path: root/audio/mods/maxtrax.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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#include "common/scummsys.h"
#include "common/stream.h"
#include "common/util.h"
#include "common/debug.h"
#include "common/textconsole.h"

#include "audio/mods/maxtrax.h"

// test for engines using this class.
#if defined(AUDIO_MODS_MAXTRAX_H)

namespace {

enum { K_VALUE = 0x9fd77, PREF_PERIOD = 0x8fd77, PERIOD_LIMIT = 0x6f73d };
enum { NO_BEND = 64 << 7, MAX_BEND_RANGE = 24 };

int32 precalcNote(byte baseNote, int16 tune, byte octave) {
	return K_VALUE + 0x3C000 - ((baseNote << 14) + (tune << 11) / 3) / 3 - (octave << 16);
}

int32 calcVolumeDelta(int32 delta, uint16 time, uint16 vBlankFreq) {
	const int32 div = time * vBlankFreq;
	// div <= 1000 means time to small (or even 0)
	return (div <= 1000) ? delta : (1000 * delta) / div;
}

int32 calcTempo(const uint16 tempo, uint16 vBlankFreq) {
	return (int32)(((uint32)(tempo & 0xFFF0) << 8) / (uint16)(5 * vBlankFreq));
}

void nullFunc(int) {}

// Function to calculate 2^x, where x is a fixedpoint number with 16 fraction bits
// using exp would be more accurate and needs less space if mathlibrary is already linked
// but this function should be faster and doesn't use floats
#if 1
inline uint32 pow2Fixed(int32 val) {
	static const uint16 tablePow2[] = {
			0,   178,   356,   535,   714,   893,  1073,  1254,  1435,  1617,  1799,  1981,  2164,  2348,  2532,  2716,
		 2902,  3087,  3273,  3460,  3647,  3834,  4022,  4211,  4400,  4590,  4780,  4971,  5162,  5353,  5546,  5738,
		 5932,  6125,  6320,  6514,  6710,  6906,  7102,  7299,  7496,  7694,  7893,  8092,  8292,  8492,  8693,  8894,
		 9096,  9298,  9501,  9704,  9908, 10113, 10318, 10524, 10730, 10937, 11144, 11352, 11560, 11769, 11979, 12189,
		12400, 12611, 12823, 13036, 13249, 13462, 13676, 13891, 14106, 14322, 14539, 14756, 14974, 15192, 15411, 15630,
		15850, 16071, 16292, 16514, 16737, 16960, 17183, 17408, 17633, 17858, 18084, 18311, 18538, 18766, 18995, 19224,
		19454, 19684, 19915, 20147, 20379, 20612, 20846, 21080, 21315, 21550, 21786, 22023, 22260, 22498, 22737, 22977,
		23216, 23457, 23698, 23940, 24183, 24426, 24670, 24915, 25160, 25406, 25652, 25900, 26148, 26396, 26645, 26895,
		27146, 27397, 27649, 27902, 28155, 28409, 28664, 28919, 29175, 29432, 29690, 29948, 30207, 30466, 30727, 30988,
		31249, 31512, 31775, 32039, 32303, 32568, 32834, 33101, 33369, 33637, 33906, 34175, 34446, 34717, 34988, 35261,
		35534, 35808, 36083, 36359, 36635, 36912, 37190, 37468, 37747, 38028, 38308, 38590, 38872, 39155, 39439, 39724,
		40009, 40295, 40582, 40870, 41158, 41448, 41738, 42029, 42320, 42613, 42906, 43200, 43495, 43790, 44087, 44384,
		44682, 44981, 45280, 45581, 45882, 46184, 46487, 46791, 47095, 47401, 47707, 48014, 48322, 48631, 48940, 49251,
		49562, 49874, 50187, 50500, 50815, 51131, 51447, 51764, 52082, 52401, 52721, 53041, 53363, 53685, 54008, 54333,
		54658, 54983, 55310, 55638, 55966, 56296, 56626, 56957, 57289, 57622, 57956, 58291, 58627, 58964, 59301, 59640,
		59979, 60319, 60661, 61003, 61346, 61690, 62035, 62381, 62727, 63075, 63424, 63774, 64124, 64476, 64828, 65182,
			0
	};
	const uint16 whole = val >> 16;
	const uint8 index = (uint8)(val >> 8);
	// calculate fractional part.
	const uint16 base = tablePow2[index];
	// linear interpolation and add 1.0
	uint32 exponent = ((uint32)(uint16)(tablePow2[index + 1] - base) * (uint8)val) + ((uint32)base << 8) + (1 << 24);

	if (whole < 24) {
		// shift away all but the last fractional bit which is used for rounding,
		// then round to nearest integer
		exponent = ((exponent >> (23 - whole)) + 1) >> 1;
	} else if (whole < 32) {
		// no need to round here
		exponent <<= whole - 24;
	} else if (val > 0) {
		// overflow
		exponent = 0xFFFFFFFF;
	} else  {
		// negative integer, test if >= -0.5
		exponent = (val >= -0x8000) ? 1 : 0;
	}
	return exponent;
}
#else
inline uint32 pow2Fixed(int32 val) {
	return (uint32)(expf((float)val * (float)(0.69314718055994530942 / (1 << 16))) + 0.5f);
}
#endif

} // End of anonymous namespace

namespace Audio {

MaxTrax::MaxTrax(int rate, bool stereo, uint16 vBlankFreq, uint16 maxScores)
	: Paula(stereo, rate, rate / vBlankFreq),
	  _patch(),
	  _scores(),
	  _numScores() {
	_playerCtx.maxScoreNum = maxScores;
	_playerCtx.vBlankFreq = vBlankFreq;
	_playerCtx.frameUnit = (uint16)((1000 << 8) /  vBlankFreq);
	_playerCtx.scoreIndex = -1;
	_playerCtx.volume = 0x40;

	_playerCtx.tempo = 120;
	_playerCtx.tempoTime = 0;
	_playerCtx.filterOn = true;
	_playerCtx.syncCallBack = &nullFunc;

	resetPlayer();
	for (int i = 0; i < ARRAYSIZE(_channelCtx); ++i)
		_channelCtx[i].regParamNumber = 0;
}

MaxTrax::~MaxTrax() {
	stopMusic();
	freePatches();
	freeScores();
}

void MaxTrax::interrupt() {
	// a5 - maxtraxm a4 . globaldata

	// TODO
	// test for changes in shared struct and make changes
	// specifically all used channels get marked altered

	_playerCtx.ticks += _playerCtx.tickUnit;
	const int32 millis = _playerCtx.ticks >> 8; // d4

	for (int i = 0; i < ARRAYSIZE(_voiceCtx); ++i) {
		VoiceContext &voice = _voiceCtx[i];
		if (voice.stopEventTime >= 0) {
			assert(voice.channel);
			voice.stopEventTime -= (voice.channel < &_channelCtx[kNumChannels]) ? _playerCtx.tickUnit : _playerCtx.frameUnit;
			if (voice.stopEventTime <= 0 && voice.status > VoiceContext::kStatusRelease) {
				if ((voice.channel->flags & ChannelContext::kFlagDamper) != 0)
					voice.hasDamper = true;
				else
					voice.status = VoiceContext::kStatusRelease;
			}
		}
	}

	if (_playerCtx.scoreIndex >= 0) {
		const Event *curEvent = _playerCtx.nextEvent;
		int32 eventDelta = _playerCtx.nextEventTime - millis;
		for (; eventDelta <= 0; eventDelta += (++curEvent)->startTime) {
			const byte cmd = curEvent->command;
			ChannelContext &channel = _channelCtx[curEvent->parameter & 0x0F];

			// outPutEvent(*curEvent);
			// debug("CurTime, EventDelta, NextDelta: %d, %d, %d", millis, eventDelta, eventDelta + curEvent[1].startTime );

			if (cmd < 0x80) {	// Note
				const int8 voiceIndex = noteOn(channel, cmd, (curEvent->parameter & 0xF0) >> 1, kPriorityScore);
				if (voiceIndex >= 0)
					_voiceCtx[voiceIndex].stopEventTime = MAX<int32>(0, (eventDelta + curEvent->stopTime) << 8);

			} else {
				switch (cmd) {

				case 0x80:	// TEMPO
					if ((_playerCtx.tickUnit >> 8) > curEvent->stopTime) {
						_playerCtx.tickUnit = calcTempo(curEvent->parameter << 4, _playerCtx.vBlankFreq);
						_playerCtx.tempoTime = 0;
					} else {
						_playerCtx.tempoStart = _playerCtx.tempo;
						_playerCtx.tempoDelta = (curEvent->parameter << 4) - _playerCtx.tempoStart;
						_playerCtx.tempoTime  = (curEvent->stopTime << 8);
						_playerCtx.tempoTicks = 0;
					}
					break;

				case 0xC0:	// PROGRAM
					channel.patch = &_patch[curEvent->stopTime & (kNumPatches - 1)];
					break;

				case 0xE0:	// BEND
					channel.pitchBend = ((curEvent->stopTime & 0x7F00) >> 1) | (curEvent->stopTime & 0x7f);
					channel.pitchReal = (((int32)channel.pitchBendRange * channel.pitchBend) >> 5) - (channel.pitchBendRange << 8);
					channel.isAltered = true;
					break;

				case 0xFF:	// END
					if (_playerCtx.musicLoop) {
						curEvent = _scores[_playerCtx.scoreIndex].events;
						eventDelta = curEvent->startTime - millis;
						_playerCtx.ticks = 0;
					} else
						_playerCtx.scoreIndex = -1;
					// stop processing for this tick
					goto endOfEventLoop;

				case 0xA0: 	// SPECIAL
					switch (curEvent->stopTime >> 8) {
					case 0x01:	// SPECIAL_SYNC
						_playerCtx.syncCallBack(curEvent->stopTime & 0xFF);
						break;
					case 0x02:	// SPECIAL_BEGINREP
						// we allow a depth of 4 loops
						for (int i = 0; i < ARRAYSIZE(_playerCtx.repeatPoint); ++i) {
							if (!_playerCtx.repeatPoint[i]) {
								_playerCtx.repeatPoint[i] = curEvent;
								_playerCtx.repeatCount[i] = curEvent->stopTime & 0xFF;
								break;
							}
						}
						break;
					case 0x03:	// SPECIAL_ENDREP
						for (int i = ARRAYSIZE(_playerCtx.repeatPoint) - 1; i >= 0; --i) {
							if (_playerCtx.repeatPoint[i]) {
								if (_playerCtx.repeatCount[i]--)
									curEvent = _playerCtx.repeatPoint[i]; // gets incremented by 1 at end of loop
								else
									_playerCtx.repeatPoint[i] = 0;
								break;
							}
						}
						break;
					default:
						break;
					}
					break;

				case 0xB0:	// CONTROL
					controlCh(channel, (byte)(curEvent->stopTime >> 8), (byte)curEvent->stopTime);
					break;

				default:
					debug("Unhandled Command");
					outPutEvent(*curEvent);
				}
			}
		}
endOfEventLoop:
		_playerCtx.nextEvent = curEvent;
		_playerCtx.nextEventTime = eventDelta + millis;

		// tempoEffect
		if (_playerCtx.tempoTime) {
			_playerCtx.tempoTicks += _playerCtx.tickUnit;
			uint16 newTempo = _playerCtx.tempoStart;
			if (_playerCtx.tempoTicks < _playerCtx.tempoTime) {
				newTempo += (uint16)((_playerCtx.tempoTicks * _playerCtx.tempoDelta) / _playerCtx.tempoTime);
			} else {
				_playerCtx.tempoTime = 0;
				newTempo += _playerCtx.tempoDelta;
			}
			_playerCtx.tickUnit = calcTempo(newTempo, _playerCtx.vBlankFreq);
		}
	}

	// Handling of Envelopes and Portamento
	for (int i = 0; i < ARRAYSIZE(_voiceCtx); ++i) {
		VoiceContext &voice = _voiceCtx[i];
		if (!voice.channel)
			continue;
		const ChannelContext &channel = *voice.channel;
		const Patch &patch = *voice.patch;

		switch (voice.status) {
		case VoiceContext::kStatusSustain:
			// we need to check if some voices have no sustainSample.
			// in that case they are finished after the attackSample is done
			if (voice.dmaOff && Paula::getChannelDmaCount((byte)i) >= voice.dmaOff ) {
				voice.dmaOff = 0;
				voice.isBlocked = 0;
				voice.priority = 0;
				// disable it in next tick
				voice.stopEventTime = 0;
			}
			if (!channel.isAltered && !voice.hasPortamento && !channel.modulation)
				continue;
			// Update Volume and Period
			break;

		case VoiceContext::kStatusHalt:
			killVoice((byte)i);
			continue;

		case VoiceContext::kStatusStart:
			if (patch.attackLen) {
				voice.envelope = patch.attackPtr;
				const uint16 duration = voice.envelope->duration;
				voice.envelopeLeft = patch.attackLen;
				voice.ticksLeft = duration << 8;
				voice.status = VoiceContext::kStatusAttack;
				voice.incrVolume = calcVolumeDelta((int32)voice.envelope->volume, duration, _playerCtx.vBlankFreq);
				// Process Envelope
			} else {
				voice.status = VoiceContext::kStatusSustain;
				voice.baseVolume = patch.volume;
				// Update Volume and Period
			}
			break;

		case VoiceContext::kStatusRelease:
			if (patch.releaseLen) {
				voice.envelope = patch.attackPtr + patch.attackLen;
				const uint16 duration = voice.envelope->duration;
				voice.envelopeLeft = patch.releaseLen;
				voice.ticksLeft = duration << 8;
				voice.status = VoiceContext::kStatusDecay;
				voice.incrVolume = calcVolumeDelta((int32)voice.envelope->volume - voice.baseVolume, duration, _playerCtx.vBlankFreq);
				// Process Envelope
			} else {
				voice.status = VoiceContext::kStatusHalt;
				voice.lastVolume = 0;
				// Send Audio Packet
			}
			voice.stopEventTime = -1;
			break;

		default:
			break;
		}

		// Process Envelope
		const uint16 envUnit = _playerCtx.frameUnit;
		if (voice.envelope) {
			if (voice.ticksLeft > envUnit) {	// envelope still active
				voice.baseVolume = (uint16) MIN<int32>(MAX<int32>(0, voice.baseVolume + voice.incrVolume), 0x8000);
				voice.ticksLeft -= envUnit;
				// Update Volume and Period

			} else {	// next or last Envelope
				voice.baseVolume = voice.envelope->volume;
				assert(voice.envelopeLeft > 0);
				if (--voice.envelopeLeft) {
					++voice.envelope;
					const uint16 duration = voice.envelope->duration;
					voice.ticksLeft = duration << 8;
					voice.incrVolume = calcVolumeDelta((int32)voice.envelope->volume - voice.baseVolume, duration, _playerCtx.vBlankFreq);
					// Update Volume and Period
				} else if (voice.status == VoiceContext::kStatusDecay) {
					voice.status = VoiceContext::kStatusHalt;
					voice.envelope = 0;
					voice.lastVolume = 0;
					// Send Audio Packet
				} else {
					assert(voice.status == VoiceContext::kStatusAttack);
					voice.status = VoiceContext::kStatusSustain;
					voice.envelope = 0;
					// Update Volume and Period
				}
			}
		}

		// Update Volume and Period
		if (voice.status >= VoiceContext::kStatusDecay) {
			// Calc volume
			uint16 vol = (voice.noteVolume < (1 << 7)) ? (voice.noteVolume * _playerCtx.volume) >> 7 : _playerCtx.volume;
			if (voice.baseVolume < (1 << 15))
				vol = (uint16)(((uint32)vol * voice.baseVolume) >> 15);
			if (voice.channel->volume < (1 << 7))
				vol = (vol * voice.channel->volume) >> 7;
			voice.lastVolume = (byte)MIN(vol, (uint16)0x64);

			// Calc Period
			if (voice.hasPortamento) {
				voice.portaTicks += envUnit;
				if ((uint16)(voice.portaTicks >> 8) >= channel.portamentoTime) {
					voice.hasPortamento = false;
					voice.baseNote = voice.endNote;
					voice.preCalcNote = precalcNote(voice.baseNote, patch.tune, voice.octave);
				}
				voice.lastPeriod = calcNote(voice);
			} else if (channel.isAltered || channel.modulation)
				voice.lastPeriod = calcNote(voice);
		}

		// Send Audio Packet
		Paula::setChannelPeriod((byte)i, (voice.lastPeriod) ? voice.lastPeriod : 1000);
		Paula::setChannelVolume((byte)i, (voice.lastPeriod) ? voice.lastVolume : 0);
	}
	for (ChannelContext *c = _channelCtx; c != &_channelCtx[ARRAYSIZE(_channelCtx)]; ++c)
		c->isAltered = false;

#ifdef MAXTRAX_HAS_MODULATION
	// original player had _playerCtx.sineValue = _playerCtx.frameUnit >> 2
	// this should fit the comments that modtime=1000 is one second ?
	_playerCtx.sineValue += _playerCtx.frameUnit;
#endif
}

void MaxTrax::controlCh(ChannelContext &channel, const byte command, const byte data) {
	switch (command) {
	case 0x01:	// modulation level MSB
		channel.modulation = data << 8;
		break;
	case 0x21:	// modulation level LSB
		channel.modulation = (channel.modulation & 0xFF00) | ((data * 2) & 0xFF);
		break;
	case 0x05:	// portamento time MSB
		channel.portamentoTime = data << 7;
		break;
	case 0x25:	// portamento time LSB
		channel.portamentoTime = (channel.portamentoTime & 0x3f80) | data;
		break;
	case 0x06:	// data entry MSB
		if (channel.regParamNumber == 0) {
			channel.pitchBendRange = (int8)MIN((uint8)MAX_BEND_RANGE, (uint8)data);
			channel.pitchReal = (((int32)channel.pitchBendRange * channel.pitchBend) >> 5) - (channel.pitchBendRange << 8);
			channel.isAltered = true;
		}
		break;
	case 0x07:	// Main Volume MSB
		channel.volume = (data == 0) ? 0 : data + 1;
		channel.isAltered = true;
		break;
	case 0x0A:	// Pan
		if (data > 0x40 || (data == 0x40 && ((&channel - _channelCtx) & 1) != 0))
			channel.flags |= ChannelContext::kFlagRightChannel;
		else
			channel.flags &= ~ChannelContext::kFlagRightChannel;
		break;
	case 0x10:	// GPC as Modulation Time MSB
		channel.modulationTime = data << 7;
		break;
	case 0x30:	// GPC as Modulation Time LSB
		channel.modulationTime = (channel.modulationTime & 0x3f80) | data;
		break;
	case 0x11:	// GPC as Microtonal Set MSB
		channel.microtonal = data << 8;
		break;
	case 0x31:	// GPC as Microtonal Set LSB
		channel.microtonal = (channel.microtonal & 0xFF00) | ((data * 2) & 0xFF);
		break;
	case 0x40:	// Damper Pedal
		if ((data & 0x40) != 0)
			channel.flags |= ChannelContext::kFlagDamper;
		else {
			channel.flags &= ~ChannelContext::kFlagDamper;
			// release all dampered voices on this channel
			for (int i = 0; i < ARRAYSIZE(_voiceCtx); ++i) {
				if (_voiceCtx[i].channel == &channel && _voiceCtx[i].hasDamper) {
					_voiceCtx[i].hasDamper = false;
					_voiceCtx[i].status = VoiceContext::kStatusRelease;
				}
			}
		}
		break;
	case 0x41:	// Portamento off/on
		if ((data & 0x40) != 0)
			channel.flags |= ChannelContext::kFlagPortamento;
		else
			channel.flags &= ~ChannelContext::kFlagPortamento;
		break;
	case 0x50:	// Microtonal off/on
		if ((data & 0x40) != 0)
			channel.flags |= ChannelContext::kFlagMicrotonal;
		else
			channel.flags &= ~ChannelContext::kFlagMicrotonal;
		break;
	case 0x51:	// Audio Filter off/on
		Paula::setAudioFilter(data > 0x40 || (data == 0x40 && _playerCtx.filterOn));
		break;
	case 0x65:	// RPN MSB
		channel.regParamNumber = (data << 8) | (channel.regParamNumber & 0xFF);
		break;
	case 0x64:	// RPN LSB
		channel.regParamNumber = (channel.regParamNumber & 0xFF00) | data;
		break;
	case 0x79:	// Reset All Controllers
		resetChannel(channel, ((&channel - _channelCtx) & 1) != 0);
		break;
	case 0x7E:	// MONO mode
		channel.flags |= ChannelContext::kFlagMono;
		goto allNotesOff;
	case 0x7F:	// POLY mode
		channel.flags &= ~ChannelContext::kFlagMono;
		// Fallthrough
	case 0x7B:	// All Notes Off
allNotesOff:
		for (int i = 0; i < ARRAYSIZE(_voiceCtx); ++i) {
			if (_voiceCtx[i].channel == &channel) {
				if ((channel.flags & ChannelContext::kFlagDamper) != 0)
					_voiceCtx[i].hasDamper = true;
				else
					_voiceCtx[i].status = VoiceContext::kStatusRelease;
			}
		}
		break;
	case 0x78:	// All Sounds Off
		for (int i = 0; i < ARRAYSIZE(_voiceCtx); ++i) {
			if (_voiceCtx[i].channel == &channel)
				killVoice((byte)i);
		}
		break;
	default:
		break;
	}
}

void MaxTrax::setTempo(const uint16 tempo) {
	Common::StackLock lock(_mutex);
	_playerCtx.tickUnit = calcTempo(tempo, _playerCtx.vBlankFreq);
}

void MaxTrax::resetPlayer() {
	for (int i = 0; i < ARRAYSIZE(_voiceCtx); ++i)
		killVoice((byte)i);

	for (int i = 0; i < ARRAYSIZE(_channelCtx); ++i) {
		_channelCtx[i].flags = 0;
		_channelCtx[i].lastNote = (uint8)-1;
		resetChannel(_channelCtx[i], (i & 1) != 0);
		_channelCtx[i].patch = (i < kNumChannels) ? &_patch[i] : 0;
	}

#ifdef MAXTRAX_HAS_MICROTONAL
	for (int i = 0; i < ARRAYSIZE(_microtonal); ++i)
		_microtonal[i] = (int16)(i << 8);
#endif
}

void MaxTrax::stopMusic() {
	Common::StackLock lock(_mutex);
	_playerCtx.scoreIndex = -1;
	for (int i = 0; i < ARRAYSIZE(_voiceCtx); ++i) {
		if (_voiceCtx[i].channel < &_channelCtx[kNumChannels])
			killVoice((byte)i);
	}
}

bool MaxTrax::playSong(int songIndex, bool loop) {
	if (songIndex < 0 || songIndex >= _numScores)
		return false;
	Common::StackLock lock(_mutex);
	_playerCtx.scoreIndex = -1;
	resetPlayer();
	for (int i = 0; i < ARRAYSIZE(_playerCtx.repeatPoint); ++i)
		_playerCtx.repeatPoint[i] = 0;

	setTempo(_playerCtx.tempoInitial << 4);
	Paula::setAudioFilter(_playerCtx.filterOn);
	_playerCtx.musicLoop = loop;
	_playerCtx.tempoTime = 0;
	_playerCtx.scoreIndex = songIndex;
	_playerCtx.ticks = 0;

	_playerCtx.nextEvent = _scores[songIndex].events;
	_playerCtx.nextEventTime = _playerCtx.nextEvent->startTime;

	Paula::startPaula();
	return true;
}

void MaxTrax::advanceSong(int advance) {
	Common::StackLock lock(_mutex);
	if (_playerCtx.scoreIndex >= 0) {
		const Event *cev = _playerCtx.nextEvent;
		if (cev) {
			for (; advance > 0; --advance) {
				// TODO - check for boundaries
				for (; cev->command != 0xFF && (cev->command != 0xA0 || (cev->stopTime >> 8) != 0x00); ++cev)
					; // no end_command or special_command + end
			}
			_playerCtx.nextEvent = cev;
		}
	}
}

void MaxTrax::killVoice(byte num) {
	VoiceContext &voice = _voiceCtx[num];
	voice.channel = 0;
	voice.envelope = 0;
	voice.status = VoiceContext::kStatusFree;
	voice.isBlocked = 0;
	voice.hasDamper = false;
	voice.hasPortamento = false;
	voice.priority = 0;
	voice.stopEventTime = -1;
	voice.dmaOff = 0;
	voice.lastVolume = 0;
	voice.tieBreak = 0;
	//voice.uinqueId = 0;

	// "stop" voice, set period to 1, vol to 0
	Paula::disableChannel(num);
	Paula::setChannelPeriod(num, 1);
	Paula::setChannelVolume(num, 0);
}

int8 MaxTrax::pickvoice(uint pick, int16 pri) {
	enum { kPrioFlagFixedSide = 1 << 3 };
	pick &= 3;
	if ((pri & (kPrioFlagFixedSide)) == 0) {
		const bool leftSide = (uint)(pick - 1) > 1;
		const int leftBest = MIN(_voiceCtx[0].status, _voiceCtx[3].status);
		const int rightBest = MIN(_voiceCtx[1].status, _voiceCtx[2].status);
		const int sameSide = (leftSide) ? leftBest : rightBest;
		const int otherSide = leftBest + rightBest - sameSide;

		if (sameSide > VoiceContext::kStatusRelease && otherSide <= VoiceContext::kStatusRelease)
			pick ^= 1; // switches sides
	}
	pri &= ~kPrioFlagFixedSide;

	for (int i = 2; i > 0; --i) {
		VoiceContext *voice = &_voiceCtx[pick];
		VoiceContext *alternate = &_voiceCtx[pick ^ 3];

		const uint16 voiceVal = voice->status << 8 | voice->lastVolume;
		const uint16 altVal = alternate->status << 8 | alternate->lastVolume;

		if (voiceVal + voice->tieBreak > altVal
			|| voice->isBlocked > alternate->isBlocked) {

			// this is somewhat different to the original player,
			// but has a similar result
			voice->tieBreak = 0;
			alternate->tieBreak = 1;

			pick ^= 3; // switch channels
			VoiceContext *tmp = voice;
			voice = alternate;
			alternate = tmp;
		}

		if (voice->isBlocked || voice->priority > pri) {
			// if not already done, switch sides and try again
			pick ^= 1;
			continue;
		}
		// succeded
		return (int8)pick;
	}
	// failed
	debug(5, "MaxTrax: could not find channel for note");
	return -1;
}

uint16 MaxTrax::calcNote(const VoiceContext &voice) {
	const ChannelContext &channel = *voice.channel;
	int16 bend = channel.pitchReal;

#ifdef MAXTRAX_HAS_MICROTONAL
	if (voice.hasPortamento) {
		if ((channel.flags & ChannelContext::kFlagMicrotonal) != 0)
			bend += (int16)(((_microtonal[voice.endNote] - _microtonal[voice.baseNote]) * voice.portaTicks) >> 8) / channel.portamentoTime;
		else
			bend += (int16)(((int8)(voice.endNote - voice.baseNote)) * voice.portaTicks) / channel.portamentoTime;
	}

	if ((channel.flags & ChannelContext::kFlagMicrotonal) != 0)
		bend += _microtonal[voice.baseNote];
#else
	if (voice.hasPortamento)
		bend += (int16)(((int8)(voice.endNote - voice.baseNote)) * voice.portaTicks) / channel.portamentoTime;
#endif

#ifdef MAXTRAX_HAS_MODULATION
	static const uint8 tableSine[] = {
		  0,   5,  12,  18,  24,  30,  37,  43,  49,  55,  61,  67,  73,  79,  85,  91,
		 97, 103, 108, 114, 120, 125, 131, 136, 141, 146, 151, 156, 161, 166, 171, 176,
		180, 184, 189, 193, 197, 201, 205, 208, 212, 215, 219, 222, 225, 228, 230, 233,
		236, 238, 240, 242, 244, 246, 247, 249, 250, 251, 252, 253, 254, 254, 255, 255,
		255, 255, 255, 254, 254, 253, 252, 251, 250, 249, 247, 246, 244, 242, 240, 238,
		236, 233, 230, 228, 225, 222, 219, 215, 212, 208, 205, 201, 197, 193, 189, 184,
		180, 176, 171, 166, 161, 156, 151, 146, 141, 136, 131, 125, 120, 114, 108, 103,
		 97,  91,  85,  79,  73,  67,  61,  55,  49,  43,  37,  30,  24,  18,  12,   5
	};
	if (channel.modulation) {
		if ((channel.flags & ChannelContext::kFlagModVolume) == 0) {
			const uint8 sineByte = _playerCtx.sineValue / channel.modulationTime;
			const uint8 sineIndex = sineByte & 0x7F;
			const int16 modVal = ((uint32)(uint16)(tableSine[sineIndex] + (sineIndex ? 1 : 0)) * channel.modulation) >> 8;
			bend = (sineByte < 0x80) ? bend + modVal : bend - modVal;
		}
	}
#endif

	// tone = voice.baseNote << 8 + microtonal
	// bend = channelPitch + porta + modulation

	const int32 tone = voice.preCalcNote + (bend << 6) / 3;

	return (tone >= PERIOD_LIMIT) ? (uint16)pow2Fixed(tone) : 0;
}

int8 MaxTrax::noteOn(ChannelContext &channel, const byte note, uint16 volume, uint16 pri) {
#ifdef MAXTRAX_HAS_MICROTONAL
	if (channel.microtonal >= 0)
		_microtonal[note % 127] = channel.microtonal;
#endif

	if (!volume)
		return -1;

	const Patch &patch = *channel.patch;
	if (!patch.samplePtr || patch.sampleTotalLen == 0)
		return -1;
	int8 voiceNum = -1;
	if ((channel.flags & ChannelContext::kFlagMono) == 0) {
		voiceNum = pickvoice((channel.flags & ChannelContext::kFlagRightChannel) != 0 ? 1 : 0, pri);
	} else {
		VoiceContext *voice = ARRAYEND(_voiceCtx);
		for (voiceNum = ARRAYSIZE(_voiceCtx); voiceNum >= 0 && voice->channel != &channel; voiceNum--, voice--)
			;
		if (voiceNum < 0)
			voiceNum = pickvoice((channel.flags & ChannelContext::kFlagRightChannel) != 0 ? 1 : 0, pri);
		else if (voice->status >= VoiceContext::kStatusSustain && (channel.flags & ChannelContext::kFlagPortamento) != 0) {
			// reset previous porta
			if (voice->hasPortamento)
				voice->baseNote = voice->endNote;
			voice->preCalcNote = precalcNote(voice->baseNote, patch.tune, voice->octave);
			voice->noteVolume = (_playerCtx.handleVolume) ? volume + 1 : 128;
			voice->portaTicks = 0;
			voice->hasPortamento = true;
			voice->endNote = channel.lastNote = note;
			return voiceNum;
		}
	}

	if (voiceNum >= 0) {
		VoiceContext &voice = _voiceCtx[voiceNum];
		voice.hasDamper = false;
		voice.isBlocked = 0;
		voice.hasPortamento = false;
		if (voice.channel)
			killVoice(voiceNum);
		voice.channel = &channel;
		voice.patch = &patch;
		voice.baseNote = note;

		// always base octave on the note in the command, regardless of porta
		const int32 plainNote = precalcNote(note, patch.tune, 0);
		// calculate which sample to use
		const int useOctave = (plainNote <= PREF_PERIOD) ? 0 : MIN<int32>((plainNote + 0xFFFF - PREF_PERIOD) >> 16, patch.sampleOctaves - 1);
		voice.octave = (byte)useOctave;
		// adjust precalculated value
		voice.preCalcNote = plainNote - (useOctave << 16);

		// next calculate the actual period which depends on wether porta is enabled
		if (&channel < &_channelCtx[kNumChannels] && (channel.flags & ChannelContext::kFlagPortamento) != 0) {
			if ((channel.flags & ChannelContext::kFlagMono) != 0 && channel.lastNote < 0x80 && channel.lastNote != note) {
				voice.portaTicks = 0;
				voice.baseNote = channel.lastNote;
				voice.endNote = note;
				voice.hasPortamento = true;
				voice.preCalcNote = precalcNote(voice.baseNote, patch.tune, voice.octave);
			}
			channel.lastNote = note;
		}

		voice.lastPeriod = calcNote(voice);

		voice.priority = (byte)pri;
		voice.status = VoiceContext::kStatusStart;

		voice.noteVolume = (_playerCtx.handleVolume) ? volume + 1 : 128;
		voice.baseVolume = 0;

		// TODO: since the original player is using the OS-functions, more than 1 sample could be queued up already
		// get samplestart for the given octave
		const int8 *samplePtr = patch.samplePtr + (patch.sampleTotalLen << useOctave) - patch.sampleTotalLen;
		if (patch.sampleAttackLen) {
			Paula::setChannelSampleStart(voiceNum, samplePtr);
			Paula::setChannelSampleLen(voiceNum, (patch.sampleAttackLen << useOctave) / 2);

			Paula::enableChannel(voiceNum);
			// wait  for dma-clear
		}

		if (patch.sampleTotalLen > patch.sampleAttackLen) {
			Paula::setChannelSampleStart(voiceNum, samplePtr + (patch.sampleAttackLen << useOctave));
			Paula::setChannelSampleLen(voiceNum, ((patch.sampleTotalLen - patch.sampleAttackLen) << useOctave) / 2);
			if (!patch.sampleAttackLen)
				Paula::enableChannel(voiceNum); // need to enable channel
			// another pointless wait for DMA-Clear???

		} else { // no sustain sample
			// this means we must stop playback after the attacksample finished
			// so we queue up an "empty" sample and note that we need to kill the sample after dma finished
			Paula::setChannelSampleStart(voiceNum, 0);
			Paula::setChannelSampleLen(voiceNum, 0);
			Paula::setChannelDmaCount(voiceNum);
			voice.dmaOff = 1;
		}

		Paula::setChannelPeriod(voiceNum, (voice.lastPeriod) ? voice.lastPeriod : 1000);
		Paula::setChannelVolume(voiceNum, 0);
	}
	return voiceNum;
}

void MaxTrax::resetChannel(ChannelContext &chan, bool rightChannel) {
	chan.modulation = 0;
	chan.modulationTime = 1000;
	chan.microtonal = -1;
	chan.portamentoTime = 500;
	chan.pitchBend = NO_BEND;
	chan.pitchReal = 0;
	chan.pitchBendRange = MAX_BEND_RANGE;
	chan.volume = 128;
	chan.flags &= ~(ChannelContext::kFlagPortamento | ChannelContext::kFlagMicrotonal | ChannelContext::kFlagRightChannel);
	chan.isAltered = true;
	if (rightChannel)
		chan.flags |= ChannelContext::kFlagRightChannel;
}

void MaxTrax::freeScores() {
	if (_scores) {
		for (int i = 0; i < _numScores; ++i)
			delete[] _scores[i].events;
		delete[] _scores;
		_scores = 0;
	}
	_numScores = 0;
	_playerCtx.tempo = 120;
	_playerCtx.filterOn = true;
}

void MaxTrax::freePatches() {
	for (int i = 0; i < ARRAYSIZE(_patch); ++i) {
		delete[] _patch[i].samplePtr;
		delete[] _patch[i].attackPtr;
	}
	memset(_patch, 0, sizeof(_patch));
}

void MaxTrax::setSignalCallback(void (*callback) (int)) {
	Common::StackLock lock(_mutex);
	_playerCtx.syncCallBack = (callback == 0) ? nullFunc : callback;
}

int MaxTrax::playNote(byte note, byte patch, uint16 duration, uint16 volume, bool rightSide) {
	Common::StackLock lock(_mutex);
	assert(patch < ARRAYSIZE(_patch));

	ChannelContext &channel = _channelCtx[kNumChannels];
	channel.flags = (rightSide) ? ChannelContext::kFlagRightChannel : 0;
	channel.isAltered = false;
	channel.patch = &_patch[patch];
	const int8 voiceIndex = noteOn(channel, note, (byte)volume, kPriorityNote);
	if (voiceIndex >= 0) {
		_voiceCtx[voiceIndex].stopEventTime = duration << 8;
		Paula::startPaula();
	}
	return voiceIndex;
}

bool MaxTrax::load(Common::SeekableReadStream &musicData, bool loadScores, bool loadSamples) {
	Common::StackLock lock(_mutex);
	stopMusic();
	if (loadSamples)
		freePatches();
	if (loadScores)
		freeScores();
	const char *errorMsg = 0;
	// 0x0000: 4 Bytes Header "MXTX"
	// 0x0004: uint16 tempo
	// 0x0006: uint16 flags. bit0 = lowpassfilter, bit1 = attackvolume, bit15 = microtonal
	if (musicData.size() < 10 || musicData.readUint32BE() != 0x4D585458) {
		warning("Maxtrax: File is not a Maxtrax Module");
		return false;
	}
	const uint16 songTempo = musicData.readUint16BE();
	const uint16 flags = musicData.readUint16BE();
	if (loadScores) {
		_playerCtx.tempoInitial = songTempo;
		_playerCtx.filterOn = (flags & 1) != 0;
		_playerCtx.handleVolume = (flags & 2) != 0;
	}

	if (flags & (1 << 15)) {
		debug(5, "Maxtrax: Song has microtonal");
#ifdef MAXTRAX_HAS_MICROTONAL
		if (loadScores) {
			for (int i = 0; i < ARRAYSIZE(_microtonal); ++i)
				_microtonal[i] = musicData.readUint16BE();
		} else
			musicData.skip(128 * 2);
#else
		musicData.skip(128 * 2);
#endif
	}

	int scoresLoaded = 0;
	// uint16 number of Scores
	const uint16 scoresInFile = musicData.readUint16BE();

	if (musicData.err() || musicData.eos())
		goto ioError;

	if (loadScores) {
		const uint16 tempScores = MIN(scoresInFile, _playerCtx.maxScoreNum);
		Score *curScore = new Score[tempScores];
		if (!curScore)
			goto allocError;
		_scores = curScore;

		for (scoresLoaded = 0; scoresLoaded < tempScores; ++scoresLoaded, ++curScore) {
			const uint32 numEvents = musicData.readUint32BE();
			Event *curEvent = new Event[numEvents];
			if (!curEvent)
				goto allocError;
			curScore->events = curEvent;
			for (int j = numEvents; j > 0; --j, ++curEvent) {
				curEvent->command = musicData.readByte();
				curEvent->parameter = musicData.readByte();
				curEvent->startTime = musicData.readUint16BE();
				curEvent->stopTime = musicData.readUint16BE();
			}
			curScore->numEvents = numEvents;
		}
		_numScores = scoresLoaded;
	}

	if (loadSamples) {
		// skip over remaining scores in file
		for (int i = scoresInFile - scoresLoaded; i > 0; --i)
			musicData.skip(musicData.readUint32BE() * 6);

		// uint16 number of Samples
		const uint16 wavesInFile = musicData.readUint16BE();
		for (int i = wavesInFile; i > 0; --i) {
			// load disksample structure
			const uint16 number = musicData.readUint16BE();
			assert(number < ARRAYSIZE(_patch));

			Patch &curPatch = _patch[number];
			if (curPatch.attackPtr || curPatch.samplePtr) {
				delete curPatch.attackPtr;
				curPatch.attackPtr = 0;
				delete curPatch.samplePtr;
				curPatch.samplePtr = 0;
			}
			curPatch.tune = musicData.readSint16BE();
			curPatch.volume = musicData.readUint16BE();
			curPatch.sampleOctaves = musicData.readUint16BE();
			curPatch.sampleAttackLen = musicData.readUint32BE();
			const uint32 sustainLen = musicData.readUint32BE();
			curPatch.sampleTotalLen = curPatch.sampleAttackLen + sustainLen;
			// each octave the number of samples doubles.
			const uint32 totalSamples = curPatch.sampleTotalLen * ((1 << curPatch.sampleOctaves) - 1);
			curPatch.attackLen = musicData.readUint16BE();
			curPatch.releaseLen = musicData.readUint16BE();
			const uint32 totalEnvs = curPatch.attackLen + curPatch.releaseLen;

			// Allocate space for both attack and release Segment.
			Envelope *envPtr = new Envelope[totalEnvs];
			if (!envPtr)
				goto allocError;
			// Attack Segment
			curPatch.attackPtr = envPtr;
			// Release Segment
			// curPatch.releasePtr = envPtr + curPatch.attackLen;

			// Read Attack and Release Segments
			for (int j = totalEnvs; j > 0; --j, ++envPtr) {
				envPtr->duration = musicData.readUint16BE();
				envPtr->volume = musicData.readUint16BE();
			}

			// read Samples
			int8 *allocSamples = new int8[totalSamples];
			if (!allocSamples)
				goto allocError;
			curPatch.samplePtr = allocSamples;
			musicData.read(allocSamples, totalSamples);
		}
	}
	if (!musicData.err() && !musicData.eos())
		return true;
ioError:
	errorMsg = "Maxtrax: Encountered IO-Error";
allocError:
	if (!errorMsg)
		errorMsg = "Maxtrax: Could not allocate Memory";

	warning("%s", errorMsg);
	if (loadSamples)
		freePatches();
	if (loadScores)
		freeScores();
	return false;
}

#if !defined(NDEBUG) && 0
void MaxTrax::outPutEvent(const Event &ev, int num) {
	struct {
		byte cmd;
		const char *name;
		const char *param;
	} COMMANDS[] = {
		{0x80, "TEMPO   ", "TEMPO, N/A      "},
		{0xa0, "SPECIAL ", "CHAN, SPEC # | VAL"},
		{0xb0, "CONTROL ", "CHAN, CTRL # | VAL"},
		{0xc0, "PROGRAM ", "CHANNEL, PROG # "},
		{0xe0, "BEND    ", "CHANNEL, BEND VALUE"},
		{0xf0, "SYSEX   ", "TYPE, SIZE      "},
		{0xf8, "REALTIME", "REALTIME, N/A   "},
		{0xff, "END     ", "N/A, N/A        "},
		{0xff, "NOTE    ", "VOL | CHAN, STOP"},
	};

	int i = 0;
	for (; i < ARRAYSIZE(COMMANDS) - 1 && ev.command != COMMANDS[i].cmd; ++i)
		;

	if (num == -1)
		debug("Event    : %02X %s %s %02X %04X %04X", ev.command, COMMANDS[i].name, COMMANDS[i].param, ev.parameter, ev.startTime, ev.stopTime);
	else
		debug("Event %3d: %02X %s %s %02X %04X %04X", num, ev.command, COMMANDS[i].name, COMMANDS[i].param, ev.parameter, ev.startTime, ev.stopTime);
}

void MaxTrax::outPutScore(const Score &sc, int num) {
	if (num == -1)
		debug("score   : %i Events", sc.numEvents);
	else
		debug("score %2d: %i Events", num, sc.numEvents);
	for (uint i = 0; i < sc.numEvents; ++i)
		outPutEvent(sc.events[i], i);
	debug("");
}
#else
void MaxTrax::outPutEvent(const Event &ev, int num) {}
void MaxTrax::outPutScore(const Score &sc, int num) {}
#endif	// #ifndef NDEBUG

} // End of namespace Audio

#endif // #if defined(AUDIO_MODS_MAXTRAX_H)