gcc/ada/i-cpp.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUNTIME COMPONENTS                          --
   4 --                                                                          --
   5 --                       I N T E R F A C E S . C P P                        --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2004, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  Definitions for interfacing to C++ classes
  35
  36 --  This package corresponds to Ada.Tags but applied to tagged types which are
  37 --  are imported from C++ and correspond exactly to a C++ Class. The code that
  38 --  the GNAT front end generates does not know about the structure of the C++
  39 --  dispatch table (Vtable) but always accesses it through the procedural
  40 --  interface defined in this package, thus the implementation of this package
  41 --  (the body) can be customized to another C++ compiler without any change in
  42 --  the compiler code itself as long as this procedural interface is respected.
  43 --  Note that Ada.Tags defines a very similar procedural interface to the
  44 --  regular Ada Dispatch Table.
  45
  46 with System;
  47 with System.Storage_Elements;
  48
  49 package Interfaces.CPP is
  50
  51    package S   renames System;
  52    package SSE renames System.Storage_Elements;
  53
  54    type Vtable_Ptr is private;
  55
  56    function Expanded_Name (T : Vtable_Ptr) return String;
  57    function External_Tag  (T : Vtable_Ptr) return String;
  58
  59 private
  60    --  These subprograms are in the private part. They are never accessed
  61    --  directly except from compiler generated code, which has access to
  62    --  private components of packages via the Rtsfind interface.
  63
  64    procedure CPP_Set_Prim_Op_Address
  65      (T        : Vtable_Ptr;
  66       Position : Positive;
  67       Value    : S.Address);
  68    --  Given a pointer to a dispatch Table (T) and a position in the
  69    --  dispatch Table put the address of the virtual function in it
  70    --  (used for overriding)
  71
  72    function CPP_Get_Prim_Op_Address
  73      (T        : Vtable_Ptr;
  74       Position : Positive)
  75       return     S.Address;
  76    --  Given a pointer to a dispatch Table (T) and a position in the DT
  77    --  this function returns the address of the virtual function stored
  78    --  in it (used for dispatching calls)
  79
  80    procedure CPP_Set_Inheritance_Depth
  81      (T     : Vtable_Ptr;
  82       Value : Natural);
  83    --  Given a pointer to a dispatch Table, stores the value representing
  84    --  the depth in the inheritance tree. Used during elaboration of the
  85    --  tagged type.
  86
  87    function CPP_Get_Inheritance_Depth (T : Vtable_Ptr) return Natural;
  88    --  Given a pointer to a dispatch Table, retreives the value representing
  89    --  the depth in the inheritance tree. Used for membership.
  90
  91    procedure CPP_Set_TSD (T : Vtable_Ptr; Value : S.Address);
  92    --  Given a pointer T to a dispatch Table, stores the address of the
  93    --  record containing the Type Specific Data generated by GNAT
  94
  95    function CPP_Get_TSD (T : Vtable_Ptr) return S.Address;
  96    --  Given a pointer T to a dispatch Table, retreives the address of the
  97    --  record containing the Type Specific Data generated by GNAT
  98
  99    CPP_DT_Prologue_Size : constant SSE.Storage_Count :=
 100                             SSE.Storage_Count
 101                               (1 * (Standard'Address_Size / S.Storage_Unit));
 102    --  Size of the first part of the dispatch table
 103
 104    CPP_DT_Entry_Size : constant SSE.Storage_Count :=
 105                          SSE.Storage_Count
 106                            (1 * (Standard'Address_Size / S.Storage_Unit));
 107    --  Size of each primitive operation entry in the Dispatch Table.
 108
 109    CPP_TSD_Prologue_Size : constant SSE.Storage_Count :=
 110                              SSE.Storage_Count
 111                                (4 * (Standard'Address_Size / S.Storage_Unit));
 112    --  Size of the first part of the type specific data
 113
 114    CPP_TSD_Entry_Size : constant SSE.Storage_Count :=
 115                           SSE.Storage_Count
 116                             (1 * (Standard'Address_Size / S.Storage_Unit));
 117    --  Size of each ancestor tag entry in the TSD
 118
 119    procedure CPP_Inherit_DT
 120     (Old_T       : Vtable_Ptr;
 121      New_T       : Vtable_Ptr;
 122      Entry_Count : Natural);
 123    --  Entry point used to initialize the DT of a type knowing the
 124    --  tag of the direct ancestor and the number of primitive ops that are
 125    --  inherited (Entry_Count).
 126
 127    procedure CPP_Inherit_TSD
 128      (Old_TSD : S.Address;
 129       New_Tag : Vtable_Ptr);
 130    --  Entry point used to initialize the TSD of a type knowing the
 131    --  TSD of the direct ancestor.
 132
 133    function CPP_CW_Membership (Obj_Tag, Typ_Tag : Vtable_Ptr) return Boolean;
 134    --  Given the tag of an object and the tag associated to a type, return
 135    --  true if Obj is in Typ'Class.
 136
 137    procedure CPP_Set_External_Tag (T : Vtable_Ptr; Value : S.Address);
 138    --  Set the address of the string containing the external tag
 139    --  in the Dispatch table
 140
 141    function CPP_Get_External_Tag (T : Vtable_Ptr) return S.Address;
 142    --  Retrieve the address of a null terminated string containing
 143    --  the external name
 144
 145    procedure CPP_Set_Expanded_Name (T : Vtable_Ptr; Value : S.Address);
 146    --  Set the address of the string containing the expanded name
 147    --  in the Dispatch table
 148
 149    function CPP_Get_Expanded_Name (T : Vtable_Ptr) return S.Address;
 150    --  Retrieve the address of a null terminated string containing
 151    --  the expanded name
 152
 153    procedure CPP_Set_Remotely_Callable (T : Vtable_Ptr; Value : Boolean);
 154    --  Since the notions of spec/body distinction and categorized packages
 155    --  do not exist in C, this procedure will do nothing
 156
 157    function CPP_Get_Remotely_Callable (T : Vtable_Ptr) return Boolean;
 158    --  This function will always return True for the reason explained above
 159
 160    procedure CPP_Set_RC_Offset (T : Vtable_Ptr; Value : SSE.Storage_Offset);
 161    --  Sets the Offset of the implicit record controller when the object
 162    --  has controlled components. Set to O otherwise.
 163
 164    function CPP_Get_RC_Offset (T : Vtable_Ptr) return SSE.Storage_Offset;
 165    --  Return the Offset of the implicit record controller when the object
 166    --  has controlled components. O otherwise.
 167
 168    function Displaced_This
 169     (Current_This : S.Address;
 170      Vptr         : Vtable_Ptr;
 171      Position     : Positive)
 172      return         S.Address;
 173    --  Compute the displacement on the "this" pointer in order to be
 174    --  compatible with MI.
 175    --  (used for virtual function calls)
 176
 177    type Vtable;
 178    type Vtable_Ptr is access all Vtable;
 179
 180    pragma Inline (CPP_Set_Prim_Op_Address);
 181    pragma Inline (CPP_Get_Prim_Op_Address);
 182    pragma Inline (CPP_Set_Inheritance_Depth);
 183    pragma Inline (CPP_Get_Inheritance_Depth);
 184    pragma Inline (CPP_Set_TSD);
 185    pragma Inline (CPP_Get_TSD);
 186    pragma Inline (CPP_Inherit_DT);
 187    pragma Inline (CPP_CW_Membership);
 188    pragma Inline (CPP_Set_External_Tag);
 189    pragma Inline (CPP_Get_External_Tag);
 190    pragma Inline (CPP_Set_Expanded_Name);
 191    pragma Inline (CPP_Get_Expanded_Name);
 192    pragma Inline (CPP_Set_Remotely_Callable);
 193    pragma Inline (CPP_Get_Remotely_Callable);
 194    pragma Inline (Displaced_This);
 195
 196 end Interfaces.CPP;