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/**
* @file
*
* @ingroup RTEMSScoreOnce
*
* @brief This source file contains the implementation of
* _Once(), _Once_Lock(), and _Once_Unlock().
*/
/*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (C) 2019 embedded brains GmbH
* Copyright (C) 2019 Sebastian Huber
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/onceimpl.h>
#include <rtems/score/threadimpl.h>
#include <rtems/thread.h>
#define ONCE_STATE_INIT 0
#define ONCE_STATE_RUNNING 1
#define ONCE_STATE_COMPLETE 2
typedef struct {
rtems_mutex Mutex;
rtems_condition_variable State;
} Once_Control;
static Once_Control _Once_Information = {
.Mutex = RTEMS_MUTEX_INITIALIZER( "_Once" ),
.State = RTEMS_CONDITION_VARIABLE_INITIALIZER( "_Once" )
};
static Thread_Life_state _Once_Lock( void )
{
Thread_Life_state thread_life_state;
thread_life_state = _Thread_Set_life_protection( THREAD_LIFE_PROTECTED );
rtems_mutex_lock( &_Once_Information.Mutex );
return thread_life_state;
}
static void _Once_Unlock( Thread_Life_state thread_life_state )
{
rtems_mutex_unlock( &_Once_Information.Mutex );
_Thread_Set_life_protection( thread_life_state );
}
int _Once( unsigned char *once_state, void ( *init_routine )( void ) )
{
_Atomic_Fence( ATOMIC_ORDER_ACQUIRE );
if ( RTEMS_PREDICT_FALSE( *once_state != ONCE_STATE_COMPLETE ) ) {
Thread_Life_state thread_life_state;
thread_life_state = _Once_Lock();
if ( *once_state == ONCE_STATE_INIT ) {
*once_state = ONCE_STATE_RUNNING;
_Once_Unlock( THREAD_LIFE_PROTECTED );
( *init_routine )();
_Once_Lock();
_Atomic_Fence( ATOMIC_ORDER_RELEASE );
*once_state = ONCE_STATE_COMPLETE;
rtems_condition_variable_broadcast( &_Once_Information.State );
} else {
while ( *once_state != ONCE_STATE_COMPLETE ) {
rtems_condition_variable_wait(
&_Once_Information.State,
&_Once_Information.Mutex
);
}
}
_Once_Unlock( thread_life_state );
}
return 0;
}
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