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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_BASE_AUDIO_FIFO_H_
#define MEDIA_BASE_AUDIO_FIFO_H_
#include "base/atomicops.h"
#include "media/base/audio_bus.h"
#include "media/base/media_export.h"
namespace media {
// First-in first-out container for AudioBus elements.
// The maximum number of audio frames in the FIFO is set at construction and
// can not be extended dynamically. The allocated memory is utilized as a
// ring buffer.
// This class is thread-safe in the limited sense that one thread may call
// Push(), while a second thread calls Consume().
class MEDIA_EXPORT AudioFifo {
public:
// Creates a new AudioFifo and allocates |channels| of length |frames|.
AudioFifo(int channels, int frames);
virtual ~AudioFifo();
// Pushes all audio channel data from |source| to the FIFO.
// Push() will crash if the allocated space is insufficient.
void Push(const AudioBus* source);
// Consumes |frames_to_consume| audio frames from the FIFO and copies
// them to |destination| starting at position |start_frame|.
// Consume() will crash if the FIFO does not contain |frames_to_consume|
// frames or if there is insufficient space in |destination| to store the
// frames.
void Consume(AudioBus* destination, int start_frame, int frames_to_consume);
// Empties the FIFO without deallocating any memory.
void Clear();
// Number of actual audio frames in the FIFO.
int frames() const;
int max_frames() const { return max_frames_; }
private:
// The actual FIFO is an audio bus implemented as a ring buffer.
scoped_ptr<AudioBus> audio_bus_;
// Maximum number of elements the FIFO can contain.
// This value is set by |frames| in the constructor.
const int max_frames_;
// Number of actual elements in the FIFO.
volatile base::subtle::Atomic32 frames_pushed_;
volatile base::subtle::Atomic32 frames_consumed_;
// Current read position.
int read_pos_;
// Current write position.
int write_pos_;
DISALLOW_COPY_AND_ASSIGN(AudioFifo);
};
} // namespace media
#endif // MEDIA_BASE_AUDIO_FIFO_H_
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