/*
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <stdatomic.h>

#include "refcount.h"

typedef struct AVRefcountImpl {
    void (*free)(void *opaque);
    void *opaque;
    atomic_uint refcount;
} AVRefcountImpl;


void av_refcount_init(AVRefcount *rc, void (*free)(void *opaque),
                      void *opaque)
{
    AVRefcountImpl *rci = (AVRefcountImpl*)rc;
    rci->free   = free;
    rci->opaque = opaque;
    atomic_init(&rci->refcount, 1);
}

void av_refcount_inc(AVRefcount *rc)
{
    AVRefcountImpl *rci = (AVRefcountImpl*)rc;
    atomic_fetch_add_explicit(&rci->refcount, 1, memory_order_relaxed);
}

unsigned int av_refcount_dec(AVRefcount *rc)
{
    AVRefcountImpl *rci = (AVRefcountImpl*)rc;
    unsigned int    ret = atomic_fetch_sub_explicit(&rci->refcount, 1,
                                                    memory_order_acq_rel) - 1;

    if (!ret && rci->free)
        rci->free(rci->opaque);

    return ret;
}

int av_refcount_exclusive(AVRefcount *rc)
{
    AVRefcountImpl *rci = (AVRefcountImpl*)rc;
    return atomic_load(&rci->refcount) == 1;
}