------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
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--                       I N T E R F A C E S . C P P                        --
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------------------------------------------------------------------------------

--  This is the OpenVMS/Alpha DEC C++ (cxx) version of this package

with Ada.Tags;                use Ada.Tags;
with System;                  use System;
with System.Storage_Elements; use System.Storage_Elements;
with Unchecked_Conversion;

package body Interfaces.CPP is

   subtype Cstring is String (Positive);
   type Cstring_Ptr is access all Cstring;
   type Tag_Table is array (Natural range <>) of Vtable_Ptr;
   pragma Suppress_Initialization (Tag_Table);

   type Type_Specific_Data is record
      Idepth        : Natural;
      Expanded_Name : Cstring_Ptr;
      External_Tag  : Cstring_Ptr;
      HT_Link       : Tag;
      Ancestor_Tags : Tag_Table (Natural);
   end record;

   type Vtable_Entry is record
     Pfn    : System.Address;
   end record;

   type Type_Specific_Data_Ptr is access all Type_Specific_Data;
   type Vtable_Entry_Array is array (Positive range <>) of Vtable_Entry;

   type VTable is record
      Prims_Ptr : Vtable_Entry_Array (Positive);
      TSD       : Type_Specific_Data_Ptr;
      --  Location of TSD is unknown so it got moved here to be out of the
      --  way of Prims_Ptr. Find it later. ???
   end record;

   --------------------------------------------------------
   -- Unchecked Conversions for Tag, Vtable_Ptr, and TSD --
   --------------------------------------------------------

   function To_Type_Specific_Data_Ptr is
     new Unchecked_Conversion (Address, Type_Specific_Data_Ptr);

   function To_Address is
     new Unchecked_Conversion (Type_Specific_Data_Ptr, Address);

   ---------------------------------------------
   -- Unchecked Conversions for String Fields --
   ---------------------------------------------

   function To_Cstring_Ptr is
     new Unchecked_Conversion (Address, Cstring_Ptr);

   function To_Address is
     new Unchecked_Conversion (Cstring_Ptr, Address);

   -----------------------
   -- Local Subprograms --
   -----------------------

   function Length (Str : Cstring_Ptr) return Natural;
   --  Length of string represented by the given pointer (treating the
   --  string as a C-style string, which is Nul terminated).

   --------------------
   -- Displaced_This --
   --------------------

   function Displaced_This
    (Current_This : System.Address;
     Vptr         : Vtable_Ptr;
     Position     : Positive) return System.Address
   is
      pragma Warnings (Off, Vptr);
      pragma Warnings (Off, Position);
   begin
      return Current_This;
      --        + Storage_Offset (Vptr.Prims_Ptr (Position).Delta1);
      --  why is above line commented out ???
   end Displaced_This;

   -----------------------
   -- CPP_CW_Membership --
   -----------------------

   function CPP_CW_Membership
     (Obj_Tag : Vtable_Ptr;
      Typ_Tag : Vtable_Ptr) return Boolean
   is
      Pos : constant Integer := Obj_Tag.TSD.Idepth - Typ_Tag.TSD.Idepth;
   begin
      return Pos >= 0 and then Obj_Tag.TSD.Ancestor_Tags (Pos) = Typ_Tag;
   end CPP_CW_Membership;

   ---------------------------
   -- CPP_Get_Expanded_Name --
   ---------------------------

   function CPP_Get_Expanded_Name (T : Vtable_Ptr) return Address is
   begin
      return To_Address (T.TSD.Expanded_Name);
   end CPP_Get_Expanded_Name;

   --------------------------
   -- CPP_Get_External_Tag --
   --------------------------

   function CPP_Get_External_Tag (T : Vtable_Ptr) return Address is
   begin
      return To_Address (T.TSD.External_Tag);
   end CPP_Get_External_Tag;

   -------------------------------
   -- CPP_Get_Inheritance_Depth --
   -------------------------------

   function CPP_Get_Inheritance_Depth (T : Vtable_Ptr) return Natural is
   begin
      return T.TSD.Idepth;
   end CPP_Get_Inheritance_Depth;

   -----------------------
   -- CPP_Get_RC_Offset --
   -----------------------

   function CPP_Get_RC_Offset (T : Vtable_Ptr) return SSE.Storage_Offset is
      pragma Warnings (Off, T);
   begin
      return 0;
   end CPP_Get_RC_Offset;

   -----------------------------
   -- CPP_Get_Prim_Op_Address --
   -----------------------------

   function CPP_Get_Prim_Op_Address
     (T        : Vtable_Ptr;
      Position : Positive) return Address
   is
   begin
      return T.Prims_Ptr (Position).Pfn;
   end CPP_Get_Prim_Op_Address;

   -------------------------------
   -- CPP_Get_Remotely_Callable --
   -------------------------------

   function CPP_Get_Remotely_Callable (T : Vtable_Ptr) return Boolean is
      pragma Warnings (Off, T);
   begin
      return True;
   end CPP_Get_Remotely_Callable;

   -----------------
   -- CPP_Get_TSD --
   -----------------

   function CPP_Get_TSD  (T : Vtable_Ptr) return Address is
   begin
      return To_Address (T.TSD);
   end CPP_Get_TSD;

   --------------------
   -- CPP_Inherit_DT --
   --------------------

   procedure CPP_Inherit_DT
    (Old_T       : Vtable_Ptr;
     New_T       : Vtable_Ptr;
     Entry_Count : Natural)
   is
   begin
      if Old_T /= null then
         New_T.Prims_Ptr (1 .. Entry_Count) :=
           Old_T.Prims_Ptr (1 .. Entry_Count);
      end if;
   end CPP_Inherit_DT;

   ---------------------
   -- CPP_Inherit_TSD --
   ---------------------

   procedure CPP_Inherit_TSD
     (Old_TSD : Address;
      New_Tag : Vtable_Ptr)
   is
      TSD : constant Type_Specific_Data_Ptr :=
              To_Type_Specific_Data_Ptr (Old_TSD);

      New_TSD : Type_Specific_Data renames New_Tag.TSD.all;

   begin
      if TSD /= null then
         New_TSD.Idepth := TSD.Idepth + 1;
         New_TSD.Ancestor_Tags (1 .. New_TSD.Idepth)
           := TSD.Ancestor_Tags (0 .. TSD.Idepth);
      else
         New_TSD.Idepth := 0;
      end if;

      New_TSD.Ancestor_Tags (0) := New_Tag;
   end CPP_Inherit_TSD;

   ---------------------------
   -- CPP_Set_Expanded_Name --
   ---------------------------

   procedure CPP_Set_Expanded_Name (T : Vtable_Ptr; Value : Address) is
   begin
      T.TSD.Expanded_Name := To_Cstring_Ptr (Value);
   end CPP_Set_Expanded_Name;

   --------------------------
   -- CPP_Set_External_Tag --
   --------------------------

   procedure CPP_Set_External_Tag (T : Vtable_Ptr; Value : Address) is
   begin
      T.TSD.External_Tag := To_Cstring_Ptr (Value);
   end CPP_Set_External_Tag;

   -------------------------------
   -- CPP_Set_Inheritance_Depth --
   -------------------------------

   procedure CPP_Set_Inheritance_Depth
     (T     : Vtable_Ptr;
      Value : Natural)
   is
   begin
      T.TSD.Idepth := Value;
   end CPP_Set_Inheritance_Depth;

   -----------------------------
   -- CPP_Set_Prim_Op_Address --
   -----------------------------

   procedure CPP_Set_Prim_Op_Address
     (T        : Vtable_Ptr;
      Position : Positive;
      Value    : Address)
   is
   begin
      T.Prims_Ptr (Position).Pfn := Value;
   end CPP_Set_Prim_Op_Address;

   -----------------------
   -- CPP_Set_RC_Offset --
   -----------------------

   procedure CPP_Set_RC_Offset (T : Vtable_Ptr; Value : SSE.Storage_Offset) is
      pragma Warnings (Off, T);
      pragma Warnings (Off, Value);
   begin
      null;
   end CPP_Set_RC_Offset;

   -------------------------------
   -- CPP_Set_Remotely_Callable --
   -------------------------------

   procedure CPP_Set_Remotely_Callable (T : Vtable_Ptr; Value : Boolean) is
      pragma Warnings (Off, T);
      pragma Warnings (Off, Value);
   begin
      null;
   end CPP_Set_Remotely_Callable;

   -----------------
   -- CPP_Set_TSD --
   -----------------

   procedure CPP_Set_TSD (T : Vtable_Ptr; Value : Address) is
   begin
      T.TSD := To_Type_Specific_Data_Ptr (Value);
   end CPP_Set_TSD;

   -------------------
   -- Expanded_Name --
   -------------------

   function Expanded_Name (T : Vtable_Ptr) return String is
      Result : constant Cstring_Ptr := T.TSD.Expanded_Name;
   begin
      return Result (1 .. Length (Result));
   end Expanded_Name;

   ------------------
   -- External_Tag --
   ------------------

   function External_Tag (T : Vtable_Ptr) return String is
      Result : constant Cstring_Ptr := T.TSD.External_Tag;
   begin
      return Result (1 .. Length (Result));
   end External_Tag;

   ------------
   -- Length --
   ------------

   function Length (Str : Cstring_Ptr) return Natural is
      Len : Integer := 1;

   begin
      while Str (Len) /= ASCII.Nul loop
         Len := Len + 1;
      end loop;

      return Len - 1;
   end Length;

end Interfaces.CPP;