Definition byte1 (x : int) : Z :=
  (Z.land (Int.unsigned (Int.shru x (Int.repr 8))) (Int.unsigned (Int.repr 255))).

Lemma byte1_def: byte1 = fun (x : int) => (Z.land (Int.unsigned (Int.shru x (Int.repr 8))) (Int.unsigned (Int.repr 255))).