godot/drivers/alsamidi/midi_driver_alsamidi.cpp

/**************************************************************************/
/*  midi_driver_alsamidi.cpp                                              */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#ifdef ALSAMIDI_ENABLED

#include "midi_driver_alsamidi.h"

#include "core/os/os.h"

#include <errno.h>

MIDIDriverALSAMidi::InputConnection::InputConnection(int p_device_index,
		snd_rawmidi_t *p_rawmidi) :
		parser(p_device_index), rawmidi_ptr(p_rawmidi) {}

void MIDIDriverALSAMidi::InputConnection::read() {
	int read_count;
	do {
		uint8_t buffer[32];
		read_count = snd_rawmidi_read(rawmidi_ptr, buffer, sizeof(buffer));

		if (read_count < 0) {
			if (read_count != -EAGAIN) {
				ERR_PRINT("snd_rawmidi_read error: " + String(snd_strerror(read_count)));
			}
		} else {
			for (int i = 0; i < read_count; i++) {
				parser.parse_fragment(buffer[i]);
			}
		}
	} while (read_count > 0);
}

void MIDIDriverALSAMidi::thread_func(void *p_udata) {
	MIDIDriverALSAMidi *md = static_cast<MIDIDriverALSAMidi *>(p_udata);

	while (!md->exit_thread.is_set()) {
		md->lock();
		for (InputConnection &conn : md->connected_inputs) {
			conn.read();
		}
		md->unlock();

		OS::get_singleton()->delay_usec(1000);
	}
}

Error MIDIDriverALSAMidi::open() {
	void **hints;

	if (snd_device_name_hint(-1, "rawmidi", &hints) < 0) {
		return ERR_CANT_OPEN;
	}

	lock();
	int device_index = 0;
	for (void **h = hints; *h != nullptr; h++) {
		char *name = snd_device_name_get_hint(*h, "NAME");

		if (name != nullptr) {
			snd_rawmidi_t *midi_in;
			int ret = snd_rawmidi_open(&midi_in, nullptr, name, SND_RAWMIDI_NONBLOCK);
			if (ret >= 0) {
				// Get display name.
				snd_rawmidi_info_t *info;
				snd_rawmidi_info_malloc(&info);
				snd_rawmidi_info(midi_in, info);
				connected_input_names.push_back(snd_rawmidi_info_get_name(info));
				snd_rawmidi_info_free(info);

				connected_inputs.push_back(InputConnection(device_index, midi_in));
				// Only increment device_index for successfully connected devices.
				device_index++;
			}
		}

		if (name != nullptr) {
			free(name);
		}
	}
	snd_device_name_free_hint(hints);
	unlock();

	exit_thread.clear();
	thread.start(MIDIDriverALSAMidi::thread_func, this);

	return OK;
}

void MIDIDriverALSAMidi::close() {
	exit_thread.set();
	if (thread.is_started()) {
		thread.wait_to_finish();
	}

	for (const InputConnection &conn : connected_inputs) {
		snd_rawmidi_close(conn.rawmidi_ptr);
	}

	connected_inputs.clear();
	connected_input_names.clear();
}

void MIDIDriverALSAMidi::lock() const {
	mutex.lock();
}

void MIDIDriverALSAMidi::unlock() const {
	mutex.unlock();
}

MIDIDriverALSAMidi::MIDIDriverALSAMidi() {
	exit_thread.clear();
}

MIDIDriverALSAMidi::~MIDIDriverALSAMidi() {
	close();
}

#endif // ALSAMIDI_ENABLED