INT8U    err;
    OS_TCB  *ptcb;


    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);
    }
    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);
    } else {
        OS_ENTER_CRITICAL();
        if ((ptcb = OSTCBPrioTbl[prio]) != (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*/
/*
*********************************************************************************************************
*                                        RESUME A SUSPENDED TASK
*
* Description: This function is called to resume a previously suspended task.  This is the only call that
*              will remove an explicit task suspension.
*
* Arguments  : prio     is the priority of the task to resume.
*
* Returns    : OS_NO_ERR                if the requested task is resumed
*              OS_PRIO_INVALID          if the priority you specify is higher that the maximum allowed 
*                                       (i.e. >= OS_LOWEST_PRIO)
*              OS_TASK_RESUME_PRIO      if the task to resume does not exist
*              OS_TASK_NOT_SUSPENDED    if the task to resume has not been suspended
*********************************************************************************************************
*/

#if OS_TASK_SUSPEND_EN
INT8U OSTaskResume (INT8U prio) 
{
    OS_TCB   *ptcb;


    if (prio >= OS_LOWEST_PRIO) {                               /* Make sure task priority is valid    */
        return (OS_PRIO_INVALID);
    }
    OS_ENTER_CRITICAL();
    if ((ptcb = OSTCBPrioTbl[prio]) == (OS_TCB *)0) {           /* Task to suspend must exist          */
        OS_EXIT_CRITICAL();
        return (OS_TASK_RESUME_PRIO);
    } else {
        if (ptcb->OSTCBStat & OS_STAT_SUSPEND) {                           /* Task must be suspended   */
            if (((ptcb->OSTCBStat &= ~OS_STAT_SUSPEND) == OS_STAT_RDY) &&  /* Remove suspension        */
                 (ptcb->OSTCBDly  == 0)) {                                 /* Must not be delayed      */
                OSRdyGrp               |= ptcb->OSTCBBitY;                 /* Make task ready to run   */
                OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;
                OS_EXIT_CRITICAL();
                OSSched();
            } else {
                OS_EXIT_CRITICAL();
            }
            return (OS_NO_ERR);
        } else {
            OS_EXIT_CRITICAL();
            return (OS_TASK_NOT_SUSPENDED);
        }
    }
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                             STACK CHECKING 
*
* Description: This function is called to check the amount of free memory left on the specified task's
*              stack.
*
* Arguments  : prio     is the task priority
*
*              pdata    is a pointer to a data structure of type OS_STK_DATA.
*
* Returns    : OS_NO_ERR           upon success
*              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_NOT_EXIST   if the desired task has not been created
*              OS_TASK_OPT_ERR     if you did NOT specified OS_TASK_OPT_STK_CHK when the task was created
*********************************************************************************************************
*/
#if   OS_TASK_CREATE_EXT_EN
INT8U OSTaskStkChk (INT8U prio, OS_STK_DATA *ppdata) 
{
    OS_TCB  *ptcb;
    OS_STK  *pchk;
    INT32U   free;
    INT32U   size;


    ppdata->OSFree = 0;                                          /* Assume failure, set to 0 size       */
    ppdata->OSUsed = 0;
    if (prio > OS_LOWEST_PRIO && prio != OS_PRIO_SELF) {        /* Make sure task priority is valid    */
        return (OS_PRIO_INVALID);
    }
    OS_ENTER_CRITICAL();
    if (prio == OS_PRIO_SELF) {                        /* See if check for SELF                        */
        prio = OSTCBCur->OSTCBPrio;
    }
    ptcb = OSTCBPrioTbl[prio];
    if (ptcb == (OS_TCB *)0) {                         /* Make sure task exist                         */
        OS_EXIT_CRITICAL();
        return (OS_TASK_NOT_EXIST);
    }
    if ((ptcb->OSTCBOpt & OS_TASK_OPT_STK_CHK) == 0) { /* Make sure stack checking option is set       */
        OS_EXIT_CRITICAL();
        return (OS_TASK_OPT_ERR);
    }
    free = 0;
    size = ptcb->OSTCBStkSize;
    pchk = ptcb->OSTCBStkBottom;
    OS_EXIT_CRITICAL();
#if OS_STK_GROWTH == 1
    while (*pchk++ == 0) {                            /* Compute the number of zero entries on the stk */
        free++;
    }
#else
    while (*pchk-- == 0) {
        free++;
    }
#endif
    ppdata->OSFree = free * sizeof(OS_STK);            /* Compute number of free bytes on the stack     */
    ppdata->OSUsed = (size - free) * sizeof(OS_STK);   /* Compute number of bytes used on the stack     */
    return (OS_NO_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                            SUSPEND A TASK
*
* Description: This function is called to suspend a task.  The task can be the calling task if the
*              priority passed to OSTaskSuspend() is the priority of the calling task or OS_PRIO_SELF.
*
* Arguments  : prio     is the priority of the task to suspend.  If you specify OS_PRIO_SELF, the
*                       calling task will suspend itself and rescheduling will occur.
*
* Returns    : OS_NO_ERR                if the requested task is suspended
*              OS_TASK_SUSPEND_IDLE     if you attempted to suspend the idle task which is not allowed.
*              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_SUSPEND_PRIO     if the task to suspend does not exist
*
* Note       : You should use this function with great care.  If you suspend a task that is waiting for
*              an event (i.e. a message, a semaphore, a queue ...) you will prevent this task from
*              running when the event arrives.
*********************************************************************************************************
*/

#if OS_TASK_SUSPEND_EN
INT8U OSTaskSuspend (INT8U prio) 
{
    BOOLEAN   self;
    OS_TCB   *ptcb;


    if (prio == OS_IDLE_PRIO) {                                 /* Not allowed to suspend idle task    */
        return (OS_TASK_SUSPEND_IDLE);
    }
    if (prio >= OS_LOWEST_PRIO && prio != OS_PRIO_SELF) {       /* Task priority valid ?               */
        return (OS_PRIO_INVALID);
    }
    OS_ENTER_CRITICAL();
    if (prio == OS_PRIO_SELF) {                                 /* See if suspend SELF                 */
        prio = OSTCBCur->OSTCBPrio;
        self = TRUE;
    } else if (prio == OSTCBCur->OSTCBPrio) {                   /* See if suspending self              */
        self = TRUE;
    } else {
        self = FALSE;                                           /* No suspending another task          */
    }
    if ((ptcb = OSTCBPrioTbl[prio]) == (OS_TCB *)0) {                /* Task to suspend must exist     */
        OS_EXIT_CRITICAL();
        return (OS_TASK_SUSPEND_PRIO);
    } else {
        if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) {     /* Make task not ready            */
            OSRdyGrp &= ~ptcb->OSTCBBitY;
        }
        ptcb->OSTCBStat |= OS_STAT_SUSPEND;                          /* Status of task is 'SUSPENDED'  */
        OS_EXIT_CRITICAL();
        if (self == TRUE) {                                          /* Context switch only if SELF    */
            OSSched();
        }
        return (OS_NO_ERR);
    }
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                            QUERY A TASK
*
* Description: This function is called to obtain a copy of the desired task's TCB.
*
* Arguments  : prio     is the priority of the task to obtain information from.  
*
* Returns    : OS_NO_ERR       if the requested task is suspended
*              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_PRIO_ERR     if the desired task has not been created 
*********************************************************************************************************
*/

INT8U OSTaskQuery (INT8U prio, OS_TCB *ppdata) 
{
    OS_TCB *ptcb;


    if (prio > OS_LOWEST_PRIO && prio != OS_PRIO_SELF) {   /* Task priority valid ?                    */
        return (OS_PRIO_INVALID);
    }
    OS_ENTER_CRITICAL();
    if (prio == OS_PRIO_SELF) {                            /* See if suspend SELF                      */
        prio = OSTCBCur->OSTCBPrio;
    }
    if ((ptcb = OSTCBPrioTbl[prio]) == (OS_TCB *)0) {      /* Task to query must exist                 */
        OS_EXIT_CRITICAL();
        return (OS_PRIO_ERR);
    }
    *ppdata = *ptcb;                                        /* Copy TCB into user storage area          */
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}