------------------------------------------------------------------------------
--                                                                          --
--                         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                                  --
--                                                                          --
--          Copyright (C) 1996-2005, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 2,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
-- for  more details.  You should have  received  a copy of the GNU General --
-- Public License  distributed with GNAT;  see file COPYING.  If not, write --
-- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
-- Boston, MA 02110-1301, USA.                                              --
--                                                                          --
-- As a special exception,  if other files  instantiate  generics from this --
-- unit, or you link  this unit with other files  to produce an executable, --
-- this  unit  does not  by itself cause  the resulting  executable  to  be --
-- covered  by the  GNU  General  Public  License.  This exception does not --
-- however invalidate  any other reasons why  the executable file  might be --
-- covered by the  GNU Public License.                                      --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

--  This is the Alpha/VMS version

with Unchecked_Conversion;
package body Interfaces.C_Streams is

   use type System.CRTL.size_t;

   --  As the functions fread, fwrite and setvbuf are too big to be inlined,
   --  they are just wrappers to the following implementation functions.

   function fread_impl
     (buffer : voids;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t;

   function fread_impl
     (buffer : voids;
      index  : size_t;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t;

   function fwrite_impl
     (buffer : voids;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t;

   function setvbuf_impl
     (stream : FILEs;
      buffer : chars;
      mode   : int;
      size   : size_t) return int;

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

   function fread_impl
     (buffer : voids;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t
   is
      Get_Count : size_t := 0;

      type Buffer_Type is array (size_t range 1 .. count,
                                 size_t range 1 .. size) of Character;
      type Buffer_Access is access Buffer_Type;
      function To_BA is new Unchecked_Conversion (voids, Buffer_Access);

      BA : constant Buffer_Access := To_BA (buffer);
      Ch : int;

   begin
      --  This Fread goes with the Fwrite below. The C library fread sometimes
      --  can't read fputc generated files.

      for C in 1 .. count loop
         for S in 1 .. size loop
            Ch := fgetc (stream);

            if Ch = EOF then
               return Get_Count;
            end if;

            BA.all (C, S) := Character'Val (Ch);
         end loop;

         Get_Count := Get_Count + 1;
      end loop;

      return Get_Count;
   end fread_impl;

   function fread_impl
     (buffer : voids;
      index  : size_t;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t
   is
      Get_Count : size_t := 0;

      type Buffer_Type is array (size_t range 1 .. count,
                                 size_t range 1 .. size) of Character;
      type Buffer_Access is access Buffer_Type;
      function To_BA is new Unchecked_Conversion (voids, Buffer_Access);

      BA : constant Buffer_Access := To_BA (buffer);
      Ch : int;

   begin
      --  This Fread goes with the Fwrite below. The C library fread sometimes
      --  can't read fputc generated files.

      for C in 1 + index .. count + index loop
         for S in 1 .. size loop
            Ch := fgetc (stream);

            if Ch = EOF then
               return Get_Count;
            end if;

            BA.all (C, S) := Character'Val (Ch);
         end loop;

         Get_Count := Get_Count + 1;
      end loop;

      return Get_Count;
   end fread_impl;

   function fread
     (buffer : voids;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t
   is
   begin
      return fread_impl (buffer, size, count, stream);
   end fread;

   function fread
     (buffer : voids;
      index  : size_t;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t
   is
   begin
      return fread_impl (buffer, index, size, count, stream);
   end fread;

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

   function fwrite_impl
     (buffer : voids;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t
   is
      Put_Count : size_t := 0;

      type Buffer_Type is array (size_t range 1 .. count,
                                 size_t range 1 .. size) of Character;
      type Buffer_Access is access Buffer_Type;
      function To_BA is new Unchecked_Conversion (voids, Buffer_Access);

      BA : constant Buffer_Access := To_BA (buffer);

   begin
      --  Fwrite on VMS has the undesirable effect of always generating at
      --  least one record of output per call, regardless of buffering.  To
      --  get around this, we do multiple fputc calls instead.

      for C in 1 .. count loop
         for S in 1 .. size loop
            if fputc (Character'Pos (BA.all (C, S)), stream) = EOF then
               return Put_Count;
            end if;
         end loop;

         Put_Count := Put_Count + 1;
      end loop;

      return Put_Count;
   end fwrite_impl;

   function fwrite
     (buffer : voids;
      size   : size_t;
      count  : size_t;
      stream : FILEs) return size_t
   is
   begin
      return fwrite_impl (buffer, size, count, stream);
   end fwrite;

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

   function setvbuf_impl
     (stream : FILEs;
      buffer : chars;
      mode   : int;
      size   : size_t) return int
   is
      use type System.Address;

   begin
      --  In order for the above fwrite hack to work, we must always buffer
      --  stdout and stderr. Is_regular_file on VMS cannot detect when
      --  these are redirected to a file, so checking for that condition
      --  doesnt help.

      if mode = IONBF
        and then (stream = stdout or else stream = stderr)
      then
         return System.CRTL.setvbuf
           (stream, buffer, IOLBF, System.CRTL.size_t (size));
      else
         return System.CRTL.setvbuf
           (stream, buffer, mode, System.CRTL.size_t (size));
      end if;
   end setvbuf_impl;

   function setvbuf
     (stream : FILEs;
      buffer : chars;
      mode   : int;
      size   : size_t) return int
   is
   begin
      return setvbuf_impl (stream, buffer, mode, size);
   end setvbuf;

end Interfaces.C_Streams;