Unix2PST PDT

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/LSL

Function: list Unix2PST_PDT(integer unixtime);

Returns a string containing the SLT date and time, annotated with PST or PDT as appropriate, corresponding to the given Unix time.

e.g. Wed 2013-12-25 06:48 PST

• integer

unixtime

–

a point in time represented by the number of seconds since 00:00 hours, Jan 1, 1970 UTC, e.g. a value returned by llGetUnixTime()

Specification

<lsl> // Convert Unix Time to SLT, identifying whether it is currently PST or PDT (i.e. Daylight Saving aware) // Omei Qunhua December 2013

list weekdays = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];

string Unix2PST_PDT(integer insecs) {

   string str = Convert(insecs - (3600 * 8) );   // PST is 8 hours behind GMT
   if (llGetSubString(str, -3, -1) == "PDT")     // if the result indicates Daylight Saving Time ...
       str = Convert(insecs - (3600 * 7) );      // ... Recompute at 1 hour later
   return str;

}

// This leap year test is correct for all years from 1901 to 2099 and hence is quite adequate for Unix Time computations integer LeapYear(integer year) {

   return !(year & 3);

}

integer DaysPerMonth(integer year, integer month) {

   if (month == 2)      return 28 + LeapYear(year);
   return 30 + ( (month + (month > 7) ) & 1);           // Odd months up to July, and even months after July, have 31 days

}

string Convert(integer insecs) {

   integer w; integer month; integer daysinyear;
   integer mins = insecs / 60;
   integer secs = insecs % 60;
   integer hours = mins / 60;
   mins = mins % 60;
   integer days = hours / 24;
   hours = hours % 24;
   integer DayOfWeek = (days + 4) % 7;    // 0=Sun thru 6=Sat

   integer years = 1970 +  4 * (days / 1461);
   days = days % 1461;                  // number of days into a 4-year cycle

   @loop;
   daysinyear = 365 + LeapYear(years);
   if (days >= daysinyear)
   {
       days -= daysinyear;
       ++years;
       jump loop;
   }
   ++days;

   for (w = month = 0; days > w; )
   {
       days -= w;
       w = DaysPerMonth(years, ++month);
   }
   string str =  ((string) years + "-" + llGetSubString ("0" + (string) month, -2, -1) + "-" + llGetSubString ("0" + (string) days, -2, -1) + " " +

llGetSubString ("0" + (string) hours, -2, -1) + ":" + llGetSubString ("0" + (string) mins, -2, -1) );

   integer LastSunday = days - DayOfWeek;
   string PST_PDT = " PST";                  // start by assuming Pacific Standard Time
   // Up to 2006, PDT is from the first Sunday in April to the last Sunday in October
   // After 2006, PDT is from the 2nd Sunday in March to the first Sunday in November
   if (years > 2006 && month == 3  && LastSunday >  7)     PST_PDT = " PDT";
   if (month > 3)                                          PST_PDT = " PDT";
   if (month > 10)                                         PST_PDT = " PST";
   if (years < 2007 && month == 10 && LastSunday > 24)     PST_PDT = " PST";
   return (llList2String(weekdays, DayOfWeek) + " " + str + PST_PDT);

} </lsl>

Example

<lsl> default {

   state_entry()
   {
       llOwnerSay( Unix2PST_PDT (llGetUnixTime() ) );
   }

} </lsl>