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----------------------------------------------------------------

--  ZLib for Ada thick binding.                               --

--                                                            --

--  Copyright (C) 2002-2003 Dmitriy Anisimkov                 --

--                                                            --

--  Open source license information is in the zlib.ads file.  --

----------------------------------------------------------------

--  $Id: read.adb,v 1.8 2004/05/31 10:53:40 vagul Exp $

--  Test/demo program for the generic read interface.

with Ada.Numerics.Discrete_Random;

with Ada.Streams;

with Ada.Text_IO;

with ZLib;

procedure Read is

   use Ada.Streams;

   ------------------------------------

   --  Test configuration parameters --

   ------------------------------------

   File_Size   : Stream_Element_Offset := 100_000;

   Continuous  : constant Boolean          := False;

   --  If this constant is True, the test would be repeated again and again,

   --  with increment File_Size for every iteration.

   Header      : constant ZLib.Header_Type := ZLib.Default;

   --  Do not use Header other than Default in ZLib versions 1.1.4 and older.

   Init_Random : constant := 8;

   --  We are using the same random sequence, in case of we catch bug,

   --  so we would be able to reproduce it.

   -- End --

   Pack_Size : Stream_Element_Offset;

   Offset    : Stream_Element_Offset;

   Filter     : ZLib.Filter_Type;

   subtype Visible_Symbols

      is Stream_Element range 16#20# .. 16#7E#;

   package Random_Elements is new

      Ada.Numerics.Discrete_Random (Visible_Symbols);

   Gen : Random_Elements.Generator;

   Period  : constant Stream_Element_Offset := 200;

   --  Period constant variable for random generator not to be very random.

   --  Bigger period, harder random.

   Read_Buffer : Stream_Element_Array (1 .. 2048);

   Read_First  : Stream_Element_Offset;

   Read_Last   : Stream_Element_Offset;

   procedure Reset;

   procedure Read

     (Item : out Stream_Element_Array;

      Last : out Stream_Element_Offset);

   --  this procedure is for generic instantiation of

   --  ZLib.Read

   --  reading data from the File_In.

   procedure Read is new ZLib.Read

                           (Read,

                            Read_Buffer,

                            Rest_First => Read_First,

                            Rest_Last  => Read_Last);

   ----------

   -- Read --

   ----------

   procedure Read

     (Item : out Stream_Element_Array;

      Last : out Stream_Element_Offset) is

   begin

      Last := Stream_Element_Offset'Min

               (Item'Last,

                Item'First + File_Size - Offset);

      for J in Item'First .. Last loop

         if J < Item'First + Period then

            Item (J) := Random_Elements.Random (Gen);

         else

            Item (J) := Item (J - Period);

         end if;

         Offset   := Offset + 1;

      end loop;

   end Read;

   -----------

   -- Reset --

   -----------

   procedure Reset is

   begin

      Random_Elements.Reset (Gen, Init_Random);

      Pack_Size := 0;

      Offset := 1;

      Read_First := Read_Buffer'Last + 1;

      Read_Last  := Read_Buffer'Last;

   end Reset;

begin

   Ada.Text_IO.Put_Line ("ZLib " & ZLib.Version);

   loop

      for Level in ZLib.Compression_Level'Range loop

         Ada.Text_IO.Put ("Level ="

            & ZLib.Compression_Level'Image (Level));

         --  Deflate using generic instantiation.

         ZLib.Deflate_Init

               (Filter,

                Level,

                Header => Header);

         Reset;

         Ada.Text_IO.Put

           (Stream_Element_Offset'Image (File_Size) & " ->");

         loop

            declare

               Buffer : Stream_Element_Array (1 .. 1024);

               Last   : Stream_Element_Offset;

            begin

               Read (Filter, Buffer, Last);

               Pack_Size := Pack_Size + Last - Buffer'First + 1;

               exit when Last < Buffer'Last;

            end;

         end loop;

         Ada.Text_IO.Put_Line (Stream_Element_Offset'Image (Pack_Size));

         ZLib.Close (Filter);

      end loop;

      exit when not Continuous;

      File_Size := File_Size + 1;

   end loop;

end Read;