org.armedbear.lisp.time.lisp Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of abcl Show documentation
Show all versions of abcl Show documentation
Common Lisp implementation running on the JVM
;;; time.lisp
;;;
;;; Copyright (C) 2003-2005 Peter Graves
;;; $Id: time.lisp 11391 2008-11-15 22:38:34Z vvoutilainen $
;;;
;;; This program is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU General Public License
;;; as published by the Free Software Foundation; either version 2
;;; of the License, or (at your option) any later version.
;;;
;;; This program is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program; if not, write to the Free Software
;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
;;;
;;; As a special exception, the copyright holders of this library give you
;;; permission to link this library with independent modules to produce an
;;; executable, regardless of the license terms of these independent
;;; modules, and to copy and distribute the resulting executable under
;;; terms of your choice, provided that you also meet, for each linked
;;; independent module, the terms and conditions of the license of that
;;; module. An independent module is a module which is not derived from
;;; or based on this library. If you modify this library, you may extend
;;; this exception to your version of the library, but you are not
;;; obligated to do so. If you do not wish to do so, delete this
;;; exception statement from your version.
;;; Adapted from SBCL.
(in-package #:system)
(defconstant seconds-in-week (* 60 60 24 7))
(defconstant weeks-offset 2145)
(defconstant seconds-offset 432000)
(defconstant minutes-per-day (* 24 60))
(defconstant quarter-days-per-year (1+ (* 365 4)))
(defconstant quarter-days-per-century 146097)
(defconstant november-17-1858 678882)
(defconstant weekday-november-17-1858 2)
;;; decode-universal-time universal-time &optional time-zone
;;; => second minute hour date month year day daylight-p zone
;;; If time-zone is not supplied, it defaults to the current time zone adjusted
;;; for daylight saving time. If time-zone is supplied, daylight saving time
;;; information is ignored. The daylight saving time flag is nil if time-zone
;;; is supplied.
(defun decode-universal-time (universal-time &optional time-zone)
(let (seconds-west daylight)
(if time-zone
(setf seconds-west (* time-zone 3600)
daylight nil)
(multiple-value-bind (time-zone daylight-p) (default-time-zone)
(setf seconds-west (* time-zone 3600)
daylight daylight-p)))
(multiple-value-bind (weeks secs)
(truncate (+ (- universal-time seconds-west) seconds-offset)
seconds-in-week)
(let ((weeks (+ weeks weeks-offset)))
(multiple-value-bind (t1 second)
(truncate secs 60)
(let ((tday (truncate t1 minutes-per-day)))
(multiple-value-bind (hour minute)
(truncate (- t1 (* tday minutes-per-day)) 60)
(let* ((t2 (1- (* (+ (* weeks 7) tday november-17-1858) 4)))
(tcent (truncate t2 quarter-days-per-century)))
(setq t2 (mod t2 quarter-days-per-century))
(setq t2 (+ (- t2 (mod t2 4)) 3))
(let* ((year (+ (* tcent 100)
(truncate t2 quarter-days-per-year)))
(days-since-mar0
(1+ (truncate (mod t2 quarter-days-per-year) 4)))
(day (mod (+ tday weekday-november-17-1858) 7))
(t3 (+ (* days-since-mar0 5) 456)))
(cond ((>= t3 1989)
(setq t3 (- t3 1836))
(setq year (1+ year))))
(multiple-value-bind (month t3)
(truncate t3 153)
(let ((date (1+ (truncate t3 5))))
(values second minute hour date month year day
daylight
(if daylight
(1+ (/ seconds-west 3600))
(/ seconds-west 3600))))))))))))))
(defun get-decoded-time ()
(decode-universal-time (get-universal-time)))
(defun pick-obvious-year (year)
(declare (type (mod 100) year))
(let* ((current-year (nth-value 5 (get-decoded-time)))
(guess (+ year (* (truncate (- current-year 50) 100) 100))))
(declare (type (integer 1900 9999) current-year guess))
(if (> (- current-year guess) 50)
(+ guess 100)
guess)))
(defun leap-years-before (year)
(let ((years (- year 1901)))
(+ (- (truncate years 4)
(truncate years 100))
(truncate (+ years 300) 400))))
(defvar *days-before-month*
#.(let ((reversed-result nil)
(sum 0))
(push nil reversed-result)
(dolist (days-in-month '(31 28 31 30 31 30 31 31 30 31 30 31))
(push sum reversed-result)
(incf sum days-in-month))
(coerce (nreverse reversed-result) 'simple-vector)))
(defun encode-universal-time (second minute hour date month year
&optional time-zone)
(let* ((year (if (< year 100)
(pick-obvious-year year)
year))
(days (+ (1- date)
(aref *days-before-month* month)
(if (> month 2)
(leap-years-before (1+ year))
(leap-years-before year))
(* (- year 1900) 365)))
(hours (+ hour (* days 24))))
(cond (time-zone
(+ second (* (+ minute (* (+ hours time-zone) 60)) 60)))
((> year 2037)
(labels ((leap-year-p (year)
(cond ((zerop (mod year 400)) t)
((zerop (mod year 100)) nil)
((zerop (mod year 4)) t)
(t nil))))
(let* ((fake-year (if (leap-year-p year) 2036 2037))
(fake-time (encode-universal-time second minute hour
date month fake-year)))
(+ fake-time
(* 86400 (+ (* 365 (- year fake-year))
(- (leap-years-before year)
(leap-years-before fake-year))))))))
(t
(+ second (* (+ minute (* (+ hours (default-time-zone)) 60)) 60))))))