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/*
* Copyright (C) 2016 Theobroma Systems Design & Consulting GmbH
*
* 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.
*/
/**
* @ingroup core_sync Synchronization
* @brief Recursive Mutex for thread synchronization
* @{
*
* @file
* @brief RIOT synchronization API
*
* @author Martin Elshuber <martin.elshuber@theobroma-systems.com>
*
*/
#ifndef RMUTEX_H_
#define RMUTEX_H_
#include <stdatomic.h>
#include "mutex.h"
#include "kernel_types.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Mutex structure. Must never be modified by the user.
*/
typedef struct rmutex_t {
/* fields are managed by mutex functions, don't touch */
/**
* @brief The mutex used for locking. **Must never be changed by
* the user.**
* @internal
*/
mutex_t mutex;
/**
* @brief Number of locks owned by the thread owner
* @internal
*/
uint16_t refcount;
/**
* @brief Owner thread of the mutex.
* @details Owner is written by the mutex holder, and read
* concurrently to ensure consistency,
* atomic_int_least16_t is used. Note @ref kernel_pid_t is an int16
* @internal
*/
atomic_int_least16_t owner;
} rmutex_t;
/**
* @brief Static initializer for rmutex_t.
* @details This initializer is preferable to rmutex_init().
*/
#define RMUTEX_INIT { MUTEX_INIT, 0, ATOMIC_VAR_INIT(KERNEL_PID_UNDEF) }
/**
* @brief Initializes a recursive mutex object.
* @details For initialization of variables use RMUTEX_INIT instead.
* Only use the function call for dynamically allocated mutexes.
* @param[out] rmutex pre-allocated mutex structure, must not be NULL.
*/
static inline void rmutex_init(rmutex_t *rmutex)
{
rmutex_t empty_rmutex = RMUTEX_INIT;
*rmutex = empty_rmutex;
}
/**
* @brief Tries to get a recursive mutex, non-blocking.
*
* @param[in] rmutex Recursive 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 rmutex_trylock(rmutex_t *rmutex);
/**
* @brief Locks a recursive mutex, blocking.
*
* @param[in] rmutex Recursive mutex object to lock. Has to be
* initialized first. Must not be NULL.
*/
void rmutex_lock(rmutex_t *rmutex);
/**
* @brief Unlocks the recursive mutex.
*
* @param[in] rmutex Recursive mutex object to unlock, must not be NULL.
*/
void rmutex_unlock(rmutex_t *rmutex);
#ifdef __cplusplus
}
#endif
#endif /* RMUTEX_H_ */
/** @} */