Definition store_byte_list m b ofs lv :=
Mem.storebytes m b ofs (concat (map (encode_val Mint8unsigned) lv)).

Lemma has_ext_join : forall {Z} phi1 phi2 phi3 (z1 z2 : Z) (Hext : nth O (ghost_of phi1) None = Some (ext_ghost z1, NoneP))
(Hj : join phi1 phi2 phi3) (Hrest : joins (ghost_of phi3) [Some (ext_ref z2, NoneP)]),
z1 = z2 /\ nth O (ghost_of phi3) None = Some (ext_ghost z1, NoneP).