(** ** Properties of rotations *)

(* Specifications: *)
Lemma bits_rol:
forall x y i,
0 <= i < zwordsize ->
testbit (rol x y) i = testbit x ((i - unsigned y) mod zwordsize).
Lemma bits_ror:
forall x y i,
0 <= i < zwordsize ->
testbit (ror x y) i = testbit x ((i + unsigned y) mod zwordsize).