Klang, Klank: Fix initialization

[mtmccrea]

Purpose and Motivation

Part fo the initialization sample fix project, specifically in the OscUGens subset.

Types of changes

• Bug fix

Changes to Klang:

• correct the initial phase (it was off by 1 sample).

Change to Klank:

• Don’t assume init sample is zero—reorganize coeff calc func and ctor to get correct init sample.
• The memory allocation for m_coefs was moved to the Ctor, otherwise, the return statement escapes the Klank_SetCoefs, but not the Ctor, so m_coefs might still be accessed after allocation fails.
• Calculate the correct init sample by calling Klank_next(unit, 1), temporarily setting mFilterLoops and mFilterRemain for the single cycle of initialization.
  • Usually the pattern of calling _next(unit, 1) works, but Klank_next doesn’t actually use the inNumSamples argument, because it uses the looping scheme designed to optimize second-order filter calculations. As a consequence, a full block of calculations are run over which memory assigned for input data is accessed before it’s been written, so it’s running unnecessary calculations with garbage memory.
  • Here’s a small dump from that internal loop:

[Klank_next 133] 0.052083
[Klank_next 144] 0.103113
[Klank_next 155] 5818479576238205845020707127296.000000
[Klank_next 133] 11667158119450385126825574531072.000000
[Klank_next 144] 17284522609726230684285924278272.000000
...

• The last commit removes commented Print statements. I’m not sure what the etiquette is for touching old code for trivial changes, so I can revert this commit if needed.

To-do list

• Code is tested
• All tests are passing (TestUGen_RTAlloc)
• [-] Updated documentation
• This PR is ready for review

[telephon]

Don’t assume init sample is zero—reorganize coeff calc func and ctor to get correct init sample.

just to make sure: if you write

{ Klank.ar(`[[1000], [1], [1]], Impulse.ar(0)) }.play

The Klank does interpret the input as a trigger, right?

[jamshark70]

@telephon --

if you write { Klank.ar(Ref([[1000], [1], [1]]), Impulse.ar(0)) }.play, the Klank does interpret the input as a trigger, right?

[mtmccrea]

Yes, just to show the triggered behavior a bit more clearly, here is
{ Klank.ar(`[[1000], [1], [0.05]], Impulse.ar(0)) }.plot(0.1)