git.sesse.net Git - nageru/blob - nageru/midi_device.cpp

   1 #include "midi_device.h"
   2
   3 #include <alsa/asoundlib.h>
   4 #include <sys/eventfd.h>
   5 #include <unistd.h>
   6 #include <thread>
   7 #include <utility>
   8
   9 using namespace std;
  10
  11 MIDIDevice::MIDIDevice(MIDIReceiver *receiver)
  12         : receiver(receiver)
  13 {
  14         should_quit_fd = eventfd(/*initval=*/0, /*flags=*/0);
  15         assert(should_quit_fd != -1);
  16 }
  17
  18 MIDIDevice::~MIDIDevice()
  19 {
  20         should_quit = true;
  21         const uint64_t one = 1;
  22         if (write(should_quit_fd, &one, sizeof(one)) != sizeof(one)) {
  23                 perror("write(should_quit_fd)");
  24                 exit(1);
  25         }
  26         midi_thread.join();
  27         close(should_quit_fd);
  28 }
  29
  30 void MIDIDevice::start_thread()
  31 {
  32         midi_thread = thread(&MIDIDevice::thread_func, this);
  33 }
  34
  35 #define RETURN_ON_ERROR(msg, expr) do {                            \
  36         int err = (expr);                                          \
  37         if (err < 0) {                                             \
  38                 fprintf(stderr, msg ": %s\n", snd_strerror(err));  \
  39                 return;                                            \
  40         }                                                          \
  41 } while (false)
  42
  43 #define WARN_ON_ERROR(msg, expr) do {                              \
  44         int err = (expr);                                          \
  45         if (err < 0) {                                             \
  46                 fprintf(stderr, msg ": %s\n", snd_strerror(err));  \
  47         }                                                          \
  48 } while (false)
  49
  50
  51 void MIDIDevice::thread_func()
  52 {
  53         pthread_setname_np(pthread_self(), "MIDIDevice");
  54
  55         snd_seq_t *seq;
  56         int err;
  57
  58         RETURN_ON_ERROR("snd_seq_open", snd_seq_open(&seq, "default", SND_SEQ_OPEN_DUPLEX, 0));
  59         RETURN_ON_ERROR("snd_seq_nonblock", snd_seq_nonblock(seq, 1));
  60         RETURN_ON_ERROR("snd_seq_client_name", snd_seq_set_client_name(seq, "nageru"));
  61         RETURN_ON_ERROR("snd_seq_create_simple_port",
  62                 snd_seq_create_simple_port(seq, "nageru",
  63                         SND_SEQ_PORT_CAP_READ |
  64                                 SND_SEQ_PORT_CAP_SUBS_READ |
  65                                 SND_SEQ_PORT_CAP_WRITE |
  66                                 SND_SEQ_PORT_CAP_SUBS_WRITE,
  67                         SND_SEQ_PORT_TYPE_MIDI_GENERIC |
  68                                 SND_SEQ_PORT_TYPE_APPLICATION));
  69
  70         int queue_id = snd_seq_alloc_queue(seq);
  71         RETURN_ON_ERROR("snd_seq_create_queue", queue_id);
  72         RETURN_ON_ERROR("snd_seq_start_queue", snd_seq_start_queue(seq, queue_id, nullptr));
  73
  74         // The sequencer object is now ready to be used from other threads.
  75         {
  76                 lock_guard<mutex> lock(mu);
  77                 alsa_seq = seq;
  78                 alsa_queue_id = queue_id;
  79         }
  80
  81         // Listen to the announce port (0:1), which will tell us about new ports.
  82         RETURN_ON_ERROR("snd_seq_connect_from", snd_seq_connect_from(seq, 0, /*client=*/0, /*port=*/1));
  83
  84         // Now go through all ports and subscribe to them.
  85         snd_seq_client_info_t *cinfo;
  86         snd_seq_client_info_alloca(&cinfo);
  87
  88         snd_seq_client_info_set_client(cinfo, -1);
  89         while (snd_seq_query_next_client(seq, cinfo) >= 0) {
  90                 int client = snd_seq_client_info_get_client(cinfo);
  91
  92                 snd_seq_port_info_t *pinfo;
  93                 snd_seq_port_info_alloca(&pinfo);
  94
  95                 snd_seq_port_info_set_client(pinfo, client);
  96                 snd_seq_port_info_set_port(pinfo, -1);
  97                 while (snd_seq_query_next_port(seq, pinfo) >= 0) {
  98                         constexpr int mask = SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_READ;
  99                         if ((snd_seq_port_info_get_capability(pinfo) & mask) == mask) {
 100                                 lock_guard<mutex> lock(mu);
 101                                 subscribe_to_port_lock_held(seq, *snd_seq_port_info_get_addr(pinfo));
 102                         }
 103                 }
 104         }
 105
 106         int num_alsa_fds = snd_seq_poll_descriptors_count(seq, POLLIN);
 107         unique_ptr<pollfd[]> fds(new pollfd[num_alsa_fds + 1]);
 108
 109         while (!should_quit) {
 110                 snd_seq_poll_descriptors(seq, fds.get(), num_alsa_fds, POLLIN);
 111                 fds[num_alsa_fds].fd = should_quit_fd;
 112                 fds[num_alsa_fds].events = POLLIN;
 113                 fds[num_alsa_fds].revents = 0;
 114
 115                 err = poll(fds.get(), num_alsa_fds + 1, -1);
 116                 if (err == 0 || (err == -1 && errno == EINTR)) {
 117                         continue;
 118                 }
 119                 if (err == -1) {
 120                         perror("poll");
 121                         break;
 122                 }
 123                 if (fds[num_alsa_fds].revents) {
 124                         // Activity on should_quit_fd.
 125                         break;
 126                 }
 127
 128                 // Seemingly we can get multiple events in a single poll,
 129                 // and if we don't handle them all, poll will _not_ alert us!
 130                 while (!should_quit) {
 131                         snd_seq_event_t *event;
 132                         err = snd_seq_event_input(seq, &event);
 133                         if (err < 0) {
 134                                 if (err == -EINTR) continue;
 135                                 if (err == -EAGAIN) break;
 136                                 if (err == -ENOSPC) {
 137                                         fprintf(stderr, "snd_seq_event_input: Some events were lost.\n");
 138                                         continue;
 139                                 }
 140                                 fprintf(stderr, "snd_seq_event_input: %s\n", snd_strerror(err));
 141                                 return;
 142                         }
 143                         if (event) {
 144                                 handle_event(seq, event);
 145                         }
 146                 }
 147         }
 148 }
 149
 150 void MIDIDevice::handle_event(snd_seq_t *seq, snd_seq_event_t *event)
 151 {
 152         if (event->source.client == snd_seq_client_id(seq)) {
 153                 // Ignore events we sent out ourselves.
 154                 return;
 155         }
 156
 157         lock_guard<mutex> lock(mu);
 158         switch (event->type) {
 159         case SND_SEQ_EVENT_CONTROLLER: {
 160                 receiver->controller_received(event->data.control.param, event->data.control.value);
 161                 break;
 162         }
 163         case SND_SEQ_EVENT_NOTEON: {
 164                 receiver->note_on_received(event->data.note.note);
 165                 break;
 166         }
 167         case SND_SEQ_EVENT_PORT_START:
 168                 subscribe_to_port_lock_held(seq, event->data.addr);
 169                 break;
 170         case SND_SEQ_EVENT_PORT_EXIT:
 171                 printf("MIDI port %d:%d went away.\n", event->data.addr.client, event->data.addr.port);
 172                 break;
 173         case SND_SEQ_EVENT_PORT_SUBSCRIBED:
 174                 if (event->data.connect.sender.client != 0 &&  // Ignore system senders.
 175                     event->data.connect.sender.client != snd_seq_client_id(seq) &&
 176                     event->data.connect.dest.client == snd_seq_client_id(seq)) {
 177                         receiver->update_num_subscribers(++num_subscribed_ports);
 178                 }
 179                 break;
 180         case SND_SEQ_EVENT_PORT_UNSUBSCRIBED:
 181                 if (event->data.connect.sender.client != 0 &&  // Ignore system senders.
 182                     event->data.connect.sender.client != snd_seq_client_id(seq) &&
 183                     event->data.connect.dest.client == snd_seq_client_id(seq)) {
 184                         receiver->update_num_subscribers(--num_subscribed_ports);
 185                 }
 186                 break;
 187         case SND_SEQ_EVENT_NOTEOFF:
 188         case SND_SEQ_EVENT_CLIENT_START:
 189         case SND_SEQ_EVENT_CLIENT_EXIT:
 190         case SND_SEQ_EVENT_CLIENT_CHANGE:
 191         case SND_SEQ_EVENT_PORT_CHANGE:
 192                 break;
 193         default:
 194                 printf("Ignoring MIDI event of unknown type %d.\n", event->type);
 195         }
 196 }
 197
 198 void MIDIDevice::subscribe_to_port_lock_held(snd_seq_t *seq, const snd_seq_addr_t &addr)
 199 {
 200         // Client 0 (SNDRV_SEQ_CLIENT_SYSTEM) is basically the system; ignore it.
 201         // MIDI through (SNDRV_SEQ_CLIENT_DUMMY) echoes back what we give it, so ignore that, too.
 202         if (addr.client == 0 || addr.client == 14) {
 203                 return;
 204         }
 205
 206         // Don't listen to ourselves.
 207         if (addr.client == snd_seq_client_id(seq)) {
 208                 return;
 209         }
 210
 211         int err = snd_seq_connect_from(seq, 0, addr.client, addr.port);
 212         if (err < 0) {
 213                 // Just print out a warning (i.e., don't die); it could
 214                 // very well just be e.g. another application.
 215                 printf("Couldn't subscribe to MIDI port %d:%d (%s).\n",
 216                         addr.client, addr.port, snd_strerror(err));
 217         } else {
 218                 printf("Subscribed to MIDI port %d:%d.\n", addr.client, addr.port);
 219         }
 220
 221         // For sending data back.
 222         err = snd_seq_connect_to(seq, 0, addr.client, addr.port);
 223         if (err < 0) {
 224                 printf("Couldn't subscribe MIDI port %d:%d (%s) to us.\n",
 225                         addr.client, addr.port, snd_strerror(err));
 226         } else {
 227                 printf("Subscribed MIDI port %d:%d to us.\n", addr.client, addr.port);
 228         }
 229
 230         // The current status of the device is unknown, so refresh it.
 231         set<unsigned> active_lights;
 232         for (const auto &it : current_light_status) {
 233                 if (it.second) {
 234                         active_lights.insert(it.first);
 235                 }
 236         }
 237         current_light_status.clear();
 238         update_lights_lock_held(active_lights);
 239 }
 240
 241 void MIDIDevice::update_lights_lock_held(const set<unsigned> &active_lights)
 242 {
 243         if (alsa_seq == nullptr) {
 244                 return;
 245         }
 246
 247         unsigned num_events = 0;
 248         for (unsigned note_num = 1; note_num <= 127; ++note_num) {
 249                 bool active = active_lights.count(note_num);
 250                 if (current_light_status.count(note_num) &&
 251                     current_light_status[note_num] == active) {
 252                         // Already known to be in the desired state.
 253                         continue;
 254                 }
 255
 256                 snd_seq_event_t ev;
 257                 snd_seq_ev_clear(&ev);
 258
 259                 // Some devices drop events if we throw them onto them
 260                 // too quickly. Add a 1 ms delay for each.
 261                 snd_seq_real_time_t tm{0, num_events++ * 1000000};
 262                 snd_seq_ev_schedule_real(&ev, alsa_queue_id, true, &tm);
 263                 snd_seq_ev_set_source(&ev, 0);
 264                 snd_seq_ev_set_subs(&ev);
 265
 266                 // For some reason, not all devices respond to note off.
 267                 // Use note-on with velocity of 0 (which is equivalent) instead.
 268                 snd_seq_ev_set_noteon(&ev, /*channel=*/0, note_num, active ? 1 : 0);
 269                 WARN_ON_ERROR("snd_seq_event_output", snd_seq_event_output(alsa_seq, &ev));
 270                 current_light_status[note_num] = active;
 271         }
 272         WARN_ON_ERROR("snd_seq_drain_output", snd_seq_drain_output(alsa_seq));
 273 }