evc.c

test file nucleus source

    /* Call stack checking function to check for an overflow condition.  */
    TCT_Check_Stack();

#endif

#ifdef  NU_ENABLE_HISTORY

    /* Make an entry that corresponds to this function in the system history
       log.  */
    HIC_Make_History_Entry(NU_DELETE_EVENT_GROUP_ID, (UNSIGNED) event_group,
                                        (UNSIGNED) 0, (UNSIGNED) 0);

#endif

    /* Protect against simultaneous access to the event group.  */
    TCT_System_Protect();

#ifdef INCLUDE_PROVIEW
    _RTProf_DumpEventGroup(RT_PROF_DELETE_EVENT_GROUP, event_group, RT_PROF_OK);
#endif /*INCLUDE_PROVIEW*/

    /* Clear the event group ID.  */
    event_group -> ev_id =  0;

    /* Release protection.  */
    TCT_Unprotect();

    /* Protect against access to the list of created event groups.  */
    TCT_Protect(&EVD_List_Protect);

    /* Remove the event_group from the list of created event groups.  */
    CSC_Remove_From_List(&EVD_Created_Event_Groups_List,
                                        &(event_group -> ev_created));

    /* Decrement the total number of created event groups.  */
    EVD_Total_Event_Groups--;

    /* Pickup the suspended task pointer list.  */
    suspend_ptr =  event_group -> ev_suspension_list;

    /* Walk the chain task(s) currently suspended on the event_group.  */
    preempt =  0;
    while (suspend_ptr)
    {

        /* Protect against system access.  */
        TCT_System_Protect();

        /* Resume the suspended task.  Insure that the status returned is
           NU_GROUP_DELETED.  */
        suspend_ptr -> ev_return_status =  NU_GROUP_DELETED;

        /* Point to the next suspend structure in the link.  */
        next_ptr =  (EV_SUSPEND *) (suspend_ptr -> ev_suspend_link.cs_next);

        /* Resume the specified task.  */
        preempt =  preempt |
            TCC_Resume_Task((NU_TASK *) suspend_ptr -> ev_suspended_task,
                                                NU_EVENT_SUSPEND);

        /* Determine if the next is the same as the current pointer.  */
        if (next_ptr == event_group -> ev_suspension_list)

            /* Clear the suspension pointer to signal the end of the list
               traversal.  */
            suspend_ptr =  NU_NULL;
        else

            /* Move the next pointer into the suspend block pointer.  */
            suspend_ptr =  next_ptr;

        /* Modify current protection.  */
        TCT_Set_Current_Protect(&EVD_List_Protect);

        /* Clear the system protection.  */
        TCT_System_Unprotect();
    }

    /* Determine if preemption needs to occur.  */
    if (preempt)

        /* Transfer control to system to facilitate preemption.  */
        TCT_Control_To_System();

    /* Release protection against access to the list of created
       event groups. */
    TCT_Unprotect();

    /* Return to user mode */
    NU_USER_MODE();

    /* Return a successful completion.  */
    return(NU_SUCCESS);
}


/*************************************************************************/
/*                                                                       */
/* FUNCTION                                                              */
/*                                                                       */
/*      EVC_Set_Events                                                   */
/*                                                                       */
/* DESCRIPTION                                                           */
/*                                                                       */
/*      This function sets event flags within the specified event flag   */
/*      group.  Event flags may be ANDed or ORed against the current     */
/*      events of the group.  Any task that is suspended on the group    */
/*      that has its request satisfied is resumed.                       */
/*                                                                       */
/* CALLED BY                                                             */
/*                                                                       */
/*      Application                                                      */
/*      EVCE_Set_Events                     Error checking shell         */
/*                                                                       */
/* CALLS                                                                 */
/*                                                                       */
/*      CSC_Remove_From_List                Remove from suspend list     */
/*      [HIC_Make_History_Entry]            Make entry in history log    */
/*      TCC_Resume_Task                     Resume a suspended task      */
/*      [TCT_Check_Stack]                   Stack checking function      */
/*      TCT_Control_To_System               Transfer control to system   */
/*      TCT_System_Protect                  Protect event group          */
/*      TCT_Unprotect                       Release protection           */
/*                                                                       */
/* INPUTS                                                                */
/*                                                                       */
/*      event_group_ptr                     Event Group control block ptr*/
/*      events                              Event flag setting           */
/*      operation                           Operation to perform on the  */
/*                                            event flag group (AND/OR)  */
/*                                                                       */
/* OUTPUTS                                                               */
/*                                                                       */
/*      NU_SUCCESS                          If service is successful     */
/*                                                                       */
/* HISTORY                                                               */
/*                                                                       */
/*         DATE                    REMARKS                               */
/*                                                                       */
/*      03-01-1993      Created initial version 1.0                      */
/*      04-19-1993      Verified version 1.0                             */
/*      03-01-1994      Changed function interfaces to                   */
/*                      match those in prototype,                        */
/*                      added register options, changed                  */
/*                      protection logic to reduce                       */
/*                      overhead, resulting in                           */
/*                      version 1.1                                      */
/*                                                                       */
/*      03-18-1994      Verified version 1.1                             */
/*      11-19-1996      Corrected SPR190.                                */
/*                                                                       */
/*************************************************************************/
STATUS  EVC_Set_Events(NU_EVENT_GROUP *event_group_ptr, UNSIGNED events,
                                                OPTION operation)
{

R1 EV_GCB      *event_group;                /* Event control block ptr   */
R2 EV_SUSPEND  *suspend_ptr;                /* Pointer to suspension blk */
R3 EV_SUSPEND  *next_ptr;                   /* Pointer to next suspend   */
R4 EV_SUSPEND  *last_ptr;                   /* Last suspension block ptr */
UNSIGNED        consume;                    /* Event flags to consume    */
UNSIGNED        compare;                    /* Event comparison variable */
INT             preempt;                    /* Preemption required flag  */
NU_SUPERV_USER_VARIABLES

    /* Switch to supervisor mode */
    NU_SUPERVISOR_MODE();

    /* Move input event group pointer into internal pointer.  */
    event_group =  (EV_GCB *) event_group_ptr;


#ifdef  NU_ENABLE_STACK_CHECK

    /* Call stack checking function to check for an overflow condition.  */
    TCT_Check_Stack();

#endif

#ifdef  NU_ENABLE_HISTORY

    /* Make an entry that corresponds to this function in the system history
       log.  */
    HIC_Make_History_Entry(NU_SET_EVENTS_ID, (UNSIGNED) event_group,
                                      (UNSIGNED) events, (UNSIGNED) operation);

#endif

    /* Protect against simultaneous access to the event group.  */
    TCT_System_Protect();

    /* Perform the specified operation on the current event flags in the
       group.  */
    if (operation & EV_AND)

        /* AND the specified events with the current events.  */
        event_group -> ev_current_events =
                        event_group -> ev_current_events & events;
    else

        /* OR the specified events with the current events.  */
        event_group -> ev_current_events =
                        event_group -> ev_current_events | events;

#ifdef INCLUDE_PROVIEW
    _RTProf_DumpEventGroup(RT_PROF_SET_EVENTS,event_group , RT_PROF_OK);
#endif /*INCLUDE_PROVIEW*/
    /* Determine if there are any tasks suspended for events from this
       event flag group.  */
    if (event_group -> ev_suspension_list)
    {

        /* Initialize the consumption bits to 0.  */
        consume =  0;

        /* Now, walk the chain of tasks suspended on this event flag group to
           determine if any of their requests can be satisfied.  */
        suspend_ptr =  event_group -> ev_suspension_list;

        /* Setup a pointer to the last suspension block.  */
        last_ptr =  (EV_SUSPEND *) suspend_ptr -> ev_suspend_link.cs_previous;

        /* Clear the preempt flag.  */
        preempt =  0;
        do
        {

            /* Determine if this request has been satisfied.  */

            /* First, find the event flags in common.  */
            compare =  event_group -> ev_current_events &
                                        suspend_ptr -> ev_requested_events;

            /* Second, determine if all the event flags must match.  */
            if (suspend_ptr -> ev_operation & EV_AND)

                /* Yes, an AND condition is present.  All requested events
                   must be present.  */
                compare =  (compare == suspend_ptr -> ev_requested_events);

            /* Setup the next pointer.  Note that this must be done before
               the suspended task is resumed, since its suspend block could
               get corrupted.  */
            next_ptr =  (EV_SUSPEND *) suspend_ptr -> ev_suspend_link.cs_next;

            /* If compare is non-zero, the suspended task's event request is
               satisfied.  */
            if (compare)
            {

                /* Decrement the number of tasks waiting counter.  */
                event_group -> ev_tasks_waiting--;

                /* Determine if consumption is requested.  */
                if (suspend_ptr -> ev_operation & EV_CONSUME)

                    /* Keep track of the event flags to consume.  */
                    consume =  consume | suspend_ptr -> ev_requested_events;

                /* Remove the first suspended block from the list.  */
                CSC_Remove_From_List((CS_NODE **)
                        &(event_group -> ev_suspension_list),
                                &(suspend_ptr -> ev_suspend_link));

                /* Setup the appropriate return value.  */
                suspend_ptr -> ev_return_status =  NU_SUCCESS;
                suspend_ptr -> ev_actual_events =
                                        event_group -> ev_current_events;

                /* Resume the suspended task.  */
                preempt = preempt |
                 TCC_Resume_Task((NU_TASK *) suspend_ptr -> ev_suspended_task,
                                                       NU_EVENT_SUSPEND);

            }

            /* Determine if there is another suspension block to examine.  */
            if (suspend_ptr != last_ptr)

                /* More to examine in the suspension list.  Look at the
                   next suspend block.  */
                suspend_ptr =  next_ptr;
            else

                /* End of the list has been reached.  Set the suspend pointer
                   to NULL to end the search.  */
                suspend_ptr =  NU_NULL;

        } while (suspend_ptr);

        /* Apply all of the gathered consumption bits.  */
        event_group -> ev_current_events =
           event_group -> ev_current_events & ~consume;

        /* Determine if a preempt condition is present.  */