(** Expressing 64-bit operations in terms of 32-bit operations *)

Lemma decompose_shr_2:
forall xh xl y,
Int.zwordsize <= Int.unsigned y < zwordsize ->
shr' (ofwords xh xl) y =
ofwords (Int.shr xh (Int.sub Int.iwordsize Int.one))
(Int.shr xh (Int.sub y Int.iwordsize)).