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/*
* Generic buffer queue
* Copyright (c) 2012 Nicolas George
*
* 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 AVFILTER_BUFFERQUEUE_H
#define AVFILTER_BUFFERQUEUE_H
/**
* FFBufQueue: simple AVFilterBufferRef queue API
*
* Note: this API is not thread-safe. Concurrent access to the same queue
* must be protected by a mutex or any synchronization mechanism.
*/
/**
* Maximum size of the queue.
*
* This value can be overridden by definying it before including this
* header.
* Powers of 2 are recommended.
*/
#ifndef FF_BUFQUEUE_SIZE
#define FF_BUFQUEUE_SIZE 32
#endif
#include "avfilter.h"
#include "libavutil/avassert.h"
/**
* Structure holding the queue
*/
struct FFBufQueue {
AVFilterBufferRef *queue[FF_BUFQUEUE_SIZE];
unsigned short head;
unsigned short available; /**< number of available buffers */
};
#define BUCKET(i) queue->queue[(queue->head + (i)) % FF_BUFQUEUE_SIZE]
/**
* Add a buffer to the queue.
*
* If the queue is already full, then the current last buffer is dropped
* (and unrefed) with a warning before adding the new buffer.
*/
static inline void ff_bufqueue_add(void *log, struct FFBufQueue *queue,
AVFilterBufferRef *buf)
{
if (queue->available == FF_BUFQUEUE_SIZE) {
av_log(log, AV_LOG_WARNING, "Buffer queue overflow, dropping.\n");
avfilter_unref_buffer(BUCKET(--queue->available));
}
BUCKET(queue->available++) = buf;
}
/**
* Get a buffer from the queue without altering it.
*
* Buffer with index 0 is the first buffer in the queue.
* Return NULL if the queue has not enough buffers.
*/
static inline AVFilterBufferRef *ff_bufqueue_peek(struct FFBufQueue *queue,
unsigned index)
{
return index < queue->available ? BUCKET(index) : NULL;
}
/**
* Get the first buffer from the queue and remove it.
*
* Do not use on an empty queue.
*/
static inline AVFilterBufferRef *ff_bufqueue_get(struct FFBufQueue *queue)
{
AVFilterBufferRef *ret = queue->queue[queue->head];
av_assert0(queue->available);
queue->available--;
queue->queue[queue->head] = NULL;
queue->head = (queue->head + 1) % FF_BUFQUEUE_SIZE;
return ret;
}
/**
* Unref and remove all buffers from the queue.
*/
static inline void ff_bufqueue_discard_all(struct FFBufQueue *queue)
{
while (queue->available)
avfilter_unref_buffer(ff_bufqueue_get(queue));
}
#undef BUCKET
#endif /* AVFILTER_BUFFERQUEUE_H */