/***********************************************************************************

  emu2413.c -- YM2413 emulator written by Mitsutaka Okazaki 2001

  2001 01-08 : Version 0.10 -- 1st version.
  2001 01-15 : Version 0.20 -- semi-public version.
  2001 01-16 : Version 0.30 -- 1st public version.
  2001 01-17 : Version 0.31 -- Fixed bassdrum problem.
             : Version 0.32 -- LPF implemented.
  2001 01-18 : Version 0.33 -- Fixed the drum problem, refine the mix-down method.
                            -- Fixed the LFO bug.
  2001 01-24 : Version 0.35 -- Fixed the drum problem,
                               support undocumented EG behavior.
  2001 02-02 : Version 0.38 -- Improved the performance.
                               Fixed the hi-hat and cymbal model.
                               Fixed the default percussive datas.
                               Noise reduction.
                               Fixed the feedback problem.
  2001 03-03 : Version 0.39 -- Fixed some drum bugs.
                               Improved the performance.
  2001 03-04 : Version 0.40 -- Improved the feedback.
                               Change the default table size.
                               Clock and Rate can be changed during play.
  2001 06-24 : Version 0.50 -- Improved the hi-hat and the cymbal tone.
                               Added VRC7 patch (OPLL_reset_patch is changed).
                               Fixed OPLL_reset() bug.
                               Added OPLL_setMask, OPLL_getMask and OPLL_toggleMask.
                               Added OPLL_writeIO.
  2001 09-28 : Version 0.51 -- Removed the noise table.
  2002 01-28 : Version 0.52 -- Added Stereo mode.
  2002 02-07 : Version 0.53 -- Fixed some drum bugs.
  2002 02-20 : Version 0.54 -- Added the best quality mode.
  2002 03-02 : Version 0.55 -- Removed OPLL_init & OPLL_close.
  2002 05-30 : Version 0.60 -- Fixed HH&CYM generator and all voice datas.

  2004 01-24 : Modified by xodnizel to remove code not needed for the VRC7, among other things.

  References:
    fmopl.c        -- 1999,2000 written by Tatsuyuki Satoh (MAME development).
    fmopl.c(fixed) -- (C) 2002 Jarek Burczynski.
    s_opl.c        -- 2001 written by Mamiya (NEZplug development).
    fmgen.cpp      -- 1999,2000 written by cisc.
    fmpac.ill      -- 2000 created by NARUTO.
    MSX-Datapack
    YMU757 data sheet
    YM2143 data sheet

**************************************************************************************/
#include "emu2413.h"

static const unsigned char default_inst[15][8] = {
	/* 2019-03-19 VRC7 instrument patchset dumped by Nuke.YKT */
	/* https://wiki.nesdev.com/w/index.php/VRC7_audio */
	{ 0x03, 0x21, 0x05, 0x06, 0xE8, 0x81, 0x42, 0x27 },
	{ 0x13, 0x41, 0x14, 0x0D, 0xD8, 0xF6, 0x23, 0x12 },
	{ 0x11, 0x11, 0x08, 0x08, 0xFA, 0xB2, 0x20, 0x12 },
	{ 0x31, 0x61, 0x0C, 0x07, 0xA8, 0x64, 0x61, 0x27 },
	{ 0x32, 0x21, 0x1E, 0x06, 0xE1, 0x76, 0x01, 0x28 },
	{ 0x02, 0x01, 0x06, 0x00, 0xA3, 0xE2, 0xF4, 0xF4 },
	{ 0x21, 0x61, 0x1D, 0x07, 0x82, 0x81, 0x11, 0x07 },
	{ 0x23, 0x21, 0x22, 0x17, 0xA2, 0x72, 0x01, 0x17 },
	{ 0x35, 0x11, 0x25, 0x00, 0x40, 0x73, 0x72, 0x01 },
	{ 0xB5, 0x01, 0x0F, 0x0F, 0xA8, 0xA5, 0x51, 0x02 },
	{ 0x17, 0xC1, 0x24, 0x07, 0xF8, 0xF8, 0x22, 0x12 },
	{ 0x71, 0x23, 0x11, 0x06, 0x65, 0x74, 0x18, 0x16 },
	{ 0x01, 0x02, 0xD3, 0x05, 0xC9, 0x95, 0x03, 0x02 },
	{ 0x61, 0x63, 0x0C, 0x00, 0x94, 0xC0, 0x33, 0xF6 },
	{ 0x21, 0x72, 0x0D, 0x00, 0xC1, 0xD5, 0x56, 0x06 }
};

/* Size of Sintable ( 8 -- 18 can be used. 9 recommended.)*/
#define PG_BITS 9
#define PG_WIDTH (1 << PG_BITS)

/* Phase increment counter */
#define DP_BITS 18
#define DP_WIDTH (1 << DP_BITS)
#define DP_BASE_BITS (DP_BITS - PG_BITS)

/* Dynamic range (Accuracy of sin table) */
#define DB_BITS 8
#define DB_STEP (48.0 / (1 << DB_BITS))
#define DB_MUTE (1 << DB_BITS)

/* Dynamic range of envelope */
#define EG_STEP 0.375
#define EG_BITS 7
#define EG_MUTE (1 << EG_BITS)

/* Dynamic range of total level */
#define TL_STEP 0.75
#define TL_BITS 6
#define TL_MUTE (1 << TL_BITS)

/* Dynamic range of sustine level */
#define SL_STEP 3.0
#define SL_BITS 4
#define SL_MUTE (1 << SL_BITS)

#define EG2DB(d) ((d) * (int32)(EG_STEP / DB_STEP))
#define TL2EG(d) ((d) * (int32)(TL_STEP / EG_STEP))
#define SL2EG(d) ((d) * (int32)(SL_STEP / EG_STEP))

#define DB_POS(x) (uint32)((x) / DB_STEP)
#define DB_NEG(x) (uint32)(DB_MUTE + DB_MUTE + (x) / DB_STEP)

/* Bits for liner value */
#define DB2LIN_AMP_BITS 11
#define SLOT_AMP_BITS (DB2LIN_AMP_BITS)

/* Bits for envelope phase incremental counter */
#define EG_DP_BITS 22
#define EG_DP_WIDTH (1 << EG_DP_BITS)

/* Bits for Pitch and Amp modulator */
#define PM_PG_BITS 8
#define PM_PG_WIDTH (1 << PM_PG_BITS)
#define PM_DP_BITS 16
#define PM_DP_WIDTH (1 << PM_DP_BITS)
#define AM_PG_BITS 8
#define AM_PG_WIDTH (1 << AM_PG_BITS)
#define AM_DP_BITS 16
#define AM_DP_WIDTH (1 << AM_DP_BITS)

/* PM table is calcurated by PM_AMP * pow(2,PM_DEPTH*sin(x)/1200) */
#define PM_AMP_BITS 8
#define PM_AMP (1 << PM_AMP_BITS)

/* PM speed(Hz) and depth(cent) */
#define PM_SPEED 6.4
#define PM_DEPTH 13.75

/* AM speed(Hz) and depth(dB) */
#define AM_SPEED 3.7
/* #define AM_DEPTH 4.8 */
#define AM_DEPTH 2.4

/* Cut the lower b bit(s) off. */
#define HIGHBITS(c, b) ((c) >> (b))

/* Leave the lower b bit(s). */
#define LOWBITS(c, b) ((c) & ((1 << (b)) - 1))

/* Expand x which is s bits to d bits. */
#define EXPAND_BITS(x, s, d) ((x) << ((d) - (s)))

/* Expand x which is s bits to d bits and fill expanded bits '1' */
#define EXPAND_BITS_X(x, s, d) (((x) << ((d) - (s))) | ((1 << ((d) - (s))) - 1))

/* Adjust envelope speed which depends on sampling rate. */
#define rate_adjust(x) (rate == 49716 ? x : (uint32)((double)(x) * clk / 72 / rate + 0.5))			/* added 0.5 to round the value*/

#define MOD(o, x) (&(o)->slot[(x) << 1])
#define CAR(o, x) (&(o)->slot[((x) << 1) | 1])

#define BIT(s, b) (((s) >> (b)) & 1)

/* Input clock */
static uint32 clk = 844451141;
/* Sampling rate */
static uint32 rate = 3354932;

/* WaveTable for each envelope amp */
static uint16 fullsintable[PG_WIDTH];
static uint16 halfsintable[PG_WIDTH];

static uint16 *waveform[2] = { fullsintable, halfsintable };

/* LFO Table */
static int32 pmtable[PM_PG_WIDTH];
static int32 amtable[AM_PG_WIDTH];

/* Phase delta for LFO */
static uint32 pm_dphase;
static uint32 am_dphase;

/* dB to Liner table */
static int16 DB2LIN_TABLE[(DB_MUTE + DB_MUTE) * 2];

/* Liner to Log curve conversion table (for Attack rate). */
static uint16 AR_ADJUST_TABLE[1 << EG_BITS];

/* Definition of envelope mode */
enum
{ SETTLE, ATTACK, DECAY, SUSHOLD, SUSTINE, RELEASE, FINISH };

/* Phase incr table for Attack */
static uint32 dphaseARTable[16][16];
/* Phase incr table for Decay and Release */
static uint32 dphaseDRTable[16][16];

/* KSL + TL Table */
static uint32 tllTable[16][8][1 << TL_BITS][4];
static int32 rksTable[2][8][2];

/* Phase incr table for PG */
static uint32 dphaseTable[512][8][16];

/***************************************************

                  Create tables

****************************************************/
INLINE static int32 Min(int32 i, int32 j) {
	if (i < j)
		return i;
	else
		return j;
}

/* Table for AR to LogCurve. */
static void makeAdjustTable(void) {
	int32 i;

	AR_ADJUST_TABLE[0] = (1 << EG_BITS);
	for (i = 1; i < 128; i++)
		AR_ADJUST_TABLE[i] = (uint16)((double)(1 << EG_BITS) - 1 - (1 << EG_BITS) * log(i) / log(128));
}


/* Table for dB(0 -- (1<<DB_BITS)-1) to Liner(0 -- DB2LIN_AMP_WIDTH) */
static void makeDB2LinTable(void) {
	int32 i;

	for (i = 0; i < DB_MUTE + DB_MUTE; i++) {
		DB2LIN_TABLE[i] = (int16)((double)((1 << DB2LIN_AMP_BITS) - 1) * pow(10, -(double)i * DB_STEP / 20));
		if (i >= DB_MUTE) DB2LIN_TABLE[i] = 0;
		DB2LIN_TABLE[i + DB_MUTE + DB_MUTE] = (int16)(-DB2LIN_TABLE[i]);
	}
}

/* Liner(+0.0 - +1.0) to dB((1<<DB_BITS) - 1 -- 0) */
static int32 lin2db(double d) {
	if (d == 0)
		return(DB_MUTE - 1);
	else
		return Min(-(int32)(20.0 * log10(d) / DB_STEP), DB_MUTE - 1);	/* 0 -- 127 */
}


/* Sin Table */
static void makeSinTable(void) {
	int32 i;

	for (i = 0; i < PG_WIDTH / 4; i++) {
		fullsintable[i] = (uint32)lin2db(sin(2.0 * PI * i / PG_WIDTH));
	}

	for (i = 0; i < PG_WIDTH / 4; i++) {
		fullsintable[PG_WIDTH / 2 - 1 - i] = fullsintable[i];
	}

	for (i = 0; i < PG_WIDTH / 2; i++) {
		fullsintable[PG_WIDTH / 2 + i] = (uint32)(DB_MUTE + DB_MUTE + fullsintable[i]);
	}

	for (i = 0; i < PG_WIDTH / 2; i++)
		halfsintable[i] = fullsintable[i];
	for (i = PG_WIDTH / 2; i < PG_WIDTH; i++)
		halfsintable[i] = fullsintable[0];
}

/* Table for Pitch Modulator */
static void makePmTable(void) {
	int32 i;

	for (i = 0; i < PM_PG_WIDTH; i++)
		pmtable[i] = (int32)((double)PM_AMP * pow(2, (double)PM_DEPTH * sin(2.0 * PI * i / PM_PG_WIDTH) / 1200));
}

/* Table for Amp Modulator */
static void makeAmTable(void) {
	int32 i;

	for (i = 0; i < AM_PG_WIDTH; i++)
		amtable[i] = (int32)((double)AM_DEPTH / 2 / DB_STEP * (1.0 + sin(2.0 * PI * i / PM_PG_WIDTH)));
}

/* Phase increment counter table */
static void makeDphaseTable(void) {
	uint32 fnum, block, ML;
	uint32 mltable[16] =
	{ 1, 1 * 2, 2 * 2, 3 * 2, 4 * 2, 5 * 2, 6 * 2, 7 * 2, 8 * 2, 9 * 2, 10 * 2, 10 * 2, 12 * 2, 12 * 2, 15 * 2, 15 * 2 };

	for (fnum = 0; fnum < 512; fnum++)
		for (block = 0; block < 8; block++)
			for (ML = 0; ML < 16; ML++)
				dphaseTable[fnum][block][ML] = rate_adjust(((fnum * mltable[ML]) << block) >> (20 - DP_BITS));
}

static void makeTllTable(void) {
#define dB2(x) ((x) * 2)

	static double kltable[16] = {
		dB2(0.000), dB2(9.000), dB2(12.000), dB2(13.875), dB2(15.000), dB2(16.125), dB2(16.875), dB2(17.625),
		dB2(18.000), dB2(18.750), dB2(19.125), dB2(19.500), dB2(19.875), dB2(20.250), dB2(20.625), dB2(21.000)
	};

	int32 tmp;
	int32 fnum, block, TL, KL;

	for (fnum = 0; fnum < 16; fnum++)
		for (block = 0; block < 8; block++)
			for (TL = 0; TL < 64; TL++)
				for (KL = 0; KL < 4; KL++) {
					if (KL == 0) {
						tllTable[fnum][block][TL][KL] = TL2EG(TL);
					} else {
						tmp = (int32)(kltable[fnum] - dB2(3.000) * (7 - block));
						if (tmp <= 0)
							tllTable[fnum][block][TL][KL] = TL2EG(TL);
						else
							tllTable[fnum][block][TL][KL] = (uint32)((tmp >> (3 - KL)) / EG_STEP) + TL2EG(TL);
					}
				}
}

/* Rate Table for Attack */
static void makeDphaseARTable(void) {
	int32 AR, Rks, RM, RL;
	for (AR = 0; AR < 16; AR++)
		for (Rks = 0; Rks < 16; Rks++) {
			RM = AR + (Rks >> 2);
			RL = Rks & 3;
			if (RM > 15)
				RM = 15;
			switch (AR) {
			case 0:
				dphaseARTable[AR][Rks] = 0;
				break;
			case 15:
				dphaseARTable[AR][Rks] = 0;	/*EG_DP_WIDTH;*/
				break;
			default:
				dphaseARTable[AR][Rks] = rate_adjust((3 * (RL + 4) << (RM + 1)));
				break;
			}
		}
}

/* Rate Table for Decay and Release */
static void makeDphaseDRTable(void) {
	int32 DR, Rks, RM, RL;

	for (DR = 0; DR < 16; DR++)
		for (Rks = 0; Rks < 16; Rks++) {
			RM = DR + (Rks >> 2);
			RL = Rks & 3;
			if (RM > 15)
				RM = 15;
			switch (DR) {
			case 0:
				dphaseDRTable[DR][Rks] = 0;
				break;
			default:
				dphaseDRTable[DR][Rks] = rate_adjust((RL + 4) << (RM - 1));
				break;
			}
		}
}

static void makeRksTable(void) {
	int32 fnum8, block, KR;

	for (fnum8 = 0; fnum8 < 2; fnum8++)
		for (block = 0; block < 8; block++)
			for (KR = 0; KR < 2; KR++) {
				if (KR != 0)
					rksTable[fnum8][block][KR] = (block << 1) + fnum8;
				else
					rksTable[fnum8][block][KR] = block >> 1;
			}
}

/************************************************************

                      Calc Parameters

************************************************************/

INLINE static uint32 calc_eg_dphase(OPLL_SLOT * slot) {
	switch (slot->eg_mode) {
	case ATTACK:
		return dphaseARTable[slot->patch.AR][slot->rks];

	case DECAY:
		return dphaseDRTable[slot->patch.DR][slot->rks];

	case SUSHOLD:
		return 0;

	case SUSTINE:
		return dphaseDRTable[slot->patch.RR][slot->rks];

	case RELEASE:
		if (slot->sustine)
			return dphaseDRTable[5][slot->rks];
		else if (slot->patch.EG)
			return dphaseDRTable[slot->patch.RR][slot->rks];
		else
			return dphaseDRTable[7][slot->rks];

	case FINISH:
		return 0;

	default:
		return 0;
	}
}

/*************************************************************

                    OPLL internal interfaces

*************************************************************/

#define UPDATE_PG(S)  (S)->dphase = dphaseTable[(S)->fnum][(S)->block][(S)->patch.ML]
#define UPDATE_TLL(S) \
	(((S)->type == 0) ?	\
	 ((S)->tll = tllTable[((S)->fnum) >> 5][(S)->block][(S)->patch.TL][(S)->patch.KL]) : \
	 ((S)->tll = tllTable[((S)->fnum) >> 5][(S)->block][(S)->volume][(S)->patch.KL]))
#define UPDATE_RKS(S) (S)->rks = rksTable[((S)->fnum) >> 8][(S)->block][(S)->patch.KR]
#define UPDATE_WF(S)  (S)->sintbl = waveform[(S)->patch.WF]
#define UPDATE_EG(S)  (S)->eg_dphase = calc_eg_dphase(S)
#define UPDATE_ALL(S) \
	UPDATE_PG(S); \
	UPDATE_TLL(S); \
	UPDATE_RKS(S); \
	UPDATE_WF(S); \
	UPDATE_EG(S)				/* EG should be updated last. */


/* Slot key on  */
INLINE static void slotOn(OPLL_SLOT * slot) {
	slot->eg_mode = ATTACK;
	slot->eg_phase = 0;
	slot->phase = 0;
}

/* Slot key on without reseting the phase */
INLINE static void slotOn2(OPLL_SLOT * slot) {
	slot->eg_mode = ATTACK;
	slot->eg_phase = 0;
}

/* Slot key off */
INLINE static void slotOff(OPLL_SLOT * slot) {
	if (slot->eg_mode == ATTACK)
		slot->eg_phase = EXPAND_BITS(AR_ADJUST_TABLE[HIGHBITS(slot->eg_phase, EG_DP_BITS - EG_BITS)], EG_BITS, EG_DP_BITS);
	slot->eg_mode = RELEASE;
}

/* Channel key on */
INLINE static void keyOn(OPLL * opll, int32 i) {
	if (!opll->slot_on_flag[i * 2])
		slotOn(MOD(opll, i));
	if (!opll->slot_on_flag[i * 2 + 1])
		slotOn(CAR(opll, i));
	opll->key_status[i] = 1;
}

/* Channel key off */
INLINE static void keyOff(OPLL * opll, int32 i) {
	if (opll->slot_on_flag[i * 2 + 1])
		slotOff(CAR(opll, i));
	opll->key_status[i] = 0;
}

/* Set sustine parameter */
INLINE static void setSustine(OPLL * opll, int32 c, int32 sustine) {
	CAR(opll, c)->sustine = sustine;
	if (MOD(opll, c)->type)
		MOD(opll, c)->sustine = sustine;
}

/* Volume : 6bit ( Volume register << 2 ) */
INLINE static void setVolume(OPLL * opll, int32 c, int32 volume) {
	CAR(opll, c)->volume = volume;
}

INLINE static void setSlotVolume(OPLL_SLOT * slot, int32 volume) {
	slot->volume = volume;
}

/* Set F-Number ( fnum : 9bit ) */
INLINE static void setFnumber(OPLL * opll, int32 c, int32 fnum) {
	CAR(opll, c)->fnum = fnum;
	MOD(opll, c)->fnum = fnum;
}

/* Set Block data (block : 3bit ) */
INLINE static void setBlock(OPLL * opll, int32 c, int32 block) {
	CAR(opll, c)->block = block;
	MOD(opll, c)->block = block;
}

INLINE static void update_key_status(OPLL * opll) {
	int ch;

	for (ch = 0; ch < 6; ch++)
		opll->slot_on_flag[ch * 2] = opll->slot_on_flag[ch * 2 + 1] = (opll->HiFreq[ch]) & 0x10;
}

/***********************************************************

                      Initializing

***********************************************************/

static void OPLL_SLOT_reset(OPLL_SLOT * slot, int type) {
	slot->type = type;
	slot->sintbl = waveform[0];
	slot->phase = 0;
	slot->dphase = 0;
	slot->output[0] = 0;
	slot->output[1] = 0;
	slot->feedback = 0;
	slot->eg_mode = SETTLE;
	slot->eg_phase = EG_DP_WIDTH;
	slot->eg_dphase = 0;
	slot->rks = 0;
	slot->tll = 0;
	slot->sustine = 0;
	slot->fnum = 0;
	slot->block = 0;
	slot->volume = 0;
	slot->pgout = 0;
	slot->egout = 0;
}

static void internal_refresh(void) {
	makeDphaseTable();
	makeDphaseARTable();
	makeDphaseDRTable();
	pm_dphase = (uint32)rate_adjust(PM_SPEED * PM_DP_WIDTH / (clk / 72));
	am_dphase = (uint32)rate_adjust(AM_SPEED * AM_DP_WIDTH / (clk / 72));
}

static void maketables(uint32 c, uint32 r) {
	if (c != clk) {
		clk = c;
		makePmTable();
		makeAmTable();
		makeDB2LinTable();
		makeAdjustTable();
		makeTllTable();
		makeRksTable();
		makeSinTable();
		/* makeDefaultPatch (); */
	}

	if (r != rate) {
		rate = r;
		internal_refresh();
	}
}

OPLL *OPLL_new(uint32 clk, uint32 rate) {
	OPLL *opll;

	maketables(clk, rate);

	opll = (OPLL*)calloc(sizeof(OPLL), 1);
	if (opll == NULL)
		return NULL;

	opll->mask = 0;

	OPLL_reset(opll);

	return opll;
}


void OPLL_delete(OPLL * opll) {
	free(opll);
}

/* Reset whole of OPLL except patch datas. */
void OPLL_reset(OPLL * opll) {
	int32 i;

	if (!opll)
		return;

	opll->adr = 0;
	opll->out = 0;

	opll->pm_phase = 0;
	opll->am_phase = 0;

	opll->mask = 0;

	for (i = 0; i < 12; i++)
		OPLL_SLOT_reset(&opll->slot[i], i % 2);

	for (i = 0; i < 6; i++) {
		opll->key_status[i] = 0;
		/* setPatch (opll, i, 0); */
	}

	for (i = 0; i < 0x40; i++)
		OPLL_writeReg(opll, i, 0);

	opll->realstep = (uint32)((1 << 31) / rate);
	opll->opllstep = (uint32)((1 << 31) / (clk / 72));
	opll->oplltime = 0;
}

/* Force Refresh (When external program changes some parameters). */
void OPLL_forceRefresh(OPLL * opll) {
	int32 i;

	if (opll == NULL)
		return;

	for (i = 0; i < 12; i++) {
		UPDATE_PG(&opll->slot[i]);
		UPDATE_RKS(&opll->slot[i]);
		UPDATE_TLL(&opll->slot[i]);
		UPDATE_WF(&opll->slot[i]);
		UPDATE_EG(&opll->slot[i]);
	}
}

void OPLL_set_rate(OPLL * opll, uint32 r) {
	if (opll->quality)
		rate = 49716;
	else
		rate = r;
	internal_refresh();
	rate = r;
}

void OPLL_set_quality(OPLL * opll, uint32 q) {
	opll->quality = q;
	OPLL_set_rate(opll, rate);
}

/*********************************************************

                 Generate wave data

*********************************************************/
/* Convert Amp(0 to EG_HEIGHT) to Phase(0 to 2PI). */
#if (SLOT_AMP_BITS - PG_BITS) > 0
#define wave2_2pi(e)  ((e) >> (SLOT_AMP_BITS - PG_BITS))
#else
#define wave2_2pi(e)  ((e) << (PG_BITS - SLOT_AMP_BITS))
#endif

/* Convert Amp(0 to EG_HEIGHT) to Phase(0 to 4PI). */
#if (SLOT_AMP_BITS - PG_BITS - 1) == 0
#define wave2_4pi(e)  (e)
#elif (SLOT_AMP_BITS - PG_BITS - 1) > 0
#define wave2_4pi(e)  ((e) >> (SLOT_AMP_BITS - PG_BITS - 1))
#else
#define wave2_4pi(e)  ((e) << (1 + PG_BITS - SLOT_AMP_BITS))
#endif

/* Convert Amp(0 to EG_HEIGHT) to Phase(0 to 8PI). */
#if (SLOT_AMP_BITS - PG_BITS - 2) == 0
#define wave2_8pi(e)  (e)
#elif (SLOT_AMP_BITS - PG_BITS - 2) > 0
#define wave2_8pi(e)  ((e) >> (SLOT_AMP_BITS - PG_BITS - 2))
#else
#define wave2_8pi(e)  ((e) << (2 + PG_BITS - SLOT_AMP_BITS))
#endif



/* Update AM, PM unit */
static void update_ampm(OPLL * opll) {
	opll->pm_phase = (opll->pm_phase + pm_dphase) & (PM_DP_WIDTH - 1);
	opll->am_phase = (opll->am_phase + am_dphase) & (AM_DP_WIDTH - 1);
	opll->lfo_am = amtable[HIGHBITS(opll->am_phase, AM_DP_BITS - AM_PG_BITS)];
	opll->lfo_pm = pmtable[HIGHBITS(opll->pm_phase, PM_DP_BITS - PM_PG_BITS)];
}

/* PG */
INLINE static void calc_phase(OPLL_SLOT * slot, int32 lfo) {
	if (slot->patch.PM)
		slot->phase += (slot->dphase * lfo) >> PM_AMP_BITS;
	else
		slot->phase += slot->dphase;

	slot->phase &= (DP_WIDTH - 1);

	slot->pgout = HIGHBITS(slot->phase, DP_BASE_BITS);
}

/* EG */
static void calc_envelope(OPLL_SLOT * slot, int32 lfo) {
#define S2E(x) (SL2EG((int32)(x / SL_STEP)) << (EG_DP_BITS - EG_BITS))

	static uint32 SL[16] = {
		S2E(0.0), S2E(3.0), S2E(6.0), S2E(9.0), S2E(12.0), S2E(15.0), S2E(18.0), S2E(21.0),
		S2E(24.0), S2E(27.0), S2E(30.0), S2E(33.0), S2E(36.0), S2E(39.0), S2E(42.0), S2E(48.0)
	};

	uint32 egout;

	switch (slot->eg_mode) {
	case ATTACK:
		egout = AR_ADJUST_TABLE[HIGHBITS(slot->eg_phase, EG_DP_BITS - EG_BITS)];
		slot->eg_phase += slot->eg_dphase;
		if ((EG_DP_WIDTH & slot->eg_phase) || (slot->patch.AR == 15)) {
			egout = 0;
			slot->eg_phase = 0;
			slot->eg_mode = DECAY;
			UPDATE_EG(slot);
		}
		break;

	case DECAY:
		egout = HIGHBITS(slot->eg_phase, EG_DP_BITS - EG_BITS);
		slot->eg_phase += slot->eg_dphase;
		if (slot->eg_phase >= SL[slot->patch.SL]) {
			if (slot->patch.EG) {
				slot->eg_phase = SL[slot->patch.SL];
				slot->eg_mode = SUSHOLD;
				UPDATE_EG(slot);
			} else {
				slot->eg_phase = SL[slot->patch.SL];
				slot->eg_mode = SUSTINE;
				UPDATE_EG(slot);
			}
		}
		break;

	case SUSHOLD:
		egout = HIGHBITS(slot->eg_phase, EG_DP_BITS - EG_BITS);
		if (slot->patch.EG == 0) {
			slot->eg_mode = SUSTINE;
			UPDATE_EG(slot);
		}
		break;

	case SUSTINE:
	case RELEASE:
		egout = HIGHBITS(slot->eg_phase, EG_DP_BITS - EG_BITS);
		slot->eg_phase += slot->eg_dphase;
		if (egout >= (1 << EG_BITS)) {
			slot->eg_mode = FINISH;
			egout = (1 << EG_BITS) - 1;
		}
		break;

	case FINISH:
		egout = (1 << EG_BITS) - 1;
		break;

	default:
		egout = (1 << EG_BITS) - 1;
		break;
	}

	if (slot->patch.AM)
		egout = EG2DB(egout + slot->tll) + lfo;
	else
		egout = EG2DB(egout + slot->tll);

	if (egout >= DB_MUTE)
		egout = DB_MUTE - 1;

	slot->egout = egout;
}

/* CARRIOR */
INLINE static int32 calc_slot_car(OPLL_SLOT * slot, int32 fm) {
	slot->output[1] = slot->output[0];

	if (slot->egout >= (DB_MUTE - 1)) {
		slot->output[0] = 0;
	} else {
		slot->output[0] = DB2LIN_TABLE[slot->sintbl[(slot->pgout + wave2_8pi(fm)) & (PG_WIDTH - 1)] + slot->egout];
	}

	return (slot->output[1] + slot->output[0]) >> 1;
}

/* MODULATOR */
INLINE static int32 calc_slot_mod(OPLL_SLOT * slot) {
	int32 fm;

	slot->output[1] = slot->output[0];

	if (slot->egout >= (DB_MUTE - 1)) {
		slot->output[0] = 0;
	} else if (slot->patch.FB != 0) {
		fm = wave2_4pi(slot->feedback) >> (7 - slot->patch.FB);
		slot->output[0] = DB2LIN_TABLE[slot->sintbl[(slot->pgout + fm) & (PG_WIDTH - 1)] + slot->egout];
	} else {
		slot->output[0] = DB2LIN_TABLE[slot->sintbl[slot->pgout] + slot->egout];
	}

	slot->feedback = (slot->output[1] + slot->output[0]) >> 1;

	return slot->feedback;
}

static INLINE int16 calc(OPLL * opll) {
	int32 inst = 0, out = 0;
	int32 i;

	update_ampm(opll);

	for (i = 0; i < 12; i++) {
		calc_phase(&opll->slot[i], opll->lfo_pm);
		calc_envelope(&opll->slot[i], opll->lfo_am);
	}

	for (i = 0; i < 6; i++)
		if (!(opll->mask & OPLL_MASK_CH(i)) && (CAR(opll, i)->eg_mode != FINISH))
			inst += calc_slot_car(CAR(opll, i), calc_slot_mod(MOD(opll, i)));

	out = inst;
	return (int16)out;
}

void OPLL_fillbuf(OPLL* opll, int32 *buf, int32 len, int shift) {
	while (len > 0) {
		*buf += (calc(opll) + 32768) << shift;
		buf++;
		len--;
	}
}

int16 OPLL_calc(OPLL * opll) {
	if (!opll->quality)
		return calc(opll);

	while (opll->realstep > opll->oplltime) {
		opll->oplltime += opll->opllstep;
		opll->prev = opll->next;
		opll->next = calc(opll);
	}

	opll->oplltime -= opll->realstep;
	opll->out = (int16)(((double)opll->next * (opll->opllstep - opll->oplltime)
						 + (double)opll->prev * opll->oplltime) / opll->opllstep);

	return (int16)opll->out;
}

uint32 OPLL_setMask(OPLL * opll, uint32 mask) {
	uint32 ret;

	if (opll) {
		ret = opll->mask;
		opll->mask = mask;
		return ret;
	} else
		return 0;
}

uint32 OPLL_toggleMask(OPLL * opll, uint32 mask) {
	uint32 ret;

	if (opll) {
		ret = opll->mask;
		opll->mask ^= mask;
		return ret;
	} else
		return 0;
}

/****************************************************

                       I/O Ctrl

*****************************************************/

static void setInstrument(OPLL * opll, uint32 i, uint32 inst) {
	const uint8 *src;
	OPLL_PATCH *modp, *carp;

	opll->patch_number[i] = inst;

	if (inst)
		src = default_inst[inst - 1];
	else
		src = opll->CustInst;

	modp = &MOD(opll, i)->patch;
	carp = &CAR(opll, i)->patch;

	modp->AM = (src[0] >> 7) & 1;
	modp->PM = (src[0] >> 6) & 1;
	modp->EG = (src[0] >> 5) & 1;
	modp->KR = (src[0] >> 4) & 1;
	modp->ML = (src[0] & 0xF);

	carp->AM = (src[1] >> 7) & 1;
	carp->PM = (src[1] >> 6) & 1;
	carp->EG = (src[1] >> 5) & 1;
	carp->KR = (src[1] >> 4) & 1;
	carp->ML = (src[1] & 0xF);

	modp->KL = (src[2] >> 6) & 3;
	modp->TL = (src[2] & 0x3F);

	carp->KL = (src[3] >> 6) & 3;
	carp->WF = (src[3] >> 4) & 1;

	modp->WF = (src[3] >> 3) & 1;

	modp->FB = (src[3]) & 7;

	modp->AR = (src[4] >> 4) & 0xF;
	modp->DR = (src[4] & 0xF);

	carp->AR = (src[5] >> 4) & 0xF;
	carp->DR = (src[5] & 0xF);

	modp->SL = (src[6] >> 4) & 0xF;
	modp->RR = (src[6] & 0xF);

	carp->SL = (src[7] >> 4) & 0xF;
	carp->RR = (src[7] & 0xF);
}


void OPLL_writeReg(OPLL * opll, uint32 reg, uint32 data) {
	int32 i, v, ch;

	data = data & 0xff;
	reg = reg & 0x3f;

	switch (reg) {
	case 0x00:
		opll->CustInst[0] = data;
		for (i = 0; i < 6; i++) {
			if (opll->patch_number[i] == 0) {
				setInstrument(opll, i, 0);
				UPDATE_PG(MOD(opll, i));
				UPDATE_RKS(MOD(opll, i));
				UPDATE_EG(MOD(opll, i));
			}
		}
		break;

	case 0x01:
		opll->CustInst[1] = data;
		for (i = 0; i < 6; i++) {
			if (opll->patch_number[i] == 0) {
				setInstrument(opll, i, 0);
				UPDATE_PG(CAR(opll, i));
				UPDATE_RKS(CAR(opll, i));
				UPDATE_EG(CAR(opll, i));
			}
		}
		break;

	case 0x02:
		opll->CustInst[2] = data;
		for (i = 0; i < 6; i++) {
			if (opll->patch_number[i] == 0) {
				setInstrument(opll, i, 0);
				UPDATE_TLL(MOD(opll, i));
			}
		}
		break;

	case 0x03:
		opll->CustInst[3] = data;
		for (i = 0; i < 6; i++) {
			if (opll->patch_number[i] == 0) {
				setInstrument(opll, i, 0);
				UPDATE_WF(MOD(opll, i));
				UPDATE_WF(CAR(opll, i));
			}
		}
		break;

	case 0x04:
		opll->CustInst[4] = data;
		for (i = 0; i < 6; i++) {
			if (opll->patch_number[i] == 0) {
				setInstrument(opll, i, 0);
				UPDATE_EG(MOD(opll, i));
			}
		}
		break;

	case 0x05:
		opll->CustInst[5] = data;
		for (i = 0; i < 6; i++) {
			if (opll->patch_number[i] == 0) {
				setInstrument(opll, i, 0);
				UPDATE_EG(CAR(opll, i));
			}
		}
		break;

	case 0x06:
		opll->CustInst[6] = data;
		for (i = 0; i < 6; i++) {
			if (opll->patch_number[i] == 0) {
				setInstrument(opll, i, 0);
				UPDATE_EG(MOD(opll, i));
			}
		}
		break;

	case 0x07:
		opll->CustInst[7] = data;
		for (i = 0; i < 6; i++) {
			if (opll->patch_number[i] == 0) {
				setInstrument(opll, i, 0);
				UPDATE_EG(CAR(opll, i));
			}
		}
		break;

	case 0x10:
	case 0x11:
	case 0x12:
	case 0x13:
	case 0x14:
	case 0x15:
		ch = reg - 0x10;
		opll->LowFreq[ch] = data;
		setFnumber(opll, ch, data + ((opll->HiFreq[ch] & 1) << 8));
		UPDATE_ALL(MOD(opll, ch));
		UPDATE_ALL(CAR(opll, ch));
		break;

	case 0x20:
	case 0x21:
	case 0x22:
	case 0x23:
	case 0x24:
	case 0x25:
		ch = reg - 0x20;
		opll->HiFreq[ch] = data;

		setFnumber(opll, ch, ((data & 1) << 8) + opll->LowFreq[ch]);
		setBlock(opll, ch, (data >> 1) & 7);
		setSustine(opll, ch, (data >> 5) & 1);
		if (data & 0x10)
			keyOn(opll, ch);
		else
			keyOff(opll, ch);
		UPDATE_ALL(MOD(opll, ch));
		UPDATE_ALL(CAR(opll, ch));
		update_key_status(opll);
		break;

	case 0x30:
	case 0x31:
	case 0x32:
	case 0x33:
	case 0x34:
	case 0x35:
		opll->InstVol[reg - 0x30] = data;
		i = (data >> 4) & 15;
		v = data & 15;
		setInstrument(opll, reg - 0x30, i);
		setVolume(opll, reg - 0x30, v << 2);
		UPDATE_ALL(MOD(opll, reg - 0x30));
		UPDATE_ALL(CAR(opll, reg - 0x30));
		break;

	default:
		break;
	}
}

void OPLL_writeIO(OPLL * opll, uint32 adr, uint32 val) {
	if (adr & 1)
		OPLL_writeReg(opll, opll->adr, val);
	else
		opll->adr = val;
}

