114 lines
4.4 KiB
C++
114 lines
4.4 KiB
C++
/**
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* @file PeriodicTask.h
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*
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* @brief This file contains the definition for the PeriodicTask class.
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*
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* @author Bastian Baetz
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*
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* @date 07/21/2010
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*
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*/
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#ifndef OPUSPERIODICTASK_H_
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#define OPUSPERIODICTASK_H_
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#include <framework/tasks/TaskBase.h>
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/**
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*
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* @brief This class represents a specialized task for periodic activities.
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*
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* @details A simple, but very important task type is the periodic task. Each task of this type has
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* a certain period assigned. When started, the task's functionality (a simple function)
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* is executed. On finishing, the task is blocked for the rest of the period and restarted
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* afterwards. A missed deadline is detected and a function to perform necessary failure
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* detection may be called.
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*
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* @author Bastian Baetz
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*
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* @date 07/21/2010
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*
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* @ingroup task_handling
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*/
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class PeriodicTask: public TaskBase {
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protected:
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/**
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* @brief The period of the task.
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* @details The period determines the frequency of the task's execution. It is expressed in clock ticks.
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*/
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Interval_t period;
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/**
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* @brief id of the associated OS period
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*/
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PeriodId_t periodId;
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/**
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* @brief This is the function executed in the new task's context.
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* @details It converts the argument back to the thread object type and copies the class instance
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* to the task context. The taskFunctionality method is called afterwards.
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* @param A pointer to the task object itself is passed as argument.
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*/
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static TaskReturn_t taskEntryPoint( TaskArgument_t argument );
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/**
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* @brief The pointer to the deadline-missed function.
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* @details This pointer stores the function that is executed if the task's deadline is missed.
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* So, each may react individually on a timing failure. The pointer may be NULL,
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* then nothing happens on missing the deadline. The deadline is equal to the next execution
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* of the periodic task.
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*/
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void ( *deadlineMissedFunc )( void );
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/**
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* @brief The function containing the actual functionality of the task.
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* @image latex act_OPUSPeriodicThread.eps "Activity diagram of the PeriodicThread functionality." width=0.6@textwidth
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* @image html act_OPUSPeriodicThread.png "Activity diagram of the PeriodicThread functionality."
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* @details The figure above shows the functional execution of this method. It sets and starts
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* the task's period, then enters a loop that is repeated as long as the isRunning
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* attribute is true. Within the loop, the taskFunction is called, and
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* afterwards the checkAndRestartPeriod system call to block the task until the next
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* period. On missing the deadline, the deadlineMissedFunction is executed.
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*/
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void taskFunctionality( void );
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/**
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* @brief In this attribute the pointer to the function which shall be executed periodically
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* is stored.
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*/
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ReturnValue_t ( *taskFunction )( TaskBase* );
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public:
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/**
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* @brief The standard constructor of the class.
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* @details This is the general constructor of the class. In the underlying TaskBase class,
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* a new operating system task is created. In addition to the TaskBase parameters,
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* the period, the actual function to be executed and an optional "deadline-missed"
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* function pointer is passed.
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* @param priority Sets the priority of a task. Values range from a low 0 to a high 99.
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* @param stack_size The stack size reserved by the operating system for the task.
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* @param setPeriod The length of the period with which the task's functionality will be
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* executed. It is expressed in clock ticks.
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* @param (*setDeadlineMissedFunc)() The function pointer to the deadline missed function
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* that shall be assigned.
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* @param ( *setTaskFunction )( TaskBase* ) A pointer to the actual function to be executed.
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*/
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PeriodicTask( const char *name, TaskPriority_t setPriority, size_t setStack, Interval_t setPeriod, void ( *setDeadlineMissedFunc )(), ReturnValue_t ( *setTaskFunction )( TaskBase* ) );
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/**
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* @brief The destructor of the class.
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* @details Similar to the destructor in the parent class, no memory clean-ups are necessary.
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* Thus, the destructor is empty.
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*/
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virtual ~PeriodicTask( void );
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/**
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* @brief The method to start the task.
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* @details The method starts the task with the respective system call.
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* Entry point is the taskEntryPoint method described below.
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* The address of the task object is passed as an argument
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* to the system call.
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*/
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virtual ReturnValue_t startTask( void );
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};
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#endif /* OPUSPERIODICTASK_H_ */
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