/*
* Copyright (c) 2015 embedded brains GmbH. All rights reserved.
*
* embedded brains GmbH
* Dornierstr. 4
* 82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/semaphoreimpl.h>
#include <rtems/score/statesimpl.h>
#include <limits.h>
RTEMS_STATIC_ASSERT(
offsetof( Sem_Control, Queue )
== offsetof( struct _Semaphore_Control, _Queue ),
SEMAPHORE_CONTROL_QUEUE
);
RTEMS_STATIC_ASSERT(
offsetof( Sem_Control, count )
== offsetof( struct _Semaphore_Control, _count ),
SEMAPHORE_CONTROL_COUNT
);
RTEMS_STATIC_ASSERT(
sizeof( Sem_Control ) == sizeof( struct _Semaphore_Control ),
SEMAPHORE_CONTROL_SIZE
);
void _Semaphore_Wait( struct _Semaphore_Control *_sem )
{
Sem_Control *sem;
ISR_Level level;
Thread_queue_Context queue_context;
Thread_Control *executing;
unsigned int count;
sem = _Sem_Get( _sem );
_Thread_queue_Context_initialize( &queue_context );
_Thread_queue_Context_ISR_disable( &queue_context, level );
executing = _Sem_Queue_acquire_critical( sem, &queue_context );
count = sem->count;
if ( __predict_true( count > 0 ) ) {
sem->count = count - 1;
_Sem_Queue_release( sem, level, &queue_context );
} else {
_Thread_queue_Context_set_thread_state(
&queue_context,
STATES_WAITING_FOR_SEMAPHORE
);
_Thread_queue_Context_set_enqueue_do_nothing_extra( &queue_context );
_Thread_queue_Context_set_ISR_level( &queue_context, level );
_Thread_queue_Enqueue(
&sem->Queue.Queue,
SEMAPHORE_TQ_OPERATIONS,
executing,
&queue_context
);
}
}
void _Semaphore_Post( struct _Semaphore_Control *_sem )
{
Sem_Control *sem;
ISR_Level level;
Thread_queue_Context queue_context;
Thread_queue_Heads *heads;
sem = _Sem_Get( _sem );
_Thread_queue_Context_initialize( &queue_context );
_Thread_queue_Context_ISR_disable( &queue_context, level );
_Sem_Queue_acquire_critical( sem, &queue_context );
heads = sem->Queue.Queue.heads;
if ( __predict_true( heads == NULL ) ) {
_Assert( sem->count < UINT_MAX );
++sem->count;
_Sem_Queue_release( sem, level, &queue_context );
} else {
const Thread_queue_Operations *operations;
Thread_Control *first;
_Thread_queue_Context_set_ISR_level( &queue_context, level );
operations = SEMAPHORE_TQ_OPERATIONS;
first = ( *operations->first )( heads );
_Thread_queue_Extract_critical(
&sem->Queue.Queue,
operations,
first,
&queue_context
);
}
}