s_fmopl.c

一款游戏机的模拟器

		else          SLOT->Cnt += SLOT->Incr;
		/* connectoion */
		outd += OP_OUT(SLOT,env_out, feedback2);
	}
}

/* ----------- initialize time tabls ----------- */
static void init_timetables( FM_OPL *OPL , int ARRATE , int DRRATE )
{
	int i;
	double rate;

	/* make attack rate & decay rate tables */
	for (i = 0;i < 4;i++) OPL->AR_TABLE[i] = OPL->DR_TABLE[i] = 0;
	for (i = 4;i <= 60;i++){
		rate  = OPL->freqbase;						/* frequency rate */
		if( i < 60 ) rate *= 1.0+(i&3)*0.25;		/* b0-1 : x1 , x1.25 , x1.5 , x1.75 */
		rate *= 1<<((i>>2)-1);						/* b2-5 : shift bit */
		rate *= (double)(EG_ENT<<ENV_BITS);
		OPL->AR_TABLE[i] = (s32)(rate / ARRATE);
		OPL->DR_TABLE[i] = (s32)(rate / DRRATE);
	}
	for (i = 60;i < 76;i++)
	{
		OPL->AR_TABLE[i] = EG_AED-1;
		OPL->DR_TABLE[i] = OPL->DR_TABLE[60];
	}
}

/* ---------- generic table initialize ---------- */
static int OPLOpenTable( void )
{
	int s,t;
	double rate;
	int i,j;
	double pom;

	/* allocate dynamic tables */
	if( (TL_TABLE = malloc(TL_MAX*2*sizeof(s32))) == NULL)
		return 0;
	if( (SIN_TABLE = malloc(SIN_ENT*4 *sizeof(s32 *))) == NULL)
	{
		free(TL_TABLE);
		return 0;
	}
	if( (AMS_TABLE = malloc(AMS_ENT*2 *sizeof(s32))) == NULL)
	{
		free(TL_TABLE);
		free(SIN_TABLE);
		return 0;
	}
	if( (VIB_TABLE = malloc(VIB_ENT*2 *sizeof(s32))) == NULL)
	{
		free(TL_TABLE);
		free(SIN_TABLE);
		free(AMS_TABLE);
		return 0;
	}
	/* make total level table */
	for (t = 0;t < EG_ENT-1 ;t++){
		rate = ((1<<TL_BITS)-1)/pow(10,EG_STEP*t/20);	/* dB -> voltage */
		TL_TABLE[       t] =  (int)rate;
		TL_TABLE[TL_MAX+t] = -TL_TABLE[t];
	}
	/* fill volume off area */
	for ( t = EG_ENT-1; t < TL_MAX ;t++){
		TL_TABLE[t] = TL_TABLE[TL_MAX+t] = 0;
	}

	/* make sinwave table (total level offet) */
	/* degree 0 = degree 180                   = off */
	SIN_TABLE[0] = SIN_TABLE[SIN_ENT/2]         = &TL_TABLE[EG_ENT-1];
	for (s = 1;s <= SIN_ENT/4;s++){
		pom = sin(2*PI*s/SIN_ENT); /* sin     */
		pom = 20*log10(1/pom);	   /* decibel */
		j = (int)(pom / EG_STEP);         /* TL_TABLE steps */

        /* degree 0   -  90    , degree 180 -  90 : plus section */
		SIN_TABLE[          s] = SIN_TABLE[SIN_ENT/2-s] = &TL_TABLE[j];
        /* degree 180 - 270    , degree 360 - 270 : minus section */
		SIN_TABLE[SIN_ENT/2+s] = SIN_TABLE[SIN_ENT  -s] = &TL_TABLE[TL_MAX+j];
	}
	for (s = 0;s < SIN_ENT;s++)
	{
		SIN_TABLE[SIN_ENT*1+s] = s<(SIN_ENT/2) ? SIN_TABLE[s] : &TL_TABLE[EG_ENT];
		SIN_TABLE[SIN_ENT*2+s] = SIN_TABLE[s % (SIN_ENT/2)];
		SIN_TABLE[SIN_ENT*3+s] = (s/(SIN_ENT/4))&1 ? &TL_TABLE[EG_ENT] : SIN_TABLE[SIN_ENT*2+s];
	}

	/* envelope counter -> envelope output table */
	for (i=0; i<EG_ENT; i++)
	{
		/* ATTACK curve */
		pom = pow( ((double)(EG_ENT-1-i)/EG_ENT) , 8 ) * EG_ENT;
		/* if( pom >= EG_ENT ) pom = EG_ENT-1; */
		ENV_CURVE[i] = (int)pom;
		/* DECAY ,RELEASE curve */
		ENV_CURVE[(EG_DST>>ENV_BITS)+i]= i;
	}
	/* off */
	ENV_CURVE[EG_OFF>>ENV_BITS]= EG_ENT-1;
	/* make LFO ams table */
	for (i=0; i<AMS_ENT; i++)
	{
		pom = (1.0+sin(2*PI*i/AMS_ENT))/2; /* sin */
		AMS_TABLE[i]         = (s32)((1.0/EG_STEP)*pom); /* 1dB   */
		AMS_TABLE[AMS_ENT+i] = (s32)((4.8/EG_STEP)*pom); /* 4.8dB */
	}
	/* make LFO vibrate table */
	for (i=0; i<VIB_ENT; i++)
	{
		/* 100cent = 1seminote = 6% ?? */
		pom = (double)VIB_RATE*0.06*sin(2*PI*i/VIB_ENT); /* +-100sect step */
		VIB_TABLE[i]         = (s32)(VIB_RATE + (pom*0.07)); /* +- 7cent */
		VIB_TABLE[VIB_ENT+i] = (s32)(VIB_RATE + (pom*0.14)); /* +-14cent */
	}
	return 1;
}


static void OPLCloseTable( void )
{
	free(TL_TABLE);
	free(SIN_TABLE);
	free(AMS_TABLE);
	free(VIB_TABLE);
}

/* CSM Key Controll */
INLINE void CSMKeyControll(OPL_CH *CH)
{
	OPL_SLOT *slot1 = &CH->SLOT[SLOT1];
	OPL_SLOT *slot2 = &CH->SLOT[SLOT2];
	/* all key off */
	OPL_KEYOFF(slot1);
	OPL_KEYOFF(slot2);
	/* total level latch */
	slot1->TLL = slot1->TL + (CH->ksl_base>>slot1->ksl);
	slot1->TLL = slot1->TL + (CH->ksl_base>>slot1->ksl);
	/* key on */
	CH->op1_out[0] = CH->op1_out[1] = 0;
	OPL_KEYON(slot1);
	OPL_KEYON(slot2);
}

/* ---------- opl initialize ---------- */
static void OPL_initalize(FM_OPL *OPL)
{
	int fn;

	/* frequency base */
	OPL->freqbase = (OPL->rate) ? ((double)OPL->clock / OPL->rate) / 72  : 0;
	/* make time tables */
	init_timetables( OPL , OPL_ARRATE , OPL_DRRATE );
	/* make fnumber -> increment counter table */
	for( fn=0 ; fn < 1024 ; fn++ )
	{
		OPL->FN_TABLE[fn] = (u32)(OPL->freqbase * fn * FREQ_RATE * (1<<7) / 2);
	}
	/* LFO freq.table */
	OPL->amsIncr = (u32)(OPL->rate ? (double)AMS_ENT*(1<<AMS_SHIFT) / OPL->rate * 3.7 * ((double)OPL->clock/3600000) : 0);
	OPL->vibIncr = (u32)(OPL->rate ? (double)VIB_ENT*(1<<VIB_SHIFT) / OPL->rate * 6.4 * ((double)OPL->clock/3600000) : 0);
}

/* ---------- write a OPL registers ---------- */
static void OPLWriteReg(FM_OPL *OPL, int r, int v)
{
	OPL_CH *CH;
	int slot;
	int block_fnum;

	switch(r&0xe0)
	{
	case 0x00: /* 00-1f:controll */
		switch(r&0x1f)
		{
		case 0x01:
			OPL->wavesel = v&0x20;
			if(!OPL->wavesel)
			{
				/* preset compatible mode */
				int c;
				for(c=0;c<OPL->max_ch;c++)
				{
					OPL->P_CH[c].SLOT[SLOT1].wavetable = &SIN_TABLE[0];
					OPL->P_CH[c].SLOT[SLOT2].wavetable = &SIN_TABLE[0];
				}
			}
			return;
		}
		break;
	case 0x20:	/* am,vib,ksr,eg type,mul */
		slot = slot_array[r&0x1f];
		if(slot == -1) return;
		set_mul(OPL,slot,v);
		return;
	case 0x40:
		slot = slot_array[r&0x1f];
		if(slot == -1) return;
		set_ksl_tl(OPL,slot,v);
		return;
	case 0x60:
		slot = slot_array[r&0x1f];
		if(slot == -1) return;
		set_ar_dr(OPL,slot,v);
		return;
	case 0x80:
		slot = slot_array[r&0x1f];
		if(slot == -1) return;
		set_sl_rr(OPL,slot,v);
		return;
	case 0xa0:
		switch(r)
		{
		case 0xbd:
			/* amsep,vibdep,r,bd,sd,tom,tc,hh */
			{
			OPL->ams_table = &AMS_TABLE[v&0x80 ? AMS_ENT : 0];
			OPL->vib_table = &VIB_TABLE[v&0x40 ? VIB_ENT : 0];
			OPL->rythm  = v&0x3f;
			}
			return;
		}
		/* keyon,block,fnum */
		if( (r&0x0f) > 8) return;
		CH = &OPL->P_CH[r&0x0f];
		if(!(r&0x10))
		{	/* a0-a8 */
			block_fnum  = (CH->block_fnum&0x1f00) | v;
		}
		else
		{	/* b0-b8 */
			int keyon = (v>>5)&1;
			block_fnum = ((v&0x1f)<<8) | (CH->block_fnum&0xff);
			if(CH->keyon != keyon)
			{
				if( (CH->keyon=keyon) )
				{
					CH->op1_out[0] = CH->op1_out[1] = 0;
					OPL_KEYON(&CH->SLOT[SLOT1]);
					OPL_KEYON(&CH->SLOT[SLOT2]);
				}
				else
				{
					OPL_KEYOFF(&CH->SLOT[SLOT1]);
					OPL_KEYOFF(&CH->SLOT[SLOT2]);
				}
			}
		}
		/* update */
		if((unsigned)CH->block_fnum != (unsigned)block_fnum)
		{
			int blockRv = 7-(block_fnum>>10);
			int fnum   = block_fnum&0x3ff;
			CH->block_fnum = block_fnum;

			CH->ksl_base = KSL_TABLE[block_fnum>>6];
			CH->fc = OPL->FN_TABLE[fnum]>>blockRv;
			CH->kcode = (u8)(CH->block_fnum>>9);
			if( (OPL->mode&0x40) && CH->block_fnum&0x100) CH->kcode |=1;
			CALC_FCSLOT(CH,&CH->SLOT[SLOT1]);
			CALC_FCSLOT(CH,&CH->SLOT[SLOT2]);
		}
		return;
	case 0xc0:
		/* FB,C */
		if( (r&0x0f) > 8) return;
		CH = &OPL->P_CH[r&0x0f];
		{
		int feedback = (v>>1)&7;
		CH->FB   = feedback ? (8+1) - feedback : 0;
		CH->CON = v&1;
		set_algorythm(CH);
		}
		return;
	case 0xe0: /* wave type */
		slot = slot_array[r&0x1f];
		if(slot == -1) return;
		CH = &OPL->P_CH[slot/2];
		if(OPL->wavesel)
		{
			CH->SLOT[slot&1].wavetable = &SIN_TABLE[(v&0x03)*SIN_ENT];
		}
		return;
	}
}

/* lock/unlock for common table */
static int OPL_LockTable(void)
{
	num_lock++;
	if(num_lock>1) return 0;
	/* first time */
	cur_chip = NULL;
	/* allocate total level table (128kb space) */
	if( !OPLOpenTable() )
	{
		num_lock--;
		return -1;
	}
	return 0;
}

static void OPL_UnLockTable(void)
{
	if(num_lock) num_lock--;
	if(num_lock) return;
	/* last time */
	cur_chip = NULL;
	OPLCloseTable();
}

/*******************************************************************************/
/*		YM3812 local section                                                   */
/*******************************************************************************/

/* ---------- update one of chip ----------- */
void YM3812UpdateOne(FM_OPL *OPL, s16 *buffer, int length)
{
	int i;
	s16 *buf = buffer;
	u32 amsCnt  = OPL->amsCnt;
	u32 vibCnt  = OPL->vibCnt;
	OPL_CH *CH,*R_CH;

	if( (void *)OPL != cur_chip ){
		cur_chip = (void *)OPL;
		/* channel pointers */
		S_CH = OPL->P_CH;
		E_CH = &S_CH[6];
		/* LFO state */
		amsIncr = OPL->amsIncr;
		vibIncr = OPL->vibIncr;
		ams_table = OPL->ams_table;
		vib_table = OPL->vib_table;
	}
	R_CH = E_CH;
    for( i=0; i < length ; i++ )
	{
		/*            channel A         channel B         channel C      */
		/* LFO */
		ams = ams_table[(amsCnt+=amsIncr)>>AMS_SHIFT];
		vib = vib_table[(vibCnt+=vibIncr)>>VIB_SHIFT];
		outd = 0;
		/* FM part */
		for(CH=S_CH ; CH < R_CH ; CH++)
			OPL_CALC_CH(CH);
		/* store to sound buffer */
		buf[i] += (s16)((outd >> OPL_OUTSB) / 56);
	}

	OPL->amsCnt = amsCnt;
	OPL->vibCnt = vibCnt;
}

/* ---------- reset one of chip ---------- */
void OPLResetChip(FM_OPL *OPL)
{
	int c,s;
	int i;

	/* reset chip */
	OPL->mode   = 0;	/* normal mode */
	OPL_STATUS_RESET(OPL,0x7f);
	/* reset with register write */
	OPLWriteReg(OPL,0x01,0); /* wabesel disable */
	for(i = 0xff ; i >= 0x20 ; i-- ) OPLWriteReg(OPL,i,0);
	/* reset OPerator paramater */
	for( c = 0 ; c < OPL->max_ch ; c++ )
	{
		OPL_CH *CH = &OPL->P_CH[c];
		/* OPL->P_CH[c].PAN = OPN_CENTER; */
		for(s = 0 ; s < 2 ; s++ )
		{
			/* wave table */
			CH->SLOT[s].wavetable = &SIN_TABLE[0];
			/* CH->SLOT[s].evm = ENV_MOD_RR; */
			CH->SLOT[s].evc = EG_OFF;
			CH->SLOT[s].eve = EG_OFF+1;
			CH->SLOT[s].evs = 0;
		}
	}
}

/* ----------  Create one of vietual YM3812 ----------       */
/* 'rate'  is sampling rate and 'bufsiz' is the size of the  */
FM_OPL *OPLCreate(int clock, int rate)
{
	char *ptr;
	FM_OPL *OPL;
	int state_size;
	int max_ch = 9; /* normaly 9 channels */

	if( OPL_LockTable() ==-1) return NULL;
	/* allocate OPL state space */
	state_size  = sizeof(FM_OPL);
	state_size += sizeof(OPL_CH)*max_ch;

	/* allocate memory block */
	ptr = malloc(state_size);
	if(ptr==NULL) return NULL;
	/* clear */
	memset(ptr,0,state_size);
	OPL        = (FM_OPL *)ptr; ptr+=sizeof(FM_OPL);
	OPL->P_CH  = (OPL_CH *)ptr; ptr+=sizeof(OPL_CH)*max_ch;

	/* set channel state pointer */
	OPL->clock = clock;
	OPL->rate  = rate;
	OPL->max_ch = max_ch;
	/* init grobal tables */
	OPL_initalize(OPL);
	/* reset chip */
	OPLResetChip(OPL);
	return OPL;
}

/* ----------  Destroy one of vietual YM3812 ----------       */
void OPLDestroy(FM_OPL *OPL)
{
	OPL_UnLockTable();
	free(OPL);
}

/* ---------- YM3812 I/O interface ---------- */
int OPLWrite(FM_OPL *OPL,int a,int v)
{
	if( !(a&1) )
	{	/* address port */
		OPL->address = v & 0xff;
	}
	else
	{	/* data port */
		if(OPL->UpdateHandler) OPL->UpdateHandler(OPL->UpdateParam,0);
		OPLWriteReg(OPL,OPL->address,v);
	}
	return OPL->status>>7;
}