(*
Definition size_chunk (chunk: memory_chunk) : Z :=
  match chunk with
  | Mint8signed => 1
  | Mint8unsigned => 1
  | Mint16signed => 2
  | Mint16unsigned => 2
  | Mint32 => 4
  | Mfloat32 => 4
  | Mfloat64 => 8
  | Mfloat64al32 => 4
  end.
*)

Remark size_chunk_pos:
  forall chunk1, size_chunk chunk1 > 0.

Lemma zero_in_chunk: forall ch, 0 <= 0 < size_chunk ch.