Ada Programming/Libraries/Interfaces.C.Streams

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float
------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                 I N T E R F A C E S . C _ S T R E A M S                  --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--                            $Revision: 24601 $
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--          Copyright (C) 1996-2001 Free Software Foundation, Inc.          --
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-- unit, or you link  this unit with other files  to produce an executable, --
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------------------------------------------------------------------------------

--  This is the default version which just calls the C versions directly
--  Note: the reason that we provide for specialization here is that on
--  some systems, notably VMS, we may need to worry about buffering.

with Unchecked_Conversion;

package body Interfaces.C_Streams is

   ------------
   -- fread --
   ------------

   function fread 
     (buffer : voids; 
      size   : size_t; 
      count  : size_t; 
      stream : FILEs) 
      return   size_t
   is
      function C_fread 
        (buffer : voids; 
         size   : size_t; 
         count  : size_t; 
         stream : FILEs) 
         return   size_t;
      pragma Import (C, C_fread, "fread");

   begin
      return C_fread (buffer, size, count, stream);
   end fread;

   ------------
   -- fread --
   ------------

   function fread 
     (buffer : voids; 
      index  : size_t; 
      size   : size_t; 
      count  : size_t; 
      stream : FILEs) 
      return   size_t
   is
      function C_fread 
        (buffer : voids; 
         size   : size_t; 
         count  : size_t; 
         stream : FILEs) 
         return   size_t;
      pragma Import (C, C_fread, "fread");

      type Byte_Buffer is array (0 .. size_t'Last / 2 - 1) of Unsigned_8; 
      --  This should really be 0 .. size_t'last, but there is a problem
      --  in gigi in handling such types (introduced in GCC 3 Sep 2001)
      --  since the size in bytes of this array overflows ???

      type Acc_Bytes is access all Byte_Buffer; 

      function To_Acc_Bytes is new Unchecked_Conversion (voids, Acc_Bytes); 

   begin
      return C_fread
        (To_Acc_Bytes (buffer) (index * size)'Address, size, count, stream);
   end fread;

   ------------
   -- fwrite --
   ------------

   function fwrite 
     (buffer : voids; 
      size   : size_t; 
      count  : size_t; 
      stream : FILEs) 
      return   size_t
   is
      function C_fwrite 
        (buffer : voids; 
         size   : size_t; 
         count  : size_t; 
         stream : FILEs) 
         return   size_t;
      pragma Import (C, C_fwrite, "fwrite");

   begin
      return C_fwrite (buffer, size, count, stream);
   end fwrite;

   -------------
   -- setvbuf --
   -------------

   function setvbuf 
     (stream : FILEs; 
      buffer : chars; 
      mode   : int; 
      size   : size_t) 
      return   int
   is
      function C_setvbuf 
        (stream : FILEs; 
         buffer : chars; 
         mode   : int; 
         size   : size_t) 
         return   int;
      pragma Import (C, C_setvbuf, "setvbuf");

   begin
      return C_setvbuf (stream, buffer, mode, size);
   end setvbuf;

end Interfaces.C_Streams;

See also[edit]

Wikibook[edit]

GNAT Reference Manual[edit]