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/*
* Copyright 2023 jacqueline <me@jacqueline.id.au>
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#pragma once
#include <cstddef>
#include <cstdint>
#include "freertos/FreeRTOS.h"
#include "freertos/message_buffer.h"
#include "span.hpp"
namespace audio {
/*
* A collection of the buffers required for two IAudioElement implementations to
* stream data between each other.
*
* Currently, we use a FreeRTOS MessageBuffer to hold the byte stream, and also
* maintain two chunk-sized buffers for the elements to stage their read and
* write operations (as MessageBuffer copies the given data into its memory
* space). A future optimisation here could be to instead post himem memory
* addresses to the message buffer, and then maintain address spaces into which
* we map these messages, rather than 'real' allocated buffers as we do now.
*/
class StreamBuffer {
public:
explicit StreamBuffer(std::size_t chunk_size, std::size_t buffer_size);
~StreamBuffer();
/* Returns the handle for the underlying message buffer. */
auto Handle() -> MessageBufferHandle_t* { return &handle_; }
/*
* Returns a chunk-sized staging buffer that should be used *only* by the
* reader (sink) element.
*/
auto ReadBuffer() -> cpp::span<std::byte> { return input_chunk_; }
/*
* Returns a chunk-sized staging buffer that should be used *only* by the
* writer (source) element.
*/
auto WriteBuffer() -> cpp::span<std::byte> { return output_chunk_; }
StreamBuffer(const StreamBuffer&) = delete;
StreamBuffer& operator=(const StreamBuffer&) = delete;
private:
std::byte* raw_memory_;
StaticMessageBuffer_t metadata_;
MessageBufferHandle_t handle_;
std::byte* raw_input_chunk_;
cpp::span<std::byte> input_chunk_;
std::byte* raw_output_chunk_;
cpp::span<std::byte> output_chunk_;
};
} // namespace audio
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