Field_ops_lib.Modulo_subtractor_pipeComputes (a - b mod P) over multiple pipeline stages.
val create : 
  clock:Hardcaml.Signal.t ->
  enable:Hardcaml.Signal.t ->
  stages:int ->
  p:Z.t ->
  Hardcaml.Signal.t ->
  Hardcaml.Signal.t ->
  Hardcaml.Signal.tmodule With_interface (M : sig ... end) : sig ... end