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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_CONTAINER_FIFO_H
#define AVUTIL_CONTAINER_FIFO_H
#include <stddef.h>
/**
* AVContainerFifo is a FIFO for "containers" - dynamically allocated reusable
* structs (e.g. AVFrame or AVPacket). AVContainerFifo uses an internal pool of
* such containers to avoid allocating and freeing them repeatedly.
*/
typedef struct AVContainerFifo AVContainerFifo;
enum AVContainerFifoFlags {
/**
* Signal to av_container_fifo_write() that it should make a new reference
* to data in src rather than consume its contents.
*
* @note you must handle this flag manually in your own fifo_transfer()
* callback
*/
AV_CONTAINER_FIFO_FLAG_REF = (1 << 0),
/**
* This and all higher bits in flags may be set to any value by the caller
* and are guaranteed to be passed through to the fifo_transfer() callback
* and not be interpreted by AVContainerFifo code.
*/
AV_CONTAINER_FIFO_FLAG_USER = (1 << 16),
};
/**
* Allocate a new AVContainerFifo for the container type defined by provided
* callbacks.
*
* @param opaque user data that will be passed to the callbacks provided to this
* function
* @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_transfer Transfer the contents of container src to dst.
* @param flags currently unused
*
* @return newly allocated AVContainerFifo, or NULL on failure
*/
AVContainerFifo*
av_container_fifo_alloc(void *opaque,
void* (*container_alloc)(void *opaque),
void (*container_reset)(void *opaque, void *obj),
void (*container_free) (void *opaque, void *obj),
int (*fifo_transfer) (void *opaque, void *dst, void *src, unsigned flags),
unsigned flags);
/**
* Allocate an AVContainerFifo instance for AVFrames.
*
* @param flags currently unused
*/
AVContainerFifo *av_container_fifo_alloc_avframe(unsigned flags);
/**
* Free a AVContainerFifo and everything in it.
*/
void av_container_fifo_free(AVContainerFifo **cf);
/**
* Write the contents of obj to the FIFO.
*
* The fifo_transfer() callback previously provided to av_container_fifo_alloc()
* will be called with obj as src in order to perform the actual transfer.
*/
int av_container_fifo_write(AVContainerFifo *cf, void *obj, unsigned flags);
/**
* Read the next available object from the FIFO into obj.
*
* The fifo_read() callback previously provided to av_container_fifo_alloc()
* will be called with obj as dst in order to perform the actual transfer.
*/
int av_container_fifo_read(AVContainerFifo *cf, void *obj, unsigned flags);
/**
* Access objects stored in the FIFO without retrieving them. The
* fifo_transfer() callback will NOT be invoked and the FIFO state will not be
* modified.
*
* @param pobj Pointer to the object stored in the FIFO will be written here on
* success. The object remains owned by the FIFO and the caller may
* only access it as long as the FIFO is not modified.
* @param offset Position of the object to retrieve - 0 is the next item that
* would be read, 1 the one after, etc. Must be smaller than
* av_container_fifo_can_read().
*
* @retval 0 success, a pointer was written into pobj
* @retval AVERROR(EINVAL) invalid offset value
*/
int av_container_fifo_peek(AVContainerFifo *cf, void **pobj, size_t offset);
/**
* Discard the specified number of elements from the FIFO.
*
* @param nb_elems number of elements to discard, MUST NOT be larger than
* av_fifo_can_read(f)
*/
void av_container_fifo_drain(AVContainerFifo *cf, size_t nb_elems);
/**
* @return number of objects available for reading
*/
size_t av_container_fifo_can_read(const AVContainerFifo *cf);
#endif // AVCODEC_CONTAINER_FIFO_H
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