nes-proj/os/sys/mutex.h
2017-12-09 17:09:57 +00:00

130 lines
5.2 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 sys
* @{
*
* \defgroup mutex Mutexes
* @{
*
* This library provides an API and generic implementation of mutexes.
*
* Calling code should manipulate mutexes through the mutex_try_lock() and
* mutex_unlock() macros. By default, those macros will expand to the generic
* mutex manipulation implementations provided here. While these will work,
* they do reply on disabling the master interrupt in order to perform the
* lock/unlock operation.
*
* It is possible to override those generic implementation with CPU-specific
* implementations that exploit synchronisation instructions. To do so,
* create a CPU-specific header file. In this file, define mutex_try_lock()
* and mutex_unlock() to expand to the respective CPU function names. These
* can (but do not have to) be inlined. Then define MUTEX_CONF_ARCH_HEADER_PATH
* as this header's filename.
*/
/*---------------------------------------------------------------------------*/
#ifndef MUTEX_H_
#define MUTEX_H_
/*---------------------------------------------------------------------------*/
#include "contiki.h"
#include <stdint.h>
#include <stdbool.h>
/*---------------------------------------------------------------------------*/
#define MUTEX_STATUS_LOCKED 1 /** The mutex is locked */
#define MUTEX_STATUS_UNLOCKED 0 /** The mutex is not locked */
/*---------------------------------------------------------------------------*/
#ifdef MUTEX_CONF_ARCH_HEADER_PATH
#include MUTEX_CONF_ARCH_HEADER_PATH
#endif /* MUTEX_CONF_ARCH_HEADER_PATH */
/*---------------------------------------------------------------------------*/
#if !MUTEX_CONF_HAS_MUTEX_T
/**
* \brief Mutex data type
*
* It is possible for the platform to override this with its own typedef. In
* this scenario, make sure to also define MUTEX_CONF_HAS_MUTEX_T as 1.
*/
typedef uint_fast8_t mutex_t;
#endif
/*---------------------------------------------------------------------------*/
#ifndef mutex_try_lock
/**
* \brief Try to lock a mutex
* \param m A pointer to the mutex to be locked
* \retval true Locking succeeded
* \retval false Locking failed (the mutex is already locked)
*
* This macro will expand to mutex_generic_try_lock() or to a CPU-provided
* implementation. Platform-independent code should use this macro instead
* of mutex_generic_try_lock().
*/
#define mutex_try_lock(m) mutex_generic_try_lock(m)
#endif
#ifndef mutex_unlock
/**
* \brief Unlock a previously acquired mutex
* \param m A pointer to the mutex to be unlocked
*
* This macro will expand to mutex_generic_unlock() or to a CPU-provided
* implementation. Platform-independent code should use this macro instead
* of mutex_generic_unlock().
*/
#define mutex_unlock(m) mutex_generic_unlock(m)
#endif
/*---------------------------------------------------------------------------*/
/**
* \brief Try to lock a mutex
* \param mutex A pointer to the mutex to be locked
* \retval true Locking succeeded
* \retval false Locking failed (the mutex is already locked)
*
* Do not call this function directly. Use the mutex_try_lock() macro instead.
*/
bool mutex_generic_try_lock(volatile mutex_t *mutex);
/**
* \brief Unlock a previously acquired mutex
* \param mutex A pointer to the mutex to be unlocked
*
* Do not call this function directly. Use the mutex_unlock() macro instead.
*/
void mutex_generic_unlock(volatile mutex_t *mutex);
/*---------------------------------------------------------------------------*/
#endif /* MUTEX_H_ */
/*---------------------------------------------------------------------------*/
/**
* @}
* @}
*/