Remark two_p_range:
forall n,
0 <= n < zwordsize ->
0 <= two_p n <= max_unsigned.
Remark Z_one_bits_zero:
forall n i, Z_one_bits n 0 i = nil.
Remark Z_one_bits_two_p:
forall n x i,
0 <= x < Z.of_nat n ->
Z_one_bits n (two_p x) i = (i + x) :: nil.

Lemma is_power2_two_p:
forall n, 0 <= n < zwordsize ->
is_power2 (repr (two_p n)) = Some (repr n).