System.Globalization.EastAsianLunisolarCalendar.GregorianToLunar C# (CSharp) Method

        internal void GregorianToLunar(int nSYear, int nSMonth, int nSDate, ref int nLYear, ref int nLMonth, ref int nLDate) {
            //    unsigned int nLYear, nLMonth, nLDate;    // lunar ymd
            int nSolarDay;        // day # in solar year
            int nLunarDay;        // day # in lunar year
            int fLeap;                    // is it a solar leap year?
            int LDpM;        // lunar days/month bitfield
            int mask;        // mask for extracting bits
            int nDays;        // # days this lunar month
            int nJan1Month, nJan1Date;

            // calc the solar day of year
            fLeap = GergIsleap(nSYear);
            nSolarDay = (fLeap==1) ? DaysToMonth366[nSMonth-1]: DaysToMonth365[nSMonth-1] ;
            nSolarDay += nSDate;

            // init lunar year info
            nLunarDay = nSolarDay;
            nLYear = nSYear;
            if (nLYear == (MaxCalendarYear + 1)) {
                nLYear--;
                nLunarDay += ((GergIsleap(nLYear)==1) ? 366 : 365);
                nJan1Month = GetYearInfo(nLYear, Jan1Month);
                nJan1Date = GetYearInfo(nLYear,Jan1Date);
            } else {

                nJan1Month = GetYearInfo(nLYear, Jan1Month);
                nJan1Date = GetYearInfo(nLYear,Jan1Date);

                // check if this solar date is actually part of the previous
                // lunar year
                if ((nSMonth < nJan1Month) ||
                    (nSMonth == nJan1Month && nSDate < nJan1Date)) {
                    // the corresponding lunar day is actually part of the previous
                    // lunar year
                    nLYear--;

                    // add a solar year to the lunar day #
                    nLunarDay += ((GergIsleap(nLYear)==1) ? 366 : 365);

                    // update the new start of year
                    nJan1Month = GetYearInfo(nLYear, Jan1Month);
                    nJan1Date = GetYearInfo(nLYear, Jan1Date);
                }
            }

            // convert solar day into lunar day.
            // subtract off the beginning part of the solar year which is not
            // part of the lunar year.  since this part is always in Jan or Feb,
            // we don't need to handle Leap Year (LY only affects March
            // and later).
            nLunarDay -= DaysToMonth365[nJan1Month-1];
            nLunarDay -= (nJan1Date - 1);

            // convert the lunar day into a lunar month/date
            mask = 0x8000;
            LDpM = GetYearInfo(nLYear, nDaysPerMonth);
            nDays = ((LDpM & mask) != 0) ? 30 : 29;
            nLMonth = 1;
            while (nLunarDay > nDays) {
                nLunarDay -= nDays;
                nLMonth++;
                mask >>= 1;
                nDays = ((LDpM & mask) != 0) ? 30 : 29;
            }
            nLDate = nLunarDay;
        }