coresemsurrender.c

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

/*
 *  CORE Semaphore Handler
 *
 *  DESCRIPTION:
 *
 *  This package is the implementation of the CORE Semaphore Handler.
 *  This core object utilizes standard Dijkstra counting semaphores to provide
 *  synchronization and mutual exclusion capabilities.
 *
 *  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: coresemsurrender.c,v 1.2.6.2 2003/09/04 18:52:47 joel Exp $
 */

#include <rtems/system.h>
#include <rtems/score/isr.h>
#include <rtems/score/coresem.h>
#include <rtems/score/states.h>
#include <rtems/score/thread.h>
#include <rtems/score/threadq.h>
#if defined(RTEMS_MULTIPROCESSING)
#include <rtems/score/mpci.h>
#endif

/*PAGE
 *
 *  _CORE_semaphore_Surrender
 *
 *  Input parameters:
 *    the_semaphore            - the semaphore to be flushed
 *    id                       - id of parent semaphore
 *    api_semaphore_mp_support - api dependent MP support actions
 *
 *  Output parameters:
 *    CORE_SEMAPHORE_STATUS_SUCCESSFUL - if successful
 *    core error code                  - if unsuccessful
 *
 *  Output parameters:
 */

CORE_semaphore_Status _CORE_semaphore_Surrender(
  CORE_semaphore_Control                *the_semaphore,
  Objects_Id                             id,
  CORE_semaphore_API_mp_support_callout  api_semaphore_mp_support
)
{
  Thread_Control *the_thread;
  ISR_Level       level;
  CORE_semaphore_Status status;

  status = CORE_SEMAPHORE_STATUS_SUCCESSFUL;

  if ( (the_thread = _Thread_queue_Dequeue(&the_semaphore->Wait_queue)) ) {

    if ( !_Objects_Is_local_id( the_thread->Object.id ) )
      (*api_semaphore_mp_support) ( the_thread, id );

  } else {
    _ISR_Disable( level );
      if ( the_semaphore->count < the_semaphore->Attributes.maximum_count )
        the_semaphore->count += 1;
      else
        status = CORE_SEMAPHORE_MAXIMUM_COUNT_EXCEEDED;
    _ISR_Enable( level );
  }

  return status;
}