taskvarlib.c

VxWorks操作系统内核源代码

*         }
*
*     if ((opGlobal = (OP_GLOBAL *) malloc (sizeof (OP_GLOBAL))) == NULL)
*         {
*         printErr ("operator%d: can't malloc opGlobal\en", opNum);
*         taskSuspend (0);
*         }
*     ...
*     }
* .CE
*
* RETURNS:
* OK, or ERROR if memory is insufficient for the task variable descriptor.
*
* INTERNAL
* The first time this routine is called the task switch and delete
* routines, taskVarSwitchHook() and taskVarDeleteHook(), are installed.
*
* SEE ALSO: taskVarDelete(), taskVarGet(), taskVarSet()
*/

STATUS taskVarAdd
    (
    int tid,    /* ID of task to have new variable */
    int *pVar   /* pointer to variable to be switched for task */
    )
    {
    FAST WIND_TCB *pTcb = taskTcb (tid);
    FAST TASK_VAR *pTaskVar;
    int	level;

    /* make sure task variable facility is installed */

    if (taskVarInit () != OK)
	return (ERROR);


    /* allocate descriptor for new task variable */

    pTaskVar = (TASK_VAR *) malloc (sizeof (TASK_VAR));

    if (pTaskVar == NULL)
	return (ERROR);

    pTaskVar->address = pVar;
    pTaskVar->value   = *pVar;


    /*
     * Link new task variable into list in stack header.  Locking interrupts
     * was chosen over task locking since locking and unlocking interrupts is
     * is much faster than task locking and very little code is in the
     * critical section.
     */

    level = intLock ();

    pTaskVar->next = pTcb->pTaskVar;
    pTcb->pTaskVar = pTaskVar;

    intUnlock (level);

    return (OK);
    }
/*******************************************************************************
*
* taskVarDelete - remove a task variable from a task
*
* This routine removes a specified task variable, <pVar>, from the specified
* task's context.  The private value of that variable is lost.
*
* RETURNS
* OK, or
* ERROR if the task variable does not exist for the specified task.
*
* SEE ALSO: taskVarAdd(), taskVarGet(), taskVarSet()
*/

STATUS taskVarDelete
    (
    int tid,    /* ID of task whose variable is to be removed */
    int *pVar   /* pointer to task variable to be removed */
    )
    {
    FAST TASK_VAR **ppTaskVar;		/* ptr to ptr to next node */
    FAST TASK_VAR *pTaskVar;
    WIND_TCB *pTcb = taskTcb (tid);

    if (pTcb == NULL)			/* check that task is valid */
	return (ERROR);

    /* find descriptor for specified task variable */

    for (ppTaskVar = &pTcb->pTaskVar;
	 *ppTaskVar != NULL;
	 ppTaskVar = &((*ppTaskVar)->next))
	{
	pTaskVar = *ppTaskVar;

	if (pTaskVar->address == pVar)
	    {
	    /* if active task, replace background value */

	    if (taskIdCurrent == pTcb)
		*pVar = pTaskVar->value;

	    *ppTaskVar = pTaskVar->next;/* delete variable from list */

	    free ((char *)pTaskVar);	/* free storage of deleted cell */

	    return (OK);
	    }
	}


    /* specified address is not a task variable for specified task */

    errnoSet (S_taskLib_TASK_VAR_NOT_FOUND);
    return (ERROR);
    }
/*******************************************************************************
*
* taskVarGet - get the value of a task variable
*
* This routine returns the private value of a task variable for a
* specified task.  The specified task is usually not the calling task,
* which can get its private value by directly accessing the variable.
* This routine is provided primarily for debugging purposes.
*
* RETURNS:
* The private value of the task variable, or
* ERROR if the task is not found or it
* does not own the task variable.
*
* SEE ALSO: taskVarAdd(), taskVarDelete(), taskVarSet()
*/

int taskVarGet
    (
    int tid,            /* ID of task whose task variable is to be retrieved */
    int *pVar           /* pointer to task variable */
    )
    {
    FAST TASK_VAR *pTaskVar;		/* ptr to next node */
    WIND_TCB *pTcb = taskTcb (tid);

    if (pTcb == NULL)
	return (ERROR);

    /* find descriptor for specified task variable */

    for (pTaskVar = pTcb->pTaskVar;
	 pTaskVar != NULL;
	 pTaskVar = pTaskVar->next)
	{
	if (pTaskVar->address == pVar)
	    return (taskIdCurrent == pTcb ? *pVar : pTaskVar->value);
	}


    /* specified address is not a task variable for specified task */

    errnoSet (S_taskLib_TASK_VAR_NOT_FOUND);
    return (ERROR);
    }
/*******************************************************************************
*
* taskVarSet - set the value of a task variable
*
* This routine sets the private value of the task variable for a specified
* task.  The specified task is usually not the calling task, which can set
* its private value by directly modifying the variable.  This routine is
* provided primarily for debugging purposes.
*
* RETURNS:
* OK, or
* ERROR if the task is not found or it
* does not own the task variable.
*
* SEE ALSO: taskVarAdd(), taskVarDelete(), taskVarGet()
*/

STATUS taskVarSet
    (
    int tid,    /* ID of task whose task variable is to be set */
    int *pVar,  /* pointer to task variable to be set for this task */
    int value   /* new value of task variable */
    )
    {
    FAST TASK_VAR *pTaskVar;	/* ptr to next node */
    WIND_TCB *pTcb = taskTcb (tid);

    if (pTcb == NULL)
	return (ERROR);

    /* find descriptor for specified task variable */

    for (pTaskVar = pTcb->pTaskVar;
	 pTaskVar != NULL;
	 pTaskVar = pTaskVar->next)
	{
	if (pTaskVar->address == pVar)
	    {
	    if (taskIdCurrent == pTcb)
		{
		*pVar = value;
		}
	    else
		pTaskVar->value = value;
	    return (OK);
	    }
	}

    /* specified address is not a task variable for specified task */

    errnoSet (S_taskLib_TASK_VAR_NOT_FOUND);
    return (ERROR);
    }
/********************************************************************************
* taskVarInfo - get a list of task variables of a task
*
* This routine provides the calling task with a list of all of the task
* variables of a specified task.  The unsorted array of task variables is
* copied to <varList>.
*
* CAVEATS
* Kernel rescheduling is disabled with taskLock() while task variables are
* looked up.  There is no guarantee that all the task variables are still
* valid or that new task variables have not been created by the time this
* routine returns.
*
* RETURNS: The number of task variables in the list.
*/

int taskVarInfo
    (
    int tid,            /* ID of task whose task variable is to be set */
    TASK_VAR varList[], /* array to hold task variable addresses */
    int maxVars         /* maximum variables varList can accommodate */
    )
    {
    FAST TASK_VAR *pTaskVar;			/* ptr to next node */
    WIND_TCB *	   pTcb	  = taskTcb (tid);
    int		   active = 0;

    if (pTcb == NULL)
	return (ERROR);

    taskLock ();				/* LOCK PREEMPTION */

    for (pTaskVar = pTcb->pTaskVar;
	 (pTaskVar != NULL) && (active < maxVars);
	 pTaskVar = pTaskVar->next, active ++)
	{
	varList[active] = *pTaskVar;
	}

    taskUnlock ();				/* UNLOCK PREEMPTION */

    return (active);
    }