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) 1992-2005, 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 with Unchecked_Conversion;
  49
  50 package Interfaces.CPP is
  51
  52    type Vtable_Ptr is private;
  53
  54    function Expanded_Name (T : Vtable_Ptr) return String;
  55    function External_Tag  (T : Vtable_Ptr) return String;
  56
  57 private
  58    package S   renames System;
  59    package SSE renames System.Storage_Elements;
  60
  61    type Vtable;
  62    type Vtable_Ptr is access all Vtable;
  63
  64    type Type_Specific_Data;
  65    type Type_Specific_Data_Ptr is access all Type_Specific_Data;
  66
  67    --  These subprograms are in the private part. They are never accessed
  68    --  directly except from compiler generated code, which has access to
  69    --  private components of packages via the Rtsfind interface.
  70
  71    procedure CPP_Set_Prim_Op_Address
  72      (T        : Vtable_Ptr;
  73       Position : Positive;
  74       Value    : S.Address);
  75    --  Given a pointer to a dispatch Table (T) and a position in the
  76    --  dispatch Table put the address of the virtual function in it
  77    --  (used for overriding)
  78
  79    function CPP_Get_Prim_Op_Address
  80      (T        : Vtable_Ptr;
  81       Position : Positive)
  82       return     S.Address;
  83    --  Given a pointer to a dispatch Table (T) and a position in the DT
  84    --  this function returns the address of the virtual function stored
  85    --  in it (used for dispatching calls)
  86
  87    procedure CPP_Set_Inheritance_Depth
  88      (T     : Vtable_Ptr;
  89       Value : Natural);
  90    --  Given a pointer to a dispatch Table, stores the value representing
  91    --  the depth in the inheritance tree. Used during elaboration of the
  92    --  tagged type.
  93
  94    function CPP_Get_Inheritance_Depth (T : Vtable_Ptr) return Natural;
  95    --  Given a pointer to a dispatch Table, retreives the value representing
  96    --  the depth in the inheritance tree. Used for membership.
  97
  98    procedure CPP_Set_TSD (T : Vtable_Ptr; Value : S.Address);
  99    --  Given a pointer T to a dispatch Table, stores the address of the
 100    --  record containing the Type Specific Data generated by GNAT
 101
 102    function CPP_Get_TSD (T : Vtable_Ptr) return S.Address;
 103    --  Given a pointer T to a dispatch Table, retreives the address of the
 104    --  record containing the Type Specific Data generated by GNAT
 105
 106    CPP_DT_Prologue_Size : constant SSE.Storage_Count :=
 107                             SSE.Storage_Count
 108                               (2 * (Standard'Address_Size / S.Storage_Unit));
 109    --  Size of the first part of the dispatch table
 110
 111    CPP_DT_Typeinfo_Ptr_Size : constant SSE.Storage_Count :=
 112                             SSE.Storage_Count
 113                               (Standard'Address_Size / System.Storage_Unit);
 114    --  Size of the Typeinfo_Ptr field of the Dispatch Table.
 115
 116    CPP_DT_Entry_Size : constant SSE.Storage_Count :=
 117                          SSE.Storage_Count
 118                            (1 * (Standard'Address_Size / S.Storage_Unit));
 119    --  Size of each primitive operation entry in the Dispatch Table.
 120
 121    CPP_TSD_Prologue_Size : constant SSE.Storage_Count :=
 122                              SSE.Storage_Count
 123                                (4 * (Standard'Address_Size / S.Storage_Unit));
 124    --  Size of the first part of the type specific data
 125
 126    CPP_TSD_Entry_Size : constant SSE.Storage_Count :=
 127                           SSE.Storage_Count
 128                             (1 * (Standard'Address_Size / S.Storage_Unit));
 129    --  Size of each ancestor tag entry in the TSD
 130
 131    procedure CPP_Inherit_DT
 132     (Old_T       : Vtable_Ptr;
 133      New_T       : Vtable_Ptr;
 134      Entry_Count : Natural);
 135    --  Entry point used to initialize the DT of a type knowing the
 136    --  tag of the direct ancestor and the number of primitive ops that are
 137    --  inherited (Entry_Count).
 138
 139    procedure CPP_Inherit_TSD
 140      (Old_TSD : S.Address;
 141       New_Tag : Vtable_Ptr);
 142    --  Entry point used to initialize the TSD of a type knowing the
 143    --  TSD of the direct ancestor.
 144
 145    function CPP_CW_Membership (Obj_Tag, Typ_Tag : Vtable_Ptr) return Boolean;
 146    --  Given the tag of an object and the tag associated to a type, return
 147    --  true if Obj is in Typ'Class.
 148
 149    procedure CPP_Set_External_Tag (T : Vtable_Ptr; Value : S.Address);
 150    --  Set the address of the string containing the external tag
 151    --  in the Dispatch table
 152
 153    function CPP_Get_External_Tag (T : Vtable_Ptr) return S.Address;
 154    --  Retrieve the address of a null terminated string containing
 155    --  the external name
 156
 157    procedure CPP_Set_Expanded_Name (T : Vtable_Ptr; Value : S.Address);
 158    --  Set the address of the string containing the expanded name
 159    --  in the Dispatch table
 160
 161    function CPP_Get_Expanded_Name (T : Vtable_Ptr) return S.Address;
 162    --  Retrieve the address of a null terminated string containing
 163    --  the expanded name
 164
 165    procedure CPP_Set_Remotely_Callable (T : Vtable_Ptr; Value : Boolean);
 166    --  Since the notions of spec/body distinction and categorized packages
 167    --  do not exist in C, this procedure will do nothing
 168
 169    function CPP_Get_Remotely_Callable (T : Vtable_Ptr) return Boolean;
 170    --  This function will always return True for the reason explained above
 171
 172    procedure CPP_Set_RC_Offset (T : Vtable_Ptr; Value : SSE.Storage_Offset);
 173    --  Sets the Offset of the implicit record controller when the object
 174    --  has controlled components. Set to O otherwise.
 175
 176    function CPP_Get_RC_Offset (T : Vtable_Ptr) return SSE.Storage_Offset;
 177    --  Return the Offset of the implicit record controller when the object
 178    --  has controlled components. O otherwise.
 179
 180    function Displaced_This
 181     (Current_This : S.Address;
 182      Vptr         : Vtable_Ptr;
 183      Position     : Positive)
 184      return         S.Address;
 185    --  Compute the displacement on the "this" pointer in order to be
 186    --  compatible with MI.
 187    --  (used for virtual function calls)
 188
 189    function TSD (T : Vtable_Ptr) return Type_Specific_Data_Ptr;
 190    --  This function is conceptually equivalent to Get_TSD, but
 191    --  returning a Type_Specific_Data_Ptr type (rather than an Address)
 192    --  simplifies the implementation of the other subprograms.
 193
 194    type Addr_Ptr is access System.Address;
 195
 196    function To_Address is
 197      new Unchecked_Conversion (Vtable_Ptr, System.Address);
 198
 199    function To_Addr_Ptr is
 200       new Unchecked_Conversion (System.Address, Addr_Ptr);
 201
 202    function To_Type_Specific_Data_Ptr is
 203      new Unchecked_Conversion (System.Address, Type_Specific_Data_Ptr);
 204
 205    pragma Inline (CPP_Set_Prim_Op_Address);
 206    pragma Inline (CPP_Get_Prim_Op_Address);
 207    pragma Inline (CPP_Set_Inheritance_Depth);
 208    pragma Inline (CPP_Get_Inheritance_Depth);
 209    pragma Inline (CPP_Set_TSD);
 210    pragma Inline (CPP_Get_TSD);
 211    pragma Inline (CPP_Inherit_DT);
 212    pragma Inline (CPP_CW_Membership);
 213    pragma Inline (CPP_Set_External_Tag);
 214    pragma Inline (CPP_Get_External_Tag);
 215    pragma Inline (CPP_Set_Expanded_Name);
 216    pragma Inline (CPP_Get_Expanded_Name);
 217    pragma Inline (CPP_Set_Remotely_Callable);
 218    pragma Inline (CPP_Get_Remotely_Callable);
 219    pragma Inline (Displaced_This);
 220    pragma Inline (TSD);
 221
 222 end Interfaces.CPP;