2001-07-16 07:46:48 +00:00
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;;; cal-dst.el --- calendar functions for daylight savings rules
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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1996-12-19 01:17:26 +00:00
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;; Copyright (C) 1993, 1994, 1995, 1996 Free Software Foundation, Inc.
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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;; Author: Paul Eggert <eggert@twinsun.com>
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;; Edward M. Reingold <reingold@cs.uiuc.edu>
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;; Keywords: calendar
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;; Human-Keywords: daylight savings time, calendar, diary, holidays
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;; This file is part of GNU Emacs.
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1994-04-07 20:30:18 +00:00
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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;; GNU Emacs is distributed in the hope that it will be useful,
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1994-04-07 20:30:18 +00:00
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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1996-01-14 07:34:30 +00:00
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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2005-07-04 17:55:18 +00:00
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;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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;; Boston, MA 02110-1301, USA.
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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;;; Commentary:
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;; This collection of functions implements the features of calendar.el and
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;; holiday.el that deal with daylight savings time.
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;; Comments, corrections, and improvements should be sent to
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;; Edward M. Reingold Department of Computer Science
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;; (217) 333-6733 University of Illinois at Urbana-Champaign
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;; reingold@cs.uiuc.edu 1304 West Springfield Avenue
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;; Urbana, Illinois 61801
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;;; Code:
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(require 'calendar)
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1996-12-19 01:17:26 +00:00
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(require 'cal-persia)
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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(defvar calendar-current-time-zone-cache nil
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"Cache for result of calendar-current-time-zone.")
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(defvar calendar-system-time-basis
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(calendar-absolute-from-gregorian '(1 1 1970))
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"Absolute date of starting date of system clock.")
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(defun calendar-absolute-from-time (x utc-diff)
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"Absolute local date of time X; local time is UTC-DIFF seconds from UTC.
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X is (HIGH . LOW) or (HIGH LOW . IGNORED) where HIGH and LOW are the
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high and low 16 bits, respectively, of the number of seconds since
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1970-01-01 00:00:00 UTC, ignoring leap seconds.
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Returns the pair (ABS-DATE . SECONDS) where SECONDS after local midnight on
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absolute date ABS-DATE is the equivalent moment to X."
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(let* ((h (car x))
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(xtail (cdr x))
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(l (+ utc-diff (if (numberp xtail) xtail (car xtail))))
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1993-08-10 17:57:31 +00:00
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(u (+ (* 512 (mod h 675)) (floor l 128))))
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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;; Overflow is a terrible thing!
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(cons (+ calendar-system-time-basis
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;; floor((2^16 h +l) / (60*60*24))
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(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
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(* 512 (floor h 675)) (floor u 675))
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1993-11-13 23:59:53 +00:00
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;; (2^16 h +l) mod (60*60*24)
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(+ (* (mod u 675) 128) (mod l 128)))))
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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(defun calendar-time-from-absolute (abs-date s)
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"Time of absolute date ABS-DATE, S seconds after midnight.
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2004-07-14 23:22:14 +00:00
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Returns the list (HIGH LOW) where HIGH and LOW are the high and low
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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16 bits, respectively, of the number of seconds 1970-01-01 00:00:00 UTC,
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ignoring leap seconds, that is the equivalent moment to S seconds after
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midnight UTC on absolute date ABS-DATE."
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(let* ((a (- abs-date calendar-system-time-basis))
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1993-08-10 17:57:31 +00:00
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(u (+ (* 163 (mod a 512)) (floor s 128))))
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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;; Overflow is a terrible thing!
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2004-07-14 23:22:14 +00:00
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(list
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1993-11-13 23:59:53 +00:00
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;; floor((60*60*24*a + s) / 2^16)
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1993-08-10 17:57:31 +00:00
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(+ a (* 163 (floor a 512)) (floor u 512))
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1993-11-13 23:59:53 +00:00
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;; (60*60*24*a + s) mod 2^16
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1993-08-10 17:57:31 +00:00
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(+ (* 128 (mod u 512)) (mod s 128)))))
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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(defun calendar-next-time-zone-transition (time)
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"Return the time of the next time zone transition after TIME.
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Both TIME and the result are acceptable arguments to current-time-zone.
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Return nil if no such transition can be found."
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(let* ((base 65536);; 2^16 = base of current-time output
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(quarter-multiple 120);; approx = (seconds per quarter year) / base
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(time-zone (current-time-zone time))
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(time-utc-diff (car time-zone))
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hi
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hi-zone
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(hi-utc-diff time-utc-diff)
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(quarters '(2 1 3)))
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;; Heuristic: probe the time zone offset in the next three calendar
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;; quarters, looking for a time zone offset different from TIME.
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(while (and quarters (eq time-utc-diff hi-utc-diff))
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(setq hi (cons (+ (car time) (* (car quarters) quarter-multiple)) 0))
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(setq hi-zone (current-time-zone hi))
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(setq hi-utc-diff (car hi-zone))
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(setq quarters (cdr quarters)))
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(and
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time-utc-diff
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hi-utc-diff
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(not (eq time-utc-diff hi-utc-diff))
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;; Now HI is after the next time zone transition.
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;; Set LO to TIME, and then binary search to increase LO and decrease HI
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;; until LO is just before and HI is just after the time zone transition.
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(let* ((tail (cdr time))
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(lo (cons (car time) (if (numberp tail) tail (car tail))))
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probe)
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(while
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;; Set PROBE to halfway between LO and HI, rounding down.
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;; If PROBE equals LO, we are done.
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(let* ((lsum (+ (cdr lo) (cdr hi)))
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(hsum (+ (car lo) (car hi) (/ lsum base)))
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(hsumodd (logand 1 hsum)))
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(setq probe (cons (/ (- hsum hsumodd) 2)
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(/ (+ (* hsumodd base) (% lsum base)) 2)))
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(not (equal lo probe)))
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;; Set either LO or HI to PROBE, depending on probe results.
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(if (eq (car (current-time-zone probe)) hi-utc-diff)
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(setq hi probe)
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(setq lo probe)))
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hi))))
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(defun calendar-time-zone-daylight-rules (abs-date utc-diff)
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"Return daylight transition rule for ABS-DATE, UTC-DIFF sec offset from UTC.
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1996-12-19 01:17:26 +00:00
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ABS-DATE must specify a day that contains a daylight savings transition.
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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The result has the proper form for calendar-daylight-savings-starts'."
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(let* ((date (calendar-gregorian-from-absolute abs-date))
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(weekday (% abs-date 7))
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(m (extract-calendar-month date))
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(d (extract-calendar-day date))
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(y (extract-calendar-year date))
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(last (calendar-last-day-of-month m y))
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(candidate-rules
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(append
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;; Day D of month M.
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(list (list 'list m d 'year))
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;; The first WEEKDAY of month M.
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(if (< d 8)
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(list (list 'calendar-nth-named-day 1 weekday m 'year)))
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;; The last WEEKDAY of month M.
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(if (> d (- last 7))
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(list (list 'calendar-nth-named-day -1 weekday m 'year)))
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;; The first WEEKDAY after day J of month M, for D-6 < J <= D.
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(let (l)
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(calendar-for-loop j from (max 2 (- d 6)) to (min d (- last 8)) do
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(setq l
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(cons
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(list 'calendar-nth-named-day 1 weekday m 'year j)
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l)))
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1996-12-19 01:17:26 +00:00
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l)
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;; 01-01 and 07-01 for this year's Persian calendar.
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(if (and (= m 3) (<= 20 d) (<= d 21))
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'((calendar-gregorian-from-absolute
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(calendar-absolute-from-persian
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(list 1 1 (- year 621))))))
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(if (and (= m 9) (<= 22 d) (<= d 23))
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'((calendar-gregorian-from-absolute
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(calendar-absolute-from-persian
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(list 7 1 (- year 621))))))))
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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(prevday-sec (- -1 utc-diff)) ;; last sec of previous local day
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(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
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(year (1+ y)))
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;; Scan through the next few years until only one rule remains.
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(while
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(let ((rules candidate-rules)
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new-rules)
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(while
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(let*
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((rule (car rules))
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(date
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;; The following is much faster than
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;; (calendar-absolute-from-gregorian (eval rule)).
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(cond ((eq (car rule) 'calendar-nth-named-day)
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(eval (cons 'calendar-nth-named-absday (cdr rule))))
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((eq (car rule) 'calendar-gregorian-from-absolute)
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(eval (car (cdr rule))))
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(t (let ((g (eval rule)))
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(calendar-absolute-from-gregorian g))))))
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(or (equal
|
|
|
|
(current-time-zone
|
|
|
|
(calendar-time-from-absolute date prevday-sec))
|
|
|
|
(current-time-zone
|
|
|
|
(calendar-time-from-absolute (1+ date) prevday-sec)))
|
|
|
|
(setq new-rules (cons rule new-rules)))
|
|
|
|
(setq rules (cdr rules))))
|
|
|
|
;; If no rules remain, just use the first candidate rule;
|
|
|
|
;; it's wrong in general, but it's right for at least one year.
|
|
|
|
(setq candidate-rules (if new-rules (nreverse new-rules)
|
|
|
|
(list (car candidate-rules))))
|
|
|
|
(setq year (1+ year))
|
|
|
|
(cdr candidate-rules)))
|
|
|
|
(car candidate-rules)))
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
|
|
|
(defun calendar-current-time-zone ()
|
|
|
|
"Return UTC difference, dst offset, names and rules for current time zone.
|
|
|
|
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
Returns (UTC-DIFF DST-OFFSET STD-ZONE DST-ZONE DST-STARTS DST-ENDS
|
|
|
|
DST-STARTS-TIME DST-ENDS-TIME), based on a heuristic probing of what the
|
|
|
|
system knows:
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
|
|
|
UTC-DIFF is an integer specifying the number of minutes difference between
|
|
|
|
standard time in the current time zone and Coordinated Universal Time
|
|
|
|
(Greenwich Mean Time). A negative value means west of Greenwich.
|
|
|
|
DST-OFFSET is an integer giving the daylight savings time offset in minutes.
|
|
|
|
STD-ZONE is a string giving the name of the time zone when no seasonal time
|
|
|
|
adjustment is in effect.
|
|
|
|
DST-ZONE is a string giving the name of the time zone when there is a seasonal
|
|
|
|
time adjustment in effect.
|
|
|
|
DST-STARTS and DST-ENDS are sexps in the variable `year' giving the daylight
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
savings time start and end rules, in the form expected by
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
`calendar-daylight-savings-starts'.
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
DST-STARTS-TIME and DST-ENDS-TIME are integers giving the number of minutes
|
|
|
|
after midnight that daylight savings time starts and ends.
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
If the local area does not use a seasonal time adjustment, STD-ZONE and
|
|
|
|
DST-ZONE are equal, and all the DST-* integer variables are 0.
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
|
|
|
Some operating systems cannot provide all this information to Emacs; in this
|
|
|
|
case, `calendar-current-time-zone' returns a list containing nil for the data
|
|
|
|
it can't find."
|
|
|
|
(or
|
|
|
|
calendar-current-time-zone-cache
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(setq
|
|
|
|
calendar-current-time-zone-cache
|
|
|
|
(let* ((t0 (current-time))
|
|
|
|
(t0-zone (current-time-zone t0))
|
|
|
|
(t0-utc-diff (car t0-zone))
|
|
|
|
(t0-name (car (cdr t0-zone))))
|
|
|
|
(if (not t0-utc-diff)
|
|
|
|
;; Little or no time zone information is available.
|
|
|
|
(list nil nil t0-name t0-name nil nil nil nil)
|
|
|
|
(let* ((t1 (calendar-next-time-zone-transition t0))
|
|
|
|
(t2 (and t1 (calendar-next-time-zone-transition t1))))
|
|
|
|
(if (not t2)
|
|
|
|
;; This locale does not have daylight savings time.
|
|
|
|
(list (/ t0-utc-diff 60) 0 t0-name t0-name nil nil 0 0)
|
|
|
|
;; Use heuristics to find daylight savings parameters.
|
|
|
|
(let* ((t1-zone (current-time-zone t1))
|
|
|
|
(t1-utc-diff (car t1-zone))
|
|
|
|
(t1-name (car (cdr t1-zone)))
|
|
|
|
(t1-date-sec (calendar-absolute-from-time t1 t0-utc-diff))
|
|
|
|
(t2-date-sec (calendar-absolute-from-time t2 t1-utc-diff))
|
|
|
|
(t1-rules (calendar-time-zone-daylight-rules
|
|
|
|
(car t1-date-sec) t0-utc-diff))
|
|
|
|
(t2-rules (calendar-time-zone-daylight-rules
|
|
|
|
(car t2-date-sec) t1-utc-diff))
|
|
|
|
(t1-time (/ (cdr t1-date-sec) 60))
|
|
|
|
(t2-time (/ (cdr t2-date-sec) 60)))
|
|
|
|
(cons
|
|
|
|
(/ (min t0-utc-diff t1-utc-diff) 60)
|
|
|
|
(cons
|
|
|
|
(/ (abs (- t0-utc-diff t1-utc-diff)) 60)
|
|
|
|
(if (< t0-utc-diff t1-utc-diff)
|
1994-05-30 10:26:56 +00:00
|
|
|
(list t0-name t1-name t1-rules t2-rules t1-time t2-time)
|
|
|
|
(list t1-name t0-name t2-rules t1-rules t2-time t1-time)
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
)))))))))))
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
1995-09-21 02:54:58 +00:00
|
|
|
;;; The following eight defvars relating to daylight savings time should NOT be
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
;;; marked to go into loaddefs.el where they would be evaluated when Emacs is
|
|
|
|
;;; dumped. These variables' appropriate values depend on the conditions under
|
|
|
|
;;; which the code is INVOKED; so it's inappropriate to initialize them when
|
|
|
|
;;; Emacs is dumped---they should be initialized when calendar.el is loaded.
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
;;; They default to US Eastern time if time zone info is not available.
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
|
|
|
(calendar-current-time-zone)
|
|
|
|
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(defvar calendar-time-zone (or (car calendar-current-time-zone-cache) -300)
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
"*Number of minutes difference between local standard time at
|
|
|
|
`calendar-location-name' and Coordinated Universal (Greenwich) Time. For
|
|
|
|
example, -300 for New York City, -480 for Los Angeles.")
|
|
|
|
|
|
|
|
(defvar calendar-daylight-time-offset
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(or (car (cdr calendar-current-time-zone-cache)) 60)
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
"*Number of minutes difference between daylight savings and standard time.
|
2003-02-04 13:24:35 +00:00
|
|
|
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
If the locale never uses daylight savings time, set this to 0.")
|
|
|
|
|
|
|
|
(defvar calendar-standard-time-zone-name
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(or (car (nthcdr 2 calendar-current-time-zone-cache)) "EST")
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
"*Abbreviated name of standard time zone at `calendar-location-name'.
|
|
|
|
For example, \"EST\" in New York City, \"PST\" for Los Angeles.")
|
|
|
|
|
|
|
|
(defvar calendar-daylight-time-zone-name
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(or (car (nthcdr 3 calendar-current-time-zone-cache)) "EDT")
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
"*Abbreviated name of daylight-savings time zone at `calendar-location-name'.
|
|
|
|
For example, \"EDT\" in New York City, \"PDT\" for Los Angeles.")
|
2003-02-04 13:24:35 +00:00
|
|
|
|
1994-04-07 19:05:41 +00:00
|
|
|
;;;###autoload
|
|
|
|
(put 'calendar-daylight-savings-starts 'risky-local-variable t)
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
(defvar calendar-daylight-savings-starts
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(or (car (nthcdr 4 calendar-current-time-zone-cache))
|
|
|
|
(and (not (zerop calendar-daylight-time-offset))
|
|
|
|
'(calendar-nth-named-day 1 0 4 year)))
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
"*Sexp giving the date on which daylight savings time starts.
|
|
|
|
This is an expression in the variable `year' whose value gives the Gregorian
|
|
|
|
date in the form (month day year) on which daylight savings time starts. It is
|
|
|
|
used to determine the starting date of daylight savings time for the holiday
|
|
|
|
list and for correcting times of day in the solar and lunar calculations.
|
|
|
|
|
|
|
|
For example, if daylight savings time is mandated to start on October 1,
|
|
|
|
you would set `calendar-daylight-savings-starts' to
|
|
|
|
|
|
|
|
'(10 1 year)
|
|
|
|
|
1993-09-06 22:37:51 +00:00
|
|
|
If it starts on the first Sunday in April, you would set it to
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
1993-09-06 22:37:51 +00:00
|
|
|
'(calendar-nth-named-day 1 0 4 year)
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
|
|
|
If the locale never uses daylight savings time, set this to nil.")
|
|
|
|
|
1994-04-07 19:05:41 +00:00
|
|
|
;;;###autoload
|
1994-05-30 09:36:20 +00:00
|
|
|
(put 'calendar-daylight-savings-ends 'risky-local-variable t)
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
(defvar calendar-daylight-savings-ends
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(or (car (nthcdr 5 calendar-current-time-zone-cache))
|
|
|
|
(and (not (zerop calendar-daylight-time-offset))
|
|
|
|
'(calendar-nth-named-day -1 0 10 year)))
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
"*Sexp giving the date on which daylight savings time ends.
|
|
|
|
This is an expression in the variable `year' whose value gives the Gregorian
|
|
|
|
date in the form (month day year) on which daylight savings time ends. It is
|
|
|
|
used to determine the starting date of daylight savings time for the holiday
|
|
|
|
list and for correcting times of day in the solar and lunar calculations.
|
|
|
|
|
1993-09-06 22:37:51 +00:00
|
|
|
For example, if daylight savings time ends on the last Sunday in October:
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
1993-09-06 22:37:51 +00:00
|
|
|
'(calendar-nth-named-day -1 0 10 year)
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
|
|
|
If the locale never uses daylight savings time, set this to nil.")
|
2003-02-04 13:24:35 +00:00
|
|
|
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(defvar calendar-daylight-savings-starts-time
|
|
|
|
(or (car (nthcdr 6 calendar-current-time-zone-cache)) 120)
|
|
|
|
"*Number of minutes after midnight that daylight savings time starts.")
|
2003-02-04 13:24:35 +00:00
|
|
|
|
(calendar-time-zone-daylight-rules): Scan through the
next few years until at most one rule remains; if none remain, then
just use the first candidate rule; it's wrong in general, but it's
right for at least one year. This is a better heuristic in case the
underlying time zone implementation has bugs (which is all too
common). If possible, don't convert back and forth between gregorian
and absolute; this speeds things up noticeably. This uses the new
calendar-nth-named-absday function.
(calendar-current-time-zone): Some locales start DST at a different
time of day than they end; allow for this by yielding both times. The
performance speedups in calendar.el are great enough that we now no
longer need the "Checking time zone data..." message. If
current-time-zone yields nil, don't bother with
calendar-next-time-zone-transition. Use clearer names for local vars.
(calendar-time-zone, calendar-daylight-time-offset,
calendar-{standard,daylight}-time-zone-name,
calendar-daylight-savings-{starts,ends}): Default to US Eastern rules
for information that is not available.
(calendar-daylight-savings-{starts,ends}-time): New vars, replacing
calendar-daylight-savings-switchover-time, to support locales that
start DST at a different time of day than they end.
(calendar-absolute-from-time):
Fix typo by interchanging floor and mod.
1993-08-28 04:14:25 +00:00
|
|
|
(defvar calendar-daylight-savings-ends-time
|
|
|
|
(or (car (nthcdr 7 calendar-current-time-zone-cache))
|
|
|
|
calendar-daylight-savings-starts-time)
|
|
|
|
"*Number of minutes after midnight that daylight savings time ends.")
|
* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
|
|
|
|
1995-09-21 02:54:58 +00:00
|
|
|
(defun dst-in-effect (date)
|
|
|
|
"True if on absolute DATE daylight savings time is in effect.
|
1995-12-05 22:55:22 +00:00
|
|
|
Fractional part of DATE is local standard time of day."
|
1995-09-21 02:54:58 +00:00
|
|
|
(let* ((year (extract-calendar-year
|
|
|
|
(calendar-gregorian-from-absolute (floor date))))
|
1995-12-05 22:55:22 +00:00
|
|
|
(dst-starts-gregorian (eval calendar-daylight-savings-starts))
|
|
|
|
(dst-ends-gregorian (eval calendar-daylight-savings-ends))
|
|
|
|
(dst-starts (and dst-starts-gregorian
|
1995-09-21 02:54:58 +00:00
|
|
|
(+ (calendar-absolute-from-gregorian
|
1995-12-05 22:55:22 +00:00
|
|
|
dst-starts-gregorian)
|
1995-09-21 02:54:58 +00:00
|
|
|
(/ calendar-daylight-savings-starts-time
|
|
|
|
60.0 24.0))))
|
1995-12-05 22:55:22 +00:00
|
|
|
(dst-ends (and dst-ends-gregorian
|
1995-09-21 02:54:58 +00:00
|
|
|
(+ (calendar-absolute-from-gregorian
|
1995-12-05 22:55:22 +00:00
|
|
|
dst-ends-gregorian)
|
1995-09-21 02:54:58 +00:00
|
|
|
(/ (- calendar-daylight-savings-ends-time
|
|
|
|
calendar-daylight-time-offset)
|
|
|
|
60.0 24.0)))))
|
1995-12-05 22:55:22 +00:00
|
|
|
(and dst-starts dst-ends
|
|
|
|
(if (< dst-starts dst-ends)
|
|
|
|
(and (<= dst-starts date) (< date dst-ends))
|
|
|
|
(or (<= dst-starts date) (< date dst-ends))))))
|
1995-09-21 02:54:58 +00:00
|
|
|
|
|
|
|
(defun dst-adjust-time (date time &optional style)
|
|
|
|
"Adjust, to account for dst on DATE, decimal fraction standard TIME.
|
|
|
|
Returns a list (date adj-time zone) where `date' and `adj-time' are the values
|
|
|
|
adjusted for `zone'; here `date' is a list (month day year), `adj-time' is a
|
|
|
|
decimal fraction time, and `zone' is a string.
|
|
|
|
|
|
|
|
Optional parameter STYLE forces the result time to be standard time when its
|
|
|
|
value is 'standard and daylight savings time (if available) when its value is
|
|
|
|
'daylight.
|
|
|
|
|
|
|
|
Conversion to daylight savings time is done according to
|
|
|
|
`calendar-daylight-savings-starts', `calendar-daylight-savings-ends',
|
|
|
|
`calendar-daylight-savings-starts-time',
|
|
|
|
`calendar-daylight-savings-ends-time', and
|
|
|
|
`calendar-daylight-savings-offset'."
|
|
|
|
|
|
|
|
(let* ((rounded-abs-date (+ (calendar-absolute-from-gregorian date)
|
|
|
|
(/ (round (* 60 time)) 60.0 24.0)))
|
|
|
|
(dst (dst-in-effect rounded-abs-date))
|
|
|
|
(time-zone (if dst
|
|
|
|
calendar-daylight-time-zone-name
|
|
|
|
calendar-standard-time-zone-name))
|
|
|
|
(time (+ rounded-abs-date
|
|
|
|
(if dst (/ calendar-daylight-time-offset 24.0 60.0) 0))))
|
|
|
|
(list (calendar-gregorian-from-absolute (truncate time))
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(* 24.0 (- time (truncate time)))
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time-zone)))
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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(provide 'cal-dst)
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2003-09-01 15:45:59 +00:00
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;;; arch-tag: a141d204-213c-4ca5-bdc6-f9df3aa92aad
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* cal-dst.el: New file.
(calendar-/, calendar-%, calendar-absolute-from-time,
calendar-time-from-absolute, calendar-next-time-zone-transition,
calendar-time-zone-daylight-rules): New functions.
(calendar-current-time-zone): Moved from calendar.el and rewritten.
(calendar-current-time-zone-cache): New variable.
(calendar-current-time-zone, calendar-time-zone,
calendar-daylight-time-offset, calendar-standard-time-zone-name,
calendar-daylight-time-zone-name,
calendar-daylight-savings-starts, calendar-daylight-savings-ends,
calendar-daylight-savings-switchover-time): Moved from calendar.el.
1993-06-22 03:25:13 +00:00
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;;; cal-dst.el ends here
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