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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;