type cbitmap

external cbitmap_create : int -> cbitmap = "caml_bitmap_create"
external cbitmap_setbit : cbitmap -> int -> int -> unit = "caml_bitmap_setbit"
external cbitmap_resize : cbitmap -> int -> cbitmap = "caml_bitmap_resize"


type bitmap = { mutable data : cbitmap;
		mutable size : int;
		mutable capacity : int; (* in bits *)
	      }
let bitmap_increment = 4096

let bitmap_create () =
  {
    data = cbitmap_create bitmap_increment;
    size = 0;
    capacity = bitmap_increment;
  }

let bitmap_push_back b i =
  if b.size >= b.capacity then begin
    let ncap = b.capacity + bitmap_increment in
    b.data <- cbitmap_resize b.data ncap;
    b.capacity <- ncap;
  end;
  cbitmap_setbit b.data b.size i;
  b.size <- b.size + 1


type t
external bp_construct : cbitmap -> int -> t = "caml_bp_construct"
external alloc_stats : unit -> int = "caml_bp_alloc_stats"
external save : t -> Unix.file_descr -> unit = "caml_bp_save"
external load : Unix.file_descr -> t = "caml_bp_load"
external first_child : t -> int -> int = "caml_bp_first_child" "noalloc"
external next_sibling : t -> int -> int = "caml_bp_next_sibling" "noalloc"
external preorder_rank : t -> int -> int = "caml_bp_preorder_rank" "noalloc"

let create bm = bp_construct bm.data bm.size