tangara-fw/src/audio/chunk.cpp

#include "chunk.hpp"

#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <optional>

#include "cbor.h"
#include "esp_log.h"

#include "stream_buffer.hpp"
#include "stream_message.hpp"

namespace audio {

ChunkReader::ChunkReader(std::size_t chunk_size)
    : raw_working_buffer_(static_cast<std::byte*>(
          heap_caps_malloc(chunk_size * 1.5, MALLOC_CAP_SPIRAM))),
      working_buffer_(raw_working_buffer_, chunk_size * 1.5) {}

ChunkReader::~ChunkReader() {
  free(raw_working_buffer_);
}

auto ChunkReader::HandleNewData(cpp::span<std::byte> data)
    -> cpp::span<std::byte> {
  // Copy the new data onto the front for anything that was left over from the
  // last portion. Note: this could be optimised for the '0 leftover bytes'
  // case, which technically shouldn't need a copy.
  cpp::span<std::byte> new_data_dest = working_buffer_.subspan(leftover_bytes_);
  std::copy(data.begin(), data.end(), new_data_dest.begin());
  last_data_in_working_buffer_ =
      working_buffer_.first(leftover_bytes_ + data.size());
  leftover_bytes_ = 0;
  return last_data_in_working_buffer_;
}

auto ChunkReader::HandleLeftovers(std::size_t bytes_used) -> void {
  leftover_bytes_ = last_data_in_working_buffer_.size() - bytes_used;
  if (leftover_bytes_ > 0) {
    auto data_to_keep = last_data_in_working_buffer_.last(leftover_bytes_);
    // Copy backwards, since if more than half of the data was unused then the
    // source and destination will overlap.
    std::copy_backward(data_to_keep.begin(), data_to_keep.end(),
                       working_buffer_.begin());
  }
}

}  // namespace audio