nes-proj/arch/cpu/arm/cortex-m/mutex-cortex.h
2017-12-09 17:09:58 +00:00

83 lines
3.1 KiB
C

/*
* Copyright (c) 2017, George Oikonomou - http://www.spd.gr
* All rights reserved.
*
* 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.
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* 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 HOLDER 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.
*/
/*---------------------------------------------------------------------------*/
/**
* \addtogroup arm
*
* Arm Cortex-M implementation of mutexes using the LDREX, STREX and DMB
* instructions.
*
* @{
*/
/*---------------------------------------------------------------------------*/
#ifndef MUTEX_CORTEX_H_
#define MUTEX_CORTEX_H_
/*---------------------------------------------------------------------------*/
#include "contiki.h"
#ifdef CMSIS_CONF_HEADER_PATH
#include CMSIS_CONF_HEADER_PATH
#endif
#include <stdint.h>
#include <stdbool.h>
/*---------------------------------------------------------------------------*/
#define mutex_try_lock(m) mutex_cortex_try_lock(m)
#define mutex_unlock(m) mutex_cortex_unlock(m)
/*---------------------------------------------------------------------------*/
#define MUTEX_CONF_HAS_MUTEX_T 1
typedef uint8_t mutex_t;
/*---------------------------------------------------------------------------*/
static inline bool
mutex_cortex_try_lock(volatile mutex_t *mutex)
{
int status = 1;
if(__LDREXB(mutex) == 0) {
status = __STREXB(1, mutex);
}
__DMB();
return status == 0 ? true : false;
}
/*---------------------------------------------------------------------------*/
static inline void
mutex_cortex_unlock(volatile mutex_t *mutex)
{
__DMB();
*mutex = 0;
}
/*---------------------------------------------------------------------------*/
#endif /* MUTEX_CORTEX_H_ */
/*---------------------------------------------------------------------------*/
/** @} */