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.
This commit is contained in:
Ibrahn Sahir
parent
0d28820c81
commit
81575174cb
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@ -37,85 +37,135 @@
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#include <errno.h>
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static int get_message_size(uint8_t message) {
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switch (message & 0xF0) {
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case 0x80: // note off
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case 0x90: // note on
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case 0xA0: // aftertouch
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case 0xB0: // continuous controller
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case 0xE0: // pitch bend
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case 0xF2: // song position pointer
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return 3;
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MIDIDriverALSAMidi::MessageCategory MIDIDriverALSAMidi::msg_category(uint8_t msg_part) {
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if (msg_part >= 0xf8) {
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return MessageCategory::RealTime;
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} else if (msg_part >= 0xf0) {
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// System Exclusive begin/end are specified as System Common Category messages,
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// but we separate them here and give them their own categories as their
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// behaviour is significantly different.
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if (msg_part == 0xf0) {
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return MessageCategory::SysExBegin;
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} else if (msg_part == 0xf7) {
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return MessageCategory::SysExEnd;
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}
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return MessageCategory::SystemCommon;
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} else if (msg_part >= 0x80) {
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return MessageCategory::Voice;
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}
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return MessageCategory::Data;
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}
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case 0xC0: // patch change
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case 0xD0: // channel pressure
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case 0xF1: // time code quarter frame
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case 0xF3: // song select
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size_t MIDIDriverALSAMidi::msg_expected_data(uint8_t status_byte) {
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if (msg_category(status_byte) == MessageCategory::Voice) {
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// Voice messages have a channel number in the status byte, mask it out.
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status_byte &= 0xf0;
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}
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switch (status_byte) {
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case 0x80: // Note Off
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case 0x90: // Note On
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case 0xA0: // Polyphonic Key Pressure (Aftertouch)
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case 0xB0: // Control Change (CC)
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case 0xE0: // Pitch Bend Change
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case 0xF2: // Song Position Pointer
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return 2;
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case 0xF0: // SysEx start
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case 0xF4: // reserved
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case 0xF5: // reserved
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case 0xF6: // tune request
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case 0xF7: // SysEx end
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case 0xF8: // timing clock
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case 0xF9: // reserved
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case 0xFA: // start
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case 0xFB: // continue
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case 0xFC: // stop
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case 0xFD: // reserved
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case 0xFE: // active sensing
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case 0xFF: // reset
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case 0xC0: // Program Change
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case 0xD0: // Channel Pressure (Aftertouch)
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case 0xF1: // MIDI Time Code Quarter Frame
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case 0xF3: // Song Select
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return 1;
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}
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return 256;
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return 0;
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}
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void MIDIDriverALSAMidi::thread_func(void *p_udata) {
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MIDIDriverALSAMidi *md = static_cast<MIDIDriverALSAMidi *>(p_udata);
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uint64_t timestamp = 0;
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uint8_t buffer[256];
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int expected_size = 255;
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int bytes = 0;
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void MIDIDriverALSAMidi::InputConnection::parse_byte(uint8_t byte, MIDIDriverALSAMidi &driver,
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uint64_t timestamp) {
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switch (msg_category(byte)) {
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case MessageCategory::RealTime:
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// Real-Time messages are single byte messages that can
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// occur at any point.
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// We pass them straight through.
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driver.receive_input_packet(timestamp, &byte, 1);
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break;
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while (!md->exit_thread.is_set()) {
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case MessageCategory::Data:
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// We don't currently forward System Exclusive messages so skip their data.
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// Collect any expected data for other message types.
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if (!skipping_sys_ex && expected_data > received_data) {
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buffer[received_data + 1] = byte;
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received_data++;
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// Forward a complete message and reset relevant state.
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if (received_data == expected_data) {
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driver.receive_input_packet(timestamp, buffer, received_data + 1);
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received_data = 0;
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if (msg_category(buffer[0]) != MessageCategory::Voice) {
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// Voice Category messages can be sent with "running status".
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// This means they don't resend the status byte until it changes.
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// For other categories, we reset expected data, to require a new status byte.
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expected_data = 0;
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}
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}
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}
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break;
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case MessageCategory::SysExBegin:
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buffer[0] = byte;
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skipping_sys_ex = true;
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break;
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case MessageCategory::SysExEnd:
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expected_data = 0;
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skipping_sys_ex = false;
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break;
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case MessageCategory::Voice:
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case MessageCategory::SystemCommon:
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buffer[0] = byte;
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received_data = 0;
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expected_data = msg_expected_data(byte);
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skipping_sys_ex = false;
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if (expected_data == 0) {
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driver.receive_input_packet(timestamp, &byte, 1);
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}
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break;
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}
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}
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int MIDIDriverALSAMidi::InputConnection::read_in(MIDIDriverALSAMidi &driver, uint64_t timestamp) {
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int ret;
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md->lock();
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for (int i = 0; i < md->connected_inputs.size(); i++) {
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snd_rawmidi_t *midi_in = md->connected_inputs[i];
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do {
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uint8_t byte = 0;
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ret = snd_rawmidi_read(midi_in, &byte, 1);
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ret = snd_rawmidi_read(rawmidi_ptr, &byte, 1);
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if (ret < 0) {
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if (ret != -EAGAIN) {
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ERR_PRINT("snd_rawmidi_read error: " + String(snd_strerror(ret)));
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}
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} else {
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if (byte & 0x80) {
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// Flush previous packet if there is any
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if (bytes) {
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md->receive_input_packet(timestamp, buffer, bytes);
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bytes = 0;
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}
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expected_size = get_message_size(byte);
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// After a SysEx start, all bytes are data until a SysEx end, so
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// we're going to end the command at the SES, and let the common
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// driver ignore the following data bytes.
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}
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if (bytes < 256) {
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buffer[bytes++] = byte;
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// If we know the size of the current packet receive it if it reached the expected size
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if (bytes >= expected_size) {
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md->receive_input_packet(timestamp, buffer, bytes);
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bytes = 0;
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}
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}
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parse_byte(byte, driver, timestamp);
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}
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} while (ret > 0);
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return ret;
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}
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void MIDIDriverALSAMidi::thread_func(void *p_udata) {
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MIDIDriverALSAMidi *md = static_cast<MIDIDriverALSAMidi *>(p_udata);
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uint64_t timestamp = 0;
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while (!md->exit_thread.is_set()) {
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md->lock();
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InputConnection *connections = md->connected_inputs.ptrw();
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size_t connection_count = md->connected_inputs.size();
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for (size_t i = 0; i < connection_count; i++) {
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connections[i].read_in(*md, timestamp);
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}
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md->unlock();
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@ -139,7 +189,7 @@ Error MIDIDriverALSAMidi::open() {
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snd_rawmidi_t *midi_in;
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int ret = snd_rawmidi_open(&midi_in, nullptr, name, SND_RAWMIDI_NONBLOCK);
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if (ret >= 0) {
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connected_inputs.insert(i++, midi_in);
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connected_inputs.insert(i++, InputConnection(midi_in));
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}
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}
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@ -160,7 +210,7 @@ void MIDIDriverALSAMidi::close() {
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thread.wait_to_finish();
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for (int i = 0; i < connected_inputs.size(); i++) {
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snd_rawmidi_t *midi_in = connected_inputs[i];
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snd_rawmidi_t *midi_in = connected_inputs[i].rawmidi_ptr;
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snd_rawmidi_close(midi_in);
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}
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connected_inputs.clear();
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@ -179,7 +229,7 @@ PackedStringArray MIDIDriverALSAMidi::get_connected_inputs() {
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lock();
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for (int i = 0; i < connected_inputs.size(); i++) {
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snd_rawmidi_t *midi_in = connected_inputs[i];
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snd_rawmidi_t *midi_in = connected_inputs[i].rawmidi_ptr;
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snd_rawmidi_info_t *info;
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snd_rawmidi_info_malloc(&info);
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@ -46,12 +46,48 @@ class MIDIDriverALSAMidi : public MIDIDriver {
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Thread thread;
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Mutex mutex;
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Vector<snd_rawmidi_t *> connected_inputs;
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class InputConnection {
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public:
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InputConnection() = default;
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InputConnection(snd_rawmidi_t *midi_in) :
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rawmidi_ptr{ midi_in } {}
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// Read in and parse available data, forwarding any complete messages through the driver.
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int read_in(MIDIDriverALSAMidi &driver, uint64_t timestamp);
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snd_rawmidi_t *rawmidi_ptr = nullptr;
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private:
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static const size_t MSG_BUFFER_SIZE = 3;
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uint8_t buffer[MSG_BUFFER_SIZE] = { 0 };
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size_t expected_data = 0;
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size_t received_data = 0;
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bool skipping_sys_ex = false;
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void parse_byte(uint8_t byte, MIDIDriverALSAMidi &driver, uint64_t timestamp);
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};
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Vector<InputConnection> connected_inputs;
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SafeFlag exit_thread;
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static void thread_func(void *p_udata);
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enum class MessageCategory {
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Data,
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Voice,
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SysExBegin,
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SystemCommon, // excluding System Exclusive Begin/End
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SysExEnd,
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RealTime,
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};
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// If the passed byte is a status byte, return the associated message category,
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// else return MessageCategory::Data.
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static MessageCategory msg_category(uint8_t msg_part);
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// Return the number of data bytes expected for the provided status byte.
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static size_t msg_expected_data(uint8_t status_byte);
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void lock() const;
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void unlock() const;
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