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

--  ZLib for Ada thick binding.                               --

--                                                            --

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

--                                                            --

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

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

--  $Id: zlib.adb,v 1.31 2004/09/06 06:53:19 vagul Exp $

with Ada.Exceptions;

with Ada.Unchecked_Conversion;

with Ada.Unchecked_Deallocation;

with Interfaces.C.Strings;

with ZLib.Thin;

package body ZLib is

   use type Thin.Int;

   type Z_Stream is new Thin.Z_Stream;

   type Return_Code_Enum is

      (OK,

       STREAM_END,

       NEED_DICT,

       ERRNO,

       STREAM_ERROR,

       DATA_ERROR,

       MEM_ERROR,

       BUF_ERROR,

       VERSION_ERROR);

   type Flate_Step_Function is access

     function (Strm : in Thin.Z_Streamp; Flush : in Thin.Int) return Thin.Int;

   pragma Convention (C, Flate_Step_Function);

   type Flate_End_Function is access

      function (Ctrm : in Thin.Z_Streamp) return Thin.Int;

   pragma Convention (C, Flate_End_Function);

   type Flate_Type is record

      Step : Flate_Step_Function;

      Done : Flate_End_Function;

   end record;

   subtype Footer_Array is Stream_Element_Array (1 .. 8);

   Simple_GZip_Header : constant Stream_Element_Array (1 .. 10)

     := (16#1f#, 16#8b#,                 --  Magic header

         16#08#,                         --  Z_DEFLATED

         16#00#,                         --  Flags

         16#00#, 16#00#, 16#00#, 16#00#, --  Time

         16#00#,                         --  XFlags

         16#03#                          --  OS code

        );

   --  The simplest gzip header is not for informational, but just for

   --  gzip format compatibility.

   --  Note that some code below is using assumption

   --  Simple_GZip_Header'Last > Footer_Array'Last, so do not make

   --  Simple_GZip_Header'Last <= Footer_Array'Last.

   Return_Code : constant array (Thin.Int range <>) of Return_Code_Enum

     := (0 => OK,

         1 => STREAM_END,

         2 => NEED_DICT,

        -1 => ERRNO,

        -2 => STREAM_ERROR,

        -3 => DATA_ERROR,

        -4 => MEM_ERROR,

        -5 => BUF_ERROR,

        -6 => VERSION_ERROR);

   Flate : constant array (Boolean) of Flate_Type

     := (True  => (Step => Thin.Deflate'Access,

                   Done => Thin.DeflateEnd'Access),

         False => (Step => Thin.Inflate'Access,

                   Done => Thin.InflateEnd'Access));

   Flush_Finish : constant array (Boolean) of Flush_Mode

     := (True => Finish, False => No_Flush);

   procedure Raise_Error (Stream : in Z_Stream);

   pragma Inline (Raise_Error);

   procedure Raise_Error (Message : in String);

   pragma Inline (Raise_Error);

   procedure Check_Error (Stream : in Z_Stream; Code : in Thin.Int);

   procedure Free is new Ada.Unchecked_Deallocation

      (Z_Stream, Z_Stream_Access);

   function To_Thin_Access is new Ada.Unchecked_Conversion

     (Z_Stream_Access, Thin.Z_Streamp);

   procedure Translate_GZip

     (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);

   --  Separate translate routine for make gzip header.

   procedure Translate_Auto

     (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);

   --  translate routine without additional headers.

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

   -- Check_Error --

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

   procedure Check_Error (Stream : in Z_Stream; Code : in Thin.Int) is

      use type Thin.Int;

   begin

      if Code /= Thin.Z_OK then

         Raise_Error

            (Return_Code_Enum'Image (Return_Code (Code))

              & ": " & Last_Error_Message (Stream));

      end if;

   end Check_Error;

   -----------

   -- Close --

   -----------

   procedure Close

     (Filter       : in out Filter_Type;

      Ignore_Error : in     Boolean := False)

   is

      Code : Thin.Int;

   begin

      if not Ignore_Error and then not Is_Open (Filter) then

         raise Status_Error;

      end if;

      Code := Flate (Filter.Compression).Done (To_Thin_Access (Filter.Strm));

      if Ignore_Error or else Code = Thin.Z_OK then

         Free (Filter.Strm);

      else

         declare

            Error_Message : constant String

              := Last_Error_Message (Filter.Strm.all);

         begin

            Free (Filter.Strm);

            Ada.Exceptions.Raise_Exception

               (ZLib_Error'Identity,

                Return_Code_Enum'Image (Return_Code (Code))

                  & ": " & Error_Message);

         end;

      end if;

   end Close;

   -----------

   -- CRC32 --

   -----------

   function CRC32

     (CRC  : in Unsigned_32;

      Data : in Ada.Streams.Stream_Element_Array)

      return Unsigned_32

   is

      use Thin;

   begin

      return Unsigned_32 (crc32 (ULong (CRC),

                                 Data'Address,

                                 Data'Length));

   end CRC32;

   procedure CRC32

     (CRC  : in out Unsigned_32;

      Data : in     Ada.Streams.Stream_Element_Array) is

   begin

      CRC := CRC32 (CRC, Data);

   end CRC32;

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

   -- Deflate_Init --

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

   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)

   is

      use type Thin.Int;

      Win_Bits : Thin.Int := Thin.Int (Window_Bits);

   begin

      if Is_Open (Filter) then

         raise Status_Error;

      end if;

      --  We allow ZLib to make header only in case of default header type.

      --  Otherwise we would either do header by ourselfs, or do not do

      --  header at all.

      if Header = None or else Header = GZip then

         Win_Bits := -Win_Bits;

      end if;

      --  For the GZip CRC calculation and make headers.

      if Header = GZip then

         Filter.CRC    := 0;

         Filter.Offset := Simple_GZip_Header'First;

      else

         Filter.Offset := Simple_GZip_Header'Last + 1;

      end if;

      Filter.Strm        := new Z_Stream;

      Filter.Compression := True;

      Filter.Stream_End  := False;

      Filter.Header      := Header;

      if Thin.Deflate_Init

           (To_Thin_Access (Filter.Strm),

            Level      => Thin.Int (Level),

            method     => Thin.Int (Method),

            windowBits => Win_Bits,

            memLevel   => Thin.Int (Memory_Level),

            strategy   => Thin.Int (Strategy)) /= Thin.Z_OK

      then

         Raise_Error (Filter.Strm.all);

      end if;

   end Deflate_Init;

   -----------

   -- Flush --

   -----------

   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)

   is

      No_Data : Stream_Element_Array := (1 .. 0 => 0);

      Last    : Stream_Element_Offset;

   begin

      Translate (Filter, No_Data, Last, Out_Data, Out_Last, Flush);

   end Flush;

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

   -- Generic_Translate --

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

   procedure Generic_Translate

     (Filter          : in out ZLib.Filter_Type;

      In_Buffer_Size  : in     Integer := Default_Buffer_Size;

      Out_Buffer_Size : in     Integer := Default_Buffer_Size)

   is

      In_Buffer  : Stream_Element_Array

                     (1 .. Stream_Element_Offset (In_Buffer_Size));

      Out_Buffer : Stream_Element_Array

                     (1 .. Stream_Element_Offset (Out_Buffer_Size));

      Last       : Stream_Element_Offset;

      In_Last    : Stream_Element_Offset;

      In_First   : Stream_Element_Offset;

      Out_Last   : Stream_Element_Offset;

   begin

      Main : loop

         Data_In (In_Buffer, Last);

         In_First := In_Buffer'First;

         loop

            Translate

              (Filter   => Filter,

               In_Data  => In_Buffer (In_First .. Last),

               In_Last  => In_Last,

               Out_Data => Out_Buffer,

               Out_Last => Out_Last,

               Flush    => Flush_Finish (Last < In_Buffer'First));

            if Out_Buffer'First <= Out_Last then

               Data_Out (Out_Buffer (Out_Buffer'First .. Out_Last));

            end if;

            exit Main when Stream_End (Filter);

            --  The end of in buffer.

            exit when In_Last = Last;

            In_First := In_Last + 1;

         end loop;

      end loop Main;

   end Generic_Translate;

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

   -- Inflate_Init --

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

   procedure Inflate_Init

     (Filter      : in out Filter_Type;

      Window_Bits : in     Window_Bits_Type := Default_Window_Bits;

      Header      : in     Header_Type      := Default)

   is

      use type Thin.Int;

      Win_Bits : Thin.Int := Thin.Int (Window_Bits);

      procedure Check_Version;

      --  Check the latest header types compatibility.

      procedure Check_Version is

      begin

         if Version <= "1.1.4" then

            Raise_Error

              ("Inflate header type " & Header_Type'Image (Header)

               & " incompatible with ZLib version " & Version);

         end if;

      end Check_Version;

   begin

      if Is_Open (Filter) then

         raise Status_Error;

      end if;

      case Header is

         when None =>

            Check_Version;

            --  Inflate data without headers determined

            --  by negative Win_Bits.

            Win_Bits := -Win_Bits;

         when GZip =>

            Check_Version;

            --  Inflate gzip data defined by flag 16.

            Win_Bits := Win_Bits + 16;

         when Auto =>

            Check_Version;

            --  Inflate with automatic detection

            --  of gzip or native header defined by flag 32.

            Win_Bits := Win_Bits + 32;

         when Default => null;

      end case;

      Filter.Strm        := new Z_Stream;

      Filter.Compression := False;

      Filter.Stream_End  := False;

      Filter.Header      := Header;

      if Thin.Inflate_Init

         (To_Thin_Access (Filter.Strm), Win_Bits) /= Thin.Z_OK

      then

         Raise_Error (Filter.Strm.all);

      end if;

   end Inflate_Init;

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

   -- Is_Open --

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

   function Is_Open (Filter : in Filter_Type) return Boolean is

   begin

      return Filter.Strm /= null;

   end Is_Open;

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

   -- Raise_Error --

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

   procedure Raise_Error (Message : in String) is

   begin

      Ada.Exceptions.Raise_Exception (ZLib_Error'Identity, Message);

   end Raise_Error;

   procedure Raise_Error (Stream : in Z_Stream) is

   begin

      Raise_Error (Last_Error_Message (Stream));

   end Raise_Error;

   ----------

   -- Read --

   ----------

   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)

   is

      In_Last    : Stream_Element_Offset;

      Item_First : Ada.Streams.Stream_Element_Offset := Item'First;

      V_Flush    : Flush_Mode := Flush;

   begin

      pragma Assert (Rest_First in Buffer'First .. Buffer'Last + 1);

      pragma Assert (Rest_Last in Buffer'First - 1 .. Buffer'Last);

      loop

         if Rest_Last = Buffer'First - 1 then

            V_Flush := Finish;

         elsif Rest_First > Rest_Last then

            Read (Buffer, Rest_Last);

            Rest_First := Buffer'First;

            if Rest_Last < Buffer'First then

               V_Flush := Finish;

            end if;

         end if;

         Translate

           (Filter   => Filter,

            In_Data  => Buffer (Rest_First .. Rest_Last),

            In_Last  => In_Last,

            Out_Data => Item (Item_First .. Item'Last),

            Out_Last => Last,

            Flush    => V_Flush);

         Rest_First := In_Last + 1;

         exit when Stream_End (Filter)

           or else Last = Item'Last

           or else (Last >= Item'First and then Allow_Read_Some);

         Item_First := Last + 1;

      end loop;

   end Read;

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

   -- Stream_End --

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

   function Stream_End (Filter : in Filter_Type) return Boolean is

   begin

      if Filter.Header = GZip and Filter.Compression then

         return Filter.Stream_End

            and then Filter.Offset = Footer_Array'Last + 1;

      else

         return Filter.Stream_End;

      end if;

   end Stream_End;

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

   -- Total_In --

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

   function Total_In (Filter : in Filter_Type) return Count is

   begin

      return Count (Thin.Total_In (To_Thin_Access (Filter.Strm).all));

   end Total_In;

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

   -- Total_Out --

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

   function Total_Out (Filter : in Filter_Type) return Count is

   begin

      return Count (Thin.Total_Out (To_Thin_Access (Filter.Strm).all));

   end Total_Out;

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

   -- Translate --

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

   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) is

   begin

      if Filter.Header = GZip and then Filter.Compression then

         Translate_GZip

           (Filter   => Filter,

            In_Data  => In_Data,

            In_Last  => In_Last,

            Out_Data => Out_Data,

            Out_Last => Out_Last,

            Flush    => Flush);

      else

         Translate_Auto

           (Filter   => Filter,

            In_Data  => In_Data,

            In_Last  => In_Last,

            Out_Data => Out_Data,

            Out_Last => Out_Last,

            Flush    => Flush);

      end if;

   end Translate;

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

   -- Translate_Auto --

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

   procedure Translate_Auto

     (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)

   is

      use type Thin.Int;

      Code : Thin.Int;

   begin

      if not Is_Open (Filter) then

         raise Status_Error;

      end if;

      if Out_Data'Length = 0 and then In_Data'Length = 0 then

         raise Constraint_Error;

      end if;

      Set_Out (Filter.Strm.all, Out_Data'Address, Out_Data'Length);

      Set_In  (Filter.Strm.all, In_Data'Address, In_Data'Length);