Subversion Repositories openrisc

/*

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

 *

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

 *

 *  This routine attempts to allocate a core semaphore to the calling thread.

 *

 *  Input parameters:

 *    the_semaphore - pointer to semaphore control block

 *    id            - id of object to wait on

 *    wait          - TRUE if wait is allowed, FALSE otherwise

 *    timeout       - number of ticks to wait (0 means forever)

 *

 *  Output parameters:  NONE

 *

 *  INTERRUPT LATENCY:

 *    available

 *    wait

 */

void _CORE_semaphore_Seize(

  CORE_semaphore_Control  *the_semaphore,

  Objects_Id               id,

  boolean                  wait,

  Watchdog_Interval        timeout

)

{

  Thread_Control *executing;

  ISR_Level       level;

  executing = _Thread_Executing;

  executing->Wait.return_code = CORE_SEMAPHORE_STATUS_SUCCESSFUL;

  _ISR_Disable( level );

  if ( the_semaphore->count != 0 ) {

    the_semaphore->count -= 1;

    _ISR_Enable( level );

    return;

  }

  if ( !wait ) {

    _ISR_Enable( level );

    executing->Wait.return_code = CORE_SEMAPHORE_STATUS_UNSATISFIED_NOWAIT;

    return;

  }

  _Thread_queue_Enter_critical_section( &the_semaphore->Wait_queue );

  executing->Wait.queue          = &the_semaphore->Wait_queue;

  executing->Wait.id             = id;

  _ISR_Enable( level );

  _Thread_queue_Enqueue( &the_semaphore->Wait_queue, timeout );

}