< base register (or M680X_REG_INVALID if
< 0: no inc-/decrement < 1 .. 8: increment by 1 .. 8 < -1 .. -8: decrement by 1 .. 8 < if flag M680X_IDX_POST_INC_DEC set it is post < inc-/decrement otherwise pre inc-/decrement +////< 8-bit flags (see above
< inc. or dec. value:
< irrelevant) +////< 5-,8- or 16-bit offset. See also offset_bits
< = offset addr. if base_reg == M680X_REG_PC.
< calculated as offset + PC +////< offset width in bits for indexed addressin
< irrelevant) +////< offset register (or M680X_REG_INVALID i
Instruction's operand referring to indexed addressing