Base register (or M680xRegisterId.invalid if irrelevant)
If flag M680xFlag.postIncDec set it is post inc-/decrement otherwise pre inc-/decrement/// 8-bit flags (see above)
Inc. or dec. value: 0: no inc-/decrement, 1 .. 8: increment by 1 .. 8, -1 .. -8: decrement by 1 .. 8.
5-,8- or 16-bit offset
= offset addr. if baseReg.id == M680xRegisterId.pc. Calculated as offset + PC
Offset width in bits for indexed addressing
Offset register (or M680xRegisterId.invalid if irrelevant)
Instruction's operand referring to indexed addressing