1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2007 AT&T Knowledge Ventures * 5 * and is licensed under the * 6 * Common Public License, Version 1.0 * 7 * by AT&T Knowledge Ventures * 8 * * 9 * A copy of the License is available at * 10 * http://www.opensource.org/licenses/cpl1.0.txt * 11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) * 12 * * 13 * Information and Software Systems Research * 14 * AT&T Research * 15 * Florham Park NJ * 16 * * 17 * Glenn Fowler <gsf@research.att.com> * 18 * David Korn <dgk@research.att.com> * 19 * Phong Vo <kpv@research.att.com> * 20 * * 21 ***********************************************************************/ 22 #pragma prototyped 23 /* 24 * Glenn Fowler 25 * AT&T Research 26 * 27 * time_t conversion support 28 */ 29 30 #include <tm.h> 31 32 /* 33 * use one of the 14 equivalent calendar years to determine 34 * daylight savings time for future years beyond the range 35 * of the local system (via tmxmake()) 36 */ 37 38 static const short equiv[] = 39 { 40 2006, 2012, 41 2001, 2024, 42 2002, 2008, 43 2003, 2020, 44 2009, 2004, 45 2010, 2016, 46 2005, 2000, 47 }; 48 49 /* 50 * return the circa 2000 equivalent calendar year for tm 51 */ 52 53 int 54 tmequiv(Tm_t* tm) 55 { 56 return tm->tm_year < (2038 - 1900) ? (tm->tm_year + 1900) : equiv[tm->tm_wday + tmisleapyear(tm->tm_year)]; 57 } 58