os_task.c

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*
* Returns    : OS_NO_ERR        if the function was successful.
*              OS_PRIO_EXIT     if the task priority already exist
*                               (each task MUST have a unique priority).
*              OS_PRIO_INVALID  if the priority you specify is higher that the maximum allowed
*                               (i.e. > OS_LOWEST_PRIO)
*********************************************************************************************************
*/
/*$PAGE*/
#if OS_TASK_CREATE_EXT_EN > 0
INT8U  OSTaskCreateExt (void   (*task)(void *pd),
                        void    *pdata,
                        OS_STK  *ptos,
                        INT8U    prio,
                        INT16U   id,
                        OS_STK  *pbos,
                        INT32U   stk_size,
                        void    *pext,
                        INT16U   opt)
{
#if OS_CRITICAL_METHOD == 3                  /* Allocate storage for CPU status register               */
    OS_CPU_SR  cpu_sr;
#endif
    OS_STK    *psp;
    INT8U      err;


#if OS_ARG_CHK_EN > 0
    if (prio > OS_LOWEST_PRIO) {             /* Make sure priority is within allowable range           */
        return (OS_PRIO_INVALID);
    }
#endif
    OS_ENTER_CRITICAL();
    if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* Make sure task doesn't already exist at this priority  */
        OSTCBPrioTbl[prio] = (OS_TCB *)1;    /* Reserve the priority to prevent others from doing ...  */
                                             /* ... the same thing until task is created.              */
        OS_EXIT_CRITICAL();

        if (((opt & OS_TASK_OPT_STK_CHK) != 0x0000) ||   /* See if stack checking has been enabled     */
            ((opt & OS_TASK_OPT_STK_CLR) != 0x0000)) {   /* See if stack needs to be cleared           */
            #if OS_STK_GROWTH == 1
            (void)memset(pbos, 0, stk_size * sizeof(OS_STK));
            #else
            (void)memset(ptos, 0, stk_size * sizeof(OS_STK));
            #endif
        }

        psp = (OS_STK *)OSTaskStkInit(task, pdata, ptos, opt); /* Initialize the task's stack          */
        err = OS_TCBInit(prio, psp, pbos, id, stk_size, pext, opt);
        if (err == OS_NO_ERR) {
            OS_ENTER_CRITICAL();
            OSTaskCtr++;                                       /* Increment the #tasks counter         */
            OS_EXIT_CRITICAL();
            if (OSRunning == TRUE) {                           /* Find HPT if multitasking has started */
                OS_Sched();
            }
        } else {
            OS_ENTER_CRITICAL();
            OSTCBPrioTbl[prio] = (OS_TCB *)0;                  /* Make this priority avail. to others  */
            OS_EXIT_CRITICAL();
        }
        return (err);
    }
    OS_EXIT_CRITICAL();
    return (OS_PRIO_EXIST);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                            DELETE A TASK
*
* Description: This function allows you to delete a task.  The calling task can delete itself by
*              its own priority number.  The deleted task is returned to the dormant state and can be
*              re-activated by creating the deleted task again.
*
* Arguments  : prio    is the priority of the task to delete.  Note that you can explicitely delete
*                      the current task without knowing its priority level by setting 'prio' to
*                      OS_PRIO_SELF.
*
* Returns    : OS_NO_ERR           if the call is successful
*              OS_TASK_DEL_IDLE    if you attempted to delete uC/OS-II's idle task
*              OS_PRIO_INVALID     if the priority you specify is higher that the maximum allowed
*                                  (i.e. >= OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
*              OS_TASK_DEL_ERR     if the task you want to delete does not exist
*              OS_TASK_DEL_ISR     if you tried to delete a task from an ISR
*
* Notes      : 1) To reduce interrupt latency, OSTaskDel() 'disables' the task:
*                    a) by making it not ready
*                    b) by removing it from any wait lists
*                    c) by preventing OSTimeTick() from making the task ready to run.
*                 The task can then be 'unlinked' from the miscellaneous structures in uC/OS-II.
*              2) The function OS_Dummy() is called after OS_EXIT_CRITICAL() because, on most processors,
*                 the next instruction following the enable interrupt instruction is ignored.  
*              3) An ISR cannot delete a task.
*              4) The lock nesting counter is incremented because, for a brief instant, if the current
*                 task is being deleted, the current task would not be able to be rescheduled because it
*                 is removed from the ready list.  Incrementing the nesting counter prevents another task
*                 from being schedule.  This means that an ISR would return to the current task which is
*                 being deleted.  The rest of the deletion would thus be able to be completed.
*********************************************************************************************************
*/
/*$PAGE*/
#if OS_TASK_DEL_EN > 0
INT8U  OSTaskDel (INT8U prio)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR     cpu_sr;
#endif

#if OS_EVENT_EN > 0
    OS_EVENT     *pevent;
#endif    
#if (OS_VERSION >= 251) && (OS_FLAG_EN > 0) && (OS_MAX_FLAGS > 0)
    OS_FLAG_NODE *pnode;
#endif
    OS_TCB       *ptcb;
    BOOLEAN       self;


    self = self;
    if (OSIntNesting > 0) {                                     /* See if trying to delete from ISR    */
        return (OS_TASK_DEL_ISR);
    }
#if OS_ARG_CHK_EN > 0
    if (prio == OS_IDLE_PRIO) {                                 /* Not allowed to delete idle task     */
        return (OS_TASK_DEL_IDLE);
    }
    if (prio >= OS_LOWEST_PRIO && prio != OS_PRIO_SELF) {       /* Task priority valid ?               */
        return (OS_PRIO_INVALID);
    }
#endif
    OS_ENTER_CRITICAL();
    if (prio == OS_PRIO_SELF) {                                 /* See if requesting to delete self    */
        prio = OSTCBCur->OSTCBPrio;                             /* Set priority to delete to current   */
    }
    ptcb = OSTCBPrioTbl[prio];
    if (ptcb != (OS_TCB *)0) {                                       /* Task to delete must exist      */
        if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0x00) {  /* Make task not ready            */
            OSRdyGrp &= ~ptcb->OSTCBBitY;
        }
#if OS_EVENT_EN > 0
        pevent = ptcb->OSTCBEventPtr;
        if (pevent != (OS_EVENT *)0) {                          /* If task is waiting on event         */
            if ((pevent->OSEventTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) { /* ... remove task from */
                pevent->OSEventGrp &= ~ptcb->OSTCBBitY;                        /* ... event ctrl block */
            }
        }
#endif
#if (OS_VERSION >= 251) && (OS_FLAG_EN > 0) && (OS_MAX_FLAGS > 0)
        pnode = ptcb->OSTCBFlagNode;
        if (pnode != (OS_FLAG_NODE *)0) {                       /* If task is waiting on event flag    */
            OS_FlagUnlink(pnode);                               /* Remove from wait list               */
        }
#endif
        ptcb->OSTCBDly  = 0;                                    /* Prevent OSTimeTick() from updating  */
        ptcb->OSTCBStat = OS_STAT_RDY;                          /* Prevent task from being resumed     */
		if (OSLockNesting < 255) {
            OSLockNesting++;
		}
        OS_EXIT_CRITICAL();                                     /* Enabling INT. ignores next instruc. */
        OS_Dummy();                                             /* ... Dummy ensures that INTs will be */
        OS_ENTER_CRITICAL();                                    /* ... disabled HERE!                  */
		if (OSLockNesting > 0) {
            OSLockNesting--;
		}
        OSTaskDelHook(ptcb);                                    /* Call user defined hook              */
        OSTaskCtr--;                                            /* One less task being managed         */
        OSTCBPrioTbl[prio] = (OS_TCB *)0;                       /* Clear old priority entry            */
        if (ptcb->OSTCBPrev == (OS_TCB *)0) {                   /* Remove from TCB chain               */
            ptcb->OSTCBNext->OSTCBPrev = (OS_TCB *)0;
            OSTCBList                  = ptcb->OSTCBNext;
        } else {
            ptcb->OSTCBPrev->OSTCBNext = ptcb->OSTCBNext;
            ptcb->OSTCBNext->OSTCBPrev = ptcb->OSTCBPrev;
        }
        ptcb->OSTCBNext = OSTCBFreeList;                        /* Return TCB to free TCB list         */
        OSTCBFreeList   = ptcb;
        OS_EXIT_CRITICAL();
        OS_Sched();                                             /* Find new highest priority task      */
        return (OS_NO_ERR);
    }
    OS_EXIT_CRITICAL();
    return (OS_TASK_DEL_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                    REQUEST THAT A TASK DELETE ITSELF
*
* Description: This function is used to:
*                   a) notify a task to delete itself.
*                   b) to see if a task requested that the current task delete itself.
*              This function is a little tricky to understand.  Basically, you have a task that needs
*              to be deleted however, this task has resources that it has allocated (memory buffers,
*              semaphores, mailboxes, queues etc.).  The task cannot be deleted otherwise these
*              resources would not be freed.  The requesting task calls OSTaskDelReq() to indicate that
*              the task needs to be deleted.  Deleting of the task is however, deferred to the task to
*              be deleted.  For example, suppose that task #10 needs to be deleted.  The requesting task
*              example, task #5, would call OSTaskDelReq(10).  When task #10 gets to execute, it calls
*              this function by specifying OS_PRIO_SELF and monitors the returned value.  If the return
*              value is OS_TASK_DEL_REQ, another task requested a task delete.  Task #10 would look like
*              this:
*
*                   void Task(void *data)
*                   {
*                       .
*                       .
*                       while (1) {
*                           OSTimeDly(1);
*                           if (OSTaskDelReq(OS_PRIO_SELF) == OS_TASK_DEL_REQ) {
*                               Release any owned resources;
*                               De-allocate any dynamic memory;
*                               OSTaskDel(OS_PRIO_SELF);
*                           }
*                       }
*                   }
*
* Arguments  : prio    is the priority of the task to request the delete from
*
* Returns    : OS_NO_ERR          if the task exist and the request has been registered
*              OS_TASK_NOT_EXIST  if the task has been deleted.  This allows the caller to know whether
*                                 the request has been executed.
*              OS_TASK_DEL_IDLE   if you requested to delete uC/OS-II's idle task
*              OS_PRIO_INVALID    if the priority you specify is higher that the maximum allowed
*                                 (i.e. >= OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
*              OS_TASK_DEL_REQ    if a task (possibly another task) requested that the running task be
*                                 deleted.
*********************************************************************************************************
*/
/*$PAGE*/
#if OS_TASK_DEL_EN > 0
INT8U  OSTaskDelReq (INT8U prio)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif
    BOOLEAN    stat;
    INT8U      err;
    OS_TCB    *ptcb;


#if OS_ARG_CHK_EN > 0
    if (prio == OS_IDLE_PRIO) {                                 /* Not allowed to delete idle task     */
        return (OS_TASK_DEL_IDLE);
    }
    if (prio >= OS_LOWEST_PRIO && prio != OS_PRIO_SELF) {       /* Task priority valid ?               */
        return (OS_PRIO_INVALID);
    }
#endif
    if (prio == OS_PRIO_SELF) {                                 /* See if a task is requesting to ...  */