godot/core/os/midi_driver.cpp

/*************************************************************************/
/*  midi_driver.cpp                                                      */
/*************************************************************************/
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/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
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#include "midi_driver.h"

#include "core/input/input.h"
#include "core/os/os.h"

uint8_t MIDIDriver::last_received_message = 0x00;
MIDIDriver *MIDIDriver::singleton = nullptr;
MIDIDriver *MIDIDriver::get_singleton() {
	return singleton;
}

void MIDIDriver::set_singleton() {
	singleton = this;
}

void MIDIDriver::receive_input_packet(uint64_t timestamp, uint8_t *data, uint32_t length) {
	Ref<InputEventMIDI> event;
	event.instantiate();
	uint32_t param_position = 1;

	if (length >= 1) {
		if (data[0] >= 0xF0) {
			// channel does not apply to system common messages
			event->set_channel(0);
			event->set_message(MIDIMessage(data[0]));
			last_received_message = data[0];
		} else if ((data[0] & 0x80) == 0x00) {
			// running status
			event->set_channel(last_received_message & 0xF);
			event->set_message(MIDIMessage(last_received_message >> 4));
			param_position = 0;
		} else {
			event->set_channel(data[0] & 0xF);
			event->set_message(MIDIMessage(data[0] >> 4));
			param_position = 1;
			last_received_message = data[0];
		}
	}

	switch (event->get_message()) {
		case MIDIMessage::AFTERTOUCH:
			if (length >= 2 + param_position) {
				event->set_pitch(data[param_position]);
				event->set_pressure(data[param_position + 1]);
			}
			break;

		case MIDIMessage::CONTROL_CHANGE:
			if (length >= 2 + param_position) {
				event->set_controller_number(data[param_position]);
				event->set_controller_value(data[param_position + 1]);
			}
			break;

		case MIDIMessage::NOTE_ON:
		case MIDIMessage::NOTE_OFF:
			if (length >= 2 + param_position) {
				event->set_pitch(data[param_position]);
				event->set_velocity(data[param_position + 1]);

				if (event->get_message() == MIDIMessage::NOTE_ON && event->get_velocity() == 0) {
					// https://www.midi.org/forum/228-writing-midi-software-send-note-off,-or-zero-velocity-note-on
					event->set_message(MIDIMessage::NOTE_OFF);
				}
			}
			break;

		case MIDIMessage::PITCH_BEND:
			if (length >= 2 + param_position) {
				event->set_pitch((data[param_position + 1] << 7) | data[param_position]);
			}
			break;

		case MIDIMessage::PROGRAM_CHANGE:
			if (length >= 1 + param_position) {
				event->set_instrument(data[param_position]);
			}
			break;

		case MIDIMessage::CHANNEL_PRESSURE:
			if (length >= 1 + param_position) {
				event->set_pressure(data[param_position]);
			}
			break;
		default:
			break;
	}

	Input *id = Input::get_singleton();
	id->parse_input_event(event);
}

PackedStringArray MIDIDriver::get_connected_inputs() {
	PackedStringArray list;
	return list;
}

MIDIDriver::MIDIDriver() {
	set_singleton();
}