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/*
* 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) 1989-2008.
* 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.
*
* $Id$
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#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,
bool 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 the semaphore was not available and the caller was not willing
* to block, then return immediately with a status indicating that
* the semaphore was not available and the caller never blocked.
*/
if ( !wait ) {
_ISR_Enable( level );
executing->Wait.return_code = CORE_SEMAPHORE_STATUS_UNSATISFIED_NOWAIT;
return;
}
/*
* If the semaphore is not available and the caller is willing to
* block, then we now block the caller with optional timeout.
*/
_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 );
}
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