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RIOT/core/include/mutex.h
2014-08-23 16:16:26 +02:00

97 lines
2.4 KiB
C

/*
* Copyright (C) 2013, 2014 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @defgroup core_sync Synchronization
* @brief Mutex for thread synchronization
* @ingroup core
* @{
*
* @file mutex.h
* @brief RIOT synchronization API
*
* @author Kaspar Schleiser <kaspar@schleiser.de>
*/
#ifndef __MUTEX_H_
#define __MUTEX_H_
#include "priority_queue.h"
/**
* @brief Mutex structure. Must never be modified by the user.
*/
typedef struct mutex_t {
/* fields are managed by mutex functions, don't touch */
/**
* @brief The value of the mutex; 0 if unlocked, 1 if locked. **Must
* never be changed by the user.**
* @internal
*/
unsigned int val;
/**
* @brief The process waiting queue of the mutex. **Must never be changed
* by the user.**
* @internal
*/
priority_queue_t queue;
} mutex_t;
/**
* @brief Static initializer for mutex_t.
* @details This initializer is preferable to mutex_init().
*/
#define MUTEX_INIT { 0, PRIORITY_QUEUE_INIT }
/**
* @brief Initializes a mutex object.
* @details For initialization of variables use MUTEX_INIT instead.
* Only use the function call for dynamically allocated mutexes.
* @param[out] mutex pre-allocated mutex structure, must not be NULL.
*/
static inline void mutex_init(mutex_t *mutex)
{
mutex_t empty_mutex = MUTEX_INIT;
*mutex = empty_mutex;
}
/**
* @brief Tries to get a mutex, non-blocking.
*
* @param[in] mutex Mutex object to lock. Has to be initialized first. Must not
* be NULL.
*
* @return 1 if mutex was unlocked, now it is locked.
* @return 0 if the mutex was locked.
*/
int mutex_trylock(mutex_t *mutex);
/**
* @brief Locks a mutex, blocking.
*
* @param[in] mutex Mutex object to lock. Has to be initialized first. Must not be NULL.
*/
void mutex_lock(mutex_t *mutex);
/**
* @brief Unlocks the mutex.
*
* @param[in] mutex Mutex object to unlock, must not be NULL.
*/
void mutex_unlock(mutex_t *mutex);
/**
* @brief Unlocks the mutex and sends the current thread to sleep
*
* @param[in] mutex Mutex object to unlock, must not be NULL.
*/
void mutex_unlock_and_sleep(mutex_t *mutex);
#endif /* __MUTEX_H_ */
/** @} */