**              id       is the task's ID (0..65535)**              pbos     is a pointer to the task's bottom of stack.  If the configuration constant *                       OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high*                       memory to low memory).  'pbos' will thus point to the LOWEST (valid) memory *                       location of the stack.  If OS_STK_GROWTH is set to 0, 'pbos' will point to the *                       HIGHEST memory location of the stack and the stack will grow with increasing*                       memory locations.  'pbos' MUST point to a valid 'free' data item.**              stk_size is the size of the stack in number of elements.  If OS_STK is set to INT8U,*                       'stk_size' corresponds to the number of bytes available.  If OS_STK is set to*                       INT16U, 'stk_size' contains the number of 16-bit entries available.  Finally, if*                       OS_STK is set to INT32U, 'stk_size' contains the number of 32-bit entries*                       available on the stack.**              pext     is a pointer to a user supplied memory location which is used as a TCB extension.*                       For example, this user memory can hold the contents of floating-point registers*                       during a context switch, the time each task takes to execute, the number of times*                       the task has been switched-in, etc. **              opt      contains additional information (or options) about the behavior of the task.  The *                       LOWER 8-bits are reserved by uC/OS-II while the upper 8 bits can be application *                       specific.  See OS_TASK_OPT_??? in uCOS-II.H.** 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    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){    void    *psp;    INT8U    err;    INT16U   i;    OS_STK  *pfill;    if (prio > OS_LOWEST_PRIO) {             /* Make sure priority is within allowable range           */        return (OS_PRIO_INVALID);    }    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) {     /* See if stack checking has been enabled                 */            if (opt & OS_TASK_OPT_STK_CLR) { /* See if stack needs to be cleared                       */                pfill = pbos;                /* Yes, fill the stack with zeros                         */                for (i = 0; i < stk_size; i++) {                    #if OS_STK_GROWTH == 1                    *pfill++ = (OS_STK)0;                    #else                    *pfill-- = (OS_STK)0;                    #endif                }            }        }                psp = (void *)OSTaskStkInit(task, pdata, ptos, opt); /* Initialize the task's stack            */        err = OSTCBInit(prio, psp, pbos, id, stk_size, pext, opt);                 if (err == OS_NO_ERR) {            OS_ENTER_CRITICAL();            OSTaskCtr++;                                     /* Increment the #tasks counter           */            OSTaskCreateHook(OSTCBPrioTbl[prio]);            /* Call user defined hook                 */            OS_EXIT_CRITICAL();            if (OSRunning) {                 /* Find highest priority task if multitasking has started */                OSSched();            }        } else {            OS_ENTER_CRITICAL();            OSTCBPrioTbl[prio] = (OS_TCB *)0;/* Make this priority available to others                 */            OS_EXIT_CRITICAL();        }        return (err);    } else {        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 OSDummy() is called after OS_EXIT_CRITICAL() because, on most processors, *                 the next instruction following the enable interrupt instruction is ignored.  You can *                 replace OSDummy() with a macro that basically executes a NO OP (i.e. OS_NOP()).  The *                 NO OP macro would avoid the execution time of the function call and return.*              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 the 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_ENINT8U OSTaskDel (INT8U prio){    OS_TCB   *ptcb;    OS_EVENT *pevent;    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);    }    OS_ENTER_CRITICAL();    if (OSIntNesting > 0) {                                     /* See if trying to delete from ISR    */        OS_EXIT_CRITICAL();        return (OS_TASK_DEL_ISR);    }    if (prio == OS_PRIO_SELF) {                                 /* See if requesting to delete self    */        prio = OSTCBCur->OSTCBPrio;                             /* Set priority to delete to current   */    }    if ((ptcb = OSTCBPrioTbl[prio]) != (OS_TCB *)0) {           /* Task to delete must exist           */        if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) {/* Make task not ready                 */            OSRdyGrp &= ~ptcb->OSTCBBitY;        }        if ((pevent = ptcb->OSTCBEventPtr) != (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 */            }        }        ptcb->OSTCBDly  = 0;                                    /* Prevent OSTimeTick() from updating  */        ptcb->OSTCBStat = OS_STAT_RDY;                          /* Prevent task from being resumed     */        OSLockNesting++;        OS_EXIT_CRITICAL();                                     /* Enabling INT. ignores next instruc. */        OSDummy();                                              /* ... Dummy ensures that INTs will be */        OS_ENTER_CRITICAL();                                    /* ... disabled HERE!                  */        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();        OSSched();                                              /* Find new highest priority task      */        return (OS_NO_ERR);    } else {        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_ENINT8U OSTaskDelReq (INT8U prio){    BOOLEAN  stat;