Clobbering of PORTAMENTO_CTRL on "reset all controllers"

[rianhunter]

FluidSynth version

$ fluidsynth --version
FluidSynth runtime version 2.1.7
Copyright (C) 2000-2021 Peter Hanappe and others.
Distributed under the LGPL license.
SoundFont(R) is a registered trademark of E-mu Systems, Inc.

FluidSynth executable version 2.1.7
Sample type=double

Describe the bug

When handling CC#121 "reset all controllers" fluidsynth will clobber PORTAMENTO_CTRL to zero without setting it to INVALID_NOTE using fluid_channel_clear_portamento. This will cause the next portamento to glide from midi note 0.

Expected behavior

I'm not sure what the intended behavior is supposed to be but at the bare minimum the PORTAMENTO_CTRL should not be clobbered without invalidating it. Either it should be invalidated or left alone.

Steps to reproduce

1. Send note on on middle C (60)
2. send reset all controllers CC#121
3. Enable portamento (send non-zero to CC#5)
4. Enable portament footswitch (send 127 to CC#65)
5. Enable legato footswitch (send 127 to CC#68)
6. send note on on C5 (72)

You will notice that it glides from midi note 0 instead of midi note 60. It should glide from midi note 60.

Additional context

The offending code is in fluid_channel_init_ctrl()

[rianhunter]

After looking more into how "reset all controllers" is intended to be used, it's my opinion that PORTAMENTO_CTRL should be invalidated. #1049 (comment)

[derselbst]

I guess PORTAMENTO_CTRL should only be invalidated if Portamento is enabled. That's because PORTAMENTO_CTRL could be used as modulator source. And I'm afraid that unconditionally invalidating it would result in some audible glitches.

[derselbst]

Nevermind. I'll unconditionally invalidate it and take care of INVALID_NOTE separately.

[derselbst]

Same!