/**
 * Return Modified Julian Day given calendar year, month (1-12), and day (1-31). Valid for Gregorian dates
 * from 17-Nov-1858.
 * Adapted from sci.astro FAQ.
 */
static S32 gps_date_to_mjd (S32 Year, S32 Month, S32 Day)
{
    return
        367 * Year
        - 7 * (Year + (Month + 9) / 12) / 4
        - 3 * ((Year + (Month - 9) / 7) / 100 + 1) / 4
        + 275 * Month / 9
        + Day
        + 1721028
        - 2400000;
}
/**
 * Convert Modified Julian Day to calendar date.
 * - Assumes Gregorian calendar.
 * - Adapted from Fliegel/van Flandern ACM 11/#10 p 657 Oct 1968.
 */
static void gps_mjd_to_date (S32 Mjd, S32 *Year, S32 *Month, S32 *Day)
{
    S32 J, C, Y, M;
    J = Mjd + 2400001 + 68569;
    C = 4 * J / 146097;
    J = J - (146097 * C + 3) / 4;
    Y = 4000 * (J + 1) / 1461001;
    J = J - 1461 * Y / 4 + 31;
    M = 80 * J / 2447;
    *Day = J - 2447 * M / 80;
    J = M / 11;
    *Month = M + 2 - (12 * J);
    *Year = 100 * (C - 49) + Y + J;
}
/**
 * Convert GPS Extended Week (that not return to 0) and Seconds to Modified Julian Day. Include UTC leap seconds.
 * 
 */
static S32 gps_gps_to_mjd (S32 GpsWeek, S32 GpsSeconds, S32 GpsOffset)
{
    S32 GpsDays;
    GpsDays = GpsWeek * 7 + ((GpsSeconds - GpsOffset) / 86400);
    return bsp_gps_date_to_mjd(1980, 1, 6) + GpsDays;
}