Hello,
you can create a Classic API semaphore using the Priority Ceiling Protocol
which is initially locked by the creating task. In this case the creating task
is not elevated to the ceiling priority:
CORE_mutex_Status _CORE_mutex_Initialize(
CORE_mutex_Control *the_mutex,
Thread_Control *executing,
const CORE_mutex_Attributes *the_mutex_attributes,
bool initially_locked
)
{
/* Add this to the RTEMS environment later ?????????
rtems_assert( initial_lock == CORE_MUTEX_LOCKED ||
initial_lock == CORE_MUTEX_UNLOCKED );
*/
the_mutex->Attributes = *the_mutex_attributes;
if ( initially_locked ) {
the_mutex->nest_count = 1;
the_mutex->holder = executing;
if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
if ( executing->current_priority <
the_mutex->Attributes.priority_ceiling )
return CORE_MUTEX_STATUS_CEILING_VIOLATED;
#ifdef __RTEMS_STRICT_ORDER_MUTEX__
_Chain_Prepend_unprotected( &executing->lock_mutex,
&the_mutex->queue.lock_queue );
the_mutex->queue.priority_before = executing->current_priority;
#endif
executing->resource_count++;
}
} else {
the_mutex->nest_count = 0;
the_mutex->holder = NULL;
}
_Thread_queue_Initialize(
&the_mutex->Wait_queue,
_CORE_mutex_Is_fifo( the_mutex_attributes ) ?
THREAD_QUEUE_DISCIPLINE_FIFO : THREAD_QUEUE_DISCIPLINE_PRIORITY,
STATES_WAITING_FOR_MUTEX,
CORE_MUTEX_TIMEOUT
);
return CORE_MUTEX_STATUS_SUCCESSFUL;
}
Is this working as intended?
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
PGP : Public key available on request.
Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
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