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/*
* 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
*/
#ifndef AVUTIL_REFCOUNT_H
#define AVUTIL_REFCOUNT_H
#include <stdint.h>
/**
* A thread-safe reference counter.
*
* Unlike most libav* structs, sizeof(AVRefcount) IS a part of the public ABI
* and so it can be embedded directly in other structs.
*
* None of its fields should be accessed directly by the caller, always use the
* av_refcount_*() functions.
*/
typedef struct AVRefcount {
void (*_internal0)(void *);
void *_internal1;
intmax_t _internal2;
} AVRefcount;
/**
* Initialize an AVRefcount to a reference count of 1. This function MUST be
* called on an AVRefcount before doing anything else with it.
*
* @param free The callback to be invoked when the counter reaches zero. May be
* NULL, then nothing is called.
* @param opaque arbitrary user data that will be passed to the free() callback.
*/
void av_refcount_init(AVRefcount *rc, void (*free)(void *opaque),
void *opaque);
/**
* Increase the reference count by 1.
*/
void av_refcount_inc(AVRefcount *rc);
/**
* Decrease the reference count by 1.
*
* @return
* - 0 when the new reference count is 0. If a free() callback was passed to
* av_refcount_init(), it has been invoked.
* - a positive value when the new reference count is non-zero
*
* @note the return value is the new reference count, which may be useful for
* debugging, but this is not guaranteed by the API and the callers MUST NOT
* rely on this
*/
unsigned int av_refcount_dec(AVRefcount *rc);
/**
* Check whether the caller is the exclusive owner of the reference.
* @return
* - a positive number if the reference count is exactly 1
* - zero otherwise
*/
int av_refcount_exclusive(AVRefcount *rc);
#endif /* AVUTIL_REFCOUNT_H */
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