to the current time zone and daylight savings time if not specified; if\n\
specified, it can be either a list (as from `current-time-zone') or an\n\
integer (as from `decode-time'), and is applied without consideration for\n\
-daylight savings time. If YEAR is less than 100, values in the range 0 to\n\
-37 are interpreted as in the 21st century, all other values are in the 20th\n\
-century.")
+daylight savings time.\n\
+If YEAR is less than 100, values in the range 0 through 69 are treated\n\
+as 2000 through 2069; values 70 through 99 are treated as 1970...1999.")
(sec, min, hour, day, month, year, zone)
Lisp_Object sec, min, hour, day, month, year, zone;
{
- double universal;
- int fullyear, mon;
- static char days[11] = { 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31 };
+ time_t time;
+ int fullyear, mon, days, seconds, tz = 0;
+ static char days_per_month[11] = { 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31 };
CHECK_NATNUM (sec, 0);
CHECK_NATNUM (min, 1);
fullyear = XINT (year);
if (fullyear < 100)
{
- if (fullyear < 38) /* end of time: 2038-01-19 03:14:08 */
+ if (fullyear < 70) /* Epoch is 1970. */
fullyear += 2000;
else
fullyear += 1900;
}
- if (NILP (zone))
- zone = Fcurrent_time_zone (Qnil);
- if (CONSP (zone))
- zone = Fcar (zone);
-
- CHECK_NUMBER (zone, 6);
-
- /* all of these should evaluate to compile-time constants. */
-#define MIN 60.0 /* 60 */
-#define HOUR (60*MIN) /* 3600 */
-#define DAY (24*HOUR) /* 86400 */
-#define YEAR (365*DAY) /* 31536000 */
-#define YEAR4 (4*YEAR+DAY) /* 126230400 */
-#define YEAR100 (25*YEAR4-DAY) /* 3155673600 */
-#define YEAR400 (4*YEAR100+DAY) /* 12622780800 */
-#define YEAR1900 (4*YEAR400+3*YEAR100) /* 59958144000 */
-#define YEAR1970 (YEAR1900+17*YEAR4+2*YEAR) /* 62167132800 */
-#define LEAPBIAS (59*DAY) /* 5097600 */
-
- mon = XINT (month) - 1;
- fullyear--;
- mon += 10;
- fullyear += mon/12;
+ /* Adjust incoming datespec to epoch = March 1, year 0. */
+ mon = XINT (month) - 1 + 10;
+ fullyear += mon/12 - 1;
mon %= 12;
- universal = XINT (sec) + XINT (min) * MIN + XINT (hour) * HOUR;
- while (mon-- > 0)
- universal += days[mon] * DAY;
- universal += (XINT (day) - 1) * DAY;
- universal += YEAR400 * (fullyear/400);
+ days = XINT (day) - 1; /* day of month */
+ while (mon-- > 0) /* day of year */
+ days += days_per_month[mon];
+ days += 146097 * (fullyear/400); /* 400 years = 146097 days */
fullyear %= 400;
- universal += YEAR100 * (fullyear/100);
+ days += 36524 * (fullyear/100); /* 100 years = 36524 days */
fullyear %= 100;
- universal += YEAR4 * (fullyear/4);
+ days += 1461 * (fullyear/4); /* 4 years = 1461 days */
fullyear %= 4;
- universal += YEAR * fullyear;
- universal -= YEAR1970 - LEAPBIAS;
-
- return make_time ((int)(universal - XINT (zone)));
-
-#undef MIN
-#undef HOUR
-#undef DAY
-#undef YEAR
-#undef YEAR4
-#undef YEAR100
-#undef YEAR400
-#undef YEAR1900
-#undef YEAR1970
-#undef LEAPBIAS
+ days += 365 * fullyear; /* 1 year = 365 days */
+
+ /* Adjust computed datespec to epoch = January 1, 1970. */
+ days += 59; /* March 1 is 59th day. */
+ days -= 719527; /* 1970 years = 719527 days */
+
+ seconds = XINT (sec) + 60 * XINT (min) + 3600 * XINT (hour);
+
+ if (sizeof (time_t) == 4
+ && ((days+(seconds/86400) > 24854) || (days+(seconds/86400) < -24854)))
+ error ("the specified time is outside the representable range");
+
+ time = days * 86400 + seconds;
+
+ /* We have the correct value for UTC. Adjust for timezones. */
+ if (NILP (zone))
+ {
+ struct tm gmt, *t;
+ time_t adjusted_time;
+ int adjusted_tz;
+ /* If the system does not use timezones, gmtime returns 0, and we
+ already have the correct value, by definition. */
+ if ((t = gmtime (&time)) != 0)
+ {
+ gmt = *t;
+ t = localtime (&time);
+ tz = difftm (t, &gmt);
+ /* The timezone returned is that at the specified Universal Time,
+ not the local time, which is what we want. Adjust, repeat. */
+ adjusted_time = time - tz;
+ gmt = *gmtime (&adjusted_time); /* this is safe now */
+ t = localtime (&adjusted_time);
+ adjusted_tz = difftm (t, &gmt);
+ /* In case of discrepancy, adjust again for extra accuracy. */
+ if (adjusted_tz != tz)
+ {
+ adjusted_time = time - adjusted_tz;
+ gmt = *gmtime (&adjusted_time);
+ t = localtime (&adjusted_time);
+ adjusted_tz = difftm (t, &gmt);
+ }
+ tz = adjusted_tz;
+ }
+ }
+ else
+ {
+ if (CONSP (zone))
+ zone = Fcar (zone);
+ CHECK_NUMBER (zone, 6);
+ tz = XINT (zone);
+ }
+
+ return make_time (time - tz);
}
DEFUN ("current-time-string", Fcurrent_time_string, Scurrent_time_string, 0, 1, 0,