bfin emulator bugs, new modules, assorted DSP inc softclip svf

[ghost]

Nothing that should be controversial in here, apart from the changes to svf code. Those could potentially affect @catfact's original modules and I admit haven't actually tested lines/waves/dsyn since making the changes but I believe old svf code was just not quite right. I'll try and get some testing done tomorrow evening. Maybe also ask for help with this on the forum...

This pull-request addresses bugs in bfin emu (see #245)

I'm claiming svf changes address these three issues:

#147
#145
#101

not actually bothering to over-sample the svf in monosynth module, ~6kHz upper limit is something I'll live with, seeing as it prob also makes this code run faster... Original oversampled version should still work exactly as before, though the code was reordered a bit to make the built-in mixer optional...

oh and there are three new modules - all works in progress but hey...

[catfact]

hot damn. fantastic. i'm going to test the old modules about before merging, though i certainly don't forsee any issues having these changes on the dev branch.

[ghost]

note to self: don't forget to add the old svf wrapping rq functionality back in & add a dsyn param to flick this feature on/off for that module.

[catfact]

ehh, i don't think that's really necessary. i was being a bit facetious, surely better to have RQ parameter work as expected in all cases.

[ghost]

I really like the idea that this 'bug' is also a feature! (kinda like the frequency wrapping 'bug' on DX7 I read about somewhere)

It's 5 minutes work to make that change - no regressions for the sake of 'correctness'! Look here:
https://github.com/rick-monster/aleph/blob/dev_rebased/dsp/filter_svf.c#L45-L89
2 completely arbitrary distortion flavours. One more doesn't hurt...

[catfact]

added ricks_tricks to lines/dsyn makefiles, so they compile. sounds fine!

[catfact]

btw maybe worth pointing out that waves uses it's own sfv implementation, so it will not benefit. but waves needs work anyways... blech

[ghost]

Maybe I'll try firing waves up in linux emulator - I would bet anyone five bucks (canadian) it will just work after removing any ifdefs from old portaudio wrapper...

[catfact]

the main problems IMO are kinda hardware-specific, i'd guess:

• glitches / drops samples every time a control change happens! really awful. optimization thing.
• truncation in multiply accumulator (i think?) means that tuning values get quantized in an unfortunate manner.

[ghost]

Explain more about the tuning values getting quantized in an unfortunate manner! Maybe open an issue? I had a minor epiphany how to do really long slews with the fract arithmetic primitives - maybe this technique helps:
https://github.com/monome/aleph/blob/dev/dsp/ricks_tricks.c#L310-L326
?

[catfact]

yechh, it's more icky than i thought. opened:
#269