Make it possible to send trigger information to microkorg 2 osc

[xiashj24]

I wanted to make a Karplus-strong osc for microkorg 2, but realized that there is no function to trigger the osc note on.

In NTS-1 there is unit_note_on

In NTS-3 there is touch event.

I propose to use something like unit_note_on(uint8_t voice_index), where voice index corresponds to one of the 8 channels of OSC.

Do you think it is possible? @davis-korgrd

[dukesrg]

Both Note On with pitch and velocity and Note Off per voice callbacks will be appreciated.
E.g. I'm having velocity enabled in drumlogue is highly valuable for my FM64 Yamaha DX emulation.

Otherwise for oscillator start/stop and EG sync unit_runtime_osc_context_t.trigger bit field can be used in mK2.

[xiashj24]

For reference, Drumlogue synth unit uses unit_gate_on and unit_gate_off

logue-sdk/platform/drumlogue/dummy-synth/unit.cc

Line 85 in a3ee2b9

__unit_callback void unit_gate_on(uint8_t velocity) {

[dukesrg]

Drumlogue uses both:

• unit_gate_on/unit_gate_on for internal sequencer gate events.
• unit_note_on/note_on_off/unit_all_notes_off (with NOTE ON pitch) for MIDI IN events.

[davis-korgrd]

Trigger information is sent via the trigger bit array

[dukesrg]

@davis-korgrd looks like trigger bit mask is set only for the first oscillator render call after the Note On and not held until Note Off. Can we have somehow the release event in the code? This limits my FM64 port a lot, since it is not about the release envelope, DX7 have a lot of voices which uses AEG and PEG on release phase.