Moved the softsynth midi drivers into a sound/softsynth; amongst other things, this fixes bug #1083058

svn-id: r16316

1 files changed, 907 insertions, 0 deletions

diff --git a/sound/softsynth/ym2612.cpp b/sound/softsynth/ym2612.cpp
new file mode 100644
index 0000000000..b9ad9b35ca
--- /dev/null
+++ b/sound/softsynth/ym2612.cpp
@@ -0,0 +1,907 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2001-2004 The ScummVM project
+ *
+ * YM2612 tone generation code written by Tomoaki Hayasaka.
+ * Used under the terms of the GNU General Public License.
+ * Adpated to ScummVM by Jamieson Christian.
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * $Header$
+ */
+
+#include "sound/softsynth/emumidi.h"
+
+#include <math.h>
+
+
+////////////////////////////////////////
+//
+// Miscellaneous
+//
+////////////////////////////////////////
+
+static int *sintbl = 0;
+static int *powtbl = 0;
+static int *frequencyTable = 0;
+static int *keycodeTable = 0;
+static int *keyscaleTable = 0;
+static int *attackOut = 0;
+
+////////////////////////////////////////
+//
+// Class declarations
+//
+////////////////////////////////////////
+
+class Operator2612;
+class Voice2612;
+class MidiChannel_YM2612;
+class MidiDriver_YM2612;
+
+class Operator2612 {
+protected:
+	Voice2612 *_owner;
+	enum State { _s_ready, _s_attacking, _s_decaying, _s_sustaining, _s_releasing };
+	State _state;
+	int32 _currentLevel;
+	int _frequency;
+	uint32 _phase;
+	int _lastOutput;
+	int _feedbackLevel;
+	int _detune;
+	int _multiple;
+	int32 _totalLevel;
+	int _keyScale;
+	int _velocity;
+	int _specifiedTotalLevel;
+	int _specifiedAttackRate;
+	int _specifiedDecayRate;
+	int _specifiedSustainLevel;
+	int _specifiedSustainRate;
+	int _specifiedReleaseRate;
+	int _tickCount;
+	int _attackTime;
+	int32 _decayRate;
+	int32 _sustainLevel;
+	int32 _sustainRate;
+	int32 _releaseRate;
+
+public:
+	Operator2612 (Voice2612 *owner);
+	~Operator2612();
+	void feedbackLevel(int level);
+	void setInstrument(byte const *instrument);
+	void velocity(int velo);
+	void keyOn();
+	void keyOff();
+	void frequency(int freq);
+	void nextTick(const int *phaseShift, int *outbuf, int buflen);
+	bool inUse() { return (_state != _s_ready); }
+};
+
+class Voice2612 {
+public:
+	Voice2612 *next;
+	uint16 _rate;
+
+protected:
+	Operator2612 *_opr[4];
+	int _velocity;
+	int _control7;
+	int _note;
+	int _frequencyOffs;
+	int _frequency;
+	int _algorithm;
+	
+	int *_buffer;
+	int _buflen;
+
+public:
+	Voice2612();
+	~Voice2612();
+	void setControlParameter(int control, int value);
+	void setInstrument(byte const *instrument);
+	void velocity(int velo);
+	void nextTick(int *outbuf, int buflen);
+	void noteOn(int n, int onVelo);
+	bool noteOff(int note);
+	void pitchBend(int value);
+	void recalculateFrequency();
+};
+
+class MidiChannel_YM2612 : public MidiChannel {
+protected:
+	uint16 _rate;
+	Voice2612 *_voices;
+	Voice2612 *_next_voice;
+
+public:
+	void removeAllVoices();
+	void nextTick(int *outbuf, int buflen);
+	void rate(uint16 r);
+
+public:
+	MidiChannel_YM2612();
+	virtual ~MidiChannel_YM2612();
+
+	// MidiChannel interface
+	MidiDriver *device() { return 0; }
+	byte getNumber() { return 0; }
+	void release() { }
+	void send(uint32 b) { }
+	void noteOff(byte note);
+	void noteOn(byte note, byte onVelo);
+	void programChange(byte program) { }
+	void pitchBend(int16 value);
+	void controlChange(byte control, byte value);
+	void pitchBendFactor(byte value) { }
+	void sysEx_customInstrument(uint32 type, byte *instr);
+};
+
+class MidiDriver_YM2612 : public MidiDriver_Emulated {
+protected:
+	MidiChannel_YM2612 *_channel[16];
+
+	int _next_voice;
+	int _volume;
+
+protected:
+	static void createLookupTables();
+	void nextTick(int16 *buf1, int buflen);
+	int volume(int val = -1) { if (val >= 0) _volume = val; return _volume; }
+	void rate(uint16 r);
+
+	void generateSamples(int16 *buf, int len);
+
+public:
+	MidiDriver_YM2612(SoundMixer *mixer);
+	virtual ~MidiDriver_YM2612();
+
+	int open();
+	void close();
+	void send(uint32 b);
+	void send(byte channel, uint32 b); // Supports higher than channel 15
+	uint32 property(int prop, uint32 param) { return 0; }
+
+	void setPitchBendRange(byte channel, uint range) { }
+	void sysEx(byte *msg, uint16 length);
+
+	MidiChannel *allocateChannel() { return 0; }
+	MidiChannel *getPercussionChannel() { return 0; }
+
+
+	// AudioStream API
+	bool isStereo() const { return true; }
+	int getRate() const { return _mixer->getOutputRate(); }
+};
+
+////////////////////////////////////////
+//
+// Operator2612 implementation
+//
+////////////////////////////////////////
+
+Operator2612::Operator2612 (Voice2612 *owner) :
+	_owner (owner),
+	_state (_s_ready),
+	_currentLevel ((int32)0x7f << 15),
+	_phase (0),
+	_lastOutput (0),
+	_feedbackLevel (0),
+	_detune (0),
+	_multiple (1),
+	_keyScale (0),
+	_specifiedTotalLevel (127),
+	_specifiedAttackRate (0),
+	_specifiedDecayRate (0),
+	_specifiedSustainRate (0),
+	_specifiedReleaseRate (15) {
+		velocity(0);
+}
+
+Operator2612::~Operator2612()
+{ }
+
+void Operator2612::velocity(int velo) {
+	_velocity = velo;
+	_totalLevel = ((int32)_specifiedTotalLevel << 15) +
+					((int32)(127-_velocity) << 13);
+	_sustainLevel = ((int32)_specifiedSustainLevel << 17);
+}
+
+void Operator2612::feedbackLevel(int level) {
+	_feedbackLevel = level;
+}
+
+void Operator2612::setInstrument(byte const *instrument) {
+	_detune = (instrument[8] >> 4) & 7;
+	_multiple = instrument[8] & 15;
+	_specifiedTotalLevel = instrument[12] & 127;
+	_keyScale = (instrument[16] >> 6) & 3;
+	_specifiedAttackRate = instrument[16] & 31;
+	_specifiedDecayRate = instrument[20] & 31;
+	_specifiedSustainRate = instrument[24] & 31;
+	_specifiedSustainLevel = (instrument[28] >> 4) & 15;
+	_specifiedReleaseRate = instrument[28] & 15;
+	_state = _s_ready; // 本物ではどうなのかな?
+	velocity(_velocity);
+}
+
+void Operator2612::keyOn() {
+	_state = _s_attacking;
+	_tickCount = 0;
+	_phase = 0;			// どうも、実際こうらしい
+	_currentLevel = ((int32)0x7f << 15); // これも、実際こうらしい
+}
+
+void Operator2612::keyOff() {
+	if (_state != _s_ready)
+		_state = _s_releasing;
+}
+
+void Operator2612::frequency(int freq) {
+	double value; // Use for intermediate computations to avoid int64 arithmetic
+	int r;
+
+	_frequency = freq / _owner->_rate;
+
+	r = _specifiedAttackRate;
+	if (r != 0) {
+		r = r * 2 + (keyscaleTable[freq/262205] >> (3-_keyScale));
+		if (r >= 64)
+		r = 63; // するべきなんだろうとは思うんだけど (赤p.207)
+	}
+
+	r = 63 - r;
+	if (_specifiedTotalLevel >= 128)
+		value = 0;
+	else {
+		value = powtbl[(r&3) << 7];
+		value *= 1 << (r >> 2);
+		value *= 41; // r == 20 のとき、0-96[db] が 10.01[ms] == 41.00096
+		value /= 1 << (15 + 5);
+		value *= 127 - _specifiedTotalLevel;
+		value /= 127;
+	}
+	_attackTime = (int32) value; // 1 秒 == (1 << 12)
+	if (_attackTime > 0)
+		_attackTime = (1 << (12+10)) / (_owner->_rate * _attackTime);
+
+	r = _specifiedDecayRate;
+	if (r != 0) {
+		r = r * 2 + (keyscaleTable[freq/262205] >> (3-_keyScale));
+		if (r >= 64)
+			r = 63;
+	}
+	value = (double) powtbl[(r&3) << 7] * (0x10 << (r>>2)) / 31;
+	_decayRate = (int32) value / _owner->_rate;
+
+	r = _specifiedSustainRate;
+	if (r != 0) {
+		r = r * 2 + (keyscaleTable[freq/262205] >> (3-_keyScale));
+		if (r >= 64)
+			r = 63;
+	}
+	value = (double) powtbl[(r&3) << 7] * (0x10 << (r>>2)) / 31;
+	_sustainRate = (int32) value / _owner->_rate;
+
+	r = _specifiedReleaseRate;
+	if (r != 0) {
+		r = r * 2 + 1;		// (Translated) I cannot know whether the timing is a good choice or not
+		r = r * 2 + (keyscaleTable[freq/262205] >> (3-_keyScale));
+		// KS による補正はあるらしい。赤p.206 では記述されてないけど。
+		if (r >= 64)
+			r = 63;
+	}
+	value = (double) powtbl[(r&3) << 7] * (0x10 << (r>>2)) / 31;
+	_releaseRate = (int32) value / _owner->_rate;
+}
+
+void Operator2612::nextTick(const int *phasebuf, int *outbuf, int buflen) {
+	if (_state == _s_ready)
+		return;
+	if (_state == _s_attacking && _attackTime <= 0) {
+		_currentLevel = 0;
+		_state = _s_decaying;
+	}
+
+	int32 levelIncrement = 0;
+	int32 target = 0;
+	State next_state = _s_ready;
+	const int32 zero_level = ((int32)0x7f << 15);
+	const int phaseIncrement = (_multiple > 0) ? (_frequency * _multiple) : (_frequency / 2);
+
+	int32 output = _lastOutput;
+	int32 level = _currentLevel + _totalLevel;
+
+	while (buflen) {
+		switch (_state) {
+		case _s_ready:
+			return;
+			break;
+		case _s_attacking:
+			next_state = _s_attacking;
+			break;
+		case _s_decaying:
+			levelIncrement = _decayRate;
+			target = _sustainLevel + _totalLevel;
+			next_state = _s_sustaining;
+			break;
+		case _s_sustaining:
+			levelIncrement = _sustainRate;
+			target = zero_level + _totalLevel;
+			next_state = _s_ready;
+			break;
+		case _s_releasing:
+			levelIncrement = _releaseRate;
+			target = zero_level + _totalLevel;
+			next_state = _s_ready;
+			break;
+		}
+
+		bool switching = false;
+		do {
+			if (next_state == _s_attacking) {
+				// Attack phase
+				++_tickCount;
+				int i = (int) (_tickCount * _attackTime);
+				if (i >= 1024) {
+					level = _totalLevel;
+					_state = _s_decaying;
+					switching = true;
+				} else {
+					level = (attackOut[i] << (31 - 8 - 16)) + _totalLevel;
+				}
+			} else {
+				// Decay, Sustain and Release phases
+				level += levelIncrement;
+				if (level >= target) {
+					level = target;
+					_state = next_state;
+					switching = true;
+				}
+			}
+
+			if (level < zero_level) {
+				int phaseShift = *phasebuf >> 2; // 正しい変調量は?  3 じゃ小さすぎで 2 じゃ大きいような。
+				if (_feedbackLevel)
+					phaseShift += (output << (_feedbackLevel - 1)) / 1024;
+				output = sintbl[((_phase >> 7) + phaseShift) & 0x7ff];
+				output >>= (level >> 18);	// 正しい減衰量は?
+				// Here is the original code, which requires 64-bit ints
+//				output *= powtbl[511 - ((level>>25)&511)];
+//				output >>= 16;
+//				output >>= 1;
+				// And here's our 32-bit trick for doing it. (Props to Fingolfin!)
+				// Result varies from original code by max of 1.
+//				int powVal = powtbl[511 - ((level>>9)&511)];
+//				int outputHI = output / 256;
+//				int powHI = powVal / 256;
+//				output = (outputHI * powHI) / 2 + (outputHI * (powVal % 256) + powHI * (output % 256)) / 512;
+				// And here's the even faster code.
+				// Result varies from original code by max of 8.
+				output = ((output >> 4) * (powtbl[511-((level>>9)&511)] >> 3)) / 1024;
+
+				_phase += phaseIncrement;
+				_phase &= 0x3ffff;
+			} else
+				output = 0;
+
+			*outbuf += output;
+			 --buflen;
+			 ++phasebuf;
+			 ++outbuf;
+		} while (buflen && !switching);
+	}
+	_lastOutput = output;
+	_currentLevel = level - _totalLevel;
+}
+
+////////////////////////////////////////
+//
+// Voice2612 implementation
+//
+////////////////////////////////////////
+
+Voice2612::Voice2612() {
+	next = 0;
+	_control7 = 127;
+	_note = 40;
+	_frequency = 440;
+	_frequencyOffs = 0x2000;
+	_algorithm = 7;
+
+	_buffer = 0;
+	_buflen = 0;
+
+	int i;
+	for (i = 0; i < ARRAYSIZE(_opr); ++i)
+		_opr[i] = new Operator2612 (this);
+	velocity(0);
+}
+
+Voice2612::~Voice2612() {
+	int i;
+	for (i = 0; i < ARRAYSIZE(_opr); ++i)
+		delete _opr[i];
+	free(_buffer);
+}
+
+void Voice2612::velocity(int velo) {
+	_velocity = velo;
+#if 0
+	int v = (velo * _control7) >> 7; // これだと精度良くないですね
+#else
+	int v = velo + (_control7 - 127) * 4;
+#endif
+	bool iscarrier[8][4] = {
+		{ false, false, false,  true, }, //0
+		{ false, false, false,  true, }, //1
+		{ false, false, false,  true, }, //2
+		{ false, false, false,  true, }, //3
+		{ false,  true, false,  true, }, //4
+		{ false,  true,  true,  true, }, //5
+		{ false,  true,  true,  true, }, //6
+		{  true,  true,  true,  true, }, //7
+	};
+	int opr;
+	for (opr = 0; opr < 4; opr++)
+		if (iscarrier[_algorithm][opr])
+			_opr[opr]->velocity(v);
+		else
+			_opr[opr]->velocity(127);
+}
+
+void Voice2612::setControlParameter(int control, int value) {
+	switch (control) {
+	case 7:
+		_control7 = value;
+		velocity(_velocity);
+		break;
+	case 123:
+		// All notes off
+		noteOff(_note);
+	};
+}
+
+void Voice2612::setInstrument(byte const *instrument) {
+	if (instrument == NULL)
+		return;
+
+	_algorithm = instrument[32] & 7;
+	_opr[0]->feedbackLevel((instrument[32] >> 3) & 7);
+	_opr[1]->feedbackLevel(0);
+	_opr[2]->feedbackLevel(0);
+	_opr[3]->feedbackLevel(0);
+	_opr[0]->setInstrument(instrument + 0);
+	_opr[1]->setInstrument(instrument + 2);
+	_opr[2]->setInstrument(instrument + 1);
+	_opr[3]->setInstrument(instrument + 3);
+}
+
+void Voice2612::nextTick(int *outbuf, int buflen) {
+	if (_velocity == 0)
+		return;
+
+	if (_buflen < buflen) {
+		free(_buffer);
+		_buflen = buflen;
+		_buffer = (int *) malloc(sizeof(int) * buflen * 2);
+	}
+
+	int *buf1 = _buffer;
+	int *buf2 = _buffer + buflen;
+	memset(_buffer, 0, sizeof(int) * buflen * 2);
+
+	switch (_algorithm) {
+	case 0:
+		_opr[0]->nextTick(buf1, buf2, buflen);
+		_opr[1]->nextTick(buf2, buf1, buflen);
+		memset (buf2, 0, sizeof (int) * buflen);
+		_opr[2]->nextTick(buf1, buf2, buflen);
+		_opr[3]->nextTick(buf2, outbuf, buflen);
+		break;
+	case 1:
+		_opr[0]->nextTick(buf1, buf2, buflen);
+		_opr[1]->nextTick(buf1, buf2, buflen);
+		_opr[2]->nextTick(buf2, buf1, buflen);
+		_opr[3]->nextTick(buf1, outbuf, buflen);
+		break;
+	case 2:
+		_opr[1]->nextTick(buf1, buf2, buflen);
+		_opr[2]->nextTick(buf2, buf1, buflen);
+		memset(buf2, 0, sizeof(int) * buflen);
+		_opr[0]->nextTick(buf2, buf1, buflen);
+		_opr[3]->nextTick(buf1, outbuf, buflen);
+		break;
+	case 3:
+		_opr[0]->nextTick(buf1, buf2, buflen);
+		_opr[1]->nextTick(buf2, buf1, buflen);
+		memset(buf2, 0, sizeof(int) * buflen);
+		_opr[2]->nextTick(buf2, buf1, buflen);
+		_opr[3]->nextTick(buf1, outbuf, buflen);
+		break;
+	case 4:
+		_opr[0]->nextTick(buf1, buf2, buflen);
+		_opr[1]->nextTick(buf2, outbuf, buflen);
+		_opr[2]->nextTick(buf1, buf1, buflen);
+		_opr[3]->nextTick(buf1, outbuf, buflen);
+		break;
+	case 5:
+		_opr[0]->nextTick(buf1, buf2, buflen);
+		_opr[1]->nextTick(buf2, outbuf, buflen);
+		_opr[2]->nextTick(buf2, outbuf, buflen);
+		_opr[3]->nextTick(buf2, outbuf, buflen);
+		break;
+	case 6:
+		_opr[0]->nextTick(buf1, buf2, buflen);
+		_opr[1]->nextTick(buf2, outbuf, buflen);
+		_opr[2]->nextTick(buf1, outbuf, buflen);
+		_opr[3]->nextTick(buf1, outbuf, buflen);
+		break;
+	case 7:
+		_opr[0]->nextTick(buf1, outbuf, buflen);
+		_opr[1]->nextTick(buf1, outbuf, buflen);
+		_opr[2]->nextTick(buf1, outbuf, buflen);
+		_opr[3]->nextTick(buf1, outbuf, buflen);
+		break;
+	};
+}
+
+void Voice2612::noteOn(int n, int onVelo) {
+	_note = n;
+	velocity(onVelo);
+	recalculateFrequency();
+	int i;
+	for (i = 0; i < ARRAYSIZE(_opr); i++)
+		_opr[i]->keyOn();
+}
+
+bool Voice2612::noteOff(int note) {
+	if (_note != note)
+		return false;
+	int i;
+	for (i = 0; i < ARRAYSIZE(_opr); i++)
+		_opr[i]->keyOff();
+	return true;
+}
+
+void Voice2612::pitchBend(int value) {
+	_frequencyOffs = value;
+	recalculateFrequency();
+}
+
+void Voice2612::recalculateFrequency() {
+	// MIDI とも違うし....
+	// どういう仕様なんだろうか?
+	// と思ったら、なんと、これ (↓) が正解らしい。
+	int32 basefreq = frequencyTable[_note];
+	int cfreq = frequencyTable[_note - (_note % 12)];
+	int oct = _note / 12;
+	int fnum = (int) (((double)basefreq * (1 << 13)) / cfreq); // OPL の fnum と同じようなもの。
+	fnum += _frequencyOffs - 0x2000;
+	if (fnum < 0x2000) {
+		fnum += 0x2000;
+		oct--;
+	}
+	if (fnum >= 0x4000) {
+		fnum -= 0x2000;
+		oct++;
+	}
+
+	// _frequency は最終的にバイアス 256*1024 倍
+	_frequency = (int) ((frequencyTable[oct*12] * (double)fnum) / 8);
+
+	int i;
+	for (i = 0; i < ARRAYSIZE(_opr); i++)
+		_opr[i]->frequency(_frequency);
+}
+
+////////////////////////////////////////
+//
+// MidiChannel_YM2612
+//
+////////////////////////////////////////
+
+MidiChannel_YM2612::MidiChannel_YM2612() {
+	_voices = 0;
+	_next_voice = 0;
+}
+
+MidiChannel_YM2612::~MidiChannel_YM2612() {
+	removeAllVoices();
+}
+
+void MidiChannel_YM2612::removeAllVoices() {
+	if (!_voices)
+		return;
+	Voice2612 *last, *voice = _voices;
+	for (; voice; voice = last) {
+		last = voice->next;
+		delete voice;
+	}
+	_voices = _next_voice = 0;
+}
+
+void MidiChannel_YM2612::noteOn(byte note, byte onVelo) {
+	if (!_voices)
+		return;
+	_next_voice = _next_voice ? _next_voice : _voices;
+	_next_voice->noteOn(note, onVelo);
+	_next_voice = _next_voice->next;
+}
+
+void MidiChannel_YM2612::noteOff(byte note) {
+	if (!_voices)
+		return;
+	if (_next_voice == _voices)
+		_next_voice = 0;
+	Voice2612 *voice = _next_voice;
+	do {
+		if (!voice)
+			voice = _voices;
+		if (voice->noteOff(note)) {
+			_next_voice = voice;
+			break;
+		}
+		voice = voice->next;
+	} while (voice != _next_voice);
+}
+
+void MidiChannel_YM2612::controlChange(byte control, byte value) {
+	// いいのかこれで?
+	if (control == 121) {
+		// Reset controller
+		removeAllVoices();
+	} else {
+		Voice2612 *voice = _voices;
+		for (; voice; voice = voice->next)
+			voice->setControlParameter(control, value);
+	}
+}
+
+void MidiChannel_YM2612::sysEx_customInstrument(uint32 type, byte *fmInst) {
+	if (type != 'EUP ')
+		return;
+	Voice2612 *voice = new Voice2612;
+	voice->next = _voices;
+	_voices = voice;
+	voice->_rate = _rate;
+	voice->setInstrument(fmInst);
+}
+
+void MidiChannel_YM2612::pitchBend(int16 value) {
+  // いいのかこれで?
+	Voice2612 *voice = _voices;
+	for (; voice; voice = voice->next)
+		voice->pitchBend(value);
+}
+
+void MidiChannel_YM2612::nextTick(int *outbuf, int buflen) {
+	Voice2612 *voice = _voices;
+	for (; voice; voice = voice->next)
+		voice->nextTick(outbuf, buflen);
+}
+
+void MidiChannel_YM2612::rate(uint16 r) {
+	_rate = r;
+	Voice2612 *voice = _voices;
+	for (; voice; voice = voice->next)
+		voice->_rate = r;
+}
+
+////////////////////////////////////////
+//
+// MidiDriver_YM2612
+//
+////////////////////////////////////////
+
+MidiDriver_YM2612::MidiDriver_YM2612(SoundMixer *mixer)
+	: MidiDriver_Emulated(mixer) {
+	_next_voice = 0;
+
+	createLookupTables();
+	_volume = 256;
+	int i;
+	for (i = 0; i < ARRAYSIZE(_channel); i++)
+		_channel[i] = new MidiChannel_YM2612;
+	rate(getRate());
+}
+
+MidiDriver_YM2612::~MidiDriver_YM2612() {
+	int i;
+	for (i = 0; i < ARRAYSIZE(_channel); i++)
+		delete _channel[i];
+	delete sintbl;
+	delete powtbl;
+	delete frequencyTable;
+	delete keycodeTable;
+	delete keyscaleTable;
+	delete attackOut;
+	sintbl = powtbl = frequencyTable = keycodeTable = keyscaleTable = attackOut = 0;
+}
+
+int MidiDriver_YM2612::open() {
+	if (_isOpen)
+		return MERR_ALREADY_OPEN;
+
+	MidiDriver_Emulated::open();
+
+	_mixer->setupPremix(this);
+	return 0;
+}
+
+void MidiDriver_YM2612::close() {
+	if (!_isOpen)
+		return;
+	_isOpen = false;
+
+	// Detach the premix callback handler
+	_mixer->setupPremix(0);
+}
+
+void MidiDriver_YM2612::send(uint32 b) {
+	send(b & 0xF, b & 0xFFFFFFF0);
+}
+
+void MidiDriver_YM2612::send(byte chan, uint32 b) {
+	//byte param3 = (byte) ((b >> 24) & 0xFF);
+	byte param2 = (byte) ((b >> 16) & 0xFF);
+	byte param1 = (byte) ((b >>  8) & 0xFF);
+	byte cmd    = (byte) (b & 0xF0);
+	if (chan > ARRAYSIZE(_channel))
+		return;
+
+	switch (cmd) {
+	case 0x80:// Note Off
+		_channel[chan]->noteOff(param1);
+		break;
+	case 0x90: // Note On
+		_channel[chan]->noteOn(param1, param2);
+		break;
+	case 0xA0: // Aftertouch
+		break; // Not supported.
+	case 0xB0: // Control Change
+		_channel[chan]->controlChange(param1, param2);
+		break;
+	case 0xC0: // Program Change
+		_channel[chan]->programChange(param1);
+		break;
+	case 0xD0: // Channel Pressure
+		break; // Not supported.
+	case 0xE0: // Pitch Bend
+		_channel[chan]->pitchBend((param1 | (param2 << 7)) - 0x2000);
+		break;
+	case 0xF0: // SysEx
+		// We should never get here! SysEx information has to be
+		// sent via high-level semantic methods.
+		warning("MidiDriver_YM2612: Receiving SysEx command on a send() call");
+		break;
+
+	default:
+		warning("MidiDriver_YM2612: Unknown send() command 0x%02X", cmd);
+	}
+}
+
+void MidiDriver_YM2612::sysEx(byte *msg, uint16 length) {
+	if (msg[0] != 0x7C || msg[1] >= ARRAYSIZE(_channel))
+		return;
+	_channel[msg[1]]->sysEx_customInstrument('EUP ', &msg[2]);
+}
+
+void MidiDriver_YM2612::generateSamples(int16 *data, int len) {
+	memset(data, 0, 2 * sizeof(int16) * len);
+	nextTick(data, len);
+}
+
+void MidiDriver_YM2612::nextTick(int16 *buf1, int buflen) {
+	int *buf0 = (int *)buf1;
+
+	int i;
+	for (i = 0; i < ARRAYSIZE(_channel); i++)
+		_channel[i]->nextTick(buf0, buflen);
+
+	for (i = 0; i < buflen; ++i)
+		buf1[i*2+1] = buf1[i*2] = ((buf0[i] * volume()) >> 10) & 0xffff;
+}
+
+void MidiDriver_YM2612::rate(uint16 r)
+{
+	int i;
+	for (i = 0; i < ARRAYSIZE(_channel); i++)
+		_channel[i]->rate(r);
+}
+
+void MidiDriver_YM2612::createLookupTables() {
+	{
+		int i;
+		sintbl = new int [2048];
+		for (i = 0; i < 2048; i++)
+			sintbl[i] = (int)(0xffff * sin(i/2048.0*2.0*PI));
+	}
+
+	{
+		int i;
+		powtbl = new int [1025];
+		for (i = 0; i <= 1024; i++)
+			powtbl[i] = (int)(0x10000 * pow(2.0, (i-512)/512.0));
+	}
+
+	{
+		int i;
+		int block;
+
+		static int fnum[] = {
+			0x026a, 0x028f, 0x02b6, 0x02df,
+			0x030b, 0x0339, 0x036a, 0x039e,
+			0x03d5, 0x0410, 0x044e, 0x048f,
+		};
+
+		// (int)(880.0 * 256.0 * pow(2.0, (note-0x51)/12.0)); // バイアス 256 倍
+		// 0x45 が 440Hz (a4)、0x51 が 880Hz (a5) らしい
+		frequencyTable = new int [120];
+		for (block = -1; block < 9; block++) {
+			for (i = 0; i < 12; i++) {
+				double freq = fnum[i] * (166400.0 / 3) * pow(2.0, block-21);
+				frequencyTable[(block+1)*12+i] = (int)(256.0 * freq);
+			}
+		}
+
+		keycodeTable = new int [120];
+		// detune 量の計算や KS による rate 変換に使うんじゃないかな
+		for (block = -1; block < 9; block++) {
+			for (i = 0; i < 12; i++) {
+				// see p.204
+				int  f8 = (fnum[i] >>  7) & 1;
+				int  f9 = (fnum[i] >>  8) & 1;
+				int f10 = (fnum[i] >>  9) & 1;
+				int f11 = (fnum[i] >> 10) & 1;
+				int  n4 = f11;
+				int  n3 = f11&(f10|f9|f8) | (~f11&f10&f9&f8);
+				int note = n4*2 + n3;
+				// see p.207
+				keycodeTable[(block+1)*12+i] = block*4 + note;
+			}
+		}
+	}
+
+	{
+		int freq;
+		keyscaleTable = new int [8192];
+		keyscaleTable[0] = 0;
+		for (freq = 1; freq < 8192; freq++) {
+			keyscaleTable[freq] = (int)(log((double)freq) / 9.03 * 32.0) - 1;
+			// 8368[Hz] (o9c) で 32くらい。9.03 =:= ln 8368
+		}
+	}
+
+	{
+		int i;
+		attackOut = new int [1024];
+		for (i = 0; i < 1024; i++)
+			attackOut[i] = (int)(((0x7fff+0x03a5)*30.0) / (30.0+i)) - 0x03a5;
+	}
+}
+
+////////////////////////////////////////
+//
+// MidiDriver_YM2612 factory
+//
+////////////////////////////////////////
+
+MidiDriver *MidiDriver_YM2612_create(SoundMixer *mixer) {
+	return new MidiDriver_YM2612(mixer);
+}