if(writing_first_sign == YES)
       {
              first_sign = c;
              if(first_sign < 58)
                     first_sign = first_sign - 48;//pretvormo v hex
              else
                     first_sign = first_sign - 55;
              writing_first_sign = NO;
              first_sign = first_sign * 0x10; //pretvormo v desetice
       }
       else
       {
              second_sign = c;
              if(second_sign < 58)
                     second_sign = second_sign - 48;//pretvormo v hex
              else
                     second_sign = second_sign - 55;
              num_hex = first_sign + second_sign;
              writing_first_sign = YES;