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(Fencode_time): Rewrite by Naggum.
This commit is contained in:
Richard M. Stallman
parent
61392e7b04
commit
1b8fa736b3
117
src/editfns.c
117
src/editfns.c
@ -741,15 +741,15 @@ This is the reverse operation of `decode-time', which see. ZONE defaults\n\
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to the current time zone and daylight savings time if not specified; if\n\
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specified, it can be either a list (as from `current-time-zone') or an\n\
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integer (as from `decode-time'), and is applied without consideration for\n\
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daylight savings time. If YEAR is less than 100, values in the range 0 to\n\
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37 are interpreted as in the 21st century, all other values are in the 20th\n\
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century.")
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daylight savings time.\n\
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If YEAR is less than 100, values in the range 0 through 69 are treated\n\
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as 2000 through 2069; values 70 through 99 are treated as 1970...1999.")
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(sec, min, hour, day, month, year, zone)
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Lisp_Object sec, min, hour, day, month, year, zone;
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{
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double universal;
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int fullyear, mon;
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static char days[11] = { 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31 };
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time_t time;
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int fullyear, mon, days, seconds, tz = 0;
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static char days_per_month[11] = { 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31 };
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CHECK_NATNUM (sec, 0);
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CHECK_NATNUM (min, 1);
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@ -761,62 +761,79 @@ century.")
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fullyear = XINT (year);
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if (fullyear < 100)
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{
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if (fullyear < 38) /* end of time: 2038-01-19 03:14:08 */
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if (fullyear < 70) /* Epoch is 1970. */
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fullyear += 2000;
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else
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fullyear += 1900;
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}
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if (NILP (zone))
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zone = Fcurrent_time_zone (Qnil);
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if (CONSP (zone))
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zone = Fcar (zone);
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CHECK_NUMBER (zone, 6);
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/* all of these should evaluate to compile-time constants. */
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#define MIN 60.0 /* 60 */
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#define HOUR (60*MIN) /* 3600 */
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#define DAY (24*HOUR) /* 86400 */
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#define YEAR (365*DAY) /* 31536000 */
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#define YEAR4 (4*YEAR+DAY) /* 126230400 */
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#define YEAR100 (25*YEAR4-DAY) /* 3155673600 */
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#define YEAR400 (4*YEAR100+DAY) /* 12622780800 */
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#define YEAR1900 (4*YEAR400+3*YEAR100) /* 59958144000 */
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#define YEAR1970 (YEAR1900+17*YEAR4+2*YEAR) /* 62167132800 */
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#define LEAPBIAS (59*DAY) /* 5097600 */
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mon = XINT (month) - 1;
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fullyear--;
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mon += 10;
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fullyear += mon/12;
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/* Adjust incoming datespec to epoch = March 1, year 0. */
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mon = XINT (month) - 1 + 10;
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fullyear += mon/12 - 1;
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mon %= 12;
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universal = XINT (sec) + XINT (min) * MIN + XINT (hour) * HOUR;
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while (mon-- > 0)
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universal += days[mon] * DAY;
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universal += (XINT (day) - 1) * DAY;
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universal += YEAR400 * (fullyear/400);
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days = XINT (day) - 1; /* day of month */
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while (mon-- > 0) /* day of year */
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days += days_per_month[mon];
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days += 146097 * (fullyear/400); /* 400 years = 146097 days */
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fullyear %= 400;
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universal += YEAR100 * (fullyear/100);
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days += 36524 * (fullyear/100); /* 100 years = 36524 days */
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fullyear %= 100;
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universal += YEAR4 * (fullyear/4);
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days += 1461 * (fullyear/4); /* 4 years = 1461 days */
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fullyear %= 4;
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universal += YEAR * fullyear;
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universal -= YEAR1970 - LEAPBIAS;
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days += 365 * fullyear; /* 1 year = 365 days */
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return make_time ((int)(universal - XINT (zone)));
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/* Adjust computed datespec to epoch = January 1, 1970. */
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days += 59; /* March 1 is 59th day. */
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days -= 719527; /* 1970 years = 719527 days */
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#undef MIN
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#undef HOUR
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#undef DAY
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#undef YEAR
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#undef YEAR4
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#undef YEAR100
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#undef YEAR400
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#undef YEAR1900
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#undef YEAR1970
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#undef LEAPBIAS
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seconds = XINT (sec) + 60 * XINT (min) + 3600 * XINT (hour);
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if (sizeof (time_t) == 4
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&& ((days+(seconds/86400) > 24854) || (days+(seconds/86400) < -24854)))
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error ("the specified time is outside the representable range");
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time = days * 86400 + seconds;
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/* We have the correct value for UTC. Adjust for timezones. */
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if (NILP (zone))
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{
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struct tm gmt, *t;
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time_t adjusted_time;
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int adjusted_tz;
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/* If the system does not use timezones, gmtime returns 0, and we
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already have the correct value, by definition. */
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if ((t = gmtime (&time)) != 0)
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{
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gmt = *t;
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t = localtime (&time);
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tz = difftm (t, &gmt);
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/* The timezone returned is that at the specified Universal Time,
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not the local time, which is what we want. Adjust, repeat. */
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adjusted_time = time - tz;
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gmt = *gmtime (&adjusted_time); /* this is safe now */
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t = localtime (&adjusted_time);
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adjusted_tz = difftm (t, &gmt);
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/* In case of discrepancy, adjust again for extra accuracy. */
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if (adjusted_tz != tz)
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{
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adjusted_time = time - adjusted_tz;
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gmt = *gmtime (&adjusted_time);
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t = localtime (&adjusted_time);
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adjusted_tz = difftm (t, &gmt);
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}
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tz = adjusted_tz;
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}
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}
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else
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{
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if (CONSP (zone))
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zone = Fcar (zone);
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CHECK_NUMBER (zone, 6);
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tz = XINT (zone);
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}
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return make_time (time - tz);
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}
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DEFUN ("current-time-string", Fcurrent_time_string, Scurrent_time_string, 0, 1, 0,
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