task.h

Show hou use semaphores in RTL-ARM

         // 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 );

/**
 * 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.
 *
 * 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 );

/**
 * task. h
 * <pre>portCHAR 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 );


/*-----------------------------------------------------------
 * TASK UTILITIES
 *----------------------------------------------------------*/

/**
 * task. h
 * <PRE>volatile portTickType xTaskGetTickCount( void );</PRE>
 *
 * @return The count of ticks since vTaskStartScheduler was called.
 *
 * \page xTaskGetTickCount xTaskGetTickCount
 * \ingroup TaskUtils
 */
portTickType xTaskGetTickCount( void );

/**
 * task. h
 * <PRE>unsigned portSHORT 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 );

/**
 * task. h
 * <PRE>void vTaskList( portCHAR *pcWriteBuffer );</PRE>
 *
 * configUSE_TRACE_FACILITY, INCLUDE_vTaskDelete and INCLUDE_vTaskSuspend
 * must all 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 portCHAR *pcWriteBuffer );

/**
 * task. h
 * <PRE>void vTaskStartTrace( portCHAR * pcBuffer, unsigned portBASE_TYPE uxBufferSize );</PRE>
 *
 * Starts a real time kernel activity trace.  The trace logs the identity of
 * which task is running when.
 *
 * The trace file is stored in binary format.  A separate DOS utility called
 * convtrce.exe is used to convert this into a tab delimited text file which
 * can be viewed and plotted in a spread sheet.
 *
 * @param pcBuffer The buffer into which the trace will be written.
 *
 * @param ulBufferSize The size of pcBuffer in bytes.  The trace will continue
 * until either the buffer in full, or ulTaskEndTrace () is called.
 *
 * \page vTaskStartTrace vTaskStartTrace
 * \ingroup TaskUtils
 */
void vTaskStartTrace( signed portCHAR * pcBuffer, unsigned portLONG ulBufferSize );

/**
 * task. h
 * <PRE>unsigned portLONG ulTaskEndTrace( void );</PRE>
 *
 * Stops a kernel activity trace.  See vTaskStartTrace ().
 *
 * @return The number of bytes that have been written into the trace buffer.
 *
 * \page usTaskEndTrace usTaskEndTrace
 * \ingroup TaskUtils
 */
unsigned portLONG ulTaskEndTrace( 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.
 */
inline void vTaskIncrementTick( void );

/*
 * 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( xList *pxEventList, portTickType xTicksToWait );

/*
 * 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 *pxEventList );

/*
 * THIS FUNCTION MUST NOT BE USED FROM APPLICATION CODE.  IT IS AN
 * INTERFACE WHICH IS FOR THE EXCLUSIVE USE OF THE SCHEDULER.
 *
 * INCLUDE_vTaskCleanUpResources and INCLUDE_vTaskSuspend must be defined as 1
 * for this function to be available.
 * See the configuration section for more information.
 *
 * Empties the ready and delayed queues of task control blocks, freeing the
 * memory allocated for the task control block and task stacks as it goes.
 */
void vTaskCleanUpResources( void );

/*
 * 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.
 */
inline void vTaskSwitchContext( void );

/*
 * Return the handle of the calling task.
 */
xTaskHandle xTaskGetCurrentTaskHandle( void );

/*
 * Capture the current time status for future reference.
 */
void vTaskSetTimeOutState( xTimeOutType *pxTimeOut );

/*
 * Compare the time status now with that previously captured to see if the
 * timeout has expired.
 */
portBASE_TYPE xTaskCheckForTimeOut( xTimeOutType *pxTimeOut, portTickType *pxTicksToWait );

/*
 * Shortcut used by the queue implementation to prevent unnecessary call to
 * taskYIELD();
 */
void vTaskMissedYield( void );

#endif /* TASK_H */