(** Powers of two with exponents given as 32-bit ints *)
Definition one_bits' (x: int) : list Int.int :=
List.map Int.repr (Z_one_bits wordsize (unsigned x) 0).
Definition is_power2' (x: int) : option Int.int :=
match Z_one_bits wordsize (unsigned x) 0 with
| i :: nil => Some (Int.repr i)
| _ => None
end.

Theorem one_bits'_range:
forall x i, In i (one_bits' x) -> Int.ltu i iwordsize' = true.