Definition compat_pointer_chunks (chunk1 chunk2: memory_chunk) : Prop :=
  match chunk1, chunk2 with
  | (Mint32 | Many32), (Mint32 | Many32) => True
  | (Mint64 | Many64), (Mint64 | Many64) => True
  | _, _ => False
  end.

Lemma setN_concat: forall bytes1 bytes2 ofs c, setN (bytes1 ++ bytes2) ofs c = setN bytes2 (ofs + Z.of_nat (length bytes1)) (setN bytes1 ofs c).