Fixpoint memory_block' (sh: share) (n: nat) (b: block) (i: Z) : mpred :=
  match n with
  | O => emp
  | S n' => mapsto_ sh (Tint I8 Unsigned noattr) (Vptr b (Ptrofs.repr i))
         * memory_block' sh n' b (i+1)
 end.Definition memory_block'_alt (sh: share) (n: nat) (b: block) (ofs: Z) : mpred :=
 if readable_share_dec sh 
 then VALspec_range (Z_of_nat n) sh (b, ofs)
 else nonlock_permission_bytes sh (b,ofs) (Z.of_nat n).

Lemma mapsto_pointer_void: forall sh t a, eqb_type (Tpointer t a) int_or_ptr_type = false -> eqb_type (Tpointer Tvoid a) int_or_ptr_type = false -> mapsto sh (Tpointer t a) = mapsto sh (Tpointer Tvoid a).