Bug in NATV implementation

[pachuco]

Stray bass on the loose in crestest.mid, channel 1, with Electric Piano 1 patch from bnk_common.bin.

https://files.catbox.moe/si7y9x.mid#crestest.mid
https://files.catbox.moe/eea12y.ogg#subbass_massage.ogg

First half is implementation as is in esfmbank(probably the driver as well).
Second half is implementation in XP x86 midi driver.

[pachuco]

https://github.com/leecher1337/esfmbank/blob/main/src/essplaymid/NATV.C#L717

Changing to:

if (gBankMem[offset + 5] & 0x10) // signed?
transpose |= ~0x7F;

seems to fix things. Inb4 I've broken something somewhere else.

[pachuco]

Ok, the above fix is alright, but I am also encountering my old friend, the broken channel volume.
https://files.catbox.moe/c33xgn.mid#meteor_herd.mid the fade at the end.

Maybe somewhere along the path of
MidiMessage() ->
case 0xb0: ->
case 7: ->
NATV_CalcNewVolume() ->
NATV_CalcVolume()

[leecher1337]

Yeah, you are definitely right about first fix. About second problem:
I think

https://github.com/leecher1337/esfmbank/blob/main/src/essplaymid/NATV.C#L430

fmwrite(i * 32 + j * 8 + 1, NATV_CalcVolume(voice->reg1[j], (voice->bVelocity & 3), voice->bChannel));

should be

fmwrite(i * 32 + j * 8 + 1, NATV_CalcVolume(voice->reg1[j], (voice->bVelocity >> (j*2)) & 3, voice->bChannel));

Does it help?

[pachuco]

Yes it does. It also fixes intro here.

https://files.catbox.moe/mb52gl.MID#NOSTALGY.MID

[pachuco]

There MIGHT also be a bug in voice stealing. Maybe-probably-perhaps, I'm not sure. I need to faff around and check.

Also, sorry about that overdue pull request. I wish not touch GIT with a 10 foot pole lately.

Edit: probs not

[pachuco]

https://files.catbox.moe/9x1rze.mid#ttd03.mid

In this midi, there is a bug that results in large detuning of the bass channels here, on aarch64(termux) and I think x86-64.
HOWEVER...
I've been able to get aarch64 to compile as a result of a refactoring/stdint-ification, which might have introduced the bug.
That, or there is a subtle bug of the integers that breaks porting.

To that end, I've recorded a bunch of reg-value dumps of above midi. Maybe diffing them helps to tell what borked.
https://files.catbox.moe/x7oq0y.log#ttd03.log (normal or slightly broken)
https://files.catbox.moe/rtitao.log#ttd03_jank.log (very broken)

Edit: Poking through the NATV code, I can only think of pitchbend.