CNtpTime::CNtpTime( const SYSTEMTIME & st )
{
// Currently this function only operates correctly in
// the 1900 - 2036 primary epoch defined by NTP
long JD = GetJulianDay( st.wYear, st.wMonth, st.wDay );
JD -= JAN_1ST_1900;
ASSERT( JD >= 0 ); // NTP only supports dates greater than 1900
unsigned __int64 Seconds = JD;
Seconds = ( Seconds * 24 ) + st.wHour;
Seconds = ( Seconds * 60 ) + st.wMinute;
Seconds = ( Seconds * 60 ) + st.wSecond;
ASSERT( Seconds <= 0xffffffff ); // NTP only supports up to 2036
m_Time = ( Seconds << 32 ) + MsToNtpFraction( st.wMilliseconds );
}
void FDateTime::GetDate( int32& OutYear, int32& OutMonth, int32& OutDay ) const
{
// Based on FORTRAN code in:
// Fliegel, H. F. and van Flandern, T. C.,
// Communications of the ACM, Vol. 11, No. 10 (October 1968).
int32 i, j, k, l, n;
l = FMath::FloorToInt(GetJulianDay() + 0.5) + 68569;
n = 4 * l / 146097;
l = l - (146097 * n + 3) / 4;
i = 4000 * (l + 1) / 1461001;
l = l - 1461 * i / 4 + 31;
j = 80 * l / 2447;
k = l - 2447 * j / 80;
l = j / 11;
j = j + 2 - 12 * l;
i = 100 * (n - 49) + i + l;
OutYear = i;
OutMonth = j;
OutDay = k;
}
