os_task.c

完整的ucos实例

* 
* 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 > 0 
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) 
{ 
#if OS_CRITICAL_METHOD == 3                  /* Allocate storage for CPU status register               */ 
    OS_CPU_SR  cpu_sr; 
#endif 
    OS_STK    *psp; 
    INT8U      err; 
 
 
#if OS_ARG_CHK_EN > 0 
    if (prio > OS_LOWEST_PRIO) {             /* Make sure priority is within allowable range           */ 
        return (OS_PRIO_INVALID); 
    } 
#endif 
    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) != 0x0000) ||   /* See if stack checking has been enabled     */ 
            ((opt & OS_TASK_OPT_STK_CLR) != 0x0000)) {   /* See if stack needs to be cleared           */ 
            #if OS_STK_GROWTH == 1 
            (void)memset(pbos, 0, stk_size * sizeof(OS_STK)); 
            #else 
            (void)memset(ptos, 0, stk_size * sizeof(OS_STK)); 
            #endif 
        } 
 
        psp = (OS_STK *)OSTaskStkInit(task, pdata, ptos, opt); /* Initialize the task's stack          */ 
        err = OS_TCBInit(prio, psp, pbos, id, stk_size, pext, opt); 
        if (err == OS_NO_ERR) { 
            OS_ENTER_CRITICAL(); 
            OSTaskCtr++;                                       /* Increment the #tasks counter         */ 
            OS_EXIT_CRITICAL(); 
            if (OSRunning == TRUE) {                           /* Find HPT if multitasking has started */ 
                OS_Sched(); 
            } 
        } else { 
            OS_ENTER_CRITICAL(); 
            OSTCBPrioTbl[prio] = (OS_TCB *)0;                  /* Make this priority avail. to others  */ 
            OS_EXIT_CRITICAL(); 
        } 
        return (err); 
    } 
    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 OS_Dummy() is called after OS_EXIT_CRITICAL() because, on most processors, 
*                 the next instruction following the enable interrupt instruction is ignored.   
*              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 an 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_EN > 0 
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); 
} 
#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_EN > 0 
INT8U  OSTaskDelReq (INT8U prio) 
{ 
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */ 
    OS_CPU_SR  cpu_sr; 
#endif 
    BOOLEAN    stat; 
    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 ...  */