/*----------------------------------------------------------------------------------------------
Core routine to map between local and Utc. This assumes that DST doesn't kick in
near a year boundary so that when the switch happens, the DST and STD times are in the
same year.
----------------------------------------------------------------------------------------------*/
int64 TimeMapper::MapMsec(int64 msecSrc, bool fToUtc)
{
int64 msecT;
int msecDay;
int day;
int dayMin;
int dyear;
int yday;
int yt;
int ymin;
// First determines the year type and minute within the year.
// Mod to 400 year period.
msecT = ModPos(msecSrc, kmsecPerPeriod);
// Find the day within the 400 year period.
day = (int)(msecT / kmsecPerDay);
Assert(0 <= day && day < kdayPerPeriod);
// Get the time within the day.
msecDay = (int)(msecT - day * (int64)kmsecPerDay);
Assert(0 <= msecDay && msecDay < kmsecPerDay);
// Find the year within the 400 year period (dyear) and the day within that year (yday).
Assert(0 <= day && day < 146097);
dyear = YearFromDayInPeriod(day, &yday);
Assert(0 <= dyear && dyear < 400);
Assert(0 <= yday && (yday < 365 || yday == 365 && SilTime::IsLeapYear(dyear + kyearBase)));
// Calculate the day number (within the 400 year period) of the first day of
// the year (dayMin).
dayMin = day - yday;
Assert(dayMin == DayFromYearInPeriod(dyear));
// Get the year type. kdayMonday is used because T0 is a Monday.
yt = ModPos(dayMin + kwdayMonday, kdayPerWeek);
if (SilTime::IsLeapYear(dyear + kyearBase))
yt += kdayPerWeek;
// Calculate the minute within the year.
ymin = yday * kminPerDay + msecDay / kmsecPerMin;
if (!fToUtc)
{
// Mapping from utc to local.
if (m_rgyminMin[yt] <= ymin && ymin < m_rgyminLim[yt])
return msecSrc + Mul(m_dminTz2, kmsecPerMin);
return msecSrc + Mul(m_dminTz1, kmsecPerMin);
}
// The overlap is always ambiguous and there's nothing we can do about it.
ymin -= m_dminTz2;
if (m_rgyminMin[yt] <= ymin && ymin < m_rgyminLim[yt])
return msecSrc - Mul(m_dminTz2, kmsecPerMin);
return msecSrc - Mul(m_dminTz1, kmsecPerMin);
}
/*----------------------------------------------------------------------------------------------
Fill in the SilTimeInfo structure from this time.
----------------------------------------------------------------------------------------------*/
void SilTime::GetTimeInfo(SilTimeInfo * psti, bool fUtc) const
{
AssertPtr(psti);
int dyear;
int day;
int msecDay;
int yday;
int64 msec = m_msec;
if (!fUtc)
msec = g_tmm.ToLcl(msec);
// Decompose m_msec into which 400 year period it is in (relative to T0) and
// the millisecond within the 400 year period.
psti->year = (int)FloorDiv(msec, kmsecPerPeriod) * kyearPerPeriod + kyearBase;
msec = ModPos(msec, kmsecPerPeriod);
Assert(0 <= 0 && msec < kmsecPerPeriod);
// Find the day within the 400 year period.
day = (int)(msec / kmsecPerDay);
Assert(0 <= day && day < kdayPerPeriod);
// Get the time within the day.
msecDay = (int)(msec - day * (int64)kmsecPerDay);
Assert(0 <= msecDay && msecDay < kmsecPerDay);
// Find the year within the 400 year period (dyear) and the day within that year (yday).
Assert(0 <= day && day < 146097);
dyear = YearFromDayInPeriod(day, &yday);
Assert(0 <= dyear && dyear < 400);
Assert(0 <= yday && (yday < 365 || yday == 365 && SilTime::IsLeapYear(dyear + kyearBase)));
// Add dyear into the year.
psti->year += dyear;
// Find the month and day in the month.
const int * prgday = g_rgyday[IsLeapYear(psti->year)];
for (psti->ymon = 1; yday >= prgday[psti->ymon]; psti->ymon++)
;
psti->mday = yday - prgday[psti->ymon - 1] + 1;
// Calculate the week day.
// kdayMonday is used because T0 is a Monday. Note that kdayPerPeriod is divisible by 7
// so we don't have to adjust the day of the week.
psti->wday = ModPos(day + kwdayMonday, kdayPerWeek);
// Fill in the time.
psti->hour = msecDay / kmsecPerHour;
psti->min = (msecDay % kmsecPerHour) / kmsecPerMin;
psti->sec = (msecDay % kmsecPerMin) / kmsecPerSec;
psti->msec = msecDay % kmsecPerSec;
}
