open Obj

module H = Hashtbl.Make(
  struct
    type t = Obj.t
    let equal = (==)
    let hash o = Hashtbl.hash (magic o : int)
  end)

let node_table = (H.create 257 : unit H.t)

let in_table o = try H.find node_table o; true with Not_found -> false

let add_in_table o = H.add node_table o ()

let reset_table () = H.clear node_table

let size_of_double = size (repr 1.0)

let count = ref 0

let rec traverse t =
  if not (in_table t) then begin
    add_in_table t;
    if is_block t then begin
      let n = size t in
      let tag = tag t in
      if tag < no_scan_tag then begin
	count := !count + 1 + n;
	for i = 0 to n - 1 do
      	  let f = field t i in
	  if is_block f then traverse f
	done
      end else if tag = string_tag then
	count := !count + 1 + n
      else if tag = double_tag then
	count := !count + size_of_double
      else if tag = double_array_tag then
	count := !count + 1 + size_of_double * n
      else
	incr count
    end
  end

let size_w o =
  reset_table ();
  count := 0;
  traverse (repr o);
  !count

let size_b o = (size_w o) * (Sys.word_size / 8)

let size_kb o = (size_b o) / 1024