?? tmc.c
字號(hào):
/* Start the specified timer. */
TMC_Start_Timer(timer, time);
}
/*************************************************************************/
/* */
/* FUNCTION */
/* */
/* TMC_Stop_Task_Timer */
/* */
/* DESCRIPTION */
/* */
/* This function is responsible for stopping a task timer. Note */
/* that there are some special protection considerations since */
/* this function is called from the task control component. This */
/* routine must be called from Supervisor mode in a Supervisor/User */
/* mode switching kernel. */
/* */
/* CALLED BY */
/* */
/* TCC_Resume_Task Resume task function */
/* TCC_Terminate_Task Terminate task function */
/* */
/* CALLS */
/* */
/* TMC_Stop_Timer Stop the timer */
/* */
/* INPUTS */
/* */
/* timer Timer control block pointer */
/* */
/* OUTPUTS */
/* */
/* None */
/* */
/* HISTORY */
/* */
/* DATE REMARKS */
/* */
/* 03-01-1993 Created initial version 1.0 */
/* 04-19-1993 Verified version 1.0 */
/* 03-01-1994 Removed protection logic since */
/* system protect is in force at */
/* the time this function is */
/* called, resulting in */
/* version 1.1 */
/* */
/* 03-18-1994 Verified version 1.1 */
/* */
/*************************************************************************/
VOID TMC_Stop_Task_Timer(TM_TCB *timer)
{
/* Stop the specified timer - if it is still active. */
if (timer -> tm_next_timer)
TMC_Stop_Timer(timer);
}
/*************************************************************************/
/* */
/* FUNCTION */
/* */
/* TMC_Start_Timer */
/* */
/* DESCRIPTION */
/* */
/* This function is responsible for starting both application and */
/* task timers. This routine must be called from Supervisor mode */
/* in a Supervisor/User mode switching kernel. */
/* */
/* CALLED BY */
/* */
/* TMC_Control_Timer Control application timer */
/* TMC_Start_Task_Timer Start task timer */
/* */
/* CALLS */
/* */
/* TMT_Read_Timer Read current timer counter */
/* TMT_Adjust_Timer Adjust the count-down timer */
/* TMT_Enable_Timer Enable count-down timer */
/* */
/* INPUTS */
/* */
/* timer Timer control block pointer */
/* time Time associated with timer */
/* */
/* OUTPUTS */
/* */
/* None */
/* */
/* HISTORY */
/* */
/* DATE REMARKS */
/* */
/* 03-01-1993 Created initial version 1.0 */
/* 04-19-1993 Verified version 1.0 */
/* 08-09-1993 Added logic to check for timer */
/* expiration before or during */
/* another LISR's access, */
/* resulting in version 1.0a */
/* 08-09-1993 Verified version 1.0a */
/* 03-01-1994 Removed disable timer logic to */
/* insure there is no timer loss, */
/* added register logic, */
/* resulting in version 1.1 */
/* */
/* 03-18-1994 Verified version 1.1 */
/* */
/*************************************************************************/
VOID TMC_Start_Timer(TM_TCB *timer, UNSIGNED time)
{
R1 TM_TCB *list_ptr; /* Working pointer timer ptr */
UNSIGNED elapsed; /* Elapsed time variable */
INT done; /* Search finished flag */
/* Note that protection over the active timer list is in force when this
function is called. */
/* Determine if the active list is empty. */
if (TMD_Active_Timers_List == NU_NULL)
{
/* Place the timer on an empty list. */
timer -> tm_next_timer = timer;
timer -> tm_previous_timer = timer;
/* Link the timer to the list head. */
TMD_Active_Timers_List = timer;
/* Setup the actual count-down timer structures. */
TMD_Timer_Start = time;
timer -> tm_remaining_time = time;
/* BUG FIX FOR NU_RESET WITH INITIAL TIME OF 0 */
/* Determine if there is any time remaining on the timer.
If so, enable the timer. Otherwise, the Timer HISR is
already pending, so skip starting the timer again. */
if (time != 0)
/* Start the actual count-down timer. */
TMT_Enable_Timer(TMD_Timer_Start);
else
TMD_Timer_State = TM_EXPIRED;
}
else
{
/* Place the new timer into the list. */
/* Pickup the head of the list. */
list_ptr = TMD_Active_Timers_List;
/* Determine if the timer is being added while the timer
expiration task is running. If so, don't attempt to adjust
the expiration list. If not, adjust the list. */
if (!TMD_Active_List_Busy)
{
/* Calculate the elapsed amount of time from the last timer
request. */
elapsed = TMD_Timer_Start - TMT_Read_Timer();
/* Adjust the first entry in the timer list and the timer
start value accordingly. */
TMD_Timer_Start = TMD_Timer_Start - elapsed;
/* Make sure the remaining time is never below zero. */
if (list_ptr -> tm_remaining_time > elapsed)
{
list_ptr -> tm_remaining_time = list_ptr -> tm_remaining_time
- elapsed;
}
else
{
list_ptr -> tm_remaining_time = 0;
}
}
/* At this point the timer list is accurate again. Find the
appropriate place on the timer list for the new timer. */
/* Determine where to place the timer in the list. */
done = NU_FALSE;
do
{
/* Determine if the timer belongs before the current timer
pointed to by list_ptr. */
if (time < list_ptr -> tm_remaining_time)
{
/* Update the time of the next timer. */
list_ptr -> tm_remaining_time =
list_ptr -> tm_remaining_time - time;
/* Determine if an insertion at the head of the list is
present. */
if (list_ptr == TMD_Active_Timers_List)
/* Move the list head to the new timer. */
TMD_Active_Timers_List = timer;
/* Set the done flag to end the search. */
done = NU_TRUE;
}
else
{
/* Decrement the time by the remaining value of each timer in
the list. In this way, the list never has to be searched
again. */
time = time - list_ptr -> tm_remaining_time;
/* Move the list pointer to the next timer in the list. */
list_ptr = list_ptr -> tm_next_timer;
/* Check to see if the list has wrapped around. */
if (list_ptr == TMD_Active_Timers_List)
/* Searching is done. */
done = NU_TRUE;
}
} while (!done);
/* Link the new timer into the list. */
timer -> tm_next_timer = list_ptr;
timer -> tm_previous_timer = list_ptr -> tm_previous_timer;
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