gamos/music.cpp

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "common/system.h"
#include "gamos/gamos.h"

namespace Gamos {

MidiMusic::MidiMusic() {
	MidiDriver::DeviceHandle dev = MidiDriver::detectDevice(MDT_MIDI | MDT_PREFER_GM);

	_driver = MidiDriver::createMidi(dev);
	_driver->open();
	_driver->sendGMReset();
}

MidiMusic::~MidiMusic() {
	g_system->getTimerManager()->removeTimerProc(_timerProc);

	if (_driver) {
		_driver->stopAllNotes(true);
		_driver->close();
		delete _driver;
	}
}

void MidiMusic::stopMusic() {
	g_system->getTimerManager()->removeTimerProc(_timerProc);

	if (_mutex.lock()) {
		_driver->stopAllNotes(true);

		_mutex.unlock();
	}
}

bool MidiMusic::playMusic(Common::Array<byte> *midiData) {
	stopMusic();

	if (!midiData || midiData->size() <= 4)
		return false;

	if (!_mutex.lock())
		return false;

	_pMidiData = *midiData;

	_dataStart = 4;
	_dataPos = _dataStart;
	_midiDelayTicks = 1;
	_midiDelayCount = 1;

	if (_pMidiData[_dataPos] == 0xf8) {
		_dataPos++;
		midi2low();
		_dataPos++;
	}

	g_system->getTimerManager()->installTimerProc(_timerProc, 10 * 1000, this, "Gamos::Music");

	_mutex.unlock();
	return true;
}

void MidiMusic::update() {
	while (true) {
		if (_dataPos >= _pMidiData.size())
			return;

		uint8 b = _pMidiData[_dataPos];

		if (b > 0x7f) {
			/* only if new event type then update _midiOp */
			_midiOp = b;
			_dataPos++;
		}

		bool doDelay = true;

		if (_midiOp == 0xf0 || _midiOp == 0xf7) {
			int16 skipLen = midi2low();
			if (skipLen >= 0)
				_dataPos += skipLen;
		} else if (_midiOp == 0xff) {
			if (_midiDelayTicks != -1) {
				_midiDelayCount = _midiDelayTicks;
				_dataPos = _dataStart;
			} else {
				g_system->getTimerManager()->removeTimerProc(_timerProc);
				_driver->stopAllNotes(true);
			}
			break;
		} else {
			uint8 param1 = _pMidiData[_dataPos];
			uint8 param2 = 0;
			_dataPos++;

			bool doSend = true;

			uint8 cmd = _midiOp & 0xf0;
			if (cmd != MidiDriver_BASE::MIDI_COMMAND_PROGRAM_CHANGE &&
			        cmd != MidiDriver_BASE::MIDI_COMMAND_CHANNEL_AFTERTOUCH) {
				if (cmd == MidiDriver_BASE::MIDI_COMMAND_NOTE_OFF ||
				        cmd == MidiDriver_BASE::MIDI_COMMAND_NOTE_ON) {
					if (_midiMute)
						doSend = false;
				}

				b = _pMidiData[_dataPos];
				_dataPos++;

				doDelay = (b & 0x80) == 0;
				param2 = b & 0x7f;

				if (cmd == MidiDriver_BASE::MIDI_COMMAND_NOTE_ON)
					param2 = param2 * _volume / 255;
			}

			if (doSend)
				_driver->send(_midiOp, param1, param2);
		}

		if (doDelay) {
			int16 ln = midi2low();
			if (ln > 0) {
				_midiTimeStamp += ln * 10;
				if (g_system->getMillis() < _midiTimeStamp)
					break;
			}
		}
	}
}

void MidiMusic::setVolume(uint8 volume) {
	if (volume == 0) {
		_midiMute = true;
		_driver->stopAllNotes();
	} else
		_midiMute = false;

	_volume = volume;
}

int16 MidiMusic::midi2low() {
	if (_dataPos >= _pMidiData.size())
		return -1;

	int16 dat = _pMidiData[_dataPos];
	_dataPos++;

	if (dat & 0x80) {
		if (_dataPos >= _pMidiData.size())
			return -1;

		dat &= 0x7f;
		dat |= _pMidiData[_dataPos] << 7;

		_dataPos++;
	}
	return dat;
}


void MidiMusic::_timerProc(void *data) {
	if (!data)
		return;

	MidiMusic *_this = (MidiMusic *)data;

	if (_this->_midiDelayCount != 0) {
		_this->_midiDelayCount--;
		if (_this->_midiDelayCount != 0)
			return;

		_this->_midiTimeStamp = g_system->getMillis();
	}

	if (_this->_midiTimeStamp <= g_system->getMillis() && _this->_mutex.lock()) {
		_this->update();
		_this->_mutex.unlock();
	}
}

}