/*
 * Adplug - Replayer for many OPL2/OPL3 audio file formats.
 * Copyright (C) 1999 - 2009 Simon Peter, <dn.tlp@gmx.net>, et al.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * cmf.cpp - CMF player by Adam Nielsen <malvineous@shikadi.net>
 *   Subset of CMF reader in MOPL code (Malvineous' OPL player), no seeking etc.
 */

#include <stdint.h> // for uintxx_t
#include <cassert>
#include <math.h> // for pow() etc.
#include <string.h> // for memset
#include "debug.h"
#include "cmf.h"

// ------------------------------
// OPTIONS
// ------------------------------

// The official Creative Labs CMF player seems to ignore the note velocity
// (playing every note at the same volume), but you can uncomment this to
// allow the note velocity to affect the volume (as presumably the composer
// originally intended.)
//
//#define USE_VELOCITY
//
// The Xargon demo song is a good example of a song that uses note velocity.

// OPL register offsets
#define BASE_CHAR_MULT  0x20
#define BASE_SCAL_LEVL  0x40
#define BASE_ATCK_DCAY  0x60
#define BASE_SUST_RLSE  0x80
#define BASE_FNUM_L     0xA0
#define BASE_KEYON_FREQ 0xB0
#define BASE_RHYTHM     0xBD
#define BASE_WAVE       0xE0
#define BASE_FEED_CONN  0xC0

#define OPLBIT_KEYON    0x20 // Bit in BASE_KEYON_FREQ register for turning a note on

// Supplied with a channel, return the offset from a base OPL register for the
// Modulator cell (e.g. channel 4's modulator is at offset 0x09.  Since 0x60 is
// the attack/decay function, register 0x69 will thus set the attack/decay for
// channel 4's modulator.)  (channels go from 0 to 8 inclusive)
#define OPLOFFSET(channel)   (((channel) / 3) * 8 + ((channel) % 3))

// These 16 instruments are repeated to fill up the 128 available slots.  A CMF
// file can override none/some/all of the 128 slots with custom instruments,
// so any that aren't overridden are still available for use with these default
// patches.  The Word Rescue CMFs are good examples of songs that rely on these
// default patches.
uint8_t cDefaultPatches[] =
"\x01\x11\x4F\x00\xF1\xD2\x53\x74\x00\x00\x06"
"\x07\x12\x4F\x00\xF2\xF2\x60\x72\x00\x00\x08"
"\x31\xA1\x1C\x80\x51\x54\x03\x67\x00\x00\x0E"
"\x31\xA1\x1C\x80\x41\x92\x0B\x3B\x00\x00\x0E"
"\x31\x16\x87\x80\xA1\x7D\x11\x43\x00\x00\x08"
"\x30\xB1\xC8\x80\xD5\x61\x19\x1B\x00\x00\x0C"
"\xF1\x21\x01\x00\x97\xF1\x17\x18\x00\x00\x08"
"\x32\x16\x87\x80\xA1\x7D\x10\x33\x00\x00\x08"
"\x01\x12\x4F\x00\x71\x52\x53\x7C\x00\x00\x0A"
"\x02\x03\x8D\x00\xD7\xF5\x37\x18\x00\x00\x04"
"\x21\x21\xD1\x00\xA3\xA4\x46\x25\x00\x00\x0A"
"\x22\x22\x0F\x00\xF6\xF6\x95\x36\x00\x00\x0A"
"\xE1\xE1\x00\x00\x44\x54\x24\x34\x02\x02\x07"
"\xA5\xB1\xD2\x80\x81\xF1\x03\x05\x00\x00\x02"
"\x71\x22\xC5\x00\x6E\x8B\x17\x0E\x00\x00\x02"
"\x32\x21\x16\x80\x73\x75\x24\x57\x00\x00\x0E";


CPlayer *CcmfPlayer::factory(Copl *newopl)
{
  return new CcmfPlayer(newopl);
}

CcmfPlayer::CcmfPlayer(Copl *newopl) :
	CPlayer(newopl),
	data(NULL),
	pInstruments(NULL),
	bPercussive(false),
	iPrevCommand(0)
{
	assert(OPLOFFSET(1-1) == 0x00);
	assert(OPLOFFSET(5-1) == 0x09);
	assert(OPLOFFSET(9-1) == 0x12);
}

CcmfPlayer::~CcmfPlayer()
{
	if (this->data) delete[] data;
	if (this->pInstruments) delete[] pInstruments;
}

bool CcmfPlayer::load(const std::string &filename, const CFileProvider &fp)
{
  binistream *f = fp.open(filename); if(!f) return false;

	char cSig[4];
	f->readString(cSig, 4);
	if (
		(cSig[0] != 'C') ||
		(cSig[1] != 'T') ||
		(cSig[2] != 'M') ||
		(cSig[3] != 'F')
	) {
		// Not a CMF file
		fp.close(f);
		return false;
	}
	uint16_t iVer = f->readInt(2);
	if ((iVer != 0x0101) && (iVer != 0x0100)) {
		AdPlug_LogWrite("CMF file is not v1.0 or v1.1 (reports %d.%d)\n", iVer >> 8 , iVer & 0xFF);
		fp.close(f);
		return false;
	}

	this->cmfHeader.iInstrumentBlockOffset = f->readInt(2);
	this->cmfHeader.iMusicOffset = f->readInt(2);
	this->cmfHeader.iTicksPerQuarterNote = f->readInt(2);
	this->cmfHeader.iTicksPerSecond = f->readInt(2);
	this->cmfHeader.iTagOffsetTitle = f->readInt(2);
	this->cmfHeader.iTagOffsetComposer = f->readInt(2);
	this->cmfHeader.iTagOffsetRemarks = f->readInt(2);

	// This checks will fix crash for a lot of broken files
	// Title, Composer and Remarks blocks usually located before Instrument block
	// But if not this will indicate invalid offset value (sometimes even bigger than filesize)
	if (this->cmfHeader.iTagOffsetTitle >= this->cmfHeader.iInstrumentBlockOffset)
		this->cmfHeader.iTagOffsetTitle = 0;
	if (this->cmfHeader.iTagOffsetComposer >= this->cmfHeader.iInstrumentBlockOffset)
		this->cmfHeader.iTagOffsetComposer = 0;
	if (this->cmfHeader.iTagOffsetRemarks >= this->cmfHeader.iInstrumentBlockOffset)
		this->cmfHeader.iTagOffsetRemarks = 0;

	f->readString((char *)this->cmfHeader.iChannelsInUse, 16);
	if (iVer == 0x0100) {
		this->cmfHeader.iNumInstruments = f->readInt(1);
		this->cmfHeader.iTempo = 0;
	} else { // 0x0101
		this->cmfHeader.iNumInstruments = f->readInt(2);
		this->cmfHeader.iTempo = f->readInt(2);
	}

	// Load the instruments

	f->seek(this->cmfHeader.iInstrumentBlockOffset);
	this->pInstruments = new SBI[
		(this->cmfHeader.iNumInstruments < 128) ? 128 : this->cmfHeader.iNumInstruments
	];  // Always at least 128 available for use

	for (int i = 0; i < this->cmfHeader.iNumInstruments; i++) {
		this->pInstruments[i].op[0].iCharMult = f->readInt(1);
		this->pInstruments[i].op[1].iCharMult = f->readInt(1);
		this->pInstruments[i].op[0].iScalingOutput = f->readInt(1);
		this->pInstruments[i].op[1].iScalingOutput = f->readInt(1);
		this->pInstruments[i].op[0].iAttackDecay = f->readInt(1);
		this->pInstruments[i].op[1].iAttackDecay = f->readInt(1);
		this->pInstruments[i].op[0].iSustainRelease = f->readInt(1);
		this->pInstruments[i].op[1].iSustainRelease = f->readInt(1);
		this->pInstruments[i].op[0].iWaveSel = f->readInt(1);
		this->pInstruments[i].op[1].iWaveSel = f->readInt(1);
		this->pInstruments[i].iConnection = f->readInt(1);
		f->seek(5, binio::Add);  // skip over the padding bytes
	}

	// Set the rest of the instruments to the CMF defaults
	for (int i = this->cmfHeader.iNumInstruments; i < 128; i++) {
		this->pInstruments[i].op[0].iCharMult =       cDefaultPatches[(i % 16) * 11 + 0];
		this->pInstruments[i].op[1].iCharMult =       cDefaultPatches[(i % 16) * 11 + 1];
		this->pInstruments[i].op[0].iScalingOutput =  cDefaultPatches[(i % 16) * 11 + 2];
		this->pInstruments[i].op[1].iScalingOutput =  cDefaultPatches[(i % 16) * 11 + 3];
		this->pInstruments[i].op[0].iAttackDecay =    cDefaultPatches[(i % 16) * 11 + 4];
		this->pInstruments[i].op[1].iAttackDecay =    cDefaultPatches[(i % 16) * 11 + 5];
		this->pInstruments[i].op[0].iSustainRelease = cDefaultPatches[(i % 16) * 11 + 6];
		this->pInstruments[i].op[1].iSustainRelease = cDefaultPatches[(i % 16) * 11 + 7];
		this->pInstruments[i].op[0].iWaveSel =        cDefaultPatches[(i % 16) * 11 + 8];
		this->pInstruments[i].op[1].iWaveSel =        cDefaultPatches[(i % 16) * 11 + 9];
		this->pInstruments[i].iConnection =           cDefaultPatches[(i % 16) * 11 + 10];
	}

	if (this->cmfHeader.iTagOffsetTitle) {
		f->seek(this->cmfHeader.iTagOffsetTitle);
		this->strTitle = f->readString('\0');
	}
	if (this->cmfHeader.iTagOffsetComposer) {
		f->seek(this->cmfHeader.iTagOffsetComposer);
		this->strComposer = f->readString('\0');
	}
	if (this->cmfHeader.iTagOffsetRemarks) {
		f->seek(this->cmfHeader.iTagOffsetRemarks);
		this->strRemarks = f->readString('\0');
	}

	// Load the MIDI data into memory
  f->seek(this->cmfHeader.iMusicOffset);
  this->iSongLen = fp.filesize(f) - this->cmfHeader.iMusicOffset;
  this->data = new unsigned char[this->iSongLen];
  f->readString((char *)data, this->iSongLen);

  fp.close(f);
	rewind(0);

  return true;
}

bool CcmfPlayer::update()
{
	// This has to be here and not in getrefresh() for some reason.
	this->iDelayRemaining = 0;

	// Read in the next event
	while (!this->iDelayRemaining) {
		uint8_t iCommand = this->data[this->iPlayPointer++];
		if ((iCommand & 0x80) == 0) {
			// Running status, use previous command
			this->iPlayPointer--;
			iCommand = this->iPrevCommand;
		} else {
			this->iPrevCommand = iCommand;
		}
		uint8_t iChannel = iCommand & 0x0F;
		switch (iCommand & 0xF0) {
			case 0x80: { // Note off (two data bytes)
				uint8_t iNote = this->data[this->iPlayPointer++];
				uint8_t iVelocity = this->data[this->iPlayPointer++]; // release velocity
				this->cmfNoteOff(iChannel, iNote, iVelocity);
				break;
			}
			case 0x90: { // Note on (two data bytes)
				uint8_t iNote = this->data[this->iPlayPointer++];
				uint8_t iVelocity = this->data[this->iPlayPointer++]; // attack velocity
				if (iVelocity) {
					if (iNotePlaying[iChannel] == iNote)
					{	// Note duplicated, turn it off
						iVelocity = 0;
						// Fix this on next Note Off event
						bNoteFix[iChannel] = true;
					}
				}
				else {
					if (bNoteFix[iChannel])
					{	// Turn on this note again
						iVelocity = 127;
						// Fix not needed anymore
						bNoteFix[iChannel] = false;
					}
				}
				// Store last played note
				iNotePlaying[iChannel] = (iVelocity ? iNote : 255);
				if (iVelocity) {
					this->cmfNoteOn(iChannel, iNote, iVelocity);
				} else {
					// This is a note-off instead (velocity == 0)
					this->cmfNoteOff(iChannel, iNote, iVelocity); // 64 is the MIDI default note-off velocity
					break;
				}
				break;
			}
			case 0xA0: { // Polyphonic key pressure (two data bytes)
				uint8_t iNote = this->data[this->iPlayPointer++];
				uint8_t iPressure = this->data[this->iPlayPointer++];
				AdPlug_LogWrite("CMF: Key pressure not yet implemented! (wanted ch%d/note %d set to %d)\n", iChannel, iNote, iPressure);
				break;
			}
			case 0xB0: { // Controller (two data bytes)
				uint8_t iController = this->data[this->iPlayPointer++];
				uint8_t iValue = this->data[this->iPlayPointer++];
				this->MIDIcontroller(iChannel, iController, iValue);
				break;
			}
			case 0xC0: { // Instrument change (one data byte)
				uint8_t iNewInstrument = this->data[this->iPlayPointer++];
				this->chMIDI[iChannel].iPatch = iNewInstrument;
				AdPlug_LogWrite("CMF: Remembering MIDI channel %d now uses patch %d\n", iChannel, iNewInstrument);
				break;
			}
			case 0xD0: { // Channel pressure (one data byte)
				uint8_t iPressure = this->data[this->iPlayPointer++];
				AdPlug_LogWrite("CMF: Channel pressure not yet implemented! (wanted ch%d set to %d)\n", iChannel, iPressure);
				break;
			}
			case 0xE0: { // Pitch bend (two data bytes)
				uint8_t iLSB = this->data[this->iPlayPointer++];
				uint8_t iMSB = this->data[this->iPlayPointer++];
				uint16_t iValue = (iMSB << 7) | iLSB;
				// 8192 is middle/off, 0 is -2 semitones, 16384 is +2 semitones
				this->chMIDI[iChannel].iPitchbend = iValue;
				this->cmfNoteUpdate(iChannel);
				AdPlug_LogWrite("CMF: Channel %d pitchbent to %d (%+.2f)\n", iChannel + 1, iValue, (float)(iValue - 8192) / 8192);
				break;
			}
			case 0xF0: // System message (arbitrary data bytes)
				switch (iCommand) {
					case 0xF0: { // Sysex
						uint8_t iNextByte;
						AdPlug_LogWrite("Sysex message: ");
						do {
							iNextByte = this->data[this->iPlayPointer++];
							AdPlug_LogWrite("%02X", iNextByte);
						} while ((iNextByte & 0x80) == 0);
						AdPlug_LogWrite("\n");
						// This will have read in the terminating EOX (0xF7) message too
						break;
					}
					case 0xF1: // MIDI Time Code Quarter Frame
						this->data[this->iPlayPointer++]; // message data (ignored)
						break;
					case 0xF2: // Song position pointer
						this->data[this->iPlayPointer++]; // message data (ignored)
						this->data[this->iPlayPointer++];
						break;
					case 0xF3: // Song select
						this->data[this->iPlayPointer++]; // message data (ignored)
						AdPlug_LogWrite("CMF: MIDI Song Select is not implemented.\n");
						break;
					case 0xF6: // Tune request
						break;
					case 0xF7: // End of System Exclusive (EOX) - should never be read, should be absorbed by Sysex handling code
						break;

					// These messages are "real time", meaning they can be sent between
					// the bytes of other messages - but we're lazy and don't handle these
					// here (hopefully they're not necessary in a MIDI file, and even less
					// likely to occur in a CMF.)
					case 0xF8: // Timing clock (sent 24 times per quarter note, only when playing)
					case 0xFA: // Start
					case 0xFB: // Continue
					case 0xFE: // Active sensing (sent every 300ms or MIDI connection assumed lost)
						break;
					case 0xFC: // Stop
						AdPlug_LogWrite("CMF: Received Real Time Stop message (0xFC)\n");
						this->bSongEnd = true;
						this->iPlayPointer = 0; // for repeat in endless-play mode
						break;
					case 0xFF: { // System reset, used as meta-events in a MIDI file
						uint8_t iEvent = this->data[this->iPlayPointer++];
						switch (iEvent) {
							case 0x2F: // end of track
								AdPlug_LogWrite("CMF: End-of-track, stopping playback\n");
								this->bSongEnd = true;
								this->iPlayPointer = 0; // for repeat in endless-play mode
								break;
							default:
								AdPlug_LogWrite("CMF: Unknown MIDI meta-event 0xFF 0x%02X\n", iEvent);
								break;
						}
						break;
					}
					default:
						AdPlug_LogWrite("CMF: Unknown MIDI system command 0x%02X\n", iCommand);
						break;
				}
				break;
			default:
				AdPlug_LogWrite("CMF: Unknown MIDI command 0x%02X\n", iCommand);
				break;
		}

		if (this->iPlayPointer >= this->iSongLen) {
			this->bSongEnd = true;
			this->iPlayPointer = 0; // for repeat in endless-play mode
		}

		// Read in the number of ticks until the next event
		this->iDelayRemaining = this->readMIDINumber();
	}

	return !this->bSongEnd;
}

void CcmfPlayer::rewind(int subsong)
{
  this->opl->init();

	// Initialise

  // Enable use of WaveSel register on OPL3 (even though we're only an OPL2!)
  // Apparently this enables nine-channel mode?
	this->writeOPL(0x01, 0x20);

	// Disable OPL3 mode (can be left enabled by a previous non-CMF song)
	this->writeOPL(0x05, 0x00);

	// Really make sure CSM+SEL are off (again, Creative's player...)
	this->writeOPL(0x08, 0x00);

	// This freq setting is required for the hihat to sound correct at the start
	// of funky.cmf, even though it's for an unrelated channel.
	// If it's here however, it makes the hihat in Word Rescue's theme.cmf
	// sound really bad.
	// TODO: How do we figure out whether we need it or not???
	this->writeOPL(BASE_FNUM_L + 8, 514 & 0xFF);
	this->writeOPL(BASE_KEYON_FREQ + 8, (1 << 2) | (514 >> 8));

	// default freqs?
	this->writeOPL(BASE_FNUM_L + 7, 509 & 0xFF);
	this->writeOPL(BASE_KEYON_FREQ + 7, (2 << 2) | (509 >> 8));
	this->writeOPL(BASE_FNUM_L + 6, 432 & 0xFF);
	this->writeOPL(BASE_KEYON_FREQ + 6, (2 << 2) | (432 >> 8));

	// Amplify AM + VIB depth.  Creative's CMF player does this, and there
	// doesn't seem to be any way to stop it from doing so - except for the
	// non-standard controller 0x63 I added :-)
	this->writeOPL(0xBD, 0xC0);

	this->bSongEnd = false;
	this->iPlayPointer = 0;
	this->iPrevCommand = 0; // just in case
	this->iNoteCount = 0;

	// Read in the number of ticks until the first event
	this->iDelayRemaining = this->readMIDINumber();

  // Reset song state.  This used to be in the constructor, but the XMMS2
  // plugin sets the song length before starting playback.  AdPlug plays the
  // song in its entirety (with no synth) to determine the song length, which
  // results in the state variables below matching the end of the song.  When
  // the real OPL synth is activated for playback, it no longer matches the
  // state variables and the instruments are not set correctly!
	for (int i = 0; i < 9; i++) {
		this->chOPL[i].iNoteStart = 0; // no note playing atm
		this->chOPL[i].iMIDINote = -1;
		this->chOPL[i].iMIDIChannel = -1;
		this->chOPL[i].iMIDIPatch = -1;

		this->chMIDI[i].iPatch = -2;
		this->chMIDI[i].iPitchbend = 8192;
		this->chMIDI[i].iTranspose = 0;
	}
	for (int i = 9; i < 16; i++) {
		this->chMIDI[i].iPatch = -2;
		this->chMIDI[i].iPitchbend = 8192;
		this->chMIDI[i].iTranspose = 0;
	}

	memset(this->iCurrentRegs, 0, 256);
	memset(this->iNotePlaying, 255, sizeof(iNotePlaying));
	memset(this->bNoteFix, false, sizeof(bNoteFix));

	return;
}

// Return value: 1 == 1 second, 2 == 0.5 seconds
float CcmfPlayer::getrefresh()
{
	if (this->iDelayRemaining) {
		return (float)this->cmfHeader.iTicksPerSecond / (float)this->iDelayRemaining;
	} else {
		// Delay-remaining is zero (e.g. start of song) so use a tiny delay
		return this->cmfHeader.iTicksPerSecond; // wait for one tick
	}
}

std::string CcmfPlayer::gettitle()
{
	return this->strTitle;
}
std::string CcmfPlayer::getauthor()
{
	return this->strComposer;
}
std::string CcmfPlayer::getdesc()
{
	return this->strRemarks;
}


//
// PROTECTED
//

// Read a variable-length integer from MIDI data
uint32_t CcmfPlayer::readMIDINumber()
{
	uint32_t iValue = 0;
	for (int i = 0; i < 4; i++) {
		uint8_t iNext = this->data[this->iPlayPointer++];
		iValue <<= 7;
		iValue |= (iNext & 0x7F); // ignore the MSB
		if ((iNext & 0x80) == 0) break; // last byte has the MSB unset
	}
	return iValue;
}

// iChannel: OPL channel (0-8)
// iOperator: 0 == Modulator, 1 == Carrier
//   Source - source operator to read from instrument definition
//   Dest - destination operator on OPL chip
// iInstrument: Index into this->pInstruments array of CMF instruments
void CcmfPlayer::writeInstrumentSettings(uint8_t iChannel, uint8_t iOperatorSource, uint8_t iOperatorDest, uint8_t iInstrument)
{
	assert(iChannel <= 8);

	uint8_t iOPLOffset = OPLOFFSET(iChannel);
	if (iOperatorDest) iOPLOffset += 3; // Carrier if iOperator == 1 (else Modulator)

	this->writeOPL(BASE_CHAR_MULT + iOPLOffset, this->pInstruments[iInstrument].op[iOperatorSource].iCharMult);
	this->writeOPL(BASE_SCAL_LEVL + iOPLOffset, this->pInstruments[iInstrument].op[iOperatorSource].iScalingOutput);
	this->writeOPL(BASE_ATCK_DCAY + iOPLOffset, this->pInstruments[iInstrument].op[iOperatorSource].iAttackDecay);
	this->writeOPL(BASE_SUST_RLSE + iOPLOffset, this->pInstruments[iInstrument].op[iOperatorSource].iSustainRelease);
	this->writeOPL(BASE_WAVE      + iOPLOffset, this->pInstruments[iInstrument].op[iOperatorSource].iWaveSel);

	// TODO: Check to see whether we should only be loading this for one or both operators
	this->writeOPL(BASE_FEED_CONN + iChannel, this->pInstruments[iInstrument].iConnection);
	return;
}

// Write a byte to the OPL "chip" and update the current record of register states
void CcmfPlayer::writeOPL(uint8_t iRegister, uint8_t iValue)
{
	this->opl->write(iRegister, iValue);
	this->iCurrentRegs[iRegister] = iValue;
	return;
}

void CcmfPlayer::getFreq(uint8_t iChannel, uint8_t iNote, uint8_t * iBlock, uint16_t * iOPLFNum)
{
	*iBlock = iNote / 12;
	if (*iBlock > 1) (*iBlock)--; // keep in the same range as the Creative player
	//if (*iBlock > 7) *iBlock = 7; // don't want to go out of range

	double d = pow(2, (
		(double)iNote + (
			(this->chMIDI[iChannel].iPitchbend - 8192) / 8192.0
		) + (
			this->chMIDI[iChannel].iTranspose / 256.0
		) - 9) / 12.0 - (*iBlock - 20))
		* 440.0 / 32.0 / 50000.0;
	*iOPLFNum = (uint16_t)(d+0.5);
}

void CcmfPlayer::cmfNoteOn(uint8_t iChannel, uint8_t iNote, uint8_t iVelocity)
{
	uint8_t iBlock = 0;
	uint16_t iOPLFNum = 0;
	getFreq(iChannel, iNote, &iBlock, &iOPLFNum);
	if (iOPLFNum > 1023) AdPlug_LogWrite("CMF: This note is out of range! (send this song to malvineous@shikadi.net!)\n");

	// See if we're playing a rhythm mode percussive instrument
	if ((iChannel > 10) && (this->bPercussive)) {
		uint8_t iPercChannel = this->getPercChannel(iChannel);

		// Will have to set every time (easier) than figuring out whether the mod
		// or car needs to be changed.
		//if (this->chOPL[iPercChannel].iMIDIPatch != this->chMIDI[iChannel].iPatch) {
			this->MIDIchangeInstrument(iPercChannel, iChannel, this->chMIDI[iChannel].iPatch);
		//}

		/*  Velocity calculations - TODO: Work out the proper formula

		iVelocity -> iLevel  (values generated by Creative's player)
		7f -> 00
		7c -> 00

		7b -> 09
		73 -> 0a
		6b -> 0b
		63 -> 0c
		5b -> 0d
		53 -> 0e
		4b -> 0f
		43 -> 10
		3b -> 11
		33 -> 13
		2b -> 15
		23 -> 19
		1b -> 1b
		13 -> 1d
		0b -> 1f
		03 -> 21

		02 -> 21
		00 -> N/A (note off)
		*/
		// Approximate formula, need to figure out more accurate one (my maths isn't so good...)
		int iLevel = 0x25 - sqrt(iVelocity * 16/*6*/);//(127 - iVelocity) * 0x20 / 127;
		if (iVelocity > 0x7b) iLevel = 0; // full volume
		if (iLevel < 0) iLevel = 0;
		if (iLevel > 0x3F) iLevel = 0x3F;
		//if (iVelocity < 0x40) iLevel = 0x10;

		int iOPLOffset = BASE_SCAL_LEVL + OPLOFFSET(iPercChannel);
		//if ((iChannel == 11) || (iChannel == 12) || (iChannel == 14)) {
		if (iChannel == 11) iOPLOffset += 3; // only do bassdrum carrier for volume control
		//iOPLOffset += 3; // carrier
		this->writeOPL(iOPLOffset, (this->iCurrentRegs[iOPLOffset] & ~0x3F) | iLevel);//(iVelocity * 0x3F / 127));
		//}
		// Bass drum (ch11) uses both operators
		//if (iChannel == 11) this->writeOPL(iOPLOffset + 3, (this->iCurrentRegs[iOPLOffset + 3] & ~0x3F) | iLevel);

/*		#ifdef USE_VELOCITY  // Official CMF player seems to ignore velocity levels
			uint16_t iLevel = 0x2F - (iVelocity * 0x2F / 127); // 0x2F should be 0x3F but it's too quiet then
			AdPlug_LogWrite("%02X + vel %d (lev %02X) == %02X\n", this->iCurrentRegs[iOPLOffset], iVelocity, iLevel, (this->iCurrentRegs[iOPLOffset] & ~0x3F) | iLevel);
			//this->writeOPL(iOPLOffset, (this->iCurrentRegs[iOPLOffset] & ~0x3F) | (0x3F - (iVelocity >> 1)));//(iVelocity * 0x3F / 127));
			this->writeOPL(iOPLOffset, (this->iCurrentRegs[iOPLOffset] & ~0x3F) | iLevel);//(iVelocity * 0x3F / 127));
		#endif*/

		// Apparently you can't set the frequency for the cymbal or hihat?
		// Vinyl requires you don't set it, Kiloblaster requires you do!
		this->writeOPL(BASE_FNUM_L + iPercChannel, iOPLFNum & 0xFF);
		this->writeOPL(BASE_KEYON_FREQ + iPercChannel, (iBlock << 2) | ((iOPLFNum >> 8) & 0x03));

		uint8_t iBit = 1 << (15 - iChannel);

		// Turn the perc instrument off if it's already playing (OPL can't do
		// polyphonic notes w/ percussion)
		if (this->iCurrentRegs[BASE_RHYTHM] & iBit) this->writeOPL(BASE_RHYTHM, this->iCurrentRegs[BASE_RHYTHM] & ~iBit);

		// I wonder whether we need to delay or anything here?

		// Turn the note on
		//if (iChannel == 15) {
		this->writeOPL(BASE_RHYTHM, this->iCurrentRegs[BASE_RHYTHM] | iBit);
		//AdPlug_LogWrite("CMF: Note %d on MIDI channel %d (mapped to OPL channel %d-1) - vel %02X, fnum %d/%d\n", iNote, iChannel, iPercChannel+1, iVelocity, iOPLFNum, iBlock);
		//}

		this->chOPL[iPercChannel].iNoteStart = ++this->iNoteCount;
		this->chOPL[iPercChannel].iMIDIChannel = iChannel;
		this->chOPL[iPercChannel].iMIDINote = iNote;

	} else { // Non rhythm-mode or a normal instrument channel

		// Figure out which OPL channel to play this note on
		int iOPLChannel = -1;
		int iNumChannels = this->bPercussive ? 6 : 9;
		for (int i = iNumChannels - 1; i >= 0; i--) {
			// If there's no note playing on this OPL channel, use that
			if (this->chOPL[i].iNoteStart == 0) {
				iOPLChannel = i;
				// See if this channel is already set to the instrument we want.
				if (this->chOPL[i].iMIDIPatch == this->chMIDI[iChannel].iPatch) {
					// It is, so stop searching
					break;
				} // else keep searching just in case there's a better match
			}
		}
		if (iOPLChannel == -1) {
			// All channels were in use, find the one with the longest note
			iOPLChannel = 0;
			int iEarliest = this->chOPL[0].iNoteStart;
			for (int i = 1; i < iNumChannels; i++) {
				if (this->chOPL[i].iNoteStart < iEarliest) {
					// Found a channel with a note being played for longer
					iOPLChannel = i;
					iEarliest = this->chOPL[i].iNoteStart;
				}
			}
			AdPlug_LogWrite("CMF: Too many polyphonic notes, cutting note on channel %d\n", iOPLChannel);
		}

		// Run through all the channels with negative notestart values - these
		// channels have had notes recently stop - and increment the counter
		// to slowly move the channel closer to being reused for a future note.
		//for (int i = 0; i < iNumChannels; i++) {
		//	if (this->chOPL[i].iNoteStart < 0) this->chOPL[i].iNoteStart++;
		//}

		// Now the new note should be played on iOPLChannel, but see if the instrument
		// is right first.
		if (this->chOPL[iOPLChannel].iMIDIPatch != this->chMIDI[iChannel].iPatch) {
			this->MIDIchangeInstrument(iOPLChannel, iChannel, this->chMIDI[iChannel].iPatch);
		}

		this->chOPL[iOPLChannel].iNoteStart = ++this->iNoteCount;
		this->chOPL[iOPLChannel].iMIDIChannel = iChannel;
		this->chOPL[iOPLChannel].iMIDINote = iNote;

		#ifdef USE_VELOCITY  // Official CMF player seems to ignore velocity levels
			// Adjust the channel volume to match the note velocity
			uint8_t iOPLOffset = BASE_SCAL_LEVL + OPLOFFSET(iChannel) + 3; // +3 == Carrier
			uint16_t iLevel = 0x2F - (iVelocity * 0x2F / 127); // 0x2F should be 0x3F but it's too quiet then
			this->writeOPL(iOPLOffset, (this->iCurrentRegs[iOPLOffset] & ~0x3F) | iLevel);
		#endif

		// Set the frequency and play the note
		this->writeOPL(BASE_FNUM_L + iOPLChannel, iOPLFNum & 0xFF);
		this->writeOPL(BASE_KEYON_FREQ + iOPLChannel, OPLBIT_KEYON | (iBlock << 2) | ((iOPLFNum & 0x300) >> 8));
	}
	return;
}

void CcmfPlayer::cmfNoteOff(uint8_t iChannel, uint8_t iNote, uint8_t iVelocity)
{
	if ((iChannel > 10) && (this->bPercussive)) {
		int iOPLChannel = this->getPercChannel(iChannel);
		if (this->chOPL[iOPLChannel].iMIDINote != iNote) return; // there's a different note playing now
		this->writeOPL(BASE_RHYTHM, this->iCurrentRegs[BASE_RHYTHM] & ~(1 << (15 - iChannel)));
		this->chOPL[iOPLChannel].iNoteStart = 0; // channel free
	} else { // Non rhythm-mode or a normal instrument channel
		int iOPLChannel = -1;
		int iNumChannels = this->bPercussive ? 6 : 9;
		for (int i = 0; i < iNumChannels; i++) {
			if (
				(this->chOPL[i].iMIDIChannel == iChannel) &&
				(this->chOPL[i].iMIDINote == iNote) &&
				(this->chOPL[i].iNoteStart != 0)
			) {
				// Found the note, switch it off
				this->chOPL[i].iNoteStart = 0;
				iOPLChannel = i;
				break;
			}
		}
		if (iOPLChannel == -1) return;

		this->writeOPL(BASE_KEYON_FREQ + iOPLChannel, this->iCurrentRegs[BASE_KEYON_FREQ + iOPLChannel] & ~OPLBIT_KEYON);
	}
	return;
}

void CcmfPlayer::cmfNoteUpdate(uint8_t iChannel)
{
	uint8_t iBlock = 0;
	uint16_t iOPLFNum = 0;

	// See if we're playing a rhythm mode percussive instrument
	if ((iChannel > 10) && (this->bPercussive)) {
		uint8_t iPercChannel = this->getPercChannel(iChannel);
		getFreq(iChannel, this->chOPL[iPercChannel].iMIDINote, &iBlock, &iOPLFNum);

		// Update note frequency
		this->writeOPL(BASE_FNUM_L + iPercChannel, iOPLFNum & 0xFF);
		this->writeOPL(BASE_KEYON_FREQ + iPercChannel, (iBlock << 2) | ((iOPLFNum >> 8) & 0x03));

	} else { // Non rhythm-mode or a normal instrument channel

		// Figure out which OPL channels should be updated
		int iNumChannels = this->bPercussive ? 6 : 9;
		for (int i = 0; i < iNumChannels; i++) {
			// Needed channel and note is playing
			if (this->chOPL[i].iMIDIChannel == iChannel && this->chOPL[i].iNoteStart > 0) {
				// Update note frequency
				getFreq(iChannel, this->chOPL[i].iMIDINote, &iBlock, &iOPLFNum);
				this->writeOPL(BASE_FNUM_L + i, iOPLFNum & 0xFF);
				this->writeOPL(BASE_KEYON_FREQ + i, OPLBIT_KEYON | (iBlock << 2) | ((iOPLFNum & 0x300) >> 8));
			}
		}
	}
	return;
}

uint8_t CcmfPlayer::getPercChannel(uint8_t iChannel)
{
	switch (iChannel) {
		case 11: return 7-1; // Bass drum
		case 12: return 8-1; // Snare drum
		case 13: return 9-1; // Tom tom
		case 14: return 9-1; // Top cymbal
		case 15: return 8-1; // Hihat
	}
	AdPlug_LogWrite("CMF ERR: Tried to get the percussion channel from MIDI channel %d - this shouldn't happen!\n", iChannel);
	return 0;
}


void CcmfPlayer::MIDIchangeInstrument(uint8_t iOPLChannel, uint8_t iMIDIChannel, uint8_t iNewInstrument)
{
	if ((iMIDIChannel > 10) && (this->bPercussive)) {
		switch (iMIDIChannel) {
			case 11: // Bass drum (operator 13+16 == channel 7 modulator+carrier)
				this->writeInstrumentSettings(7-1, 0, 0, iNewInstrument);
				this->writeInstrumentSettings(7-1, 1, 1, iNewInstrument);
				break;
			case 12: // Snare drum (operator 17 == channel 8 carrier)
			//case 15:
				this->writeInstrumentSettings(8-1, 0, 1, iNewInstrument);

				//
				//this->writeInstrumentSettings(8-1, 0, 0, iNewInstrument);
				break;
			case 13: // Tom tom (operator 15 == channel 9 modulator)
			//case 14:
				this->writeInstrumentSettings(9-1, 0, 0, iNewInstrument);

				//
				//this->writeInstrumentSettings(9-1, 0, 1, iNewInstrument);
				break;
			case 14: // Top cymbal (operator 18 == channel 9 carrier)
				this->writeInstrumentSettings(9-1, 0, 1, iNewInstrument);
				break;
			case 15: // Hi-hat (operator 14 == channel 8 modulator)
				this->writeInstrumentSettings(8-1, 0, 0, iNewInstrument);
				break;
			default:
				AdPlug_LogWrite("CMF: Invalid MIDI channel %d (not melodic and not percussive!)\n", iMIDIChannel + 1);
				break;
		}
		this->chOPL[iOPLChannel].iMIDIPatch = iNewInstrument;
	} else {
		// Standard nine OPL channels
		this->writeInstrumentSettings(iOPLChannel, 0, 0, iNewInstrument);
		this->writeInstrumentSettings(iOPLChannel, 1, 1, iNewInstrument);
		this->chOPL[iOPLChannel].iMIDIPatch = iNewInstrument;
	}
	return;
}

void CcmfPlayer::MIDIcontroller(uint8_t iChannel, uint8_t iController, uint8_t iValue)
{
	switch (iController) {
		case 0x63:
			// Custom extension to allow CMF files to switch the AM+VIB depth on and
			// off (officially both are on, and there's no way to switch them off.)
			// Controller values:
			//   0 == AM+VIB off
			//   1 == VIB on
			//   2 == AM on
			//   3 == AM+VIB on
			if (iValue) {
				this->writeOPL(BASE_RHYTHM, (this->iCurrentRegs[BASE_RHYTHM] & ~0xC0) | (iValue << 6)); // switch AM+VIB extension on
			} else {
				this->writeOPL(BASE_RHYTHM, this->iCurrentRegs[BASE_RHYTHM] & ~0xC0); // switch AM+VIB extension off
			}
			AdPlug_LogWrite("CMF: AM+VIB depth change - AM %s, VIB %s\n",
				(this->iCurrentRegs[BASE_RHYTHM] & 0x80) ? "on" : "off",
				(this->iCurrentRegs[BASE_RHYTHM] & 0x40) ? "on" : "off");
			break;
		case 0x66:
			AdPlug_LogWrite("CMF: Song set marker to 0x%02X\n", iValue);
			break;
		case 0x67:
			this->bPercussive = (iValue != 0);
			if (this->bPercussive) {
				this->writeOPL(BASE_RHYTHM, this->iCurrentRegs[BASE_RHYTHM] | 0x20); // switch rhythm-mode on
			} else {
				this->writeOPL(BASE_RHYTHM, this->iCurrentRegs[BASE_RHYTHM] & ~0x20); // switch rhythm-mode off
			}
			AdPlug_LogWrite("CMF: Percussive/rhythm mode %s\n", this->bPercussive ? "enabled" : "disabled");
			break;
		case 0x68:
			this->chMIDI[iChannel].iTranspose = iValue;
			this->cmfNoteUpdate(iChannel);
			AdPlug_LogWrite("CMF: Transposing all notes up by %d * 1/128ths of a semitone on channel %d.\n", iValue, iChannel + 1);
			break;
		case 0x69:
			this->chMIDI[iChannel].iTranspose = -iValue;
			this->cmfNoteUpdate(iChannel);
			AdPlug_LogWrite("CMF: Transposing all notes down by %d * 1/128ths of a semitone on channel %d.\n", iValue, iChannel + 1);
			break;
		default:
			AdPlug_LogWrite("CMF: Unsupported MIDI controller 0x%02X, ignoring.\n", iController);
			break;
	}
	return;
}
