-BOOL TmFromOleDate(DATE dtSrc, struct tm& tmDest)
-{
- // The legal range does not actually span year 0 to 9999.
- if (dtSrc > MAX_DATE || dtSrc < MIN_DATE) // about year 100 to about 9999
- return FALSE;
-
- long nDaysAbsolute; // Number of days since 1/1/0
- long nSecsInDay; // Time in seconds since midnight
- long nMinutesInDay; // Minutes in day
-
- long n400Years; // Number of 400 year increments since 1/1/0
- long n400Century; // Century within 400 year block (0,1,2 or 3)
- long n4Years; // Number of 4 year increments since 1/1/0
- long n4Day; // Day within 4 year block
- // (0 is 1/1/yr1, 1460 is 12/31/yr4)
- long n4Yr; // Year within 4 year block (0,1,2 or 3)
- BOOL bLeap4 = TRUE; // TRUE if 4 year block includes leap year
-
- double dblDate = dtSrc; // tempory serial date
-
- // Round to the second
- dblDate += ((dtSrc > 0.0) ? HALF_SECOND : -HALF_SECOND);
-
- nDaysAbsolute = (long)dblDate + 693959L; // Add days from 1/1/0 to 12/30/1899
-
- dblDate = fabs(dblDate);
- nSecsInDay = (long)((dblDate - floor(dblDate)) * 86400.);
-
- // Calculate the day of week (sun=1, mon=2...)
- // -1 because 1/1/0 is Sat. +1 because we want 1-based
- tmDest.tm_wday = (int)((nDaysAbsolute - 1) % 7L) + 1;
-
- // Leap years every 4 yrs except centuries not multiples of 400.
- n400Years = (long)(nDaysAbsolute / 146097L);
-
- // Set nDaysAbsolute to day within 400-year block
- nDaysAbsolute %= 146097L;
-
- // -1 because first century has extra day
- n400Century = (long)((nDaysAbsolute - 1) / 36524L);
-
- // Non-leap century
- if (n400Century != 0)
- {
- // Set nDaysAbsolute to day within century
- nDaysAbsolute = (nDaysAbsolute - 1) % 36524L;
-
- // +1 because 1st 4 year increment has 1460 days
- n4Years = (long)((nDaysAbsolute + 1) / 1461L);
-
- if (n4Years != 0)
- n4Day = (long)((nDaysAbsolute + 1) % 1461L);
- else
- {
- bLeap4 = FALSE;
- n4Day = (long)nDaysAbsolute;
- }
- }
- else
- {
- // Leap century - not special case!
- n4Years = (long)(nDaysAbsolute / 1461L);
- n4Day = (long)(nDaysAbsolute % 1461L);
- }
-
- if (bLeap4)
- {
- // -1 because first year has 366 days
- n4Yr = (n4Day - 1) / 365;
-
- if (n4Yr != 0)
- n4Day = (n4Day - 1) % 365;
- }
- else
- {
- n4Yr = n4Day / 365;
- n4Day %= 365;
- }
-
- // n4Day is now 0-based day of year. Save 1-based day of year, year number
- tmDest.tm_yday = (int)n4Day + 1;
- tmDest.tm_year = n400Years * 400 + n400Century * 100 + n4Years * 4 + n4Yr;
-
- // Handle leap year: before, on, and after Feb. 29.
- if (n4Yr == 0 && bLeap4)
- {
- // Leap Year
- if (n4Day == 59)
- {
- /* Feb. 29 */
- tmDest.tm_mon = 2;
- tmDest.tm_mday = 29;
- goto DoTime;
- }
-
- // Pretend it's not a leap year for month/day comp.
- if (n4Day >= 60)
- --n4Day;
- }
-
- // Make n4DaY a 1-based day of non-leap year and compute
- // month/day for everything but Feb. 29.
- ++n4Day;
-
- // Month number always >= n/32, so save some loop time */
- for (tmDest.tm_mon = (n4Day >> 5) + 1;
- n4Day > rgMonthDays[tmDest.tm_mon]; tmDest.tm_mon++)
- ;
-
- tmDest.tm_mday = (int)(n4Day - rgMonthDays[tmDest.tm_mon-1]);
-
-DoTime:
- if (nSecsInDay == 0)
- tmDest.tm_hour = tmDest.tm_min = tmDest.tm_sec = 0;
- else
- {
- tmDest.tm_sec = (int)nSecsInDay % 60L;
- nMinutesInDay = nSecsInDay / 60L;
- tmDest.tm_min = (int)nMinutesInDay % 60;
- tmDest.tm_hour = (int)nMinutesInDay / 60;
- }
-
- return TRUE;
-}
projects / wxWidgets.git / blobdiff