condition.h

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/*
 * Copyright (c) 2016, Xilinx Inc. and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
 
/*
 * @file        linux/condition.h
 * @brief       Linux condition variable primitives for libmetal.
 */
 
#ifndef __METAL_CONDITION__H__
#error "Include metal/condition.h instead of metal/linux/condition.h"
#endif
 
#ifndef __METAL_LINUX_CONDITION__H__
#define __METAL_LINUX_CONDITION__H__
 
#include <unistd.h>
#include <sys/syscall.h>
#include <linux/futex.h>
#include <metal/atomic.h>
#include <stdint.h>
#include <limits.h>
#include <errno.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
struct metal_condition {
        metal_mutex_t *m; 
        atomic_int waiters;    
        atomic_int wakeups;    
};
 
#define METAL_CONDITION_INIT            { NULL, ATOMIC_VAR_INIT(0), ATOMIC_VAR_INIT(0) }
 
static inline void metal_condition_init(struct metal_condition *cv)
{
        cv->m = NULL;
        atomic_init(&cv->waiters, 0);
        atomic_init(&cv->wakeups, 0);
}
 
static inline int metal_condition_signal(struct metal_condition *cv)
{
        if (!cv)
                return -EINVAL;
 
        atomic_fetch_add(&cv->wakeups, 1);
        if (atomic_load(&cv->waiters) > 0)
                syscall(SYS_futex, &cv->wakeups, FUTEX_WAKE, 1, NULL, NULL, 0);
        return 0;
}
 
static inline int metal_condition_broadcast(struct metal_condition *cv)
{
        if (!cv)
                return -EINVAL;
 
        atomic_fetch_add(&cv->wakeups, 1);
        if (atomic_load(&cv->waiters) > 0)
                syscall(SYS_futex, &cv->wakeups, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
        return 0;
}
 
#endif /* __METAL_LINUX_CONDITION__H__ */