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YM2610(B): use f-num/block baseFreq calculation

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also allow for different octave boundary f-nums depending on chip clock
This commit is contained in:
tildearrow 2022-05-10 02:22:08 -05:00
parent da71a6a804
commit 5e14177e4e
12 changed files with 198 additions and 170 deletions
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12
src/engine/engine.cpp
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@ -993,19 +993,24 @@ double DivEngine::calcBaseFreq(double clock, double divider, int note, bool peri
}
unsigned short DivEngine::calcBaseFreqFNumBlock(double clock, double divider, int note, int bits) {
double tuning=song.tuning;
if (tuning<400.0) tuning=400.0;
if (tuning>500.0) tuning=500.0;
int bf=calcBaseFreq(clock,divider,note,false);
int boundaryBottom=tuning*pow(2.0,0.25)*(divider/clock);
int boundaryTop=2.0*tuning*pow(2.0,0.25)*(divider/clock);
int block=note/12;
if (block<0) block=0;
if (block>7) block=7;
bf>>=block;
if (bf<0) bf=0;
// octave boundaries
while (bf>0 && bf<644 && block>0) {
while (bf>0 && bf<boundaryBottom && block>0) {
bf<<=1;
block--;
}
if (bf>1288) {
while (block<7) {
if (bf>boundaryTop) {
while (block<7 && bf>boundaryTop) {
bf>>=1;
block++;
}
@ -1013,6 +1018,7 @@ unsigned short DivEngine::calcBaseFreqFNumBlock(double clock, double divider, in
bf=(1<<bits)-1;
}
}
logV("f-num: %d block: %d",bf,block);
return bf|(block<<bits);
}