I'd suggest looking at code for how people have done it other projects, there are some really good open source implementations of those sorts of things in langu

I'd suggest looking at code for how people have done it other projects, there are some really good open source implementations of those sorts of things in languages like Csound, PureData, Faust, SuperCollider, etc. Csound is old school, but the band limited VCO is brilliant (the vco2 opcode)