source: rtems/cpukit/score/inline/rtems/score/coremutex.inl @ 96d0b64

/** 
 *  @file  rtems/score/coremutex.inl
 *
 *  This include file contains all of the inlined routines associated
 *  with the CORE mutexes.
 */

/*
 *  COPYRIGHT (c) 1989-2006.
 *  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.
 *
 *  $Id$
 */

#ifndef _RTEMS_SCORE_COREMUTEX_INL
#define _RTEMS_SCORE_COREMUTEX_INL

/**
 *  @addtogroup ScoreMutex 
 *  @{
 */

/**
 *  @brief Is Mutex Locked
 *
 *  This routine returns TRUE if the mutex specified is locked and FALSE
 *  otherwise.
 *
 *  @param[in] the_mutex is the mutex to check
 *
 *  @return This method returns TRUE if the mutex is locked.
 */
RTEMS_INLINE_ROUTINE boolean _CORE_mutex_Is_locked(
  CORE_mutex_Control  *the_mutex
)
{
  return the_mutex->lock == CORE_MUTEX_LOCKED;
}
 
/**
 *  @brief Does Core Mutex Use FIFO Blocking
 *
 *  This routine returns TRUE if the mutex's wait discipline is FIFO and FALSE
 *  otherwise.
 *
 *  @param[in] the_attribute is the attribute set of the mutex
 *
 *  @return This method returns TRUE if the mutex is using FIFO blocking order.
 */
RTEMS_INLINE_ROUTINE boolean _CORE_mutex_Is_fifo(
  CORE_mutex_Attributes *the_attribute
)
{
  return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_FIFO;
}
 
/**
 *  @brief Doex Core Mutex Use Priority Blocking
 *
 *  This routine returns TRUE if the mutex's wait discipline is PRIORITY and
 *  FALSE otherwise.
 *
 *  @param[in] the_attribute is the attribute set of the mutex
 *
 *  @return This method returns TRUE if the mutex is using
 *          priority blocking order.
 */
RTEMS_INLINE_ROUTINE boolean _CORE_mutex_Is_priority(
  CORE_mutex_Attributes *the_attribute
)
{
  return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_PRIORITY;
}
 
/**
 *  @brief Does Mutex Use Priority Inheritance
 *
 *  This routine returns TRUE if the mutex's wait discipline is
 *  INHERIT_PRIORITY and FALSE otherwise.
 *
 *  @param[in] the_attribute is the attribute set of the mutex
 *
 *  @return This method returns TRUE if the mutex is using priority
 *          inheritance.
 */
RTEMS_INLINE_ROUTINE boolean _CORE_mutex_Is_inherit_priority(
  CORE_mutex_Attributes *the_attribute
)
{
  return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT;
}
 
/**
 *  @brief Does Mutex Use Priority Ceiling
 *
 *  This routine returns TRUE if the mutex's wait discipline is
 *  PRIORITY_CEILING and FALSE otherwise.
 *
 *  @param[in] the_attribute is the attribute set of the mutex
 *
 *  @return This method returns TRUE if the mutex is using priority
 *          ceiling.
 */
RTEMS_INLINE_ROUTINE boolean _CORE_mutex_Is_priority_ceiling(
  CORE_mutex_Attributes *the_attribute
)
{
  return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING;
}
 
/*
 *  Seize Mutex with Quick Success Path
 *
 *  NOTE: There is no MACRO version of this routine.  A body is in
 *  coremutexseize.c that is duplicated from the .inl by hand.
 *
 *  NOTE: The Doxygen for this routine is in the .h file.
 */
RTEMS_INLINE_ROUTINE int _CORE_mutex_Seize_interrupt_trylock(
  CORE_mutex_Control  *the_mutex,
  ISR_Level           *level_p
)
{
  Thread_Control   *executing;
  ISR_Level         level = *level_p;

  /* disabled when you get here */

  executing = _Thread_Executing;
  executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL;
  if ( !_CORE_mutex_Is_locked( the_mutex ) ) {
    the_mutex->lock       = CORE_MUTEX_LOCKED;
    the_mutex->holder     = executing;
    the_mutex->holder_id  = executing->Object.id;
    the_mutex->nest_count = 1;
    if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
         _CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) )
      executing->resource_count++;
    if ( !_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
        _ISR_Enable( level );
        return 0;
    } /* else must be CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING
       *
       * we possibly bump the priority of the current holder -- which
       * happens to be _Thread_Executing.
       */
    {
      Priority_Control  ceiling;
      Priority_Control  current;

      ceiling = the_mutex->Attributes.priority_ceiling;
      current = executing->current_priority;
      if ( current == ceiling ) {
        _ISR_Enable( level );
        return 0;
      }

      if ( current > ceiling ) {
        _Thread_Disable_dispatch();
        _ISR_Enable( level );
        _Thread_Change_priority(
          the_mutex->holder,
          the_mutex->Attributes.priority_ceiling,
         FALSE
        );
        _Thread_Enable_dispatch();
        return 0;
      }
      /* if ( current < ceiling ) */ {
        executing->Wait.return_code = CORE_MUTEX_STATUS_CEILING_VIOLATED;
        the_mutex->nest_count = 0;     /* undo locking above */
        executing->resource_count--;   /* undo locking above */
        _ISR_Enable( level );
        return 0;
      }
    }
    return 0;
  }

  /*
   *  At this point, we know the mutex was not available.  If this thread
   *  is the thread that has locked the mutex, let's see if we are allowed
   *  to nest access.
   */
  if ( _Thread_Is_executing( the_mutex->holder ) ) {
    switch ( the_mutex->Attributes.lock_nesting_behavior ) {
      case CORE_MUTEX_NESTING_ACQUIRES:
        the_mutex->nest_count++;
        _ISR_Enable( level );
        return 0;
      case CORE_MUTEX_NESTING_IS_ERROR:
        executing->Wait.return_code = CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED;
        _ISR_Enable( level );
        return 0;
      case CORE_MUTEX_NESTING_BLOCKS:
        break;
    }
  }

  /*
   *  The mutex is not available and the caller must deal with the possibility
   *  of blocking.
   */
  return 1;
}

/**@}*/

#endif
/* end of include file */