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📄 os_task.lst

📁 实施操作系统的设计和开发
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                      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   */
                  }
                  if ((ptcb = OSTCBPrioTbl[prio]) != (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         */
C51 COMPILER V7.02b   OS_TASK                                                              11/29/2006 14:48:15 PAGE 8   

                      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
 435          /*$PAGE*/
 436          /*
 437          *********************************************************************************************************
 438          *                                    REQUEST THAT A TASK DELETE ITSELF
 439          *
 440          * Description: This function is used to:
 441          *                   a) notify a task to delete itself.
 442          *                   b) to see if a task requested that the current task delete itself.
 443          *              This function is a little tricky to understand.  Basically, you have a task that needs
 444          *              to be deleted however, this task has resources that it has allocated (memory buffers,
 445          *              semaphores, mailboxes, queues etc.).  The task cannot be deleted otherwise these
 446          *              resources would not be freed.  The requesting task calls OSTaskDelReq() to indicate that
 447          *              the task needs to be deleted.  Deleting of the task is however, deferred to the task to
 448          *              be deleted.  For example, suppose that task #10 needs to be deleted.  The requesting task
 449          *              example, task #5, would call OSTaskDelReq(10).  When task #10 gets to execute, it calls
 450          *              this function by specifying OS_PRIO_SELF and monitors the returned value.  If the return
 451          *              value is OS_TASK_DEL_REQ, another task requested a task delete.  Task #10 would look like
 452          *              this:
 453          *
 454          *                   void Task(void *data)
 455          *                   {
 456          *                       .
 457          *                       .
 458          *                       while (1) {
 459          *                           OSTimeDly(1);
 460          *                           if (OSTaskDelReq(OS_PRIO_SELF) == OS_TASK_DEL_REQ) {
 461          *                               Release any owned resources;
 462          *                               De-allocate any dynamic memory;
 463          *                               OSTaskDel(OS_PRIO_SELF);
 464          *                           }
 465          *                       }
 466          *                   }
 467          *
 468          * Arguments  : prio    is the priority of the task to request the delete from
 469          *
 470          * Returns    : OS_NO_ERR          if the task exist and the request has been registered
 471          *              OS_TASK_NOT_EXIST  if the task has been deleted.  This allows the caller to know whether
 472          *                                 the request has been executed.
 473          *              OS_TASK_DEL_IDLE   if you requested to delete uC/OS-II's idle task
 474          *              OS_PRIO_INVALID    if the priority you specify is higher that the maximum allowed
 475          *                                 (i.e. >= OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
 476          *              OS_TASK_DEL_REQ    if a task (possibly another task) requested that the running task be
 477          *                                 deleted.
 478          *********************************************************************************************************
 479          */
 480          /*$PAGE*/
 481          #if OS_TASK_DEL_EN > 0
              INT8U  OSTaskDelReq (INT8U prio) reentrant
              {
              #if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
                  OS_CPU_SR  cpu_sr;
              #endif
                  BOOLEAN    stat;
C51 COMPILER V7.02b   OS_TASK                                                              11/29/2006 14:48:15 PAGE 9   

                  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 ...  */
                      OS_ENTER_CRITICAL();                                    /* ... this task to delete itself      */
                      stat = OSTCBCur->OSTCBDelReq;                           /* Return request status to caller     */
                      OS_EXIT_CRITICAL();
                      return (stat);
                  }
                  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
 517          /*$PAGE*/
 518          /*
 519          *********************************************************************************************************
 520          *                                        RESUME A SUSPENDED TASK
 521          *
 522          * Description: This function is called to resume a previously suspended task.  This is the only call that
 523          *              will remove an explicit task suspension.
 524          *
 525          * Arguments  : prio     is the priority of the task to resume.
 526          *
 527          * Returns    : OS_NO_ERR                if the requested task is resumed
 528          *              OS_PRIO_INVALID          if the priority you specify is higher that the maximum allowed
 529          *                                       (i.e. >= OS_LOWEST_PRIO)
 530          *              OS_TASK_RESUME_PRIO      if the task to resume does not exist
 531          *              OS_TASK_NOT_SUSPENDED    if the task to resume has not been suspended
 532          *********************************************************************************************************
 533          */
 534          
 535          #if OS_TASK_SUSPEND_EN > 0
              INT8U  OSTaskResume (INT8U prio) reentrant
              {
              #if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
                  OS_CPU_SR  cpu_sr;
              #endif
                  OS_TCB    *ptcb;
              
              
              #if OS_ARG_CHK_EN > 0
                  if (prio >= OS_LOWEST_PRIO) {                               /* Make sure task priority is valid    */
                      return (OS_PRIO_INVALID);
                  }
              #endif
                  OS_ENTER_CRITICAL();
C51 COMPILER V7.02b   OS_TASK                                                              11/29/2006 14:48:15 PAGE 10  

                  if ((ptcb = OSTCBPrioTbl[prio]) == (OS_TCB *)0) {           /* Task to suspend must exist          */
                      OS_EXIT_CRITICAL();
                      return (OS_TASK_RESUME_PRIO);
                  }
                  if ((ptcb->OSTCBStat & OS_STAT_SUSPEND) != 0x00) {                     /* 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();
                          OS_Sched();
                      } else {
                          OS_EXIT_CRITICAL();
                      }
                      return (OS_NO_ERR);
                  }
                  OS_EXIT_CRITICAL();
                  return (OS_TASK_NOT_SUSPENDED);
              }

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