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/*
Copyright 2018 Google Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS-IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#ifndef RESONANCE_AUDIO_DSP_CIRCULAR_BUFFER_H_
#define RESONANCE_AUDIO_DSP_CIRCULAR_BUFFER_H_
#include "base/audio_buffer.h"
namespace vraudio {
// Class that implements a simple mono circular buffer, accepting input and
// output of different length.
class CircularBuffer {
public:
// Constructs a circular buffer.
//
// @param buffer_length The length of the Circular buffer. This value must be
// at least |num_input_frames| + |num_output_frames| so that we can always
// either add or remove data.
// @param num_input_frames Length of the input buffers in frames.
// @param num_output_frames Length of the output buffers in frames.
CircularBuffer(size_t buffer_length, size_t num_input_frames,
size_t num_output_frames);
// Inserts a buffer of mono input into the |CircularBuffer| if space permits.
//
// @param input A channel of input data |num_input_frames| in length.
// @return True if there was space in the buffer and the input was
// successfully inserted, false otherwise.
bool InsertBuffer(const AudioBuffer::Channel& input);
// Retrieves a buffer of output from the |CircularBuffer| if it contains
// sufficient data.
//
// @param output A channel to hold |num_output_frames| of output data. The
// channel may be greater in length than |num_output_frames|, in this
// case only the first |num_output_frames| will be overwritten.
// @return True if there was sufficient data in the buffer and the output was
// successfully retrieved.
bool RetrieveBuffer(AudioBuffer::Channel* output);
// Retrieves a buffer of output from the |CircularBuffer| to an offset
// location in an output channel, provided it contains sufficient data.
//
// @param offset Number of samples of offset into the |output| channel.
// @param output A channel to hold |num_output_frames| of output data. The
// channel may be greater in length than |num_output_frames| + |offset|,
// in this case only the first |num_output_frames| after |offset| will be
// overwritten.
// @return True if there was sufficient data in the buffer and the output was
// successfully retrieved.
bool RetrieveBufferWithOffset(size_t offset, AudioBuffer::Channel* output);
// Returns the number of samples of data currently in the |CircularBuffer|.
//
// @return The number of samples of data currently in the buffer.
size_t GetOccupancy() const { return num_valid_frames_; }
// Resets the |CircularBuffer|.
void Clear();
private:
// Number of input frames to be inserted into the buffer.
const size_t num_input_frames_;
// Number of output frames to be retrieved from the buffer.
const size_t num_output_frames_;
// Mono audio buffer to hold the data.
AudioBuffer buffer_;
// Position at which we are writing into the buffer.
size_t write_cursor_;
// position at which we are reading from the buffer.
size_t read_cursor_;
// Number of frames of data currently stored within the buffer.
size_t num_valid_frames_;
};
} // namespace vraudio
#endif // RESONANCE_AUDIO_DSP_CIRCULAR_BUFFER_H_
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