anchor.diff:    Z_FILTERED            = 1;
     Z_HUFFMAN_ONLY        = 2;
     Z_RLE                 = 3;
  +  Z_FIXED               = 4;
     Z_DEFAULT_STRATEGY    = 0;
   
     Z_BINARY   = 0;
  +  Z_TEXT     = 1;
     Z_ASCII    = 1;
     Z_UNKNOWN  = 2;
   
  
positive.code:     data_type: Integer;   (* best guess about the data type: ascii or binary *)
      adler: LongInt;       (* adler32 value of the uncompressed data *)
      reserved: LongInt;    (* reserved for future use *)
    end;
  
  (* constants *)
  
negative.code: 
  (* checksum functions *)
  function adler32(adler: LongInt; const buf: PChar; len: Integer): LongInt;
  function adler32_combine(adler1, adler2, len2: LongInt): LongInt;
  function crc32(crc: LongInt; const buf: PChar; len: Integer): LongInt;
  function crc32_combine(crc1, crc2, len2: LongInt): LongInt;
  
  (* various hacks, don't look :) *)
  function deflateInit_(var strm: z_stream; level: Integer;
  