/* ScummVM - Scumm Interpreter
 * Copyright (C) 2003 The ScummVM project
 *
 * 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 "adlibchannel.h"
#include "sound/fmopl.h"

SkyAdlibChannel::SkyAdlibChannel(uint8 *pMusicData, uint16 startOfData)
{
	_musicData = pMusicData;
	_channelData.startOfData = startOfData;
	_channelData.eventDataPtr = startOfData;
	_channelData.channelActive = 1;
	_channelData.freqDataSize = 2;
	_channelData.tremoVibro = 0;
	_channelData.assignedInstrument = 0xFF;
	_channelData.channelVolume = 0x7F;
	_channelData.nextEventTime = getNextEventTime();

	_channelData.adlibChannelNumber = _channelData.lastCommand = _channelData.note =
		_channelData.adlibReg1 = _channelData.adlibReg2 = _channelData.freqOffset = 0;
	_channelData.frequency = 0;
	_channelData.instrumentData = NULL;

	uint16 instrumentDataLoc = (_musicData[0x1206] << 8) | _musicData[0x1205];
	_instrumentMap = _musicData+instrumentDataLoc;
	_instruments = (InstrumentStruct*)(_instrumentMap+0x80);

	_frequenceTable = (uint16*)(_musicData+0x7FE);
	_registerTable = _musicData+0xDFE;
	_opOutputTable = _musicData+0xE10;
	_adlibRegMirror = _musicData+0xF5F;
	_musicVolume = 0x100;
}

void SkyAdlibChannel::updateVolume(uint16 pVolume) {

	_musicVolume = pVolume;
}

/*	This class uses the same area for the register mirror as the original
	asm driver did (_musicData[0xF5F..0x105E]), so the cache is indeed shared
	by all instances of the class.
*/
void SkyAdlibChannel::setRegister(uint8 regNum, uint8 value) {

	if (_adlibRegMirror[regNum] != value) {
		YM3812Write(0, 0, regNum);
		YM3812Write(0, 1, value);
		_adlibRegMirror[regNum] = value;
	}
}

void SkyAdlibChannel::stopNote(void) {

	if (_channelData.note & 0x20) {
		_channelData.note &= ~0x20;
		setRegister(0xB0 | _channelData.adlibChannelNumber, _channelData.note);
	}
}

int32 SkyAdlibChannel::getNextEventTime(void)
{
	int32 retV = 0; 
	uint8 cnt, lVal;
	for (cnt = 0; cnt < 4; cnt++) {
		lVal = _musicData[_channelData.eventDataPtr];
		_channelData.eventDataPtr++;
		retV = (retV << 7) | (lVal & 0x7F);
		if (!(lVal & 0x80)) break;
	}
	if (lVal & 0x80) { // should never happen
		return -1;
	} else return retV;

}

uint8 SkyAdlibChannel::process(uint16 aktTime) {

	if (!_channelData.channelActive) {
		return 0;
	}
	
	uint8 returnVal = 0;

	_channelData.nextEventTime -= aktTime;
	uint8 opcode;
	while ((_channelData.nextEventTime < 0) && (_channelData.channelActive)) {
		opcode = _musicData[_channelData.eventDataPtr];
		_channelData.eventDataPtr++;
		if (opcode&0x80) {
			if (opcode == 0xFF) {
				// dummy opcode
			} else if (opcode >= 0x90) {
				switch (opcode&0xF) {
					case 0: com90_caseNoteOff(); break;
					case 1: com90_stopChannel(); break;
					case 2: com90_setupInstrument(); break;
					case 3: 
						returnVal = com90_updateTempo();
						break;
					case 5: com90_getFreqOffset(); break;
					case 6: com90_getChannelVolume(); break;
					case 7: com90_getTremoVibro(); break;
					case 8: com90_rewindMusic(); break;
					case 9: com90_keyOff(); break;
					case 12: com90_setStartOfData(); break;
					case 4: //com90_dummy();
					case 10: //com90_error();
					case 11: //com90_doLodsb();
					case 13: //com90_do_two_Lodsb();
						error("SkyChannel: dummy music routine 0x%02X was called",opcode);
						_channelData.channelActive = 0;
						break;
					default:
						// these opcodes aren't implemented in original music driver
						error("SkyChannel: Not existant routine 0x%02X was called",opcode);
						_channelData.channelActive = 0;
						break;
				}
			} else {
				// new adlib channel assignment
				_channelData.adlibChannelNumber = opcode&0xF;
				_channelData.adlibReg1 = _registerTable[(opcode&0xF)<<1];
				_channelData.adlibReg2 = _registerTable[((opcode&0xF)<<1)|1];
			}
		} else {
			_channelData.lastCommand = opcode;
			stopNote();
			// not sure why this "if" is necessary...either a bug in my
			// code or a bug in the music data (section 1, music 2)
			if (_channelData.instrumentData || _channelData.tremoVibro) {
				setupInstrument(opcode);

				opcode = _musicData[_channelData.eventDataPtr];
				_channelData.eventDataPtr++;
				setupChannelVolume(opcode);
			} else _channelData.eventDataPtr++;
		}
		if (_channelData.channelActive)
			_channelData.nextEventTime += getNextEventTime();
	}
	return returnVal;
}

void SkyAdlibChannel::setupInstrument(uint8 opcode) {

	uint16 nextNote;
	if (_channelData.tremoVibro) {
		uint8 newInstrument = _instrumentMap[opcode];
		if (newInstrument != _channelData.assignedInstrument) {
			_channelData.assignedInstrument = newInstrument;
			_channelData.instrumentData = _instruments + newInstrument;
			adlibSetupInstrument();
		}
		_channelData.lastCommand = _channelData.instrumentData->bindedEffect;
		nextNote = getNextNote(_channelData.lastCommand);
	} else {
		nextNote = getNextNote(opcode - 0x18 + _channelData.instrumentData->bindedEffect);
	}
	_channelData.frequency = nextNote;
	setRegister(0xA0 | _channelData.adlibChannelNumber, (uint8)nextNote);
	setRegister(0xB0 | _channelData.adlibChannelNumber, (uint8)((nextNote >> 8) | 0x20));
	_channelData.note = (uint8)((nextNote >> 8) | 0x20);
}

void SkyAdlibChannel::setupChannelVolume(uint8 volume) {

	uint8 resultOp;
	uint32 resVol = ((volume + 1) * (_channelData.instrumentData->totOutLev_Op2 + 1)) << 1;
	resVol &= 0xFFFF;
	resVol *= (_channelData.channelVolume+1)<<1;
	resVol >>= 8;
	resVol *= _musicVolume;
	resVol >>= 16;
	resultOp = ((_channelData.instrumentData->scalingLevel << 6) & 0xC0) | _opOutputTable[resVol];
	setRegister(0x40 | _channelData.adlibReg2, resultOp);
	if (_channelData.instrumentData->feedBack & 1) {
		resVol = ((volume + 1) * (_channelData.instrumentData->totOutLev_Op1 + 1)) << 1;
		resVol &= 0xFFFF;
		resVol *= (_channelData.channelVolume + 1)<<1;
		resVol >>= 8;
		resVol *= (_musicVolume & 0xFF);
		resVol >>= 16;
	} else resVol = _channelData.instrumentData->totOutLev_Op1;
	resultOp = ((_channelData.instrumentData->scalingLevel << 2) & 0xC0) | _opOutputTable[resVol];
	setRegister(0x40 | _channelData.adlibReg1, resultOp);
}

void SkyAdlibChannel::adlibSetupInstrument(void) {

	setRegister(0x60 | _channelData.adlibReg1, _channelData.instrumentData->ad_Op1);
	setRegister(0x60 | _channelData.adlibReg2, _channelData.instrumentData->ad_Op2);
	setRegister(0x80 | _channelData.adlibReg1, _channelData.instrumentData->sr_Op1);
	setRegister(0x80 | _channelData.adlibReg2, _channelData.instrumentData->sr_Op2);
	setRegister(0xE0 | _channelData.adlibReg1, _channelData.instrumentData->waveSelect_Op1);
	setRegister(0xE0 | _channelData.adlibReg2, _channelData.instrumentData->waveSelect_Op2);
	setRegister(0xC0 | _channelData.adlibChannelNumber, _channelData.instrumentData->feedBack);
	setRegister(0x20 | _channelData.adlibReg1, _channelData.instrumentData->ampMod_Op1);
	setRegister(0x20 | _channelData.adlibReg2, _channelData.instrumentData->ampMod_Op2);
}

#ifdef SCUMM_BIG_ENDIAN
#define ENDIAN16(x) ((x >> 8) | ((x & 0xFF) << 8))
#else
#define ENDIAN16(x) (x)
#endif

uint16 SkyAdlibChannel::getNextNote(uint8 param) {

	int16 freqIndex = ((int16)_channelData.freqOffset) - 0x40;
	if (freqIndex >= 0x3F) freqIndex++;
	freqIndex *= _channelData.freqDataSize;
	freqIndex += param<<6;
	uint16 freqData = ENDIAN16(_frequenceTable[freqIndex % 0x300]);
	if ((freqIndex%0x300 >= 0x1C0) || (freqIndex/0x300 > 0)) {
		return (((freqIndex / 0x300) - 1) << 10) + (freqData & 0x7FF);
	} else {
		// looks like a bug. dunno why. It's what the ASM code says.
		return (uint16)(((int16)freqData) >> 1);
	}
}

//- command 90h routines

void SkyAdlibChannel::com90_caseNoteOff(void) {

	if (_musicData[_channelData.eventDataPtr] == _channelData.lastCommand)
		stopNote();
	_channelData.eventDataPtr++;
}

void SkyAdlibChannel::com90_stopChannel(void) {

	stopNote();
	_channelData.channelActive = 0;
}

void SkyAdlibChannel::com90_setupInstrument(void) {

	_channelData.channelVolume = 0x7F;
	_channelData.freqOffset = 0x40;
	_channelData.assignedInstrument = _musicData[_channelData.eventDataPtr];
	_channelData.eventDataPtr++;
	_channelData.instrumentData = _instruments + _channelData.assignedInstrument;
	adlibSetupInstrument();
}

uint8 SkyAdlibChannel::com90_updateTempo(void) {

	uint8 retV = _musicData[_channelData.eventDataPtr];
	_channelData.eventDataPtr++;
	return retV;
}

void SkyAdlibChannel::com90_getFreqOffset(void) {

	_channelData.freqOffset = _musicData[_channelData.eventDataPtr];
	_channelData.eventDataPtr++;
	if (_channelData.note & 0x20) {
		uint16 nextNote = getNextNote(
			_channelData.lastCommand - 0x18 + _channelData.instrumentData->bindedEffect);
		setRegister(0xA0 | _channelData.adlibChannelNumber, (uint8)nextNote);
		setRegister(0xB0 | _channelData.adlibChannelNumber, (uint8)((nextNote >> 8) | 0x20));
		_channelData.note = (uint8)(nextNote >> 8) | 0x20;
	}
}

void SkyAdlibChannel::com90_getChannelVolume(void) {

	_channelData.channelVolume = _musicData[_channelData.eventDataPtr];
	_channelData.eventDataPtr++;
}

void SkyAdlibChannel::com90_getTremoVibro(void) {

	_channelData.tremoVibro = _musicData[_channelData.eventDataPtr];
	_channelData.eventDataPtr++;
}

void SkyAdlibChannel::com90_rewindMusic(void) {

	_channelData.eventDataPtr = _channelData.startOfData;
}

void SkyAdlibChannel::com90_keyOff(void) {

	stopNote();
}

void SkyAdlibChannel::com90_setStartOfData(void) {

	_channelData.startOfData = _channelData.eventDataPtr;
}