From 81575174cbd99b4d1cedbe763d1df7cbc7e641c6 Mon Sep 17 00:00:00 2001 From: Ibrahn Sahir Date: Wed, 27 Oct 2021 15:14:19 +0100 Subject: [PATCH] Fix MIDI input with ALSA. Reworked the handling of ALSA RawMidi input to support: - Running Status. - RealTime Category messages arriving during other messages data. - Multiple connected RawMidi interfaces. --- drivers/alsamidi/midi_driver_alsamidi.cpp | 182 ++++++++++++++-------- drivers/alsamidi/midi_driver_alsamidi.h | 38 ++++- 2 files changed, 153 insertions(+), 67 deletions(-) diff --git a/drivers/alsamidi/midi_driver_alsamidi.cpp b/drivers/alsamidi/midi_driver_alsamidi.cpp index d2a00760231..011758e5f7b 100644 --- a/drivers/alsamidi/midi_driver_alsamidi.cpp +++ b/drivers/alsamidi/midi_driver_alsamidi.cpp @@ -37,85 +37,135 @@ #include -static int get_message_size(uint8_t message) { - switch (message & 0xF0) { - case 0x80: // note off - case 0x90: // note on - case 0xA0: // aftertouch - case 0xB0: // continuous controller - case 0xE0: // pitch bend - case 0xF2: // song position pointer - return 3; +MIDIDriverALSAMidi::MessageCategory MIDIDriverALSAMidi::msg_category(uint8_t msg_part) { + if (msg_part >= 0xf8) { + return MessageCategory::RealTime; + } else if (msg_part >= 0xf0) { + // System Exclusive begin/end are specified as System Common Category messages, + // but we separate them here and give them their own categories as their + // behaviour is significantly different. + if (msg_part == 0xf0) { + return MessageCategory::SysExBegin; + } else if (msg_part == 0xf7) { + return MessageCategory::SysExEnd; + } + return MessageCategory::SystemCommon; + } else if (msg_part >= 0x80) { + return MessageCategory::Voice; + } + return MessageCategory::Data; +} - case 0xC0: // patch change - case 0xD0: // channel pressure - case 0xF1: // time code quarter frame - case 0xF3: // song select +size_t MIDIDriverALSAMidi::msg_expected_data(uint8_t status_byte) { + if (msg_category(status_byte) == MessageCategory::Voice) { + // Voice messages have a channel number in the status byte, mask it out. + status_byte &= 0xf0; + } + + switch (status_byte) { + case 0x80: // Note Off + case 0x90: // Note On + case 0xA0: // Polyphonic Key Pressure (Aftertouch) + case 0xB0: // Control Change (CC) + case 0xE0: // Pitch Bend Change + case 0xF2: // Song Position Pointer return 2; - case 0xF0: // SysEx start - case 0xF4: // reserved - case 0xF5: // reserved - case 0xF6: // tune request - case 0xF7: // SysEx end - case 0xF8: // timing clock - case 0xF9: // reserved - case 0xFA: // start - case 0xFB: // continue - case 0xFC: // stop - case 0xFD: // reserved - case 0xFE: // active sensing - case 0xFF: // reset + case 0xC0: // Program Change + case 0xD0: // Channel Pressure (Aftertouch) + case 0xF1: // MIDI Time Code Quarter Frame + case 0xF3: // Song Select return 1; } - return 256; + return 0; +} + +void MIDIDriverALSAMidi::InputConnection::parse_byte(uint8_t byte, MIDIDriverALSAMidi &driver, + uint64_t timestamp) { + switch (msg_category(byte)) { + case MessageCategory::RealTime: + // Real-Time messages are single byte messages that can + // occur at any point. + // We pass them straight through. + driver.receive_input_packet(timestamp, &byte, 1); + break; + + case MessageCategory::Data: + // We don't currently forward System Exclusive messages so skip their data. + // Collect any expected data for other message types. + if (!skipping_sys_ex && expected_data > received_data) { + buffer[received_data + 1] = byte; + received_data++; + + // Forward a complete message and reset relevant state. + if (received_data == expected_data) { + driver.receive_input_packet(timestamp, buffer, received_data + 1); + received_data = 0; + + if (msg_category(buffer[0]) != MessageCategory::Voice) { + // Voice Category messages can be sent with "running status". + // This means they don't resend the status byte until it changes. + // For other categories, we reset expected data, to require a new status byte. + expected_data = 0; + } + } + } + break; + + case MessageCategory::SysExBegin: + buffer[0] = byte; + skipping_sys_ex = true; + break; + + case MessageCategory::SysExEnd: + expected_data = 0; + skipping_sys_ex = false; + break; + + case MessageCategory::Voice: + case MessageCategory::SystemCommon: + buffer[0] = byte; + received_data = 0; + expected_data = msg_expected_data(byte); + skipping_sys_ex = false; + if (expected_data == 0) { + driver.receive_input_packet(timestamp, &byte, 1); + } + break; + } +} + +int MIDIDriverALSAMidi::InputConnection::read_in(MIDIDriverALSAMidi &driver, uint64_t timestamp) { + int ret; + do { + uint8_t byte = 0; + ret = snd_rawmidi_read(rawmidi_ptr, &byte, 1); + + if (ret < 0) { + if (ret != -EAGAIN) { + ERR_PRINT("snd_rawmidi_read error: " + String(snd_strerror(ret))); + } + } else { + parse_byte(byte, driver, timestamp); + } + } while (ret > 0); + + return ret; } void MIDIDriverALSAMidi::thread_func(void *p_udata) { MIDIDriverALSAMidi *md = static_cast(p_udata); uint64_t timestamp = 0; - uint8_t buffer[256]; - int expected_size = 255; - int bytes = 0; while (!md->exit_thread.is_set()) { - int ret; - md->lock(); - for (int i = 0; i < md->connected_inputs.size(); i++) { - snd_rawmidi_t *midi_in = md->connected_inputs[i]; - do { - uint8_t byte = 0; - ret = snd_rawmidi_read(midi_in, &byte, 1); - if (ret < 0) { - if (ret != -EAGAIN) { - ERR_PRINT("snd_rawmidi_read error: " + String(snd_strerror(ret))); - } - } else { - if (byte & 0x80) { - // Flush previous packet if there is any - if (bytes) { - md->receive_input_packet(timestamp, buffer, bytes); - bytes = 0; - } - expected_size = get_message_size(byte); - // After a SysEx start, all bytes are data until a SysEx end, so - // we're going to end the command at the SES, and let the common - // driver ignore the following data bytes. - } + InputConnection *connections = md->connected_inputs.ptrw(); + size_t connection_count = md->connected_inputs.size(); - if (bytes < 256) { - buffer[bytes++] = byte; - // If we know the size of the current packet receive it if it reached the expected size - if (bytes >= expected_size) { - md->receive_input_packet(timestamp, buffer, bytes); - bytes = 0; - } - } - } - } while (ret > 0); + for (size_t i = 0; i < connection_count; i++) { + connections[i].read_in(*md, timestamp); } md->unlock(); @@ -139,7 +189,7 @@ Error MIDIDriverALSAMidi::open() { snd_rawmidi_t *midi_in; int ret = snd_rawmidi_open(&midi_in, nullptr, name, SND_RAWMIDI_NONBLOCK); if (ret >= 0) { - connected_inputs.insert(i++, midi_in); + connected_inputs.insert(i++, InputConnection(midi_in)); } } @@ -160,7 +210,7 @@ void MIDIDriverALSAMidi::close() { thread.wait_to_finish(); for (int i = 0; i < connected_inputs.size(); i++) { - snd_rawmidi_t *midi_in = connected_inputs[i]; + snd_rawmidi_t *midi_in = connected_inputs[i].rawmidi_ptr; snd_rawmidi_close(midi_in); } connected_inputs.clear(); @@ -179,7 +229,7 @@ PackedStringArray MIDIDriverALSAMidi::get_connected_inputs() { lock(); for (int i = 0; i < connected_inputs.size(); i++) { - snd_rawmidi_t *midi_in = connected_inputs[i]; + snd_rawmidi_t *midi_in = connected_inputs[i].rawmidi_ptr; snd_rawmidi_info_t *info; snd_rawmidi_info_malloc(&info); diff --git a/drivers/alsamidi/midi_driver_alsamidi.h b/drivers/alsamidi/midi_driver_alsamidi.h index ac3530b1b23..9265dede3d5 100644 --- a/drivers/alsamidi/midi_driver_alsamidi.h +++ b/drivers/alsamidi/midi_driver_alsamidi.h @@ -46,12 +46,48 @@ class MIDIDriverALSAMidi : public MIDIDriver { Thread thread; Mutex mutex; - Vector connected_inputs; + class InputConnection { + public: + InputConnection() = default; + InputConnection(snd_rawmidi_t *midi_in) : + rawmidi_ptr{ midi_in } {} + + // Read in and parse available data, forwarding any complete messages through the driver. + int read_in(MIDIDriverALSAMidi &driver, uint64_t timestamp); + + snd_rawmidi_t *rawmidi_ptr = nullptr; + + private: + static const size_t MSG_BUFFER_SIZE = 3; + uint8_t buffer[MSG_BUFFER_SIZE] = { 0 }; + size_t expected_data = 0; + size_t received_data = 0; + bool skipping_sys_ex = false; + void parse_byte(uint8_t byte, MIDIDriverALSAMidi &driver, uint64_t timestamp); + }; + + Vector connected_inputs; SafeFlag exit_thread; static void thread_func(void *p_udata); + enum class MessageCategory { + Data, + Voice, + SysExBegin, + SystemCommon, // excluding System Exclusive Begin/End + SysExEnd, + RealTime, + }; + + // If the passed byte is a status byte, return the associated message category, + // else return MessageCategory::Data. + static MessageCategory msg_category(uint8_t msg_part); + + // Return the number of data bytes expected for the provided status byte. + static size_t msg_expected_data(uint8_t status_byte); + void lock() const; void unlock() const;