?? os_task.lst
字號:
C51 COMPILER V7.50 OS_TASK 12/12/2007 16:55:25 PAGE 7
365 * 4) The lock nesting counter is incremented because, for a brief instant, if the current
366 * task is being deleted, the current task would not be able to be rescheduled because it
367 * is removed from the ready list. Incrementing the nesting counter prevents another task
368 * from being schedule. This means that the ISR would return to the current task which is
369 * being deleted. The rest of the deletion would thus be able to be completed.
370 *********************************************************************************************************
371 */
372 /*$PAGE*/
373 #if OS_TASK_DEL_EN
INT8U OSTaskDel (INT8U prio) reentrant
{
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();
C51 COMPILER V7.50 OS_TASK 12/12/2007 16:55:25 PAGE 8
return (OS_TASK_DEL_ERR);
}
}
#endif
431 /*$PAGE*/
432 /*
433 *********************************************************************************************************
434 * REQUEST THAT A TASK DELETE ITSELF
435 *
436 * Description: This function is used to:
437 * a) notify a task to delete itself.
438 * b) to see if a task requested that the current task delete itself.
439 * This function is a little tricky to understand. Basically, you have a task that needs
440 * to be deleted however, this task has resources that it has allocated (memory buffers,
441 * semaphores, mailboxes, queues etc.). The task cannot be deleted otherwise these
442 * resources would not be freed. The requesting task calls OSTaskDelReq() to indicate that
443 * the task needs to be deleted. Deleting of the task is however, deferred to the task to
444 * be deleted. For example, suppose that task #10 needs to be deleted. The requesting task
445 * example, task #5, would call OSTaskDelReq(10). When task #10 gets to execute, it calls
446 * this function by specifying OS_PRIO_SELF and monitors the returned value. If the return
447 * value is OS_TASK_DEL_REQ, another task requested a task delete. Task #10 would look like
448 * this:
449 *
450 * void Task(void *data)
451 * {
452 * .
453 * .
454 * while (1) {
455 * OSTimeDly(1);
456 * if (OSTaskDelReq(OS_PRIO_SELF) == OS_TASK_DEL_REQ) {
457 * Release any owned resources;
458 * De-allocate any dynamic memory;
459 * OSTaskDel(OS_PRIO_SELF);
460 * }
461 * }
462 * }
463 *
464 * Arguments : prio is the priority of the task to request the delete from
465 *
466 * Returns : OS_NO_ERR if the task exist and the request has been registered
467 * OS_TASK_NOT_EXIST if the task has been deleted. This allows the caller to know whether
468 * the request has been executed.
469 * OS_TASK_DEL_IDLE if you requested to delete uC/OS-II's idle task
470 * OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
471 * (i.e. >= OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
472 * OS_TASK_DEL_REQ if a task (possibly another task) requested that the running task be
473 * deleted.
474 *********************************************************************************************************
475 */
476 /*$PAGE*/
477 #if OS_TASK_DEL_EN
INT8U OSTaskDelReq (INT8U prio) reentrant
{
BOOLEAN stat;
INT8U err;
OS_TCB *ptcb;
if (prio == OS_IDLE_PRIO) { /* Not allowed to delete idle task */
return (OS_TASK_DEL_IDLE);
}
if (prio >= OS_LOWEST_PRIO && prio != OS_PRIO_SELF) { /* Task priority valid ? */
C51 COMPILER V7.50 OS_TASK 12/12/2007 16:55:25 PAGE 9
return (OS_PRIO_INVALID);
}
if (prio == OS_PRIO_SELF) { /* See if a task is requesting to ... */
OS_ENTER_CRITICAL(); /* ... this task to delete itself */
stat = OSTCBCur->OSTCBDelReq; /* Return request status to caller */
OS_EXIT_CRITICAL();
return (stat);
} else {
OS_ENTER_CRITICAL();
if ((ptcb = OSTCBPrioTbl[prio]) != (OS_TCB *)0) { /* Task to delete must exist */
ptcb->OSTCBDelReq = OS_TASK_DEL_REQ; /* Set flag indicating task to be DEL. */
err = OS_NO_ERR;
} else {
err = OS_TASK_NOT_EXIST; /* Task must be deleted */
}
OS_EXIT_CRITICAL();
return (err);
}
}
#endif
509 /*$PAGE*/
510 /*
511 *********************************************************************************************************
512 * RESUME A SUSPENDED TASK
513 *
514 * Description: This function is called to resume a previously suspended task. This is the only call that
515 * will remove an explicit task suspension.
516 *
517 * Arguments : prio is the priority of the task to resume.
518 *
519 * Returns : OS_NO_ERR if the requested task is resumed
520 * OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
521 * (i.e. >= OS_LOWEST_PRIO)
522 * OS_TASK_RESUME_PRIO if the task to resume does not exist
523 * OS_TASK_NOT_SUSPENDED if the task to resume has not been suspended
524 *********************************************************************************************************
525 */
526
527 #if OS_TASK_SUSPEND_EN
INT8U OSTaskResume (INT8U prio) reentrant
{
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();
}
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