coremsgflushwait.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: coremsgflushwait.c,v 1.1.6.1 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_Flush_waiting_threads
 *
 *  This function flushes the message_queue's task wait queue.  The number
 *  of messages flushed from the queue is returned.
 *
 *  Input parameters:
 *    the_message_queue - the message_queue to be flushed
 *
 *  Output parameters:
 *    returns - the number of messages flushed from the queue
 */
 
void _CORE_message_queue_Flush_waiting_threads(
  CORE_message_queue_Control *the_message_queue
)
{
  /* XXX this is not supported for global message queues */

  /*
   *  IF there are no pending messages,
   *  THEN threads may be blocked waiting to RECEIVE a message,
   *  
   *  IF the pending message queue is full
   *  THEN threads may be blocked waiting to SEND a message
   *
   *  But in either case, we will return "unsatisfied nowait"
   *  to indicate that the blocking condition was not satisfied
   *  and that the blocking state was canceled.
   */

  _Thread_queue_Flush(
    &the_message_queue->Wait_queue,
    NULL,
    CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED_NOWAIT
  );
}