Definition ror (x: nval) (amount: int) :=
match x with
| Nothing => Nothing
| I m => I (Int.rol m amount)
| All => All
end.

Lemma ror_sound:
forall v w x n,
vagree v w (ror x n) ->
vagree (Val.ror v (Vint n)) (Val.ror w (Vint n)) x.