quc.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_SEND_TO_QUEUE_ID, (UNSIGNED) queue,
                                        (UNSIGNED) message, (UNSIGNED) size);

#endif

    /* Initialize the status as successful.  */
    status =  NU_SUCCESS;

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

    /* Determine if an extra word of overhead needs to be added to the
       calculation.  */
    if (queue -> qu_fixed_size)

        /* No overhead.  */
        i =  0;
    else
    {
        /* Variable messages have one additional word of overhead.  */
        i =  1;

        /* Make special check to see if a suspension needs to be
           forced for a variable length message.  */
        if ((queue -> qu_suspension_list) && (queue -> qu_messages))
        {

            /* Pickup task control block pointer.  */
            task =  (TC_TCB *) TCT_Current_Thread();

            /* Now we know that there are other task(s) are suspended trying
               to send a variable length message.  Determine whether or not
               a suspension should be forced.  */
            if ((queue -> qu_fifo_suspend) ||
                (suspend == NU_NO_SUSPEND) ||
                ((queue -> qu_suspension_list) -> qu_suspend_link.cs_priority <=
                                                    TCC_Task_Priority(task)))

                /* Bump the computed size to avoid placing the new variable
                   length message ahead of the suspended tasks.  */
                i =  (INT) queue -> qu_available;
        }
    }

    /* Determine if there is enough room in the queue for the message.  The
       extra logic is to prevent a variable-length message from sn*/
    if (queue -> qu_available < (size + i))
    {

        /* Queue does not have room for the message.  Determine if
           suspension is required.  */
        if (suspend)
        {

            /* Suspension is requested.   */

            /* Increment the number of tasks waiting.  */
            queue -> qu_tasks_waiting++;

#ifdef INCLUDE_PROVIEW
            _RTProf_DumpQueue(RT_PROF_SEND_TO_QUEUE,queue,RT_PROF_WAIT);
#endif

            /* Setup the suspend block and suspend the calling task.  */
            suspend_ptr =  &suspend_block;
            suspend_ptr -> qu_queue =                    queue;
            suspend_ptr -> qu_suspend_link.cs_next =     NU_NULL;
            suspend_ptr -> qu_suspend_link.cs_previous = NU_NULL;
            suspend_ptr -> qu_message_area =             (UNSIGNED_PTR) message;
            suspend_ptr -> qu_message_size =             size;
            task =                            (TC_TCB *) TCT_Current_Thread();
            suspend_ptr -> qu_suspended_task =           task;

            /* Determine if priority or FIFO suspension is associated with the
               queue.  */
            if (queue -> qu_fifo_suspend)
            {

                /* FIFO suspension is required.  Link the suspend block into
                   the list of suspended tasks on this queue.  */
                CSC_Place_On_List((CS_NODE **) &(queue -> qu_suspension_list),
                                        &(suspend_ptr -> qu_suspend_link));
            }
            else
            {

                /* Get the priority of the current thread so the suspend block
                   can be placed in the appropriate place.  */
                suspend_ptr -> qu_suspend_link.cs_priority =
                                                 TCC_Task_Priority(task);

                CSC_Priority_Place_On_List((CS_NODE **)
                                &(queue -> qu_suspension_list),
                                        &(suspend_ptr -> qu_suspend_link));
            }

            /* Finally, suspend the calling task. Note that the suspension call
               automatically clears the protection on the queue.  */
            TCC_Suspend_Task((NU_TASK *) task, NU_QUEUE_SUSPEND,
                                        QUC_Cleanup, suspend_ptr, suspend);

            /* Pickup the return status.  */
            status =  suspend_ptr -> qu_return_status;
        }
        else
        {

            /* Return a status of NU_QUEUE_FULL because there is no
               room in the queue for the message.  */
            status =  NU_QUEUE_FULL;

#ifdef INCLUDE_PROVIEW
            _RTProf_DumpQueue(RT_PROF_SEND_TO_QUEUE,queue,RT_PROF_FAIL);
#endif

        }
    }
    else
    {

        /* Determine if a task is waiting on an empty queue.  */
        if ((queue -> qu_suspension_list) && (queue -> qu_messages == 0))
        {

            /* Task is waiting on an empty queue for a message.  */

            /* Decrement the number of tasks waiting on queue.  */
            queue -> qu_tasks_waiting--;

#ifdef INCLUDE_PROVIEW
        _RTProf_DumpQueue(RT_PROF_SEND_TO_QUEUE,queue,RT_PROF_OK);
#endif

            /* Remove the first suspended block from the list.  */
            suspend_ptr =  queue -> qu_suspension_list;
            CSC_Remove_From_List((CS_NODE **) &(queue -> qu_suspension_list),
                                          &(suspend_ptr -> qu_suspend_link));

            /* Setup the source and destination pointers.  */
            source =       (UNSIGNED_PTR) message;
            destination =  suspend_ptr -> qu_message_area;

            /* Initialize the return status.  */
            suspend_ptr -> qu_return_status =  NU_SUCCESS;

            /* Loop to actually copy the message.  */
            i = (INT) size;
            do
            {
                *(destination++) =  *(source);
                if ((--i) == 0)
                    break;
                source++;
            } while (1);

            /* Return the size of the message copied.  */
            suspend_ptr -> qu_actual_size =  size;

            /* Wakeup the waiting task and check for preemption.  */
            preempt =
                TCC_Resume_Task((NU_TASK *) suspend_ptr -> qu_suspended_task,
                                                     NU_QUEUE_SUSPEND);

            /* Determine if preemption needs to take place. */
            if (preempt)

                 /* Transfer control to the system if the resumed task function
                   detects a preemption condition.  */
                TCT_Control_To_System();
        }
        else
        {

            /* There is enough room in the queue and no task is waiting.  */

            /* Setup the source pointer.  */
            source =       (UNSIGNED_PTR) message;
            destination =  queue -> qu_write;

            /* Process according to the type of message supported.  */
            if (queue -> qu_fixed_size)
            {

                /* Fixed-size messages are supported by this queue.  */

                /* Loop to copy the message into the queue area.  */
                i =  (INT) size;
                do
                {
                    *(destination++) =  *(source);
                    if ((--i) == 0)
                        break;
                    source++;
                } while (1);
            }
            else
            {

                /* Variable-size messages are supported.  Processing must
                   check for queue wrap-around conditions.  */

                /* Place message size in first location.  */
                *(destination++) =  size;

                /* Check for a wrap-around condition on the queue.  */
                if (destination >= queue -> qu_end)

                    /* Wrap the write pointer back to the top of the queue
                       area.  */
                    destination =  queue -> qu_start;

                /* Decrement the number of words remaining by 1 for this
                   extra word of overhead.  */
                queue -> qu_available--;

                /* Calculate the number of words remaining from the write
                   pointer to the bottom of the queue.  */
                copy_size =  queue -> qu_end - destination;

                /* Determine if the message needs to be wrapped around the
                   edge of the queue area.  */
                if (copy_size >= size)
                {

                    /* Copy the whole message at once.  */
                    i =  (INT) size;
                    do
                    {
                        *(destination++) =  *(source);
                        if ((--i) == 0)
                            break;
                        source++;
                    } while (1);
                }
                else
                {

                    /* Copy the first half of the message.  */
                    i =  (INT) copy_size;
                    do
                    {
                        *(destination) =  *(source++);
                        if ((--i) == 0)
                            break;
                        destination++;
                    } while (1);

                    /* Copy the second half of the message.  */
                    destination =  queue -> qu_start;
                    i =  (INT) (size - copy_size);
                    do
                    {
                        *(destination++) =  *(source);
                        if ((--i) == 0)
                            break;
                        source++;
                    } while (1);
                }
            }

            /* Check again for wrap-around condition on the write pointer. */
            if (destination >= queue -> qu_end)

                /* Move the write pointer to the top of the queue area.  */
                queue -> qu_write =  queue -> qu_start;
            else

                /* Simply copy the last position of the destination pointer
                   into the write pointer.  */
                queue -> qu_write =  destination;

            /* Decrement the number of available words.  */
            queue -> qu_available =  queue -> qu_available - size;

            /* Increment the number of messages in the queue.  */
            queue -> qu_messages++;

#ifdef INCLUDE_PROVIEW
        _RTProf_DumpQueue(RT_PROF_SEND_TO_QUEUE,queue,RT_PROF_OK);
#endif

        }