viseq/include/libremidi/backends/alsa_seq.hpp

#pragma once
//*********************************************************************//
//  API: LINUX ALSA SEQUENCER
//*********************************************************************//

// API information found at:
//   - http://www.alsa-project.org/documentation.php#Library

// The ALSA Sequencer API is based on the use of a callback function for
// MIDI input.
//
// Thanks to Pedro Lopez-Cabanillas for help with the ALSA sequencer
// time stamps and other assorted fixes!!!

#include <libremidi/backends/alsa_seq/midi_in.hpp>
#include <libremidi/backends/alsa_seq/midi_out.hpp>
#include <libremidi/backends/alsa_seq/observer.hpp>

#include <unistd.h>

#include <string_view>

namespace libremidi::alsa_seq
{

struct backend
{
  using midi_in
      = alsa_seq::midi_in_impl<libremidi::input_configuration, alsa_seq::input_configuration>;
  using midi_out = alsa_seq::midi_out_impl;
  using midi_observer = alsa_seq::observer_impl<alsa_seq::observer_configuration>;
  using midi_in_configuration = alsa_seq::input_configuration;
  using midi_out_configuration = alsa_seq::output_configuration;
  using midi_observer_configuration = alsa_seq::observer_configuration;
  static const constexpr auto API = libremidi::API::ALSA_SEQ;
  static const constexpr std::string_view name = "alsa_seq";
  static const constexpr std::string_view display_name = "ALSA (sequencer)";

  static inline bool available() noexcept
  {
    static const libasound& snd = libasound::instance();
    if (!snd.available || !snd.seq.available)
      return false;

    return ::access("/dev/snd/seq", F_OK) == 0;
  }
};

}