OSTaskDel 的分析

OSTaskDel 的分析

OSTaskDel

语法：

INT8U OSTaskDel (INT8U prio);

功能描述：

删除一个任务。任务可以删除其自身，通过传递他自己的

优先级号，如果不知道优先级号，则可以传递 OS_PRIO_SELF。

被删除任务将返回到静止状态，并且通过再次创建此任务可以使

其重新激活。

参数说明：

prio

任务的优先级号

返回值：

OS_NO_ERR – 如果调用成功

OS_TASK_DEL_IDLE – 如果试图删除一个 uC/OS-II 的空闲任务

OS_PRIO_INVALID – 如果指定的优先级大于最大允许的

优先级(i.e. >= OS_LOWEST_PRIO)，或者没有指定OS_PRIO_SELF

OS_TASK_DEL_ERR – 如果要删除的任务不存在

OS_TASK_DEL_ISR – 如果试图从一个 ISR.中删除任务

 

源代码：

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;
    BOOLEAN       self;

 

    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      */
        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         */
        OSTCBFreeList   = ptcb;
        OS_EXIT_CRITICAL();
        OS_Sched();                                             /* Find new highest priority task      */
        return (OS_NO_ERR);
    }
    OS_EXIT_CRITICAL();
    return (OS_TASK_DEL_ERR);