S1 DAC Extraction

Code (Text):

1.     dreg = 0x80;
2.  
3.     for(I = 0; I < datLen; I++, drPtrDac++)
4.     {
5.  &nbsp;datL = *drPtrDac;
6.  &nbsp;datR = *drPtrDac;
7.  
8.  &nbsp;datL &= 0xF0;
9.  &nbsp;datL = datL >> 4;
10.  &nbsp;datL += 0x22;
11.  &nbsp;datL = decZ80[datL];
12.  &nbsp;datL += dreg;
13.  &nbsp;dreg = datL;
14.  
15.  &nbsp;*buf++ = dreg;
16.  
17.  &nbsp;datR &= 0x0F;
18.  &nbsp;datR += 0x22;
19.  &nbsp;datR = decZ80[datR];
20.  &nbsp;datR += dreg;
21.  &nbsp;dreg = datR;
22.  
23.  &nbsp;*buf++ = dreg;
24.     }

That produced this.

My guess is that each instrument has its own sample rate. Each time I think I've figured out Sonic 1 DAC, something trips me up. For example, the above code was only supposed to decode the bass drum sample. It didn't, and it's an exact C port of the Z80 code. :-/ Yucky.

I'm in a question answering mood. Ask me something about Sonic 1 music. I'll answer it if I can.