gcc/ada/a-sequio.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUNTIME COMPONENTS                          --
   4 --                                                                          --
   5 --                    A D A . S E Q U E N T I A L _ I O                     --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                            $Revision: 1.14 $
  10 --                                                                          --
  11 --          Copyright (C) 1992-1999, Free Software Foundation, Inc.         --
  12 --                                                                          --
  13 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNAT was originally developed  by the GNAT team at  New York University. --
  32 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 --  This is the generic template for Sequential_IO, i.e. the code that gets
  37 --  duplicated. We absolutely minimize this code by either calling routines
  38 --  in System.File_IO (for common file functions), or in System.Sequential_IO
  39 --  (for specialized Sequential_IO functions)
  40
  41 with Interfaces.C_Streams; use Interfaces.C_Streams;
  42 with System;
  43 with System.File_Control_Block;
  44 with System.File_IO;
  45 with System.Storage_Elements;
  46 with Unchecked_Conversion;
  47
  48 package body Ada.Sequential_IO is
  49
  50    package FIO renames System.File_IO;
  51    package FCB renames System.File_Control_Block;
  52    package SIO renames System.Sequential_IO;
  53    package SSE renames System.Storage_Elements;
  54
  55    SU : constant := System.Storage_Unit;
  56
  57    subtype AP is FCB.AFCB_Ptr;
  58    subtype FP is SIO.File_Type;
  59
  60    function To_FCB is new Unchecked_Conversion (File_Mode, FCB.File_Mode);
  61    function To_SIO is new Unchecked_Conversion (FCB.File_Mode, File_Mode);
  62
  63    -----------
  64    -- Close --
  65    -----------
  66
  67    procedure Close (File : in out File_Type) is
  68    begin
  69       FIO.Close (AP (File));
  70    end Close;
  71
  72    ------------
  73    -- Create --
  74    ------------
  75
  76    procedure Create
  77      (File : in out File_Type;
  78       Mode : in File_Mode := Out_File;
  79       Name : in String := "";
  80       Form : in String := "")
  81    is
  82    begin
  83       SIO.Create (FP (File), To_FCB (Mode), Name, Form);
  84    end Create;
  85
  86    ------------
  87    -- Delete --
  88    ------------
  89
  90    procedure Delete (File : in out File_Type) is
  91    begin
  92       FIO.Delete (AP (File));
  93    end Delete;
  94
  95    -----------------
  96    -- End_Of_File --
  97    -----------------
  98
  99    function End_Of_File (File : in File_Type) return Boolean is
 100    begin
 101       return FIO.End_Of_File (AP (File));
 102    end End_Of_File;
 103
 104    ----------
 105    -- Form --
 106    ----------
 107
 108    function Form (File : in File_Type) return String is
 109    begin
 110       return FIO.Form (AP (File));
 111    end Form;
 112
 113    -------------
 114    -- Is_Open --
 115    -------------
 116
 117    function Is_Open (File : in File_Type) return Boolean is
 118    begin
 119       return FIO.Is_Open (AP (File));
 120    end Is_Open;
 121
 122    ----------
 123    -- Mode --
 124    ----------
 125
 126    function Mode (File : in File_Type) return File_Mode is
 127    begin
 128       return To_SIO (FIO.Mode (AP (File)));
 129    end Mode;
 130
 131    ----------
 132    -- Name --
 133    ----------
 134
 135    function Name (File : in File_Type) return String is
 136    begin
 137       return FIO.Name (AP (File));
 138    end Name;
 139
 140    ----------
 141    -- Open --
 142    ----------
 143
 144    procedure Open
 145      (File : in out File_Type;
 146       Mode : in File_Mode;
 147       Name : in String;
 148       Form : in String := "")
 149    is
 150    begin
 151       SIO.Open (FP (File), To_FCB (Mode), Name, Form);
 152    end Open;
 153
 154    ----------
 155    -- Read --
 156    ----------
 157
 158    procedure Read (File : in File_Type; Item : out Element_Type) is
 159       Siz  : constant size_t := (Item'Size + SU - 1) / SU;
 160       Rsiz : size_t;
 161
 162    begin
 163       FIO.Check_Read_Status (AP (File));
 164
 165       --  For non-definite type or type with discriminants, read size and
 166       --  raise Program_Error if it is larger than the size of the item.
 167
 168       if not Element_Type'Definite
 169         or else Element_Type'Has_Discriminants
 170       then
 171          FIO.Read_Buf
 172            (AP (File), Rsiz'Address, size_t'Size / System.Storage_Unit);
 173
 174          --  For a type with discriminants, we have to read into a temporary
 175          --  buffer if Item is constrained, to check that the discriminants
 176          --  are correct.
 177
 178          pragma Extensions_Allowed (On);
 179          --  Needed to allow Constrained reference here
 180
 181          if Element_Type'Has_Discriminants
 182            and then Item'Constrained
 183          then
 184             declare
 185                RsizS : constant SSE.Storage_Offset :=
 186                          SSE.Storage_Offset (Rsiz - 1);
 187
 188                subtype SA is SSE.Storage_Array (0 .. RsizS);
 189                type SAP   is access all SA;
 190                type ItemP is access all Element_Type;
 191
 192                pragma Warnings (Off);
 193                --  We have to turn warnings off for this function, because
 194                --  it gets analyzed for all types, including ones which
 195                --  can't possibly come this way, and for which the size
 196                --  of the access types differs.
 197
 198                function To_ItemP is new Unchecked_Conversion (SAP, ItemP);
 199
 200                pragma Warnings (On);
 201
 202                Buffer : aliased SA;
 203
 204                pragma Unsuppress (Discriminant_Check);
 205
 206             begin
 207                FIO.Read_Buf (AP (File), Buffer'Address, Rsiz);
 208                Item := To_ItemP (Buffer'Access).all;
 209                return;
 210             end;
 211          end if;
 212
 213          --  In the case of a non-definite type, make sure the length is OK.
 214          --  We can't do this in the variant record case, because the size is
 215          --  based on the current discriminant, so may be apparently wrong.
 216
 217          if not Element_Type'Has_Discriminants and then Rsiz > Siz then
 218             raise Program_Error;
 219          end if;
 220
 221          FIO.Read_Buf (AP (File), Item'Address, Rsiz);
 222
 223       --  For definite type without discriminants, use actual size of item
 224
 225       else
 226          FIO.Read_Buf (AP (File), Item'Address, Siz);
 227       end if;
 228    end Read;
 229
 230    -----------
 231    -- Reset --
 232    -----------
 233
 234    procedure Reset (File : in out File_Type; Mode : in File_Mode) is
 235    begin
 236       FIO.Reset (AP (File), To_FCB (Mode));
 237    end Reset;
 238
 239    procedure Reset (File : in out File_Type) is
 240    begin
 241       FIO.Reset (AP (File));
 242    end Reset;
 243
 244    -----------
 245    -- Write --
 246    -----------
 247
 248    procedure Write (File : in File_Type; Item : in Element_Type) is
 249       Siz : constant size_t := (Item'Size + SU - 1) / SU;
 250
 251    begin
 252       FIO.Check_Write_Status (AP (File));
 253
 254       --  For non-definite types or types with discriminants, write the size
 255
 256       if not Element_Type'Definite
 257         or else Element_Type'Has_Discriminants
 258       then
 259          FIO.Write_Buf
 260            (AP (File), Siz'Address, size_t'Size / System.Storage_Unit);
 261       end if;
 262
 263       FIO.Write_Buf (AP (File), Item'Address, Siz);
 264    end Write;
 265
 266 end Ada.Sequential_IO;