usr/src/lib/libast/common/tm/tmweek.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   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 <tmx.h>
  31
  32 static unsigned char    offset[7][3] =
  33 {
  34         { 7, 6, 6 },
  35         { 1, 7, 7 },
  36         { 2, 1, 8 },
  37         { 3, 2, 9 },
  38         { 4, 3, 10},
  39         { 5, 4, 4 },
  40         { 6, 5, 5 },
  41 };
  42
  43 /*
  44  * type is week type
  45  *      0 sunday first day of week
  46  *      1 monday first day of week
  47  *      2 monday first day of iso week
  48  * if week<0 then return week for tm
  49  * if day<0 then set tm to first day of week
  50  * otherwise set tm to day in week
  51  * and return tm->tm_yday
  52  */
  53
  54 int
  55 tmweek(Tm_t* tm, int type, int week, int day)
  56 {
  57         int     d;
  58
  59         if (week < 0)
  60         {
  61                 if ((day = tm->tm_wday - tm->tm_yday % 7) < 0)
  62                         day += 7;
  63                 week = (tm->tm_yday + offset[day][type]) / 7;
  64                 if (type == 2)
  65                 {
  66                         if (!week)
  67                                 week = (day > 0 && day < 6 || tmisleapyear(tm->tm_year - 1)) ? 53 : 52;
  68                         else if (week == 53 && (tm->tm_wday + (31 - tm->tm_mday)) < 4)
  69                                 week = 1;
  70                 }
  71                 return week;
  72         }
  73         if (day < 0)
  74                 day = type != 0;
  75         tm->tm_mon = 0;
  76         tm->tm_mday = 1;
  77         tmfix(tm);
  78         d = tm->tm_wday;
  79         tm->tm_mday = week * 7 - offset[d][type] + ((day || type != 2) ? day : 7);
  80         tmfix(tm);
  81         if (d = tm->tm_wday - day)
  82         {
  83                 tm->tm_mday -= d;
  84                 tmfix(tm);
  85         }
  86         return tm->tm_yday;
  87 }