yading@10: /*
yading@10:  * Generic buffer queue
yading@10:  * Copyright (c) 2012 Nicolas George
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #ifndef AVFILTER_BUFFERQUEUE_H
yading@10: #define AVFILTER_BUFFERQUEUE_H
yading@10: 
yading@10: /**
yading@10:  * FFBufQueue: simple AVFrame queue API
yading@10:  *
yading@10:  * Note: this API is not thread-safe. Concurrent access to the same queue
yading@10:  * must be protected by a mutex or any synchronization mechanism.
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * Maximum size of the queue.
yading@10:  *
yading@10:  * This value can be overridden by definying it before including this
yading@10:  * header.
yading@10:  * Powers of 2 are recommended.
yading@10:  */
yading@10: #ifndef FF_BUFQUEUE_SIZE
yading@10: #define FF_BUFQUEUE_SIZE 32
yading@10: #endif
yading@10: 
yading@10: #include "avfilter.h"
yading@10: #include "libavutil/avassert.h"
yading@10: 
yading@10: /**
yading@10:  * Structure holding the queue
yading@10:  */
yading@10: struct FFBufQueue {
yading@10:     AVFrame *queue[FF_BUFQUEUE_SIZE];
yading@10:     unsigned short head;
yading@10:     unsigned short available; /**< number of available buffers */
yading@10: };
yading@10: 
yading@10: #define BUCKET(i) queue->queue[(queue->head + (i)) % FF_BUFQUEUE_SIZE]
yading@10: 
yading@10: /**
yading@10:  * Test if a buffer queue is full.
yading@10:  */
yading@10: static inline int ff_bufqueue_is_full(struct FFBufQueue *queue)
yading@10: {
yading@10:     return queue->available == FF_BUFQUEUE_SIZE;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Add a buffer to the queue.
yading@10:  *
yading@10:  * If the queue is already full, then the current last buffer is dropped
yading@10:  * (and unrefed) with a warning before adding the new buffer.
yading@10:  */
yading@10: static inline void ff_bufqueue_add(void *log, struct FFBufQueue *queue,
yading@10:                                    AVFrame *buf)
yading@10: {
yading@10:     if (ff_bufqueue_is_full(queue)) {
yading@10:         av_log(log, AV_LOG_WARNING, "Buffer queue overflow, dropping.\n");
yading@10:         av_frame_free(&BUCKET(--queue->available));
yading@10:     }
yading@10:     BUCKET(queue->available++) = buf;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Get a buffer from the queue without altering it.
yading@10:  *
yading@10:  * Buffer with index 0 is the first buffer in the queue.
yading@10:  * Return NULL if the queue has not enough buffers.
yading@10:  */
yading@10: static inline AVFrame *ff_bufqueue_peek(struct FFBufQueue *queue,
yading@10:                                         unsigned index)
yading@10: {
yading@10:     return index < queue->available ? BUCKET(index) : NULL;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Get the first buffer from the queue and remove it.
yading@10:  *
yading@10:  * Do not use on an empty queue.
yading@10:  */
yading@10: static inline AVFrame *ff_bufqueue_get(struct FFBufQueue *queue)
yading@10: {
yading@10:     AVFrame *ret = queue->queue[queue->head];
yading@10:     av_assert0(queue->available);
yading@10:     queue->available--;
yading@10:     queue->queue[queue->head] = NULL;
yading@10:     queue->head = (queue->head + 1) % FF_BUFQUEUE_SIZE;
yading@10:     return ret;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Unref and remove all buffers from the queue.
yading@10:  */
yading@10: static inline void ff_bufqueue_discard_all(struct FFBufQueue *queue)
yading@10: {
yading@10:     while (queue->available) {
yading@10:         AVFrame *buf = ff_bufqueue_get(queue);
yading@10:         av_frame_free(&buf);
yading@10:     }
yading@10: }
yading@10: 
yading@10: #undef BUCKET
yading@10: 
yading@10: #endif /* AVFILTER_BUFFERQUEUE_H */