MidiSysexArena.hpp

#pragma once
#include <libremidi/detail/conversion.hpp>
#include <libremidi/ump.hpp>
 
#include <algorithm>
#include <array>
#include <cstddef>
#include <cstdint>
#include <span>
 
namespace Process
{
class MidiSysexArena
{
public:
  static constexpr std::size_t max_message = 4096;
  static constexpr std::size_t capacity = 16384;
  using stream = libremidi::ump_to_midi1_stream<max_message>;
 
  static bool isSysex(const libremidi::ump& packet) noexcept
  {
    return packet.get_type() == libremidi::midi2::message_type::SYSEX7;
  }
 
  std::span<const uint8_t> feed(stream& s, const libremidi::ump& packet) noexcept
  {
    if(!isSysex(packet))
      return {};
 
    const auto dropped_before = s.dropped();
    const auto message = s.feed(packet);
    m_dropped += s.dropped() - dropped_before;
    if(message.empty())
      return {};
 
    if(message.size() > capacity - m_used)
    {
      ++m_dropped;
      return {};
    }
 
    uint8_t* const dst = m_bytes.data() + m_used;
    std::copy(message.begin(), message.end(), dst);
    m_used += message.size();
    return {dst, message.size()};
  }
 
  void clear() noexcept { m_used = 0; }
 
  std::size_t dropped() const noexcept { return m_dropped; }
 
private:
  std::array<uint8_t, capacity> m_bytes;
  std::size_t m_used{};
  std::size_t m_dropped{};
};
}