--- /dev/null
+#include "midi_device.h"
+
+#include <alsa/asoundlib.h>
+#include <sys/eventfd.h>
+#include <unistd.h>
+#include <thread>
+#include <utility>
+
+using namespace std;
+
+MIDIDevice::MIDIDevice(MIDIReceiver *receiver)
+ : receiver(receiver)
+{
+ should_quit_fd = eventfd(/*initval=*/0, /*flags=*/0);
+ assert(should_quit_fd != -1);
+}
+
+MIDIDevice::~MIDIDevice()
+{
+ should_quit = true;
+ const uint64_t one = 1;
+ if (write(should_quit_fd, &one, sizeof(one)) != sizeof(one)) {
+ perror("write(should_quit_fd)");
+ exit(1);
+ }
+ midi_thread.join();
+ close(should_quit_fd);
+}
+
+void MIDIDevice::start_thread()
+{
+ midi_thread = thread(&MIDIDevice::thread_func, this);
+}
+
+#define RETURN_ON_ERROR(msg, expr) do { \
+ int err = (expr); \
+ if (err < 0) { \
+ fprintf(stderr, msg ": %s\n", snd_strerror(err)); \
+ return; \
+ } \
+} while (false)
+
+#define WARN_ON_ERROR(msg, expr) do { \
+ int err = (expr); \
+ if (err < 0) { \
+ fprintf(stderr, msg ": %s\n", snd_strerror(err)); \
+ } \
+} while (false)
+
+
+void MIDIDevice::thread_func()
+{
+ pthread_setname_np(pthread_self(), "MIDIDevice");
+
+ snd_seq_t *seq;
+ int err;
+
+ RETURN_ON_ERROR("snd_seq_open", snd_seq_open(&seq, "default", SND_SEQ_OPEN_DUPLEX, 0));
+ RETURN_ON_ERROR("snd_seq_nonblock", snd_seq_nonblock(seq, 1));
+ RETURN_ON_ERROR("snd_seq_client_name", snd_seq_set_client_name(seq, "nageru"));
+ RETURN_ON_ERROR("snd_seq_create_simple_port",
+ snd_seq_create_simple_port(seq, "nageru",
+ SND_SEQ_PORT_CAP_READ |
+ SND_SEQ_PORT_CAP_SUBS_READ |
+ SND_SEQ_PORT_CAP_WRITE |
+ SND_SEQ_PORT_CAP_SUBS_WRITE,
+ SND_SEQ_PORT_TYPE_MIDI_GENERIC |
+ SND_SEQ_PORT_TYPE_APPLICATION));
+
+ int queue_id = snd_seq_alloc_queue(seq);
+ RETURN_ON_ERROR("snd_seq_create_queue", queue_id);
+ RETURN_ON_ERROR("snd_seq_start_queue", snd_seq_start_queue(seq, queue_id, nullptr));
+
+ // The sequencer object is now ready to be used from other threads.
+ {
+ lock_guard<mutex> lock(mu);
+ alsa_seq = seq;
+ alsa_queue_id = queue_id;
+ }
+
+ // Listen to the announce port (0:1), which will tell us about new ports.
+ RETURN_ON_ERROR("snd_seq_connect_from", snd_seq_connect_from(seq, 0, /*client=*/0, /*port=*/1));
+
+ // Now go through all ports and subscribe to them.
+ snd_seq_client_info_t *cinfo;
+ snd_seq_client_info_alloca(&cinfo);
+
+ snd_seq_client_info_set_client(cinfo, -1);
+ while (snd_seq_query_next_client(seq, cinfo) >= 0) {
+ int client = snd_seq_client_info_get_client(cinfo);
+
+ snd_seq_port_info_t *pinfo;
+ snd_seq_port_info_alloca(&pinfo);
+
+ snd_seq_port_info_set_client(pinfo, client);
+ snd_seq_port_info_set_port(pinfo, -1);
+ while (snd_seq_query_next_port(seq, pinfo) >= 0) {
+ constexpr int mask = SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_READ;
+ if ((snd_seq_port_info_get_capability(pinfo) & mask) == mask) {
+ lock_guard<mutex> lock(mu);
+ subscribe_to_port_lock_held(seq, *snd_seq_port_info_get_addr(pinfo));
+ }
+ }
+ }
+
+ int num_alsa_fds = snd_seq_poll_descriptors_count(seq, POLLIN);
+ unique_ptr<pollfd[]> fds(new pollfd[num_alsa_fds + 1]);
+
+ while (!should_quit) {
+ snd_seq_poll_descriptors(seq, fds.get(), num_alsa_fds, POLLIN);
+ fds[num_alsa_fds].fd = should_quit_fd;
+ fds[num_alsa_fds].events = POLLIN;
+ fds[num_alsa_fds].revents = 0;
+
+ err = poll(fds.get(), num_alsa_fds + 1, -1);
+ if (err == 0 || (err == -1 && errno == EINTR)) {
+ continue;
+ }
+ if (err == -1) {
+ perror("poll");
+ break;
+ }
+ if (fds[num_alsa_fds].revents) {
+ // Activity on should_quit_fd.
+ break;
+ }
+
+ // Seemingly we can get multiple events in a single poll,
+ // and if we don't handle them all, poll will _not_ alert us!
+ while (!should_quit) {
+ snd_seq_event_t *event;
+ err = snd_seq_event_input(seq, &event);
+ if (err < 0) {
+ if (err == -EINTR) continue;
+ if (err == -EAGAIN) break;
+ if (err == -ENOSPC) {
+ fprintf(stderr, "snd_seq_event_input: Some events were lost.\n");
+ continue;
+ }
+ fprintf(stderr, "snd_seq_event_input: %s\n", snd_strerror(err));
+ return;
+ }
+ if (event) {
+ handle_event(seq, event);
+ }
+ }
+ }
+}
+
+void MIDIDevice::handle_event(snd_seq_t *seq, snd_seq_event_t *event)
+{
+ if (event->source.client == snd_seq_client_id(seq)) {
+ // Ignore events we sent out ourselves.
+ return;
+ }
+
+ lock_guard<mutex> lock(mu);
+ switch (event->type) {
+ case SND_SEQ_EVENT_CONTROLLER: {
+ receiver->controller_received(event->data.control.param, event->data.control.value);
+ break;
+ }
+ case SND_SEQ_EVENT_NOTEON: {
+ receiver->note_on_received(event->data.note.note);
+ break;
+ }
+ case SND_SEQ_EVENT_PORT_START:
+ subscribe_to_port_lock_held(seq, event->data.addr);
+ break;
+ case SND_SEQ_EVENT_PORT_EXIT:
+ printf("MIDI port %d:%d went away.\n", event->data.addr.client, event->data.addr.port);
+ break;
+ case SND_SEQ_EVENT_PORT_SUBSCRIBED:
+ if (event->data.connect.sender.client != 0 && // Ignore system senders.
+ event->data.connect.sender.client != snd_seq_client_id(seq) &&
+ event->data.connect.dest.client == snd_seq_client_id(seq)) {
+ receiver->update_num_subscribers(++num_subscribed_ports);
+ }
+ break;
+ case SND_SEQ_EVENT_PORT_UNSUBSCRIBED:
+ if (event->data.connect.sender.client != 0 && // Ignore system senders.
+ event->data.connect.sender.client != snd_seq_client_id(seq) &&
+ event->data.connect.dest.client == snd_seq_client_id(seq)) {
+ receiver->update_num_subscribers(--num_subscribed_ports);
+ }
+ break;
+ case SND_SEQ_EVENT_NOTEOFF:
+ case SND_SEQ_EVENT_CLIENT_START:
+ case SND_SEQ_EVENT_CLIENT_EXIT:
+ case SND_SEQ_EVENT_CLIENT_CHANGE:
+ case SND_SEQ_EVENT_PORT_CHANGE:
+ break;
+ default:
+ printf("Ignoring MIDI event of unknown type %d.\n", event->type);
+ }
+}
+
+void MIDIDevice::subscribe_to_port_lock_held(snd_seq_t *seq, const snd_seq_addr_t &addr)
+{
+ // Client 0 (SNDRV_SEQ_CLIENT_SYSTEM) is basically the system; ignore it.
+ // MIDI through (SNDRV_SEQ_CLIENT_DUMMY) echoes back what we give it, so ignore that, too.
+ if (addr.client == 0 || addr.client == 14) {
+ return;
+ }
+
+ // Don't listen to ourselves.
+ if (addr.client == snd_seq_client_id(seq)) {
+ return;
+ }
+
+ int err = snd_seq_connect_from(seq, 0, addr.client, addr.port);
+ if (err < 0) {
+ // Just print out a warning (i.e., don't die); it could
+ // very well just be e.g. another application.
+ printf("Couldn't subscribe to MIDI port %d:%d (%s).\n",
+ addr.client, addr.port, snd_strerror(err));
+ } else {
+ printf("Subscribed to MIDI port %d:%d.\n", addr.client, addr.port);
+ }
+
+ // For sending data back.
+ err = snd_seq_connect_to(seq, 0, addr.client, addr.port);
+ if (err < 0) {
+ printf("Couldn't subscribe MIDI port %d:%d (%s) to us.\n",
+ addr.client, addr.port, snd_strerror(err));
+ } else {
+ printf("Subscribed MIDI port %d:%d to us.\n", addr.client, addr.port);
+ }
+
+ // The current status of the device is unknown, so refresh it.
+ set<unsigned> active_lights;
+ for (const auto &it : current_light_status) {
+ if (it.second) {
+ active_lights.insert(it.first);
+ }
+ }
+ current_light_status.clear();
+ update_lights_lock_held(active_lights);
+}
+
+void MIDIDevice::update_lights_lock_held(const set<unsigned> &active_lights)
+{
+ if (alsa_seq == nullptr) {
+ return;
+ }
+
+ unsigned num_events = 0;
+ for (unsigned note_num = 1; note_num <= 127; ++note_num) {
+ bool active = active_lights.count(note_num);
+ if (current_light_status.count(note_num) &&
+ current_light_status[note_num] == active) {
+ // Already known to be in the desired state.
+ continue;
+ }
+
+ snd_seq_event_t ev;
+ snd_seq_ev_clear(&ev);
+
+ // Some devices drop events if we throw them onto them
+ // too quickly. Add a 1 ms delay for each.
+ snd_seq_real_time_t tm{0, num_events++ * 1000000};
+ snd_seq_ev_schedule_real(&ev, alsa_queue_id, true, &tm);
+ snd_seq_ev_set_source(&ev, 0);
+ snd_seq_ev_set_subs(&ev);
+
+ // For some reason, not all devices respond to note off.
+ // Use note-on with velocity of 0 (which is equivalent) instead.
+ snd_seq_ev_set_noteon(&ev, /*channel=*/0, note_num, active ? 1 : 0);
+ WARN_ON_ERROR("snd_seq_event_output", snd_seq_event_output(alsa_seq, &ev));
+ current_light_status[note_num] = active;
+ }
+ WARN_ON_ERROR("snd_seq_drain_output", snd_seq_drain_output(alsa_seq));
+}
projects / nageru / blobdiff