chromium/media/base/audio_fifo.cc

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

#include "media/base/audio_fifo.h"

#include <cstring>

#include "base/check_op.h"
#include "base/trace_event/trace_event.h"

namespace media {

// Given current position in the FIFO, the maximum number of elements in the
// FIFO and the size of the input; this method provides two output results:
// |size| and |wrap_size|. These two results can then be utilized for memcopy
// operations to and from the FIFO.
// Under "normal" circumstances, |size| will be equal to |in_size| and
// |wrap_size| will be zero. This case corresponding to the non-wrapping case
// where we have not yet reached the "edge" of the FIFO. If |pos| + |in_size|
// exceeds the total size of the FIFO, we must wrap around and start reusing
// a part the allocated memory. The size of this part is given by |wrap_size|.
static void GetSizes(
    int pos, int max_size, int in_size, int* size, int* wrap_size) { … }

// Updates the read/write position with |step| modulo the maximum number of
// elements in the FIFO to ensure that the position counters wraps around at
// the endpoint.
static int UpdatePos(int pos, int step, int max_size) { … }

AudioFifo::AudioFifo(int channels, int frames)
    : … { … }

AudioFifo::~AudioFifo() = default;

void AudioFifo::Push(const AudioBus* source) { … }

void AudioFifo::Push(const AudioBus* source, int source_size) { … }

void AudioFifo::Consume(AudioBus* destination,
                        int start_frame,
                        int frames_to_consume) { … }

void AudioFifo::Clear() { … }

}  // namespace media