gcc/ada/i-cstrea.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                 I N T E R F A C E S . C _ S T R E A M S                  --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1996-2003 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,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, 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 --  This is the default version which just calls the C versions directly
  35 --  Note: the reason that we provide for specialization here is that on
  36 --  some systems, notably VMS, we may need to worry about buffering.
  37
  38 with Unchecked_Conversion;
  39
  40 package body Interfaces.C_Streams is
  41
  42    use type System.CRTL.size_t;
  43
  44    ----------------------------
  45    -- Interfaced C functions --
  46    ----------------------------
  47
  48    function C_fread
  49      (buffer : voids;
  50       size   : size_t;
  51       count  : size_t;
  52       stream : FILEs) return size_t;
  53    pragma Import (C, C_fread, "fread");
  54
  55    function C_fwrite
  56      (buffer : voids;
  57       size   : size_t;
  58       count  : size_t;
  59       stream : FILEs) return size_t;
  60    pragma Import (C, C_fwrite, "fwrite");
  61
  62    function C_setvbuf
  63      (stream : FILEs;
  64       buffer : chars;
  65       mode   : int;
  66       size   : size_t) return int;
  67    pragma Import (C, C_setvbuf, "setvbuf");
  68
  69    ------------
  70    -- fread --
  71    ------------
  72
  73    function fread
  74      (buffer : voids;
  75       size   : size_t;
  76       count  : size_t;
  77       stream : FILEs) return size_t
  78    is
  79    begin
  80       return C_fread (buffer, size, count, stream);
  81    end fread;
  82
  83    ------------
  84    -- fread --
  85    ------------
  86
  87    --  The following declarations should really be nested within fread, but
  88    --  limitations in front end inlining make this undesirable right now ???
  89
  90    type Byte_Buffer is array (0 .. size_t'Last / 2 - 1) of Unsigned_8;
  91    --  This should really be 0 .. size_t'last, but there is a problem
  92    --  in gigi in handling such types (introduced in GCC 3 Sep 2001)
  93    --  since the size in bytes of this array overflows ???
  94
  95    type Acc_Bytes is access all Byte_Buffer;
  96
  97    function To_Acc_Bytes is new Unchecked_Conversion (voids, Acc_Bytes);
  98
  99    function fread
 100      (buffer : voids;
 101       index  : size_t;
 102       size   : size_t;
 103       count  : size_t;
 104       stream : FILEs) return size_t
 105    is
 106    begin
 107       return C_fread
 108         (To_Acc_Bytes (buffer) (index * size)'Address, size, count, stream);
 109    end fread;
 110
 111    ------------
 112    -- fwrite --
 113    ------------
 114
 115    function fwrite
 116      (buffer : voids;
 117       size   : size_t;
 118       count  : size_t;
 119       stream : FILEs) return size_t
 120    is
 121    begin
 122       return C_fwrite (buffer, size, count, stream);
 123    end fwrite;
 124
 125    -------------
 126    -- setvbuf --
 127    -------------
 128
 129    function setvbuf
 130      (stream : FILEs;
 131       buffer : chars;
 132       mode   : int;
 133       size   : size_t) return int
 134    is
 135    begin
 136       return C_setvbuf (stream, buffer, mode, size);
 137    end setvbuf;
 138
 139 end Interfaces.C_Streams;