Contiki-NG
mutex.h
1/*
2 * Copyright (c) 2017, George Oikonomou - http://www.spd.gr
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the copyright holder nor the names of its
15 * contributors may be used to endorse or promote products derived
16 * from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
22 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
25 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
27 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
29 * OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31/*---------------------------------------------------------------------------*/
32/**
33 * \addtogroup sys
34 * @{
35 *
36 * \defgroup mutex Mutexes
37 * @{
38 *
39 * This library provides an API and generic implementation of mutexes.
40 *
41 * Calling code should manipulate mutexes through the mutex_try_lock() and
42 * mutex_unlock() macros. By default, those macros will expand to the generic
43 * mutex manipulation implementations provided here. While these will work,
44 * they do reply on disabling the master interrupt in order to perform the
45 * lock/unlock operation.
46 *
47 * It is possible to override those generic implementation with CPU-specific
48 * implementations that exploit synchronisation instructions. To do so,
49 * create a CPU-specific header file. In this file, define mutex_try_lock()
50 * and mutex_unlock() to expand to the respective CPU function names. These
51 * can (but do not have to) be inlined. Then define MUTEX_CONF_ARCH_HEADER_PATH
52 * as this header's filename.
53 */
54/*---------------------------------------------------------------------------*/
55#ifndef MUTEX_H_
56#define MUTEX_H_
57/*---------------------------------------------------------------------------*/
58#include "contiki.h"
59
60#include <stdint.h>
61#include <stdbool.h>
62/*---------------------------------------------------------------------------*/
63#define MUTEX_STATUS_LOCKED 1 /** The mutex is locked */
64#define MUTEX_STATUS_UNLOCKED 0 /** The mutex is not locked */
65/*---------------------------------------------------------------------------*/
66#ifdef MUTEX_CONF_ARCH_HEADER_PATH
67#include MUTEX_CONF_ARCH_HEADER_PATH
68#endif /* MUTEX_CONF_ARCH_HEADER_PATH */
69/*---------------------------------------------------------------------------*/
70#if !MUTEX_CONF_HAS_MUTEX_T
71/**
72 * \brief Mutex data type
73 *
74 * It is possible for the platform to override this with its own typedef. In
75 * this scenario, make sure to also define MUTEX_CONF_HAS_MUTEX_T as 1.
76 */
77typedef uint_fast8_t mutex_t;
78#endif
79/*---------------------------------------------------------------------------*/
80#ifndef mutex_try_lock
81/**
82 * \brief Try to lock a mutex
83 * \param m A pointer to the mutex to be locked
84 * \retval true Locking succeeded
85 * \retval false Locking failed (the mutex is already locked)
86 *
87 * This macro will expand to mutex_generic_try_lock() or to a CPU-provided
88 * implementation. Platform-independent code should use this macro instead
89 * of mutex_generic_try_lock().
90 */
91#define mutex_try_lock(m) mutex_generic_try_lock(m)
92#endif
93
94#ifndef mutex_unlock
95/**
96 * \brief Unlock a previously acquired mutex
97 * \param m A pointer to the mutex to be unlocked
98 *
99 * This macro will expand to mutex_generic_unlock() or to a CPU-provided
100 * implementation. Platform-independent code should use this macro instead
101 * of mutex_generic_unlock().
102 */
103#define mutex_unlock(m) mutex_generic_unlock(m)
104#endif
105/*---------------------------------------------------------------------------*/
106/**
107 * \brief Try to lock a mutex
108 * \param mutex A pointer to the mutex to be locked
109 * \retval true Locking succeeded
110 * \retval false Locking failed (the mutex is already locked)
111 *
112 * Do not call this function directly. Use the mutex_try_lock() macro instead.
113 */
114bool mutex_generic_try_lock(volatile mutex_t *mutex);
115
116/**
117 * \brief Unlock a previously acquired mutex
118 * \param mutex A pointer to the mutex to be unlocked
119 *
120 * Do not call this function directly. Use the mutex_unlock() macro instead.
121 */
122void mutex_generic_unlock(volatile mutex_t *mutex);
123/*---------------------------------------------------------------------------*/
124#endif /* MUTEX_H_ */
125/*---------------------------------------------------------------------------*/
126/**
127 * @}
128 * @}
129 */
uint_fast8_t mutex_t
Mutex data type.
Definition: mutex.h:77
bool mutex_generic_try_lock(volatile mutex_t *mutex)
Try to lock a mutex.
Definition: mutex.c:45
void mutex_generic_unlock(volatile mutex_t *mutex)
Unlock a previously acquired mutex.
Definition: mutex.c:61