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Amiga: filter emulation

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This commit is contained in:
tildearrow 2022-03-26 23:39:20 -05:00
parent b514ee30da
commit 154ef3f9a3
6 changed files with 61 additions and 8 deletions
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43
src/engine/platform/amiga.cpp
View file

@ -63,10 +63,20 @@ const char** DivPlatformAmiga::getRegisterSheet() {
return regCheatSheetAmiga;
}
const char* DivPlatformAmiga::getEffectName(unsigned char effect) {
switch (effect) {
case 0x10:
return "10xx: Toggle filter (0 disables; 1 enables)";
break;
}
return NULL;
}
void DivPlatformAmiga::acquire(short* bufL, short* bufR, size_t start, size_t len) {
static int outL, outR;
for (size_t h=start; h<start+len; h++) {
bufL[h]=0;
bufR[h]=0;
outL=0;
outR=0;
for (int i=0; i<4; i++) {
if (chan[i].sample>=0 && chan[i].sample<parent->song.sampleLen) {
chan[i].audSub-=AMIGA_DIVIDER;
@ -102,14 +112,20 @@ void DivPlatformAmiga::acquire(short* bufL, short* bufR, size_t start, size_t le
}
if (!isMuted[i]) {
if (i==0 || i==3) {
bufL[h]+=((chan[i].audDat*chan[i].outVol)*sep1)>>7;
bufR[h]+=((chan[i].audDat*chan[i].outVol)*sep2)>>7;
outL+=((chan[i].audDat*chan[i].outVol)*sep1)>>7;
outR+=((chan[i].audDat*chan[i].outVol)*sep2)>>7;
} else {
bufL[h]+=((chan[i].audDat*chan[i].outVol)*sep2)>>7;
bufR[h]+=((chan[i].audDat*chan[i].outVol)*sep1)>>7;
outL+=((chan[i].audDat*chan[i].outVol)*sep2)>>7;
outR+=((chan[i].audDat*chan[i].outVol)*sep1)>>7;
}
}
}
filter[0][0]+=(filtConst*(outL-filter[0][0]))>>12;
filter[0][1]+=(filtConst*(filter[0][0]-filter[0][1]))>>12;
filter[1][0]+=(filtConst*(outR-filter[1][0]))>>12;
filter[1][1]+=(filtConst*(filter[1][0]-filter[1][1]))>>12;
bufL[h]=filter[0][1];
bufR[h]=filter[1][1];
}
}
@ -299,6 +315,10 @@ int DivPlatformAmiga::dispatch(DivCommand c) {
chan[c.chan].audPos=c.value;
chan[c.chan].setPos=true;
break;
case DIV_CMD_AMIGA_FILTER:
filterOn=c.value;
filtConst=filterOn?filtConstOn:filtConstOff;
break;
case DIV_CMD_GET_VOLMAX:
return 64;
break;
@ -332,7 +352,11 @@ void* DivPlatformAmiga::getChanState(int ch) {
void DivPlatformAmiga::reset() {
for (int i=0; i<4; i++) {
chan[i]=DivPlatformAmiga::Channel();
filter[0][i]=0;
filter[1][i]=0;
}
filterOn=false;
filtConst=filterOn?filtConstOn:filtConstOff;
}
bool DivPlatformAmiga::isStereo() {
@ -372,6 +396,13 @@ void DivPlatformAmiga::setFlags(unsigned int flags) {
sep2=127-((flags>>8)&127);
amigaModel=flags&2;
bypassLimits=flags&4;
if (amigaModel) {
filtConstOff=4000;
filtConstOn=sin(M_PI*8000.0/(double)rate)*4096.0;
} else {
filtConstOff=sin(M_PI*16000.0/(double)rate)*4096.0;
filtConstOn=sin(M_PI*5500.0/(double)rate)*4096.0;
}
}
int DivPlatformAmiga::init(DivEngine* p, int channels, int sugRate, unsigned int flags) {

6
src/engine/platform/amiga.h
View file

@ -68,6 +68,11 @@ class DivPlatformAmiga: public DivDispatch {
bool isMuted[4];
bool bypassLimits;
bool amigaModel;
bool filterOn;
int filter[2][4];
int filtConst;
int filtConstOff, filtConstOn;
int sep1, sep2;
@ -88,6 +93,7 @@ class DivPlatformAmiga: public DivDispatch {
void notifyWaveChange(int wave);
void notifyInsDeletion(void* ins);
const char** getRegisterSheet();
const char* getEffectName(unsigned char effect);
int init(DivEngine* parent, int channels, int sugRate, unsigned int flags);
void quit();
};