(** ** Properties of [Z_one_bits] and [is_power2]. *)
Fixpoint powerserie (l: list Z): Z :=
match l with
| nil => 0
| x :: xs => two_p x + powerserie xs
end.

(* Specifications: *)
Lemma Z_one_bits_powerserie:
forall x, 0 <= x < modulus -> x = powerserie (Z_one_bits wordsize x 0).
Lemma Z_one_bits_range:
forall x i, In i (Z_one_bits wordsize x 0) -> 0 <= i < zwordsize.
Lemma is_power2_rng:
forall n logn,
is_power2 n = Some logn ->
0 <= unsigned logn < zwordsize.
Theorem is_power2_range:
forall n logn,
is_power2 n = Some logn -> ltu logn iwordsize = true.
Lemma is_power2_correct:
forall n logn,
is_power2 n = Some logn ->
unsigned n = two_p (unsigned logn).