notes:
- when offset is given as token+constant, take the offset of the *last* byte of
the token rather than the first when calculating the offset
- everything is in little endian; jukebox gold was made for 8086
instrument
offset | size | token | description
----------|----------|-------|--------------------------------------------------
0 | 3 | | flags uuuuuuuu uuuuuuuu uuuuuuuf
| | | u - unknown
| | | f - instrument is a pcm sample. if unset, the
| | | instrument is found in opl3.bnk (? TODO)
3 | 11 | | null padded instrument name
adlib instrument
offset | size | token | description
----------|----------|-------|--------------------------------------------------
0 | 28 | | 0xAA repeated
28 | 28 | | unknown (possibly opl3 parameters?)
main header
offset | size | token | description
----------|----------|-------|--------------------------------------------------
0 | 27 | | ascii signature '>>> VC2, (C) ADLIB INC <<<\x0E'
27 | 1 | | always 0
28 | 1 | | unknown
29 | 3 | | always 0, 2, 0
32 | 2 | | unknown, likely tempo?
34 | 1 | | unknown
35 | 2 | | always 1, 0
37 | 1 | | unknown
38 | 2 | | always 0
40 | 24 | | unknown
64 | 22 | | 0x7F repeated
86 | 40 | | null padded song name
126 | 1 | | unknown
127 | 2 | | always 0xFFFF
129 | 23 | | always 0
152 | 2 | | unknown
154 | 2 | | size of song data
156 | 274 | | unknown
430 | 2 | is | number of instruments
432 | [is]*14 | it | instrument table
it+1 | itn*56 | ait | adlib instrument table. itn is calculated as the
| | | number of instruments that do not have flag f set
ait+1 |