Require Recdef.
Require Coq.Strings.String.
Require Coq.Strings.Ascii.
(* LINEAR-TIME FUNCTIONAL VERSION OF SHA256 *)
Function zeros (n : Z) {measure Z.to_nat n} : list Int.int :=
if Z.gtb n 0 then Int.zero :: zeros (n-1) else nil.

Lemma length_map2_add_rnd_64:
forall regs w,
length regs = 8 ->
length (map2 Int.add regs (rnd_64 regs K256 w)) = 8.