/**
* @file
*
* @ingroup RTEMSScore
*
* @brief This source file contains the implementation of
* _Semaphore_Wait(), _Semaphore_Wait_timed_ticks(), _Semaphore_Try_wait(),
* _Semaphore_Post(), and _Semaphore_Post_binary().
*/
/*
* Copyright (c) 2015, 2017 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/semaphoreimpl.h>
#include <rtems/score/statesimpl.h>
#include <rtems/score/threadimpl.h>
#include <errno.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 ( RTEMS_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
);
}
}
int _Semaphore_Wait_timed_ticks( struct _Semaphore_Control *_sem, uint32_t ticks )
{
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 ( RTEMS_PREDICT_TRUE( count > 0 ) ) {
sem->count = count - 1;
_Sem_Queue_release( sem, level, &queue_context );
return 0;
} else {
_Thread_queue_Context_set_thread_state(
&queue_context,
STATES_WAITING_FOR_SEMAPHORE
);
_Thread_queue_Context_set_enqueue_timeout_ticks( &queue_context, ticks );
_Thread_queue_Context_set_ISR_level( &queue_context, level );
_Thread_queue_Enqueue(
&sem->Queue.Queue,
SEMAPHORE_TQ_OPERATIONS,
executing,
&queue_context
);
return STATUS_GET_POSIX( _Thread_Wait_get_status( executing ) );
}
}
int _Semaphore_Try_wait( struct _Semaphore_Control *_sem )
{
Sem_Control *sem;
ISR_Level level;
Thread_queue_Context queue_context;
unsigned int count;
int eno;
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 );
count = sem->count;
if ( RTEMS_PREDICT_TRUE( count > 0 ) ) {
sem->count = count - 1;
eno = 0;
} else {
eno = EAGAIN;
}
_Sem_Queue_release( sem, level, &queue_context );
return eno;
}
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 ( RTEMS_PREDICT_TRUE( heads == NULL ) ) {
++sem->count;
_Sem_Queue_release( sem, level, &queue_context );
} else {
_Thread_queue_Context_set_ISR_level( &queue_context, level );
_Thread_queue_Surrender_no_priority(
&sem->Queue.Queue,
heads,
&queue_context,
SEMAPHORE_TQ_OPERATIONS
);
}
}
void _Semaphore_Post_binary( 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 ( RTEMS_PREDICT_TRUE( heads == NULL ) ) {
sem->count = 1;
_Sem_Queue_release( sem, level, &queue_context );
} else {
_Thread_queue_Context_set_ISR_level( &queue_context, level );
_Thread_queue_Surrender_no_priority(
&sem->Queue.Queue,
heads,
&queue_context,
SEMAPHORE_TQ_OPERATIONS
);
}
}