function to be
* available. See the configuration section for more information.
*
* NOTE: This function will disable interrupts for its duration. It is
* not intended for normal application runtime use but as a debug aid.
*
* Lists all the current tasks, along with their current state and stack
* usage high water mark.
*
* Tasks are reported as blocked ('B'), ready ('R'), deleted ('D') or
* suspended ('S').
*
* @param pcWriteBuffer A buffer into which the above mentioned details
* will be written, in ascii form. This buffer is assumed to be large
* enough to contain the generated report. Approximately 40 bytes per
* task should be sufficient.
*
* \page vTaskList vTaskList
* \ingroup TaskUtils
*/
void vTaskList( signed char *pcWriteBuffer ) PRIVILEGED_FUNCTION;
/**
* task. h
* <PRE>void vTaskGetRunTimeStats( char *pcWriteBuffer );</PRE>
*
* configGENERATE_RUN_TIME_STATS must be defined as 1 for this function
* to be available. The application must also then provide definitions
* for portCONFIGURE_TIMER_FOR_RUN_TIME_STATS() and
* portGET_RUN_TIME_COUNTER_VALUE to configure a peripheral timer/counter
* and return the timers current count value respectively. The counter
* should be at least 10 times the frequency of the tick count.
*
* NOTE: This function will disable interrupts for its duration. It is
* not intended for normal application runtime use but as a debug aid.
*
* Setting configGENERATE_RUN_TIME_STATS to 1 will result in a total
* accumulated execution time being stored for each task. The resolution
* of the accumulated time value depends on the frequency of the timer
* configured by the portCONFIGURE_TIMER_FOR_RUN_TIME_STATS() macro.
* Calling vTaskGetRunTimeStats() writes the total execution time of each
* task into a buffer, both as an absolute count value and as a percentage
* of the total system execution time.
*
* @param pcWriteBuffer A buffer into which the execution times will be
* written, in ascii form. This buffer is assumed to be large enough to
* contain the generated report. Approximately 40 bytes per task should
* be sufficient.
*
* \page vTaskGetRunTimeStats vTaskGetRunTimeStats
* \ingroup TaskUtils
*/
void vTaskGetRunTimeStats( signed char *pcWriteBuffer ) PRIVILEGED_FUNCTION;
/**
* task.h
* <PRE>unsigned portBASE_TYPE uxTaskGetStackHighWaterMark( xTaskHandle xTask );</PRE>
*
* INCLUDE_uxTaskGetStackHighWaterMark must be set to 1 in FreeRTOSConfig.h for
* this function to be available.
*
* Returns the high water mark of the stack associated with xTask. That is,
* the minimum free stack space there has been (in words, so on a 32 bit machine
* a value of 1 means 4 bytes) since the task started. The smaller the returned
* number the closer the task has come to overflowing its stack.
*
* @param xTask Handle of the task associated with the stack to be checked.
* Set xTask to NULL to check the stack of the calling task.
*
* @return The smallest amount of free stack space there has been (in bytes)
* since the task referenced by xTask was created.
*/
unsigned portBASE_TYPE uxTaskGetStackHighWaterMark( xTaskHandle xTask ) PRIVILEGED_FUNCTION;
/* When using trace macros it is sometimes necessary to include tasks.h before
FreeRTOS.h. When this is done pdTASK_HOOK_CODE will not yet have been defined,
so the following two prototypes will cause a compilation error. This can be
fixed by simply guarding against the inclusion of these two prototypes unless
they are explicitly required by the configUSE_APPLICATION_TASK_TAG configuration
constant. */
#ifdef configUSE_APPLICATION_TASK_TAG
#if configUSE_APPLICATION_TASK_TAG == 1
/**
* task.h
* <pre>void vTaskSetApplicationTaskTag( xTaskHandle xTask, pdTASK_HOOK_CODE pxHookFunction );</pre>
*
* Sets pxHookFunction to be the task hook function used by the task xTask.
* Passing xTask as NULL has the effect of setting the calling tasks hook
* function.
*/
void vTaskSetApplicationTaskTag( xTaskHandle xTask, pdTASK_HOOK_CODE pxHookFunction ) PRIVILEGED_FUNCTION;
/**
* task.h
* <pre>void xTaskGetApplicationTaskTag( xTaskHandle xTask );</pre>
*
* Returns the pxHookFunction value assigned to the task xTask.
*/
pdTASK_HOOK_CODE xTaskGetApplicationTaskTag( xTaskHandle xTask ) PRIVILEGED_FUNCTION;
#endif /* configUSE_APPLICATION_TASK_TAG ==1 */
#endif /* ifdef configUSE_APPLICATION_TASK_TAG */
/**
* task.h
* <pre>portBASE_TYPE xTaskCallApplicationTaskHook( xTaskHandle xTask, pdTASK_HOOK_CODE pxHookFunction );</pre>
*
* Calls the hook function associated with xTask. Passing xTask as NULL has
* the effect of calling the Running tasks (the calling task) hook function.
*
* pvParameter is passed to the hook function for the task to interpret as it
* wants.
*/
portBASE_TYPE xTaskCallApplicationTaskHook( xTaskHandle xTask, void *pvParameter ) PRIVILEGED_FUNCTION;
/**
* xTaskGetIdleTaskHandle() is only available if
* INCLUDE_xTaskGetIdleTaskHandle is set to 1 in FreeRTOSConfig.h.
*
* Simply returns the handle of the idle task. It is not valid to call
* xTaskGetIdleTaskHandle() before the scheduler has been started.
*/
xTaskHandle xTaskGetIdleTaskHandle( void );
/*-----------------------------------------------------------
* SCHEDULER INTERNALS AVAILABLE FOR PORTING PURPOSES
*----------------------------------------------------------*/
/*
* THIS FUNCTION MUST NOT BE USED FROM APPLICATION CODE. IT IS ONLY
* INTENDED FOR USE WHEN IMPLEMENTING A PORT OF THE SCHEDULER AND IS
* AN INTERFACE WHICH IS FOR THE EXCLUSIVE USE OF THE SCHEDULER.
*
* Called from the real time kernel tick (either preemptive or cooperative),
* this increments the tick count and checks if any tasks that are blocked
* for a finite period required removing from a blocked list and placing on
* a ready list.
*/
void vTaskIncrementTick( void ) PRIVILEGED_FUNCTION;
/*
* THIS FUNCTION MUST NOT BE USED FROM APPLICATION CODE. IT IS AN
* INTERFACE WHICH IS FOR THE EXCLUSIVE USE OF THE SCHEDULER.
*
* THIS FUNCTION MUST BE CALLED WITH INTERRUPTS DISABLED.
*
* Removes the calling task from the ready list and places it both
* on the list of tasks waiting for a particular event, and the
* list of delayed tasks. The task will be removed from both lists
* and replaced on the ready list should either the event occur (and
* there be no higher priority tasks waiting on the same event) or
* the delay period expires.
*
* @param pxEventList The list containing tasks that are blocked waiting
* for the event to occur.
*
* @param xTicksToWait The maximum amount of time that the task should wait
* for the event to occur. This is specified in kernel ticks,the constant
* portTICK_RATE_MS can be used to convert kernel ticks into a real time
* period.
*/
void vTaskPlaceOnEventList( const xList * const pxEventList, portTickType xTicksToWait ) PRIVILEGED_FUNCTION;
/*
* THIS FUNCTION MUST NOT BE USED FROM APPLICATION CODE. IT IS AN
* INTERFACE WHICH IS FOR THE EXCLUSIVE USE OF THE SCHEDULER.
*
* THIS FUNCTION MUST BE CALLED WITH INTERRUPTS DISABLED.
*
* This function performs nearly the same function as vTaskPlaceOnEventList().
* The difference being that this function does not permit tasks to block
* indefinitely, whereas vTaskPlaceOnEventList() does.
*
* @return pdTRUE if the task being removed has a higher priority than the task
* making the call, otherwise pdFALSE.
*/
void vTaskPlaceOnEventListRestricted( const xList * const pxEventList, portTickType xTicksToWait ) PRIVILEGED_FUNCTION;
/*
* THIS FUNCTION MUST NOT BE USED FROM APPLICATION CODE. IT IS AN
* INTERFACE WHICH IS FOR THE EXCLUSIVE USE OF THE SCHEDULER.
*
* THIS FUNCTION MUST BE CALLED WITH INTERRUPTS DISABLED.
*
* Removes a task from both the specified event list and the list of blocked
* tasks, and places it on a ready queue.
*
* xTaskRemoveFromEventList () will be called if either an event occurs to
* unblock a task, or the block timeout period expires.
*
* @return pdTRUE if the task being removed has a higher priority than the task
* making the call, otherwise pdFALSE.
*/
signed portBASE_TYPE xTaskRemoveFromEventList( const xList * const pxEventList ) PRIVILEGED_FUNCTION;
/*
* THIS FUNCTION MUST NOT BE USED FROM APPLICATION CODE. IT IS ONLY
* INTENDED FOR USE WHEN IMPLEMENTING A PORT OF THE SCHEDULER AND IS
* AN INTERFACE WHICH IS FOR THE EXCLUSIVE USE OF THE SCHEDULER.
*
* Sets the pointer to the current TCB to the TCB of the highest priority task
* that is ready to run.
*/
void vTaskSwitchContext( void ) PRIVILEGED_FUNCTION;
/*
* Return the handle of the calling task.
*/
xTaskHandle xTaskGetCurrentTaskHandle( void ) PRIVILEGED_FUNCTION;
/*
* Capture the current time status for future reference.
*/
void vTaskSetTimeOutState( xTimeOutType * const pxTimeOut ) PRIVILEGED_FUNCTION;
/*
* Compare the time status now with that previously captured to see if the
* timeout has expired.
*/
portBASE_TYPE xTaskCheckForTimeOut( xTimeOutType * const pxTimeOut, portTickType * const pxTicksToWait ) PRIVILEGED_FUNCTION;
/*
* Shortcut used by the queue implementation to prevent unnecessary call to
* taskYIELD();
*/
void vTaskMissedYield( void ) PRIVILEGED_FUNCTION;
/*
* Returns the scheduler state as taskSCHEDULER_RUNNING,
* taskSCHEDULER_NOT_STARTED or taskSCHEDULER_SUSPENDED.
*/
portBASE_TYPE xTaskGetSchedulerState( void ) PRIVILEGED_FUNCTION;
/*
* Raises the priority of the mutex holder to that of the calling task should
* the mutex holder have a priority less than the calling task.
*/
void vTaskPriorityInherit( xTaskHandle * const pxMutexHolder ) PRIVILEGED_FUNCTION;
/*
* Set the priority of a task back to its proper priority in the case that it
* inherited a higher priority while it was holding a semaphore.
*/
void vTaskPriorityDisinherit( xTaskHandle * const pxMutexHolder ) PRIVILEGED_FUNCTION;
/*
* Generic version of the task creation function which is in turn called by the
* xTaskCreate() and xTaskCreateRestricted() macros.
*/
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 ) PRIVILEGED_FUNCTION;
/*
* Get the uxTCBNumber assigned to the task referenced by the xTask parameter.
*/
unsigned portBASE_TYPE uxTaskGetTaskNumber( xTaskHandle xTask );
/*
* Set the uxTCBNumber of the task referenced by the xTask parameter to
* ucHandle.
*/
void vTaskSetTaskNumber( xTaskHandle xTask, unsigned portBASE_TYPE uxHandle );
/*
* If tickless mode is being used, or a low power mode is implemented, then
* the tick interrupt will not execute during idle periods. When this is the
* case, the tick count value maintained by the scheduler needs to be kept up
* to date with the actual execution time by being skipped forward by the by
* a time equal to the idle period.
*/
void vTaskStepTick( portTickType xTicksToJump );
/*
* Provided for use within portSUPPRESS_TICKS_AND_SLEEP() to allow the port
* specific sleep function to determine if it is ok to proceed with the sleep,
* and if it is ok to proceed, if it is ok to sleep indefinitely.
*
* This function is necessary because portSUPPRESS_TICKS_AND_SLEEP() is only
* called with the scheduler suspended, not from within a critical section. It
* is therefore possible for an interrupt to request a context switch between
* portSUPPRESS_TICKS_AND_SLEEP() and the low power mode actually being
* entered. eTaskConfirmSleepModeStatus() should be called from a short
* critical section between the timer being stopped and the sleep mode being
* entered to ensure it is ok to proceed into the sleep mode.
*/
eSleepModeStatus eTaskConfirmSleepModeStatus( void );
#ifdef __cplusplus
}
#endif
#endif /* TASK_H */