Rewrite the ALSA sequencer input loop.

Seemingly we can get multiple events in one poll, and we can _not_
just go back to polling again (the poll will hang). I consider this
an ALSA bug, but it's easy to work around, the same way aseqdump
does; just set the sequencer to nonblocking and loop over it
until we get EAGAIN.

diff --git a/midi_mapper.cpp b/midi_mapper.cpp
index 32fcc1000babe87eb7721b0618a01149b0e5a6bc..fca926f13661f084dca1cb8542f59527139d7a98 100644 (file)
--- a/midi_mapper.cpp
+++ b/midi_mapper.cpp
@@ -97,6 +97,7 @@ void MIDIMapper::thread_func()
        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",
@@ -131,88 +132,112 @@ void MIDIMapper::thread_func()
                        break;
                }
 
-               snd_seq_event_t *event;
-               err = snd_seq_event_input(seq, &event);
-               if (event->type == SND_SEQ_EVENT_CONTROLLER) {
-                       printf("Controller %d changed to %d\n", event->data.control.param, event->data.control.value);
-
-                       const int controller = event->data.control.param;
-                       const float value = map_controller_to_float(event->data.control.value);
-
-                       match_controller(controller, MIDIMappingBusProto::kLocutFieldNumber, MIDIMappingProto::kLocutBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_locut, receiver, _2));
-                       match_controller(controller, MIDIMappingBusProto::kLimiterThresholdFieldNumber, MIDIMappingProto::kLimiterThresholdBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_limiter_threshold, receiver, _2));
-                       match_controller(controller, MIDIMappingBusProto::kMakeupGainFieldNumber, MIDIMappingProto::kMakeupGainBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_makeup_gain, receiver, _2));
-
-                       match_controller(controller, MIDIMappingBusProto::kTrebleFieldNumber, MIDIMappingProto::kTrebleBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_treble, receiver, _1, _2));
-                       match_controller(controller, MIDIMappingBusProto::kMidFieldNumber, MIDIMappingProto::kMidBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_mid, receiver, _1, _2));
-                       match_controller(controller, MIDIMappingBusProto::kBassFieldNumber, MIDIMappingProto::kBassBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_bass, receiver, _1, _2));
-                       match_controller(controller, MIDIMappingBusProto::kGainFieldNumber, MIDIMappingProto::kGainBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_gain, receiver, _1, _2));
-                       match_controller(controller, MIDIMappingBusProto::kCompressorThresholdFieldNumber, MIDIMappingProto::kCompressorThresholdBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_compressor_threshold, receiver, _1, _2));
-                       match_controller(controller, MIDIMappingBusProto::kFaderFieldNumber, MIDIMappingProto::kFaderBankFieldNumber,
-                               value, bind(&ControllerReceiver::set_fader, receiver, _1, _2));
-               } else if (event->type == SND_SEQ_EVENT_NOTEON) {
-                       const int note = event->data.note.note;
-
-                       printf("Note: %d\n", note);
-
-                       // Bank change commands. TODO: Highlight the bank change in the UI.
-                       for (size_t bus_idx = 0; bus_idx < size_t(mapping_proto->bus_mapping_size()); ++bus_idx) {
-                               const MIDIMappingBusProto &bus_mapping = mapping_proto->bus_mapping(bus_idx);
-                               if (bus_mapping.has_prev_bank() &&
-                                   bus_mapping.prev_bank().note_number() == note) {
-                                       current_controller_bank = (current_controller_bank + num_controller_banks - 1) % num_controller_banks;
-                               }
-                               if (bus_mapping.has_next_bank() &&
-                                   bus_mapping.next_bank().note_number() == note) {
-                                       current_controller_bank = (current_controller_bank + 1) % num_controller_banks;
-                               }
-                               if (bus_mapping.has_select_bank_1() &&
-                                   bus_mapping.select_bank_1().note_number() == note) {
-                                       current_controller_bank = 0;
-                               }
-                               if (bus_mapping.has_select_bank_2() &&
-                                   bus_mapping.select_bank_2().note_number() == note &&
-                                   num_controller_banks >= 2) {
-                                       current_controller_bank = 1;
-                               }
-                               if (bus_mapping.has_select_bank_3() &&
-                                   bus_mapping.select_bank_3().note_number() == note &&
-                                   num_controller_banks >= 3) {
-                                       current_controller_bank = 2;
-                               }
-                               if (bus_mapping.has_select_bank_4() &&
-                                   bus_mapping.select_bank_4().note_number() == note &&
-                                   num_controller_banks >= 4) {
-                                       current_controller_bank = 3;
-                               }
-                               if (bus_mapping.has_select_bank_5() &&
-                                   bus_mapping.select_bank_5().note_number() == note &&
-                                   num_controller_banks >= 5) {
-                                       current_controller_bank = 4;
-                               }
+               // 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;
+                               fprintf(stderr, "snd_seq_event_input: %s\n", snd_strerror(err));
+                               return;
                        }
+                       if (event) {
+                               handle_event(seq, event);
+                       }
+               }
+       }
+}
 
-                       match_button(note, MIDIMappingBusProto::kToggleLocutFieldNumber, MIDIMappingProto::kToggleLocutBankFieldNumber,
-                               bind(&ControllerReceiver::toggle_locut, receiver, _1));
-                       match_button(note, MIDIMappingBusProto::kToggleAutoGainStagingFieldNumber, MIDIMappingProto::kToggleAutoGainStagingBankFieldNumber,
-                               bind(&ControllerReceiver::toggle_auto_gain_staging, receiver, _1));
-                       match_button(note, MIDIMappingBusProto::kToggleCompressorFieldNumber, MIDIMappingProto::kToggleCompressorBankFieldNumber,
-                               bind(&ControllerReceiver::toggle_compressor, receiver, _1));
-                       match_button(note, MIDIMappingBusProto::kClearPeakFieldNumber, MIDIMappingProto::kClearPeakBankFieldNumber,
-                               bind(&ControllerReceiver::clear_peak, receiver, _1));
-               } else if (event->type == SND_SEQ_EVENT_NOTEOFF) {
-                       // Ignore.
-               } else {
-                       printf("Ignoring MIDI event of unknown type %d.\n", event->type);
+void MIDIMapper::handle_event(snd_seq_t *seq, snd_seq_event_t *event)
+{
+       switch (event->type) {
+       case SND_SEQ_EVENT_CONTROLLER: {
+               printf("Controller %d changed to %d\n", event->data.control.param, event->data.control.value);
+
+               const int controller = event->data.control.param;
+               const float value = map_controller_to_float(event->data.control.value);
+
+               // Global controllers.
+               match_controller(controller, MIDIMappingBusProto::kLocutFieldNumber, MIDIMappingProto::kLocutBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_locut, receiver, _2));
+               match_controller(controller, MIDIMappingBusProto::kLimiterThresholdFieldNumber, MIDIMappingProto::kLimiterThresholdBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_limiter_threshold, receiver, _2));
+               match_controller(controller, MIDIMappingBusProto::kMakeupGainFieldNumber, MIDIMappingProto::kMakeupGainBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_makeup_gain, receiver, _2));
+
+               // Bus controllers.
+               match_controller(controller, MIDIMappingBusProto::kTrebleFieldNumber, MIDIMappingProto::kTrebleBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_treble, receiver, _1, _2));
+               match_controller(controller, MIDIMappingBusProto::kMidFieldNumber, MIDIMappingProto::kMidBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_mid, receiver, _1, _2));
+               match_controller(controller, MIDIMappingBusProto::kBassFieldNumber, MIDIMappingProto::kBassBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_bass, receiver, _1, _2));
+               match_controller(controller, MIDIMappingBusProto::kGainFieldNumber, MIDIMappingProto::kGainBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_gain, receiver, _1, _2));
+               match_controller(controller, MIDIMappingBusProto::kCompressorThresholdFieldNumber, MIDIMappingProto::kCompressorThresholdBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_compressor_threshold, receiver, _1, _2));
+               match_controller(controller, MIDIMappingBusProto::kFaderFieldNumber, MIDIMappingProto::kFaderBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_fader, receiver, _1, _2));
+               break;
+       }
+       case SND_SEQ_EVENT_NOTEON: {
+               const int note = event->data.note.note;
+
+               printf("Note: %d\n", note);
+
+               // Bank change commands. TODO: Highlight the bank change in the UI.
+               for (size_t bus_idx = 0; bus_idx < size_t(mapping_proto->bus_mapping_size()); ++bus_idx) {
+                       const MIDIMappingBusProto &bus_mapping = mapping_proto->bus_mapping(bus_idx);
+                       if (bus_mapping.has_prev_bank() &&
+                           bus_mapping.prev_bank().note_number() == note) {
+                               current_controller_bank = (current_controller_bank + num_controller_banks - 1) % num_controller_banks;
+                       }
+                       if (bus_mapping.has_next_bank() &&
+                           bus_mapping.next_bank().note_number() == note) {
+                               current_controller_bank = (current_controller_bank + 1) % num_controller_banks;
+                       }
+                       if (bus_mapping.has_select_bank_1() &&
+                           bus_mapping.select_bank_1().note_number() == note) {
+                               current_controller_bank = 0;
+                       }
+                       if (bus_mapping.has_select_bank_2() &&
+                           bus_mapping.select_bank_2().note_number() == note &&
+                           num_controller_banks >= 2) {
+                               current_controller_bank = 1;
+                       }
+                       if (bus_mapping.has_select_bank_3() &&
+                           bus_mapping.select_bank_3().note_number() == note &&
+                           num_controller_banks >= 3) {
+                               current_controller_bank = 2;
+                       }
+                       if (bus_mapping.has_select_bank_4() &&
+                           bus_mapping.select_bank_4().note_number() == note &&
+                           num_controller_banks >= 4) {
+                               current_controller_bank = 3;
+                       }
+                       if (bus_mapping.has_select_bank_5() &&
+                           bus_mapping.select_bank_5().note_number() == note &&
+                           num_controller_banks >= 5) {
+                               current_controller_bank = 4;
+                       }
                }
+
+               match_button(note, MIDIMappingBusProto::kToggleLocutFieldNumber, MIDIMappingProto::kToggleLocutBankFieldNumber,
+                       bind(&ControllerReceiver::toggle_locut, receiver, _1));
+               match_button(note, MIDIMappingBusProto::kToggleAutoGainStagingFieldNumber, MIDIMappingProto::kToggleAutoGainStagingBankFieldNumber,
+                       bind(&ControllerReceiver::toggle_auto_gain_staging, receiver, _1));
+               match_button(note, MIDIMappingBusProto::kToggleCompressorFieldNumber, MIDIMappingProto::kToggleCompressorBankFieldNumber,
+                       bind(&ControllerReceiver::toggle_compressor, receiver, _1));
+               match_button(note, MIDIMappingBusProto::kClearPeakFieldNumber, MIDIMappingProto::kClearPeakBankFieldNumber,
+                       bind(&ControllerReceiver::clear_peak, receiver, _1));
+       }
+       case SND_SEQ_EVENT_NOTEOFF:
+               // Ignore.
+               break;
+       default:
+               printf("Ignoring MIDI event of unknown type %d.\n", event->type);
        }
 }
 

diff --git a/midi_mapper.h b/midi_mapper.h
index 5b8b98ec37cfc38bef11e874cbb2c0125e6ffe25..0c7bb606e05095a58c5e18101f136b71733948be 100644 (file)
--- a/midi_mapper.h
+++ b/midi_mapper.h
@@ -15,6 +15,8 @@
 #include <thread>
 
 class MIDIMappingProto;
+typedef struct snd_seq_event snd_seq_event_t;
+typedef struct _snd_seq snd_seq_t;
 
 // Interface for receiving interpreted controller messages.
 class ControllerReceiver {
@@ -47,6 +49,7 @@ public:
 
 private:
        void thread_func();
+       void handle_event(snd_seq_t *seq, snd_seq_event_t *event);
        void match_controller(int controller, int field_number, int bank_field_number, float value, std::function<void(unsigned, float)> func);
        void match_button(int note, int field_number, int bank_field_number, std::function<void(unsigned)> func);
        bool bank_mismatch(int bank_field_number);