open Ctypes
open Foreign

module Mrb_value = struct
  type t

  let typ : t structure typ = structure "mrb_value"
  let value = field typ "w" uintptr_t
  let () = seal typ
end

module Mrb_sym = struct
  type t

  let typ = uint32_t
end

module Mrb_class = struct
  type t
  type class_ptr = t structure ptr

  let typ : t structure typ = structure "RClass"

  (* as it builds by default on x86_64 linux *)
  let padding = field typ "padding" (array 40 char)
  let () = seal typ
end

module Mrb_state = struct
  type t
  type mrb_ptr = t structure ptr

  let typ : t structure typ = structure "mrb_state"
  let jmp = field typ "jmp" (ptr void)
  let c = field typ "c" (ptr void)
  let root_c = field typ "root_c" (ptr void)
  let globals = field typ "globals" (ptr void)
  let exc = field typ "exc" (ptr void)
  let top_self = field typ "top_self" (ptr void)
  let object_class = field typ "object_class" (ptr Mrb_class.typ)

  (* as it builds by default on x86_64 linux *)
  let padding = field typ "padding" (array 24464 char)
  let () = seal typ

  let has_error mrb_ptr =
    let exc_val = getf !@mrb_ptr exc in
    not (is_null exc_val)

  let clear_error mrb_ptr = setf !@mrb_ptr exc null
  let get_object_class mrb_ptr = getf !@mrb_ptr object_class
end