if N == 1 and M == 1:
decode_16bit_immed_mode(insn)
else:
+ # see immediate opcodes table
decode_16bit_nonimmed_mode(insn)
From this point onwards each of the decode_xx functions perform straightforward combinatorial decoding of the 16 bits of "insn". In sone cases this involves further analysis of bit 1, in some cases (Cmaj.m = 0b010.1) even further deep-dive decoding is required (CR ops). *All* of it is entirely combinatorial and at **no time** involves changing of, or interaction with, or disruption of, the Phase 1 determination of Length+Mode (that has *already taken place* in an earlier decoding pipeline time-schedule)