Setup proper bindings for mruby.

- and a lot more stuff.

src/mruby/types.ml

@@ -1,6 +1,31 @@
 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
@@ -11,9 +36,11 @@ module Mrb_state = struct
   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 24472 char)
+  let padding = field typ "padding" (array 24464 char)
   let () = seal typ
 
   let has_error mrb_ptr =
@@ -21,4 +48,5 @@ module Mrb_state = struct
     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