From: Edward M. Reingold Date: Fri, 29 Mar 1996 17:34:02 +0000 (+0000) Subject: Initial revision X-Git-Tag: emacs-19.34~946 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=0e41f190ebcc9a8dbf99cb6215fa309a2bae51a2;p=emacs.git Initial revision --- diff --git a/lisp/calendar/cal-persia.el b/lisp/calendar/cal-persia.el new file mode 100644 index 00000000000..4eedd819505 --- /dev/null +++ b/lisp/calendar/cal-persia.el @@ -0,0 +1,205 @@ +;;; cal-persian.el --- calendar functions for the Persian calendar. + +;; Copyright (C) 1996 Free Software Foundation, Inc. + +;; Author: Edward M. Reingold +;; Keywords: calendar +;; Human-Keywords: Persian calendar, calendar, diary + +;; This file is part of GNU Emacs. + +;; GNU Emacs 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, or (at your option) +;; any later version. + +;; GNU Emacs 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 GNU Emacs; see the file COPYING. If not, write to +;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + +;;; Commentary: + +;; This collection of functions implements the features of calendar.el and +;; diary.el that deal with the Persian calendar. + +;; Comments, corrections, and improvements should be sent to +;; Edward M. Reingold Department of Computer Science +;; (217) 333-6733 University of Illinois at Urbana-Champaign +;; reingold@cs.uiuc.edu 1304 West Springfield Avenue +;; Urbana, Illinois 61801 + +;;; Code: + +(require 'cal-julian) + +(defvar persian-calendar-month-name-array + ["Farvardin" "Ordibehest" "Xordad" "Tir" "Mordad" "Sahrivar" "Mehr" "Aban" + "Azar" "Dey" "Bahman" "Esfand"]) + +(defvar persian-calendar-epoch (calendar-absolute-from-julian '(3 19 622)) + "Absolute date of start of Persian calendar = March 19, 622 A.D. (Julian).") + +(defun persian-calendar-leap-year-p (year) + "True if YEAR is a leap year on the Persian calendar." + (< (mod (* (mod (mod (if (<= 0 year) + ; No year zero + (+ year 2346) + (+ year 2347)) + 2820) + 768) + 683) + 2820) + 683)) + +(defun persian-calendar-last-day-of-month (month year) + "Return last day of MONTH, YEAR on the Persian calendar." + (cond + ((< month 7) 31) + ((or (< month 12) (persian-calendar-leap-year-p year)) 30) + (t 29))) + +(defun calendar-absolute-from-persian (date) + "Compute absolute date from Persian date DATE. +The absolute date is the number of days elapsed since the (imaginary) +Gregorian date Sunday, December 31, 1 BC." + (let ((month (extract-calendar-month date)) + (day (extract-calendar-day date)) + (year (extract-calendar-year date))) + (if (< year 0) + (+ (calendar-absolute-from-persian + (list month day (1+ (mod year 2820)))) + (* 1029983 (floor year 2820))) + (+ (1- persian-calendar-epoch); Days before epoch + (* 365 (1- year)) ; Days in prior years. + (* 683 ; Leap days in prior 2820-year cycles + (floor (+ year 2345) 2820)) + (* 186 ; Leap days in prior 768 year cycles + (floor (mod (+ year 2345) 2820) 768)) + (floor; Leap years in current 768 or 516 year cycle + (* 683 (mod (mod (+ year 2345) 2820) 768)) + 2820) + -568 ; Leap years in Persian years -2345...-1 + (calendar-sum ; Days in prior months this year. + m 1 (< m month) + (persian-calendar-last-day-of-month m year)) + day)))) ; Days so far this month. + +(defun calendar-persian-year-from-absolute (date) + "Persian year corresponding to the absolute DATE." + (let* ((d0 ; Prior days since start of 2820 cycles + (- date (calendar-absolute-from-persian (list 1 1 -2345)))) + (n2820 ; Completed 2820-year cycles + (floor d0 1029983)) + (d1 ; Prior days not in n2820 + (mod d0 1029983)) + (n768 ; 768-year cycles not in n2820 + (floor d1 280506)) + (d2 ; Prior days not in n2820 or n768 + (mod d1 280506)) + (n1 ; Years not in n2820 or n768 + ; we want is + ; (floor (+ (* 2820 d2) (* 2820 366)) 1029983)) + ; but that causes overflow, so we use + (let ((a (floor d2 366)); we use 366 as the divisor because + ; (2820*366 mod 1029983) is small + (b (mod d2 366))) + (+ 1 a (floor (+ (* 2137 a) (* 2820 b) 2137) 1029983)))) + (year (+ (* 2820 n2820); Complete 2820 year cycles + (* 768 n768) ; Complete 768 year cycles + (if ; Remaining years + ; Last day of 2820 year cycle + (= d1 1029617) + (1- n1) + n1) + -2345))) ; Years before year 1 + (if (< year 1) + (1- year); No year zero + year))) + +(defun calendar-persian-from-absolute (date) + "Compute the Persian equivalent for absolute date DATE. +The result is a list of the form (MONTH DAY YEAR). +The absolute date is the number of days elapsed since the imaginary +Gregorian date Sunday, December 31, 1 BC." + (let* ((year (calendar-persian-year-from-absolute date)) + (month ; Search forward from Farvardin + (1+ (calendar-sum m 1 + (> date + (calendar-absolute-from-persian + (list + m + (persian-calendar-last-day-of-month m year) + year))) + 1))) + (day ; Calculate the day by subtraction + (- date (1- (calendar-absolute-from-persian + (list month 1 year)))))) + (list month day year))) + +(defun calendar-persian-date-string (&optional date) + "String of Persian date of Gregorian DATE. +Defaults to today's date if DATE is not given." + (let* ((persian-date (calendar-persian-from-absolute + (calendar-absolute-from-gregorian + (or date (calendar-current-date))))) + (y (extract-calendar-year persian-date)) + (m (extract-calendar-month persian-date))) + (let ((monthname (aref persian-calendar-month-name-array (1- m))) + (day (int-to-string (extract-calendar-day persian-date))) + (dayname nil) + (month (int-to-string m)) + (year (int-to-string y))) + (mapconcat 'eval calendar-date-display-form "")))) + +(defun calendar-print-persian-date () + "Show the Persian calendar equivalent of the selected date." + (interactive) + (message "Persian date: %s" + (calendar-persian-date-string (calendar-cursor-to-date t)))) + +(defun calendar-goto-persian-date (date &optional noecho) + "Move cursor to Persian date DATE. +Echo Persian date unless NOECHO is t." + (interactive (persian-prompt-for-date)) + (calendar-goto-date (calendar-gregorian-from-absolute + (calendar-absolute-from-persian date))) + (or noecho (calendar-print-persian-date))) + +(defun persian-prompt-for-date () + "Ask for a Persian date." + (let* ((today (calendar-current-date)) + (year (calendar-read + "Persian calendar year (not 0): " + '(lambda (x) (/= x 0)) + (int-to-string + (extract-calendar-year + (calendar-persian-from-absolute + (calendar-absolute-from-gregorian today)))))) + (completion-ignore-case t) + (month (cdr (assoc + (capitalize + (completing-read + "Persian calendar month name: " + (mapcar 'list + (append persian-calendar-month-name-array nil)) + nil t)) + (calendar-make-alist persian-calendar-month-name-array + 1 'capitalize)))) + (last (persian-calendar-last-day-of-month month year)) + (day (calendar-read + (format "Persian calendar day (1-%d): " last) + '(lambda (x) (and (< 0 x) (<= x last)))))) + (list (list month day year)))) + +(defun diary-persian-date () + "Persian calendar equivalent of date diary entry." + (calendar-persian-date-string (calendar-cursor-to-date t))) + +(provide 'cal-persian) + +;;; cal-persian.el ends here