LLBasic - a YM2413 meta-engine
by Shiru 01'2018


This is a very basic YM2413 (OPLL) FM synth engine, designed to test 
grounds for other platforms support in 1tracker. 

The engine features 6 channels of tone, built-in instruments only (no 
custom instrument), with volume and detune, 5 built-in percussion sounds 
with volume. There is no effects, just plain regular notes. 

It is not a real engine as in coded in Z80 assembly or such. Instead, it 
is 1tracker script that produces a stream of YM2413 register writes inside
a VGM file container. 


The columns are:

Sp T1 dVIn T2 dVIn T3 dVIn T4 dVIn T5 dVIn T6 dVIn BSTCH
.. ....... ....... ....... ....... ....... ....... .....
   |     | |     | |     | |     | |     | |     | |   |
   +-ch1-+ +-ch2-+ +-ch3-+ +-ch4-+ +-ch5-+ +-ch6-+ +perc
   
   Sp : Speed, 1..16
   
T1-T6 : Tone channels, has uniform capabilities
     Tn : Note, C-0..B-8
      d : Detune, 1..9
      V : Volume, 1..9
     In : Instrument, 1..15
	 
BSTCH : Percussion section
      B : Bass Drum trigger, 1..9 (volume)
      S : Snare Drum trigger, 1..9
      T : Tom trigger, 1..9
      C : Cymbal trigger, 1..9
      H : Hi-hat trigger, 1..9
