os_task.c

UCOS/II for ICCAVR - The version of UCOS/II is 2.04 - the original port was done by Ole Saether

*              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;
	INT8U         y;



    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           */
	    y            =  ptcb->OSTCBY;
		OSRdyTbl[y] &= ~ptcb->OSTCBBitX;
        if (OSRdyTbl[y] == 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         */
		    pevent->OSEventTbl[y] &= ~ptcb->OSTCBBitX;
            if (pevent->OSEventTbl[y] == 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 < 255u) {
            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;
#if OS_TASK_NAME_SIZE > 1
        ptcb->OSTCBTaskName[0] = '?';                           /* Unknown name                        */
        ptcb->OSTCBTaskName[1] = OS_ASCII_NUL;
#endif
        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 *p_arg)
*                   {
*                       .
*                       .
*                       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) {						        /* Task priority valid ?               */
        if (prio != OS_PRIO_SELF) {                       
            return (OS_PRIO_INVALID);
		}
    }
#endif
    if (prio == OS_PRIO_SELF) {                                 /* See if a task is requesting to ...  */
        OS_ENTER_CRITICAL();                                    /* ... this task to delete itself      */
        stat = OSTCBCur->OSTCBDelReq;                           /* Return request status to caller     */
        OS_EXIT_CRITICAL();
        return (stat);
    }
    OS_ENTER_CRITICAL();
    ptcb = OSTCBPrioTbl[prio];
    if (ptcb != (OS_TCB *)0) {                                  /* Task to delete must exist           */
        ptcb->OSTCBDelReq = OS_TASK_DEL_REQ;                    /* Set flag indicating task to be DEL. */
        err               = OS_NO_ERR;
    } else {
        err               = OS_TASK_NOT_EXIST;                  /* Task must be deleted                */
    }
    OS_EXIT_CRITICAL();
    return (err);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                        GET THE NAME OF A TASK
*
* Description: This function is called to obtain the name of a task.
*
* Arguments  : prio      is the priority of the task that you want to obtain the name from.
*
*              pname     is a pointer to an ASCII string that will receive the name of the task.  The 
*                        string must be able to hold at least OS_TASK_NAME_SIZE characters.
*
*              err       is a pointer to an error code that can contain one of the following values:
*
*                        OS_NO_ERR                  if the requested task is resumed
*                        OS_TASK_NOT_EXIST          if the task has not been created
*                        OS_PRIO_INVALID            if you specified an invalid priority:
*                                                   A higher value than the idle task or not OS_PRIO_SELF.
*                        OS_ERR_PNAME_NULL          You passed a NULL pointer for 'pname'
*
* Returns    : The length of the string or 0 if the task does not exist.
*********************************************************************************************************
*/

#if OS_TASK_NAME_SIZE > 1
INT8U  OSTaskNameGet (INT8U prio, char *pname, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif
    OS_TCB    *ptcb;
    INT8U      len;


    OS_ENTER_CRITICAL();
#if OS_ARG_CHK_EN > 0
    if (prio > OS_LOWEST_PRIO && prio != OS_PRIO_SELF) {        /* Task priority valid ?               */
        *err = OS_PRIO_INVALID;                                 /* No                                  */
        return (0);
    }
    if (pname == (char *)0) {                    /* Is 'pname' a NULL pointer?                         */
        OS_EXIT_CRITICAL();                      /* Yes                                                */
        *err = OS_ERR_PNAME_NULL;
        return (0);
    }
#endif
    if (prio == OS_PRIO_SELF) {                  /* See if caller desires it's own name                */
        prio = OSTCBCur->OSTCBPrio;
    }
    ptcb = OSTCBPrioTbl[prio];
    if (ptcb == (OS_TCB *)0) {                        /* Does task exist?                              */
        OS_EXIT_CRITICAL();                           /* No                                            */
        *err = OS_TASK_NOT_EXIST;
        return (0);
    }
    len  = OS_StrCopy(pname, ptcb->OSTCBTaskName);    /* Yes, copy name from TCB                       */
    OS_EXIT_CRITICAL();
    *err = OS_NO_ERR;
    return (len);
}
#endif

/*$PAGE*/
/*
*********************************************************************************************************
*                                        ASSIGN A NAME TO A TASK
*
* Description: This function is used to set the name of a task.
*
* Arguments  : prio      is the priority of the task that you want the assign a name to.
*
*              pname     is a pointer to an ASCII string that contains the name of the task.  The ASCII
*                        string must be NUL terminated.
*
*              err       is a pointer to an error code that can contain one of the following values:
*
*                        OS_NO_ERR                  if the requested task is resumed
*                        OS_TASK_NOT_EXIST          if the task has not been created
*                        OS_ERR_TASK_NAME_TOO_LONG  if the name you are giving to the task exceeds the 
*                                                   storage capacity of a task name as specified by 
*                                                   OS_TASK_NAME_SIZE.
*                        OS_ERR_PNAME_NULL          You passed a NULL pointer for 'pname'
*                        OS_PRIO_INVALID            if you specified an invalid priority:
*                                                   A higher value than the idle task or not OS_PRIO_SELF.
*
* Returns    : None
*********************************************************************************************************
*/
#if OS_TASK_NAME_SIZE > 1
void  OSTaskNameSet (INT8U prio, char *pname, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif
    INT8U      len;
    OS_TCB    *ptcb;


    OS_ENTER_CRITICAL();
#if OS_ARG_CHK_EN > 0
    if (prio > OS_LOWEST_PRIO) {                 /* Task priority valid ?                              */
        if (prio != OS_PRIO_SELF) {              
            *err = OS_PRIO_INVALID;              /* No                                                 */
            return;
        }
    }
    if (pname == (char *)0) {                    /* Is 'pname' a NULL pointer?                         */
        OS_EXIT_CRITICAL();                      /* Yes                                                */
        *err = OS_ERR_PNAME_NULL;
        return;
    }
#endif
    if (prio == OS_PRIO_SELF) {                  /* See if caller desires to set it's own name         */
        prio = OSTCBCur->OSTCBPrio;