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furnace/src/engine/platform/sound/su.cpp
tildearrow 976e193309 SoundUnit: add 1-bit PDM rev emulation
2022-08-16 02:08:10 -05:00

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#define _USE_MATH_DEFINES
#include "su.h"
#include <string.h>
#define minval(a,b) (((a)<(b))?(a):(b))
#define maxval(a,b) (((a)>(b))?(a):(b))
#define FILVOL chan[4].special1C
#define ILCTRL chan[4].special1D
#define ILSIZE chan[5].special1C
#define FIL1 chan[5].special1D
#define IL1 chan[6].special1C
#define IL2 chan[6].special1D
#define IL0 chan[7].special1C
#define MVOL chan[7].special1D
void SoundUnit::NextSample(short* l, short* r) {
// run channels
for (int i=0; i<8; i++) {
if (chan[i].vol==0 && !chan[i].flags.swvol) {
fns[i]=0;
continue;
}
if (chan[i].flags.pcm) {
ns[i]=pcm[chan[i].pcmpos];
} else switch (chan[i].flags.shape) {
case 0:
ns[i]=(((cycle[i]>>15)&127)>chan[i].duty)*127;
break;
case 1:
ns[i]=cycle[i]>>14;
break;
case 2:
ns[i]=SCsine[(cycle[i]>>14)&255];
break;
case 3:
ns[i]=SCtriangle[(cycle[i]>>14)&255];
break;
case 4: case 5:
ns[i]=(lfsr[i]&1)*127;
break;
case 6:
ns[i]=((((cycle[i]>>15)&127)>chan[i].duty)*127)^(short)SCsine[(cycle[i]>>14)&255];
break;
case 7:
ns[i]=((((cycle[i]>>15)&127)>chan[i].duty)*127)^(short)SCtriangle[(cycle[i]>>14)&255];
break;
}
if (chan[i].flags.ring) {
ns[i]=(ns[i]*ns[(i+1)&7])>>7;
}
if (chan[i].flags.pcm) {
if (chan[i].freq>0x8000) {
pcmdec[i]+=0x8000;
} else {
pcmdec[i]+=chan[i].freq;
}
if (pcmdec[i]>=32768) {
pcmdec[i]-=32768;
if (chan[i].pcmpos<chan[i].pcmbnd) {
chan[i].pcmpos++;
if (chan[i].pcmpos==chan[i].pcmbnd) {
if (chan[i].flags.pcmloop) {
chan[i].pcmpos=chan[i].pcmrst;
}
}
chan[i].pcmpos&=(pcmSize-1);
} else if (chan[i].flags.pcmloop) {
chan[i].pcmpos=chan[i].pcmrst;
}
}
} else {
ocycle[i]=cycle[i];
if (chan[i].flags.shape==5) {
switch ((chan[i].duty>>4)&3) {
case 0:
cycle[i]+=chan[i].freq*1-(chan[i].freq>>3);
break;
case 1:
cycle[i]+=chan[i].freq*2-(chan[i].freq>>3);
break;
case 2:
cycle[i]+=chan[i].freq*4-(chan[i].freq>>3);
break;
case 3:
cycle[i]+=chan[i].freq*8-(chan[i].freq>>3);
break;
}
} else {
cycle[i]+=chan[i].freq;
}
if ((cycle[i]&0xf80000)!=(ocycle[i]&0xf80000)) {
if (chan[i].flags.shape==4) {
lfsr[i]=(lfsr[i]>>1|(((lfsr[i]) ^ (lfsr[i] >> 2) ^ (lfsr[i] >> 3) ^ (lfsr[i] >> 5) ) & 1)<<31);
} else {
switch ((chan[i].duty>>4)&3) {
case 0:
lfsr[i]=(lfsr[i]>>1|(((lfsr[i] >> 3) ^ (lfsr[i] >> 4) ) & 1)<<5);
break;
case 1:
lfsr[i]=(lfsr[i]>>1|(((lfsr[i] >> 2) ^ (lfsr[i] >> 3) ) & 1)<<5);
break;
case 2:
lfsr[i]=(lfsr[i]>>1|(((lfsr[i]) ^ (lfsr[i] >> 2) ^ (lfsr[i] >> 3) ) & 1)<<5);
break;
case 3:
lfsr[i]=(lfsr[i]>>1|(((lfsr[i]) ^ (lfsr[i] >> 2) ^ (lfsr[i] >> 3) ^ (lfsr[i] >> 5) ) & 1)<<5);
break;
}
if ((lfsr[i]&63)==0) {
lfsr[i]=0xaaaa;
}
}
}
if (chan[i].flags.restim) {
if (--rcycle[i]<=0) {
cycle[i]=0;
rcycle[i]=chan[i].restimer;
lfsr[i]=0xaaaa;
}
}
}
fns[i]=ns[i]*chan[i].vol*(chan[i].flags.pcm?4:2);
if (chan[i].flags.fmode!=0) {
int ff=chan[i].cutoff;
nslow[i]=nslow[i]+(((ff)*nsband[i])>>16);
nshigh[i]=fns[i]-nslow[i]-(((256-chan[i].reson)*nsband[i])>>8);
nsband[i]=(((ff)*nshigh[i])>>16)+nsband[i];
fns[i]=(((chan[i].flags.fmode&1)?(nslow[i]):(0))+((chan[i].flags.fmode&2)?(nshigh[i]):(0))+((chan[i].flags.fmode&4)?(nsband[i]):(0)));
}
nsL[i]=(fns[i]*SCpantabL[(unsigned char)chan[i].pan])>>8;
nsR[i]=(fns[i]*SCpantabR[(unsigned char)chan[i].pan])>>8;
oldfreq[i]=chan[i].freq;
oldflags[i]=chan[i].flags.flags;
if (chan[i].flags.swvol) {
if (--swvolt[i]<=0) {
swvolt[i]=chan[i].swvol.speed;
if (chan[i].swvol.dir) {
chan[i].vol+=chan[i].swvol.amt;
if (chan[i].vol>chan[i].swvol.bound && !chan[i].swvol.loop) {
chan[i].vol=chan[i].swvol.bound;
}
if (chan[i].vol&0x80) {
if (chan[i].swvol.loop) {
if (chan[i].swvol.loopi) {
chan[i].swvol.dir=!chan[i].swvol.dir;
chan[i].vol=0xff-chan[i].vol;
} else {
chan[i].vol&=~0x80;
}
} else {
chan[i].vol=0x7f;
}
}
} else {
chan[i].vol-=chan[i].swvol.amt;
if (chan[i].vol&0x80) {
if (chan[i].swvol.loop) {
if (chan[i].swvol.loopi) {
chan[i].swvol.dir=!chan[i].swvol.dir;
chan[i].vol=-chan[i].vol;
} else {
chan[i].vol&=~0x80;
}
} else {
chan[i].vol=0x0;
}
}
if (chan[i].vol<chan[i].swvol.bound && !chan[i].swvol.loop) {
chan[i].vol=chan[i].swvol.bound;
}
}
}
}
if (chan[i].flags.swfreq) {
if (--swfreqt[i]<=0) {
swfreqt[i]=chan[i].swfreq.speed;
if (chan[i].swfreq.dir) {
if (chan[i].freq>(0xffff-chan[i].swfreq.amt)) {
chan[i].freq=0xffff;
} else {
chan[i].freq=(chan[i].freq*(0x80+chan[i].swfreq.amt))>>7;
if ((chan[i].freq>>8)>chan[i].swfreq.bound) {
chan[i].freq=chan[i].swfreq.bound<<8;
}
}
} else {
if (chan[i].freq<chan[i].swfreq.amt) {
chan[i].freq=0;
} else {
chan[i].freq=(chan[i].freq*(0xff-chan[i].swfreq.amt))>>8;
if ((chan[i].freq>>8)<chan[i].swfreq.bound) {
chan[i].freq=chan[i].swfreq.bound<<8;
}
}
}
}
}
if (chan[i].flags.swcut) {
if (--swcutt[i]<=0) {
swcutt[i]=chan[i].swcut.speed;
if (chan[i].swcut.dir) {
if (chan[i].cutoff>(0xffff-chan[i].swcut.amt)) {
chan[i].cutoff=0xffff;
} else {
chan[i].cutoff+=chan[i].swcut.amt;
if ((chan[i].cutoff>>8)>chan[i].swcut.bound) {
chan[i].cutoff=chan[i].swcut.bound<<8;
}
}
} else {
if (chan[i].cutoff<chan[i].swcut.amt) {
chan[i].cutoff=0;
} else {
chan[i].cutoff=((2048-(unsigned int)chan[i].swcut.amt)*(unsigned int)chan[i].cutoff)>>11;
if ((chan[i].cutoff>>8)<chan[i].swcut.bound) {
chan[i].cutoff=chan[i].swcut.bound<<8;
}
}
}
}
}
if (chan[i].flags.resosc) {
cycle[i]=0;
rcycle[i]=chan[i].restimer;
ocycle[i]=0;
chan[i].flags.resosc=0;
}
if (muted[i]) {
nsL[i]=0;
nsR[i]=0;
}
}
// mix
tnsL=(nsL[0]+nsL[1]+nsL[2]+nsL[3]+nsL[4]+nsL[5]+nsL[6]+nsL[7])>>2;
tnsR=(nsR[0]+nsR[1]+nsR[2]+nsR[3]+nsR[4]+nsR[5]+nsR[6]+nsR[7])>>2;
IL1=minval(32767,maxval(-32767,tnsL))>>8;
IL2=minval(32767,maxval(-32767,tnsR))>>8;
// write input lines to sample memory
if (ILSIZE&64) {
if (++ilBufPeriod>=((1+(FIL1>>4))<<2)) {
ilBufPeriod=0;
unsigned short ilLowerBound=pcmSize-((1+(ILSIZE&63))<<7);
short next;
if (ilBufPos<ilLowerBound) ilBufPos=ilLowerBound;
switch (ILCTRL&3) {
case 0:
ilFeedback0=ilFeedback1=pcm[ilBufPos];
next=((signed char)IL0)+((pcm[ilBufPos]*(FIL1&15))>>4);
if (next<-128) next=-128;
if (next>127) next=127;
pcm[ilBufPos]=next;
if (++ilBufPos>=pcmSize) ilBufPos=ilLowerBound;
break;
case 1:
ilFeedback0=ilFeedback1=pcm[ilBufPos];
next=((signed char)IL1)+((pcm[ilBufPos]*(FIL1&15))>>4);
if (next<-128) next=-128;
if (next>127) next=127;
pcm[ilBufPos]=next;
if (++ilBufPos>=pcmSize) ilBufPos=ilLowerBound;
break;
case 2:
ilFeedback0=ilFeedback1=pcm[ilBufPos];
next=((signed char)IL2)+((pcm[ilBufPos]*(FIL1&15))>>4);
if (next<-128) next=-128;
if (next>127) next=127;
pcm[ilBufPos]=next;
if (++ilBufPos>=pcmSize) ilBufPos=ilLowerBound;
break;
case 3:
ilFeedback0=pcm[ilBufPos];
next=((signed char)IL1)+((pcm[ilBufPos]*(FIL1&15))>>4);
if (next<-128) next=-128;
if (next>127) next=127;
pcm[ilBufPos]=next;
if (++ilBufPos>=pcmSize) ilBufPos=ilLowerBound;
ilFeedback1=pcm[ilBufPos];
next=((signed char)IL2)+((pcm[ilBufPos]*(FIL1&15))>>4);
if (next<-128) next=-128;
if (next>127) next=127;
pcm[ilBufPos]=next;
if (++ilBufPos>=pcmSize) ilBufPos=ilLowerBound;
break;
}
}
if (ILCTRL&4) {
if (ILSIZE&128) {
tnsL+=ilFeedback1*(signed char)FILVOL;
tnsR+=ilFeedback0*(signed char)FILVOL;
} else {
tnsL+=ilFeedback0*(signed char)FILVOL;
tnsR+=ilFeedback1*(signed char)FILVOL;
}
}
}
if (dsOut) {
tnsL=minval(32767,maxval(-32767,tnsL<<1));
tnsR=minval(32767,maxval(-32767,tnsR<<1));
short accumL=0;
short accumR=0;
for (int i=0; i<4; i++) {
if ((tnsL>>8)==0 && dsCounterL>0) dsCounterL=0;
dsCounterL+=tnsL>>8;
if (dsCounterL>=0) {
accumL+=4095;
dsCounterL-=127;
} else {
accumL+=-4095;
dsCounterL+=127;
}
if ((tnsR>>8)==0 && dsCounterR>0) dsCounterR=0;
dsCounterR+=tnsR>>8;
if (dsCounterR>=0) {
accumR+=4095;
dsCounterR-=127;
} else {
accumR+=-4095;
dsCounterR+=127;
}
}
*l=accumL;
*r=accumR;
} else {
*l=minval(32767,maxval(-32767,tnsL));
*r=minval(32767,maxval(-32767,tnsR));
}
}
void SoundUnit::Init(int sampleMemSize, bool dsOutMode) {
pcmSize=sampleMemSize;
dsOut=dsOutMode;
Reset();
memset(pcm,0,pcmSize);
for (int i=0; i<256; i++) {
SCsine[i]=sin((i/128.0f)*M_PI)*127;
SCtriangle[i]=(i>127)?(255-i):(i);
SCpantabL[i]=127;
SCpantabR[i]=127;
}
for (int i=0; i<128; i++) {
SCpantabL[i]=127-i;
SCpantabR[128+i]=i-1;
}
SCpantabR[128]=0;
}
void SoundUnit::Reset() {
for (int i=0; i<8; i++) {
ocycle[i]=0;
cycle[i]=0;
rcycle[i]=0;
resetfreq[i]=0;
voldcycles[i]=0;
volicycles[i]=0;
fscycles[i]=0;
sweep[i]=0;
ns[i]=0;
fns[i]=0;
nsL[i]=0;
nsR[i]=0;
nslow[i]=0;
nshigh[i]=0;
nsband[i]=0;
swvolt[i]=1;
swfreqt[i]=1;
swcutt[i]=1;
lfsr[i]=0xaaaa;
oldfreq[i]=0;
oldflags[i]=0;
pcmdec[i]=0;
}
dsCounterL=0;
dsCounterR=0;
tnsL=0;
tnsR=0;
ilBufPos=0;
ilBufPeriod=0;
ilFeedback0=0;
ilFeedback1=0;
memset(chan,0,sizeof(SUChannel)*8);
}
void SoundUnit::Write(unsigned char addr, unsigned char data) {
((unsigned char*)chan)[addr]=data;
}
SoundUnit::SoundUnit() {
Init(65536); // default
for (int i=0; i<8; i++) {
muted[i]=false;
}
}
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