func: static int get_num(ByteIOContext *pb, int *len)
  
  {
  
      int n, n1;
  
  
  
      n = get_be16(pb);
  
      (*len)-=2;
  
  //    n &= 0x7FFF;
  
      if (n >= 0x4000) {
  
          return n - 0x4000;
  
      } else {
  
          n1 = get_be16(pb);
  
          (*len)-=2;
  
          return (n << 16) | n1;
  
      }
  
  }
  