pic.c

test file nucleus source

            /* Move the read pointer to the top of the pipe area.  */
            source =  pipe -> pi_start;

        /* Determine if the pipe supports variable-length messages.  If
           so, pad bytes are needed to keep UNSIGNED alignment.  */
        if (pad)
        {

            /* Variable-size message.  Add pad bytes to the read
               pointer.  */

            /* Calculate the number of bytes remaining from the read
               pointer to the bottom of the pipe.  */
            copy_size =  pipe -> pi_end - source;

            /* If there is not enough room at the bottom of the pipe, the
               pad bytes must be wrapped around to the top.  */
            if (copy_size <= pad)

                /* Move read pointer to the top of the pipe and make the
                   necessary adjustment.  */
                source =  pipe -> pi_start + (pad - copy_size);
            else

                /* There is enough room in the pipe to simply add the
                   the pad bytes to the read pointer.  */
                source =  source + pad;

            /* Add pad bytes to the available bytes count.  */
            pipe -> pi_available =  pipe -> pi_available + pad;
        }

        /* Adjust the actual read pointer.  */
        pipe -> pi_read =  source;

        /* Increment the number of available bytes.  */
        pipe -> pi_available =  pipe -> pi_available + size;

        /* Decrement the number of messages in the pipe.  */
        pipe -> pi_messages--;

        /* Return the number of bytes received.  */
        *actual_size =  size;

#ifdef INCLUDE_PROVIEW
        _RTProf_DumpPipe(RT_PROF_RECEIVE_FROM_PIPE,pipe,RT_PROF_OK);
#endif /* INCLUDE_PROVIEW */

        /* Determine if any tasks suspended on a full pipe can be woken
           up.  */
        if (pipe -> pi_suspension_list)
        {

            /* Pickup the suspension list and examine suspension blocks
               to see if the message could now fit in the pipe.  */
            suspend_ptr =  pipe -> pi_suspension_list;
            preempt =      NU_FALSE;
            size =         suspend_ptr -> pi_message_size;
            i =            0;
            pad =          0;

            /* Overhead of each pipe message.  */
            if (!pipe -> pi_fixed_size)
            {

                /* Variable messages have one additional word of overhead.  */
                i =  sizeof(UNSIGNED);

                /* Calculate the number of pad bytes necessary to keep
                   the pipe write pointer on an UNSIGNED data element
                   alignment.  */
                pad =  (((size + sizeof(UNSIGNED) - 1)/sizeof(UNSIGNED)) *
                                        sizeof(UNSIGNED)) - size;

                /* Insure that padding is included in the overhead.  */
                i =  i + ((INT) pad);
            }

            while ((suspend_ptr) && ((size + i) <= pipe -> pi_available))
            {

                /* Place the suspended task's message into the pipe.  */

                /* Setup the source and destination pointers.  */
                source =       suspend_ptr -> pi_message_area;
                destination =  pipe -> pi_write;

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

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

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

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

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

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

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

                    /* Decrement the number of bytes remaining for this
                       extra word of overhead.  */
                    pipe -> pi_available =  pipe -> pi_available -
                                                        sizeof(UNSIGNED);

                    /* Calculate the number of bytes remaining from the write
                       pointer to the bottom of the pipe.  */
                    copy_size =  pipe -> pi_end - destination;

                    /* Determine if the message needs to be wrapped around the
                       edge of the pipe 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 =  pipe -> pi_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 >= pipe -> pi_end)

                    /* Move the write pointer to the top of the pipe area.  */
                    destination =  pipe -> pi_start;

                /* Determine if the pipe supports variable-length messages.  If
                   so, pad bytes are needed to keep UNSIGNED alignment.  */
                if (pad)
                {

                    /* Variable-size message.  Add pad bytes to the write
                       pointer.  */

                    /* Calculate the number of bytes remaining from the write
                       pointer to the bottom of the pipe.  */
                    copy_size =  pipe -> pi_end - destination;

                    /* If there is not enough room at the bottom of the pipe,
                       the pad bytes must be wrapped around to the top.  */
                    if (copy_size <= pad)

                        /* Move write pointer to the top of the pipe and make
                           the necessary adjustment.  */
                        destination =  pipe -> pi_start + (pad - copy_size);
                    else

                        /* There is enough room in the pipe to simply add
                           the pad bytes to the write pointer.  */
                        destination =  destination + pad;

                    /* Decrement the number of available bytes.  */
                    pipe -> pi_available =  pipe -> pi_available - pad;
                }

                /* Update the actual write pointer.  */
                pipe -> pi_write =  destination;

                /* Decrement the number of available bytes.  */
                pipe -> pi_available =  pipe -> pi_available - size;

                /* Increment the number of messages in the pipe.  */
                pipe -> pi_messages++;

                /* Decrement the number of tasks waiting counter.  */
                pipe -> pi_tasks_waiting--;

                /* Remove the first suspended block from the list.  */
                CSC_Remove_From_List((CS_NODE **)
                    &(pipe -> pi_suspension_list),
                                &(suspend_ptr -> pi_suspend_link));

                /* Return a successful status.  */
                suspend_ptr -> pi_return_status =  NU_SUCCESS;

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

                /* Setup suspend pointer to the head of the list.  */
                suspend_ptr =  pipe -> pi_suspension_list;

                /* Determine if there really is another suspended block.  If
                   there is and the pipe supports variable length messages,
                   calculate new size and padding parameters.  */
                if ((suspend_ptr) && (!pipe -> pi_fixed_size))
                {

                    /* Get the next message size.  */
                    size =   suspend_ptr -> pi_message_size;

                    /* Variable messages have one additional word of
                       overhead.  */
                    i =  sizeof(UNSIGNED);

                    /* Calculate the number of pad bytes necessary to
                       keep the pipe write pointer on an UNSIGNED data element
                       alignment.  */
                    pad =  (((size + sizeof(UNSIGNED) - 1)/sizeof(UNSIGNED)) *
                                          sizeof(UNSIGNED)) - size;

                    /* Insure that padding is included in the overhead.  */
                    i =  i + ((INT) pad);
                }
            }

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

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

        /* pipe is empty.  Determine if the task wants to suspend.  */
        if (suspend)
        {

            /* Increment the number of tasks waiting on the pipe counter. */
            pipe -> pi_tasks_waiting++;

#ifdef INCLUDE_PROVIEW
            _RTProf_DumpPipe(RT_PROF_RECEIVE_FROM_PIPE,pipe,RT_PROF_WAIT);
#endif /* INCLUDE_PROVIEW */

            /* Setup the suspend block and suspend the calling task.  */
            suspend_ptr =  &suspend_block;
            suspend_ptr -> pi_pipe =                     pipe;
            suspend_ptr -> pi_suspend_link.cs_next =     NU_NULL;
            suspend_ptr -> pi_suspend_link.cs_previous = NU_NULL;
            suspend_ptr -> pi_message_area =             (BYTE_PTR) message;
            suspend_ptr -> pi_message_size =             size;
            task =                            (TC_TCB *) TCT_Current_Thread();
            suspend_ptr -> pi_suspended_task =           task;

            /* Determine if priority or FIFO suspension is associated with the
               pipe.  */
            if (pipe -> pi_fifo_suspend)