a chebyshev 4n bandpass filter with control for cutoff frequency and ripple.

this type of a digital filter is to be found in renoise native effects.
i like it very much and i always wanted to have it on ios.
so i asked ai if they were familiar with the renoise thing. they said sure and here we are.

it is a bit cpu hungry as it is now.
any optimisation attempts somehow killed the sound. so i let go.