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SoundUnit: emulation changes

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no longer uses int for the filter stages, instead using short
this makes a 1982 design cheaper and more viable
This commit is contained in:
tildearrow 2024-09-09 19:28:16 -05:00
parent a18dea53e3
commit 4f5c6cbbb5
2 changed files with 12 additions and 11 deletions
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11
src/engine/platform/sound/su.cpp
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@ -146,7 +146,8 @@ void SoundUnit::NextSample(short* l, short* r) {
}
}
}
fns[i]=ns[i]*chan[i].vol*((chan[i].flags0&8)?4:2);
fns[i]=ns[i]*chan[i].vol;
if (!(chan[i].flags0&8)) fns[i]>>=1;
if ((chan[i].flags0&0xe0)!=0) {
int ff=chan[i].cutoff;
nslow[i]=nslow[i]+(((ff)*nsband[i])>>16);
@ -259,12 +260,12 @@ void SoundUnit::NextSample(short* l, short* r) {
// mix
if (dsOut) {
tnsL=nsL[dsChannel]<<1;
tnsR=nsR[dsChannel]<<1;
tnsL=nsL[dsChannel]<<3;
tnsR=nsR[dsChannel]<<3;
dsChannel=(dsChannel+1)&7;
} else {
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;
tnsL=(nsL[0]+nsL[1]+nsL[2]+nsL[3]+nsL[4]+nsL[5]+nsL[6]+nsL[7]);
tnsR=(nsR[0]+nsR[1]+nsR[2]+nsR[3]+nsR[4]+nsR[5]+nsR[6]+nsR[7]);
IL1=minval(32767,maxval(-32767,tnsL))>>8;
IL2=minval(32767,maxval(-32767,tnsR))>>8;

12
src/engine/platform/sound/su.h
View file

@ -33,12 +33,12 @@ class SoundUnit {
int rcycle[8];
unsigned int lfsr[8];
signed char ns[8];
int fns[8];
int nsL[8];
int nsR[8];
int nslow[8];
int nshigh[8];
int nsband[8];
short fns[8];
short nsL[8];
short nsR[8];
short nslow[8];
short nshigh[8];
short nsband[8];
int tnsL, tnsR;
unsigned char ilBufPeriod;
unsigned short ilBufPos;