modules/vliCodec.h

   1 #ifndef VLICODEC_HEADER_
   2 #define VLICODEC_HEADER_
   3
   4 #include "../headers.h"
   5 #include "../fileUtil.h"
   6
   7 class VLI;
   8
   9 /** Variable-length-integer codec optimized for encoding little-changing sequences.
  10  *      It lets user choose the number of first-level symbols. */
  11 class MDifferentialVLICodec: public IIntCodec {
  12
  13         DECLARE_TypeInfo( MDifferentialVLICodec, "Differential VLI"
  14         , "Variable-length-integer differential encoder with adjustable distribution"
  15         , {
  16                 label:  "First level symbols",
  17                 desc:   "The number of possibilities\n"
  18                                 "that will occupy least space",
  19                 type:   settingInt(0,1,8,IntLog2)
  20         } )
  21
  22 private:
  23         /** Indices for settings */
  24         enum Settings { VLIExponent };
  25
  26 private:
  27         int possib              /// the number of possibilities set by ::setPossibilities
  28         , lastSymbol;   ///< the last encoded symbol (::possib/2 at the beginning)
  29 public:
  30 /**     \name IIntCodec interface
  31  *      @{ */
  32         void setPossibilities(int possibilities) {
  33                 possib= possibilities;
  34                 lastSymbol= possib/2;
  35         }
  36         void encode(std::vector<int> &data,std::ostream &file);
  37         void decode(std::istream &file,int count,std::vector<int> &data);
  38
  39         void writeSettings(std::ostream &file)
  40                 { put<Uchar>( file, settingsInt(VLIExponent) ); }
  41         void readSettings(std::istream &file)
  42                 { settingsInt(VLIExponent)= get<Uchar>(file); }
  43 ///     @}
  44 };
  45
  46 #endif // VLICODEC_HEADER_