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

--                      ZLib for Ada thick binding.                         --

--                                                                          --

--              Copyright (C) 2002-2004 Dmitriy Anisimkov                   --

--                                                                          --

--  This library is free software; you can redistribute it and/or modify    --

--  it under the terms of the GNU General Public License as published by    --

--  the Free Software Foundation; either version 2 of the License, or (at   --

--  your option) any later version.                                         --

--                                                                          --

--  This library is distributed in the hope that it will be useful, but     --

--  WITHOUT 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       --

--  along with this library; if not, write to the Free Software Foundation, --

--  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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.                                     --

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

--  $Id: zlib.ads,v 1.26 2004/09/06 06:53:19 vagul Exp $

with Ada.Streams;

with Interfaces;

package ZLib is

   ZLib_Error   : exception;

   Status_Error : exception;

   type Compression_Level is new Integer range -1 .. 9;

   type Flush_Mode is private;

   type Compression_Method is private;

   type Window_Bits_Type is new Integer range 8 .. 15;

   type Memory_Level_Type is new Integer range 1 .. 9;

   type Unsigned_32 is new Interfaces.Unsigned_32;

   type Strategy_Type is private;

   type Header_Type is (None, Auto, Default, GZip);

   --  Header type usage have a some limitation for inflate.

   --  See comment for Inflate_Init.

   subtype Count is Ada.Streams.Stream_Element_Count;

   Default_Memory_Level : constant Memory_Level_Type := 8;

   Default_Window_Bits  : constant Window_Bits_Type  := 15;

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

   -- Compression method constants --

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

   Deflated : constant Compression_Method;

   --  Only one method allowed in this ZLib version

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

   -- Compression level constants --

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

   No_Compression      : constant Compression_Level := 0;

   Best_Speed          : constant Compression_Level := 1;

   Best_Compression    : constant Compression_Level := 9;

   Default_Compression : constant Compression_Level := -1;

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

   -- Flush mode constants --

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

   No_Flush      : constant Flush_Mode;

   --  Regular way for compression, no flush

   Partial_Flush : constant Flush_Mode;

   --  Will be removed, use Z_SYNC_FLUSH instead

   Sync_Flush    : constant Flush_Mode;

   --  All pending output is flushed to the output buffer and the output

   --  is aligned on a byte boundary, so that the decompressor can get all

   --  input data available so far. (In particular avail_in is zero after the

   --  call if enough output space has been provided  before the call.)

   --  Flushing may degrade compression for some compression algorithms and so

   --  it should be used only when necessary.

   Block_Flush   : constant Flush_Mode;

   --  Z_BLOCK requests that inflate() stop

   --  if and when it get to the next deflate block boundary. When decoding the

   --  zlib or gzip format, this will cause inflate() to return immediately

   --  after the header and before the first block. When doing a raw inflate,

   --  inflate() will go ahead and process the first block, and will return

   --  when it gets to the end of that block, or when it runs out of data.

   Full_Flush    : constant Flush_Mode;

   --  All output is flushed as with SYNC_FLUSH, and the compression state

   --  is reset so that decompression can restart from this point if previous

   --  compressed data has been damaged or if random access is desired. Using

   --  Full_Flush too often can seriously degrade the compression.

   Finish        : constant Flush_Mode;

   --  Just for tell the compressor that input data is complete.

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

   -- Compression strategy constants --

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

   --  RLE stategy could be used only in version 1.2.0 and later.

   Filtered         : constant Strategy_Type;

   Huffman_Only     : constant Strategy_Type;

   RLE              : constant Strategy_Type;

   Default_Strategy : constant Strategy_Type;

   Default_Buffer_Size : constant := 4096;

   type Filter_Type is tagged limited private;

   --  The filter is for compression and for decompression.

   --  The usage of the type is depend of its initialization.

   function Version return String;

   pragma Inline (Version);

   --  Return string representation of the ZLib version.

   procedure Deflate_Init

     (Filter       : in out Filter_Type;

      Level        : in     Compression_Level  := Default_Compression;

      Strategy     : in     Strategy_Type      := Default_Strategy;

      Method       : in     Compression_Method := Deflated;

      Window_Bits  : in     Window_Bits_Type   := Default_Window_Bits;

      Memory_Level : in     Memory_Level_Type  := Default_Memory_Level;

      Header       : in     Header_Type        := Default);

   --  Compressor initialization.

   --  When Header parameter is Auto or Default, then default zlib header

   --  would be provided for compressed data.

   --  When Header is GZip, then gzip header would be set instead of

   --  default header.

   --  When Header is None, no header would be set for compressed data.

   procedure Inflate_Init

     (Filter      : in out Filter_Type;

      Window_Bits : in     Window_Bits_Type := Default_Window_Bits;

      Header      : in     Header_Type      := Default);

   --  Decompressor initialization.

   --  Default header type mean that ZLib default header is expecting in the

   --  input compressed stream.

   --  Header type None mean that no header is expecting in the input stream.

   --  GZip header type mean that GZip header is expecting in the

   --  input compressed stream.

   --  Auto header type mean that header type (GZip or Native) would be

   --  detected automatically in the input stream.

   --  Note that header types parameter values None, GZip and Auto are

   --  supported for inflate routine only in ZLib versions 1.2.0.2 and later.

   --  Deflate_Init is supporting all header types.

   function Is_Open (Filter : in Filter_Type) return Boolean;

   pragma Inline (Is_Open);

   --  Is the filter opened for compression or decompression.

   procedure Close

     (Filter       : in out Filter_Type;

      Ignore_Error : in     Boolean := False);

   --  Closing the compression or decompressor.

   --  If stream is closing before the complete and Ignore_Error is False,

   --  The exception would be raised.

   generic

      with procedure Data_In

        (Item : out Ada.Streams.Stream_Element_Array;

         Last : out Ada.Streams.Stream_Element_Offset);

      with procedure Data_Out

        (Item : in Ada.Streams.Stream_Element_Array);

   procedure Generic_Translate

     (Filter          : in out Filter_Type;

      In_Buffer_Size  : in     Integer := Default_Buffer_Size;

      Out_Buffer_Size : in     Integer := Default_Buffer_Size);

   --  Compress/decompress data fetch from Data_In routine and pass the result

   --  to the Data_Out routine. User should provide Data_In and Data_Out

   --  for compression/decompression data flow.

   --  Compression or decompression depend on Filter initialization.

   function Total_In (Filter : in Filter_Type) return Count;

   pragma Inline (Total_In);

   --  Returns total number of input bytes read so far

   function Total_Out (Filter : in Filter_Type) return Count;

   pragma Inline (Total_Out);

   --  Returns total number of bytes output so far

   function CRC32

     (CRC    : in Unsigned_32;

      Data   : in Ada.Streams.Stream_Element_Array)

      return Unsigned_32;

   pragma Inline (CRC32);

   --  Compute CRC32, it could be necessary for make gzip format

   procedure CRC32

     (CRC  : in out Unsigned_32;

      Data : in     Ada.Streams.Stream_Element_Array);

   pragma Inline (CRC32);

   --  Compute CRC32, it could be necessary for make gzip format

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

   --  Below is more complex low level routines.  --

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

   procedure Translate

     (Filter    : in out Filter_Type;

      In_Data   : in     Ada.Streams.Stream_Element_Array;

      In_Last   :    out Ada.Streams.Stream_Element_Offset;

      Out_Data  :    out Ada.Streams.Stream_Element_Array;

      Out_Last  :    out Ada.Streams.Stream_Element_Offset;

      Flush     : in     Flush_Mode);

   --  Compress/decompress the In_Data buffer and place the result into

   --  Out_Data. In_Last is the index of last element from In_Data accepted by

   --  the Filter. Out_Last is the last element of the received data from

   --  Filter. To tell the filter that incoming data are complete put the

   --  Flush parameter to Finish.

   function Stream_End (Filter : in Filter_Type) return Boolean;

   pragma Inline (Stream_End);

   --  Return the true when the stream is complete.

   procedure Flush

     (Filter    : in out Filter_Type;

      Out_Data  :    out Ada.Streams.Stream_Element_Array;

      Out_Last  :    out Ada.Streams.Stream_Element_Offset;

      Flush     : in     Flush_Mode);

   pragma Inline (Flush);

   --  Flushing the data from the compressor.

   generic

      with procedure Write

        (Item : in Ada.Streams.Stream_Element_Array);

      --  User should provide this routine for accept

      --  compressed/decompressed data.

      Buffer_Size : in Ada.Streams.Stream_Element_Offset

         := Default_Buffer_Size;

      --  Buffer size for Write user routine.

   procedure Write

     (Filter  : in out Filter_Type;

      Item    : in     Ada.Streams.Stream_Element_Array;

      Flush   : in     Flush_Mode := No_Flush);

   --  Compress/Decompress data from Item to the generic parameter procedure

   --  Write. Output buffer size could be set in Buffer_Size generic parameter.

   generic

      with procedure Read

        (Item : out Ada.Streams.Stream_Element_Array;

         Last : out Ada.Streams.Stream_Element_Offset);

      --  User should provide data for compression/decompression

      --  thru this routine.

      Buffer : in out Ada.Streams.Stream_Element_Array;

      --  Buffer for keep remaining data from the previous

      --  back read.

      Rest_First, Rest_Last : in out Ada.Streams.Stream_Element_Offset;

      --  Rest_First have to be initialized to Buffer'Last + 1

      --  Rest_Last have to be initialized to Buffer'Last

      --  before usage.

      Allow_Read_Some : in Boolean := False;

      --  Is it allowed to return Last < Item'Last before end of data.

   procedure Read

     (Filter : in out Filter_Type;

      Item   :    out Ada.Streams.Stream_Element_Array;

      Last   :    out Ada.Streams.Stream_Element_Offset;

      Flush  : in     Flush_Mode := No_Flush);

   --  Compress/Decompress data from generic parameter procedure Read to the

   --  Item. User should provide Buffer and initialized Rest_First, Rest_Last

   --  indicators. If Allow_Read_Some is True, Read routines could return

   --  Last < Item'Last only at end of stream.

private

   use Ada.Streams;

   pragma Assert (Ada.Streams.Stream_Element'Size    =    8);

   pragma Assert (Ada.Streams.Stream_Element'Modulus = 2**8);

   type Flush_Mode is new Integer range 0 .. 5;

   type Compression_Method is new Integer range 8 .. 8;

   type Strategy_Type is new Integer range 0 .. 3;

   No_Flush      : constant Flush_Mode := 0;

   Partial_Flush : constant Flush_Mode := 1;

   Sync_Flush    : constant Flush_Mode := 2;

   Full_Flush    : constant Flush_Mode := 3;

   Finish        : constant Flush_Mode := 4;

   Block_Flush   : constant Flush_Mode := 5;

   Filtered         : constant Strategy_Type := 1;

   Huffman_Only     : constant Strategy_Type := 2;

   RLE              : constant Strategy_Type := 3;

   Default_Strategy : constant Strategy_Type := 0;

   Deflated : constant Compression_Method := 8;

   type Z_Stream;

   type Z_Stream_Access is access all Z_Stream;

   type Filter_Type is tagged limited record

      Strm        : Z_Stream_Access;

      Compression : Boolean;

      Stream_End  : Boolean;

      Header      : Header_Type;

      CRC         : Unsigned_32;

      Offset      : Stream_Element_Offset;

      --  Offset for gzip header/footer output.

   end record;

end ZLib;