mutex.h

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/*
 * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
 *               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.
 */
 
#ifndef MUTEX_H
#define MUTEX_H
 
#include <stddef.h>
#include <stdint.h>
 
#include "irq.h"
#include "kernel_defines.h"
#include "list.h"
#include "thread.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
typedef struct {
    list_node_t queue;
} mutex_t;
 
#define MUTEX_INIT { { NULL } }
 
#define MUTEX_INIT_LOCKED { { MUTEX_LOCKED } }
 
#define MUTEX_LOCKED ((list_node_t *)-1)
 
static inline void mutex_init(mutex_t *mutex)
{
    mutex->queue.next = NULL;
}
 
static inline int mutex_trylock(mutex_t *mutex)
{
    unsigned irq_state = irq_disable();
    int retval = 0;
    if (mutex->queue.next == NULL) {
        mutex->queue.next = MUTEX_LOCKED;
        retval = 1;
    };
    irq_restore(irq_state);
    return retval;
}
 
void mutex_lock(mutex_t *mutex);
 
void mutex_unlock(mutex_t *mutex);
 
void mutex_unlock_and_sleep(mutex_t *mutex);
 
#ifdef __cplusplus
}
#endif
 
#endif /* MUTEX_H */