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ffmpeg/libavcodec/container_fifo.h

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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 AVCODEC_CONTAINER_FIFO_H
#define AVCODEC_CONTAINER_FIFO_H
#include <stddef.h>
/**
* ContainerFifo is a FIFO for "containers" - dynamically allocated reusable
* structs (e.g. AVFrame or AVPacket). ContainerFifo uses an internal pool of
* such containers to avoid allocating and freeing them repeatedly.
*/
typedef struct ContainerFifo ContainerFifo;
/**
* Allocate a new ContainerFifo for the container type defined by provided
* callbacks.
*
* @param container_alloc allocate a new container instance and return a pointer
* to it, or NULL on failure
* @param container_reset reset the provided container instance to a clean state
* @param container_free free the provided container instance
* @param fifo_write transfer the contents of src to dst, where src is a
* container instance provided to ff_container_fifo_write()
* @param fifo_read transfer the contents of src to dst in other cases
*
* @note fifo_read() and fifo_write() are different parameters in order to allow
* fifo_write() implementations that make a new reference in dst, leaving
* src untouched (see e.g. ff_container_fifo_alloc_avframe())
*/
ContainerFifo*
ff_container_fifo_alloc(void* (*container_alloc)(void),
void (*container_reset)(void *obj),
void (*container_free) (void *obj),
int (*fifo_write) (void *dst, void *src),
int (*fifo_read) (void *dst, void *src));
/**
* Allocate a ContainerFifo instance for AVFrames.
* Note that ff_container_fifo_write() will call av_frame_ref() on src, making a
* new reference in dst and leaving src untouched.
*
* @param flags unused currently
*/
ContainerFifo *ff_container_fifo_alloc_avframe(unsigned flags);
/**
* Free a ContainerFifo and everything in it.
*/
void ff_container_fifo_free(ContainerFifo **pf);
/**
* Write the contents of obj to the FIFO.
*
* The fifo_write() callback previously provided to ff_container_fifo_alloc()
* will be called with obj as src in order to perform the actual transfer.
*/
int ff_container_fifo_write(ContainerFifo *pf, void *obj);
/**
* Read the next available object from the FIFO into obj.
*
* The fifo_read() callback previously provided to ff_container_fifo_alloc()
* will be called with obj as dst in order to perform the actual transfer.
*/
int ff_container_fifo_read(ContainerFifo *pf, void *obj);
/**
* @return number of objects available for reading
*/
size_t ff_container_fifo_can_read(ContainerFifo *pf);
#endif // AVCODEC_CONTAINER_FIFO_H