task.h

这是一个FreeRTOS(V511)的移植程序,MCU为FREESCALE公司的MC9S08AW60

/*
	FreeRTOS.org V5.1.1 - Copyright (C) 2003-2008 Richard Barry.

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*/


#ifndef INC_FREERTOS_H
	#error "#include FreeRTOS.h" must appear in source files before "#include task.h"
#endif



#ifndef TASK_H
#define TASK_H

#include "portable.h"
#include "list.h"

#ifdef __cplusplus
extern "C" {
#endif
/*-----------------------------------------------------------
 * MACROS AND DEFINITIONS
 *----------------------------------------------------------*/

#define tskKERNEL_VERSION_NUMBER "V5.1.0"

/**
 * 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 priority used by the idle task.  This must not be modified.
 *
 * \ingroup TaskUtils
 */
#define tskIDLE_PRIORITY			( ( unsigned portBASE_TYPE ) 0 )

/**
 * 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 portCHAR * const pcName,
                              unsigned portSHORT 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.
 *
 * @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.
 *
 * @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 time 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
 */
signed portBASE_TYPE xTaskCreate( pdTASK_CODE pvTaskCode, const signed portCHAR * const pcName, unsigned portSHORT usStackDepth, void *pvParameters, unsigned portBASE_TYPE uxPriority, xTaskHandle *pvCreatedTask );

/**
 * task. h
 * <pre>void vTaskDelete( xTaskHandle pxTask );</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 pxTask 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 pxTask );


/*-----------------------------------------------------------
 * 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 );

/**
 * 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.