X-Git-Url: http://git.kpe.io/?p=kmrcl.git;a=blobdiff_plain;f=datetime.lisp;h=52d45b2a43b044e6919f77778fd6f9d4f7218296;hp=b8d3267427878f79ff2bcacdae062aee6e293c19;hb=e4718cf4751ba0ca9029e30f40b28d17305ed7c3;hpb=4de7f25a69c218303f170314ac26217770a531ed

diff --git a/datetime.lisp b/datetime.lisp
index b8d3267..52d45b2 100644
--- a/datetime.lisp
+++ b/datetime.lisp
@@ -7,7 +7,7 @@
 ;;;; Programmer:    Kevin M. Rosenberg
 ;;;; Date Started:  Apr 2000
 ;;;;
-;;;; $Id: datetime.lisp,v 1.2 2003/04/28 23:51:59 kevin Exp $
+;;;; $Id$
 ;;;;
 ;;;; This file, part of KMRCL, is Copyright (c) 2002 by Kevin M. Rosenberg
 ;;;;
@@ -68,3 +68,68 @@
     (t
      (format t "~,2F ~A" val unit))))
 
+(defconstant +posix-epoch+
+  (encode-universal-time 0 0 0 1 1 1970 0))
+
+(defun posix-time-to-utime (time)
+  (+ time +posix-epoch+))
+
+;; Monthnames taken from net-telent-date to support lml2
+
+(defvar *monthnames*
+  '((1 . "January")
+    (2 . "February")
+    (3 . "March")
+    (4 . "April")
+    (5 . "May")
+    (6 . "June")
+    (7 . "July")
+    (8 . "August")
+    (9 . "September")
+    (10 . "October")
+    (11 . "November")
+    (12 . "December")))
+    
+(defun monthname (stream arg colon-p at-p &optional width (mincol 0) (colinc 1) (minpad 0) (padchar #\Space))
+  "Print the name of the month (1=January) corresponding to ARG on STREAM.  This is intended for embedding in a FORMAT directive: WIDTH governs the number of characters of text printed, MINCOL, COLINC, MINPAD, PADCHAR work as for ~A"
+  (let ((monthstring (cdr (assoc arg *monthnames*))))
+    (if (not monthstring) (return-from monthname nil))
+    (let ((truncate (if width (min width (length monthstring)) nil)))
+      (format stream
+              (if at-p "~V,V,V,V@A" "~V,V,V,VA")
+              mincol colinc minpad padchar
+              (subseq monthstring 0 truncate)))))
+
+;;;; Daylight Saving Time calculations 
+
+;; Daylight Saving Time begins for most of the United States at 2
+;; a.m. on the first Sunday of April. Time reverts to standard time at
+;; 2 a.m. on the last Sunday of October. In the U.S., each time zone
+;; switches at a different time.
+
+;; In the European Union, Summer Time begins and ends at 1 am
+;; Universal Time (Greenwich Mean Time). It starts the last Sunday in
+;; March, and ends the last Sunday in October. In the EU, all time
+;; zones change at the same moment.
+
+;; Spring forward, Fall back
+;; During DST, clocks are turned forward an hour, effectively moving
+;; an hour of daylight from the morning to the evening.
+
+;; United States                  European Union
+
+;; Year  DST Begins DST Ends     Summertime     Summertime
+;;       at 2 a.m.  at 2 a.m.    period begins  period ends
+;;                               at 1 a.m. UT   at 1 a.m. UT
+;; ----------------------------------------------------------
+;; 2000  April 2   October 29    March 26       October 29
+;; 2001  April 1   October 28    March 25       October 28
+;; 2002  April 7   October 27    March 31       October 27
+;; 2003  April 6   October 26    March 30       October 26
+;; 2004  April 4   October 31    March 28       October 31
+;; 2005  April 3   October 30    March 27       October 30
+;; 2006  April 2   October 29    March 26       October 29
+;; 2007  April 1   October 28    March 25       October 28
+;; 2008  April 6   October 26    March 30       October 26
+
+