coremsgsubmit.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*
 *  CORE Message Queue Handler
 *
 *  DESCRIPTION:
 *
 *  This package is the implementation of the CORE Message Queue Handler.
 *  This core object provides task synchronization and communication functions
 *  via messages passed to queue objects.
 *
 *  COPYRIGHT (c) 1989-1999.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 *
 *  $Id: coremsgsubmit.c,v 1.7.4.1 2003/09/04 18:52:47 joel Exp $
 */

#include <rtems/system.h>
#include <rtems/score/chain.h>
#include <rtems/score/isr.h>
#include <rtems/score/object.h>
#include <rtems/score/coremsg.h>
#include <rtems/score/states.h>
#include <rtems/score/thread.h>
#include <rtems/score/wkspace.h>
#if defined(RTEMS_MULTIPROCESSING)
#include <rtems/score/mpci.h>
#endif

/*PAGE
 *
 *  _CORE_message_queue_Submit
 *
 *  This routine implements the send and urgent message functions. It
 *  processes a message that is to be submitted to the designated
 *  message queue.  The message will either be processed as a
 *  send message which it will be inserted at the rear of the queue
 *  or it will be processed as an urgent message which will be inserted
 *  at the front of the queue.
 *
 *  Input parameters:
 *    the_message_queue            - message is submitted to this message queue
 *    buffer                       - pointer to message buffer
 *    size                         - size in bytes of message to send
 *    id                           - id of message queue
 *    api_message_queue_mp_support - api specific mp support callout
 *    submit_type                  - send or urgent message
 *
 *  Output parameters:
 *    CORE_MESSAGE_QUEUE_SUCCESSFUL - if successful
 *    error code                    - if unsuccessful
 */

CORE_message_queue_Status _CORE_message_queue_Submit(
  CORE_message_queue_Control                *the_message_queue,
  void                                      *buffer,
  unsigned32                                 size,
  Objects_Id                                 id,
  CORE_message_queue_API_mp_support_callout  api_message_queue_mp_support,
  CORE_message_queue_Submit_types            submit_type,
  boolean                                    wait,
  Watchdog_Interval                          timeout
)
{
  ISR_Level                            level;
  CORE_message_queue_Buffer_control   *the_message;
  Thread_Control                      *the_thread;

  if ( size > the_message_queue->maximum_message_size ) {
    return CORE_MESSAGE_QUEUE_STATUS_INVALID_SIZE;
  }

  /*
   *  Is there a thread currently waiting on this message queue?
   */
      
  if ( the_message_queue->number_of_pending_messages == 0 ) {
    the_thread = _Thread_queue_Dequeue( &the_message_queue->Wait_queue );
    if ( the_thread ) {
      _CORE_message_queue_Copy_buffer(
        buffer,
        the_thread->Wait.return_argument,
        size
      );
      *(unsigned32 *)the_thread->Wait.return_argument_1 = size;
      the_thread->Wait.count = submit_type;
    
#if defined(RTEMS_MULTIPROCESSING)
      if ( !_Objects_Is_local_id( the_thread->Object.id ) )
        (*api_message_queue_mp_support) ( the_thread, id );
#endif
      return CORE_MESSAGE_QUEUE_STATUS_SUCCESSFUL;
    }
  }

  /*
   *  No one waiting on the message queue at this time, so attempt to
   *  queue the message up for a future receive.
   */

  if ( the_message_queue->number_of_pending_messages <
       the_message_queue->maximum_pending_messages ) {

    the_message =
        _CORE_message_queue_Allocate_message_buffer( the_message_queue );

    /*
     *  NOTE: If the system is consistent, this error should never occur.
     */

    if ( !the_message ) {
      return CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED;
    }

    _CORE_message_queue_Copy_buffer(
      buffer,
      the_message->Contents.buffer,
      size
    );
    the_message->Contents.size = size;
    the_message->priority  = submit_type;

    _CORE_message_queue_Insert_message(
       the_message_queue,
       the_message,
       submit_type
    );
    return CORE_MESSAGE_QUEUE_STATUS_SUCCESSFUL;
  }

  /*
   *  No message buffers were available so we may need to return an
   *  overflow error or block the sender until the message is placed
   *  on the queue.
   */

  if ( !wait ) {
    return CORE_MESSAGE_QUEUE_STATUS_TOO_MANY;
  }

  /*
   *  Do NOT block on a send if the caller is in an ISR.  It is
   *  deadly to block in an ISR.
   */

  if ( _ISR_Is_in_progress() ) {
    return CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED;
  }

  /*
   *  WARNING!! executing should NOT be used prior to this point.
   *  Thus the unusual choice to open a new scope and declare 
   *  it as a variable.  Doing this emphasizes how dangerous it
   *  would be to use this variable prior to here.
   */

  { 
    Thread_Control  *executing = _Thread_Executing;

    _ISR_Disable( level );
    _Thread_queue_Enter_critical_section( &the_message_queue->Wait_queue );
    executing->Wait.queue              = &the_message_queue->Wait_queue;
    executing->Wait.id                 = id;
    executing->Wait.return_argument    = (void *)buffer;
    executing->Wait.return_argument_1  = (void *)size;
    executing->Wait.count              = submit_type;
    _ISR_Enable( level );

    _Thread_queue_Enqueue( &the_message_queue->Wait_queue, timeout );
  }

  return CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED_WAIT;
}