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/*

 *  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.OARcorp.com/rtems/license.html.

 *

 *  $Id: coremsgseize.c,v 1.2 2001-09-27 11:59:34 chris 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_Seize

 *

 *  This kernel routine dequeues a message, copies the message buffer to

 *  a given destination buffer, and frees the message buffer to the

 *  inactive message pool.  The thread will be blocked if wait is TRUE,

 *  otherwise an error will be given to the thread if no messages are available.

 *

 *  Input parameters:

 *    the_message_queue - pointer to message queue

 *    id                - id of object we are waitig on

 *    buffer            - pointer to message buffer to be filled

 *    size              - pointer to the size of buffer to be filled

 *    wait              - TRUE if wait is allowed, FALSE otherwise

 *    timeout           - time to wait for a message

 *

 *  Output parameters:  NONE

 *

 *  NOTE: Dependent on BUFFER_LENGTH

 *

 *  INTERRUPT LATENCY:

 *    available

 *    wait

 */

void _CORE_message_queue_Seize(

  CORE_message_queue_Control      *the_message_queue,

  Objects_Id                       id,

  void                            *buffer,

  unsigned32                      *size,

  boolean                          wait,

  Watchdog_Interval                timeout

)

{

  ISR_Level                          level;

  CORE_message_queue_Buffer_control *the_message;

  Thread_Control                    *executing;

  Thread_Control                    *the_thread;

  executing = _Thread_Executing;

  executing->Wait.return_code = CORE_MESSAGE_QUEUE_STATUS_SUCCESSFUL;

  _ISR_Disable( level );

  if ( the_message_queue->number_of_pending_messages != 0 ) {

    the_message_queue->number_of_pending_messages -= 1;

    the_message = _CORE_message_queue_Get_pending_message( the_message_queue );

    _ISR_Enable( level );

    *size = the_message->Contents.size;

    _Thread_Executing->Wait.count = the_message->priority;

    _CORE_message_queue_Copy_buffer(the_message->Contents.buffer,buffer,*size);

    /*

     *  There could be a thread waiting to send a message.  If there

     *  is not, then we can go ahead and free the buffer.

     *

     *  NOTE: If we note that the queue was not full before this receive,

     *  then we can avoid this dequeue.

     */

    the_thread = _Thread_queue_Dequeue( &the_message_queue->Wait_queue );

    if ( !the_thread ) {

      _CORE_message_queue_Free_message_buffer( the_message_queue, the_message );

      return;

    }

    /*

     *  There was a thread waiting to send a message.  This code

     *  puts the messages in the message queue on behalf of the

     *  waiting task.

     */

    the_message->priority  = the_thread->Wait.count;

    the_message->Contents.size = (unsigned32)the_thread->Wait.return_argument_1;

    _CORE_message_queue_Copy_buffer(

      the_thread->Wait.return_argument,

      the_message->Contents.buffer,

      the_message->Contents.size

    );

    _CORE_message_queue_Insert_message(

       the_message_queue,

       the_message,

       the_message->priority

    );

    return;

  }

  if ( !wait ) {

    _ISR_Enable( level );

    executing->Wait.return_code = CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED_NOWAIT;

    return;

  }

  _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;

  /* Wait.count will be filled in with the message priority */

  _ISR_Enable( level );

  _Thread_queue_Enqueue( &the_message_queue->Wait_queue, timeout );

}