(** ** Properties of [loadbytes]. *)
(** [loadbytes] succeeds if and only if we have read permissions on the accessed memory area. *)

(** Composing or decomposing [loadbytes] operations at adjacent addresses. *)
Axiom loadbytes_concat:
forall m b ofs n1 n2 bytes1 bytes2,
loadbytes m b ofs n1 = Some bytes1 ->
loadbytes m b (ofs + n1) n2 = Some bytes2 ->
n1 >= 0 -> n2 >= 0 ->
loadbytes m b ofs (n1 + n2) = Some(bytes1 ++ bytes2).