sys/dev/clock_subr.c

   1 /*      $NetBSD: clock_subr.c,v 1.14 2009/12/12 11:16:33 tsutsui Exp $  */
   2
   3 /*
   4  * Copyright (c) 1982, 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * the Systems Programming Group of the University of Utah Computer
   9  * Science Department.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  * from: Utah $Hdr: clock.c 1.18 91/01/21$
  36  *
  37  *      @(#)clock.c     8.2 (Berkeley) 1/12/94
  38  */
  39
  40 /*
  41  * Copyright (c) 1988 University of Utah.
  42  *
  43  * This code is derived from software contributed to Berkeley by
  44  * the Systems Programming Group of the University of Utah Computer
  45  * Science Department.
  46  *
  47  * Redistribution and use in source and binary forms, with or without
  48  * modification, are permitted provided that the following conditions
  49  * are met:
  50  * 1. Redistributions of source code must retain the above copyright
  51  *    notice, this list of conditions and the following disclaimer.
  52  * 2. Redistributions in binary form must reproduce the above copyright
  53  *    notice, this list of conditions and the following disclaimer in the
  54  *    documentation and/or other materials provided with the distribution.
  55  * 3. All advertising materials mentioning features or use of this software
  56  *    must display the following acknowledgement:
  57  *      This product includes software developed by the University of
  58  *      California, Berkeley and its contributors.
  59  * 4. Neither the name of the University nor the names of its contributors
  60  *    may be used to endorse or promote products derived from this software
  61  *    without specific prior written permission.
  62  *
  63  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  64  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  65  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  66  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  67  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  68  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  69  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  70  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  71  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  72  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  73  * SUCH DAMAGE.
  74  *
  75  * from: Utah $Hdr: clock.c 1.18 91/01/21$
  76  *
  77  *      @(#)clock.c     8.2 (Berkeley) 1/12/94
  78  */
  79
  80 /*
  81  * Generic routines to convert between a POSIX date
  82  * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
  83  * Derived from arch/hp300/hp300/clock.c
  84  */
  85
  86 #include <sys/cdefs.h>
  87 __KERNEL_RCSID(0, "$NetBSD: clock_subr.c,v 1.14 2009/12/12 11:16:33 tsutsui Exp $");
  88
  89 #include <sys/param.h>
  90 #include <sys/systm.h>
  91
  92 #include <dev/clock_subr.h>
  93
  94 static inline int leapyear(int year);
  95 #define FEBRUARY        2
  96 #define days_in_year(a)         (leapyear(a) ? 366 : 365)
  97 #define days_in_month(a)        (month_days[(a) - 1])
  98
  99 static const int month_days[12] = {
 100         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
 101 };
 102
 103 /*
 104  * This inline avoids some unnecessary modulo operations
 105  * as compared with the usual macro:
 106  *   ( ((year % 4) == 0 &&
 107  *      (year % 100) != 0) ||
 108  *     ((year % 400) == 0) )
 109  * It is otherwise equivalent.
 110  */
 111 static inline int
 112 leapyear(int year)
 113 {
 114         int rv = 0;
 115
 116         if ((year & 3) == 0) {
 117                 rv = 1;
 118                 if ((year % 100) == 0) {
 119                         rv = 0;
 120                         if ((year % 400) == 0)
 121                                 rv = 1;
 122                 }
 123         }
 124         return rv;
 125 }
 126
 127 time_t
 128 clock_ymdhms_to_secs(struct clock_ymdhms *dt)
 129 {
 130         uint64_t secs;
 131         int i, year, days;
 132
 133         year = dt->dt_year;
 134
 135         /*
 136          * Compute days since start of time
 137          * First from years, then from months.
 138          */
 139         if (year < POSIX_BASE_YEAR)
 140                 return -1;
 141         days = 0;
 142         for (i = POSIX_BASE_YEAR; i < year; i++)
 143                 days += days_in_year(i);
 144         if (leapyear(year) && dt->dt_mon > FEBRUARY)
 145                 days++;
 146
 147         /* Months */
 148         for (i = 1; i < dt->dt_mon; i++)
 149                 days += days_in_month(i);
 150         days += (dt->dt_day - 1);
 151
 152         /* Add hours, minutes, seconds. */
 153         secs = (((uint64_t)days
 154             * 24 + dt->dt_hour)
 155             * 60 + dt->dt_min)
 156             * 60 + dt->dt_sec;
 157
 158         if ((time_t)secs != secs)
 159                 return -1;
 160         return secs;
 161 }
 162
 163 void
 164 clock_secs_to_ymdhms(time_t secs, struct clock_ymdhms *dt)
 165 {
 166         int mthdays[12];
 167         int i;
 168         time_t days;
 169         time_t rsec;    /* remainder seconds */
 170
 171         /*
 172          * This function uses a local copy of month_days[]
 173          * so the copy can be modified (and thread-safe).
 174          * See the definition of days_in_month() above.
 175          */
 176         memcpy(mthdays, month_days, sizeof(mthdays));
 177 #define month_days mthdays
 178
 179         days = secs / SECDAY;
 180         rsec = secs % SECDAY;
 181
 182         /* Day of week (Note: 1/1/1970 was a Thursday) */
 183         dt->dt_wday = (days + 4) % 7;
 184
 185         /* Subtract out whole years, counting them in i. */
 186         for (i = POSIX_BASE_YEAR; days >= days_in_year(i); i++)
 187                 days -= days_in_year(i);
 188         dt->dt_year = i;
 189
 190         /* Subtract out whole months, counting them in i. */
 191         if (leapyear(i))
 192                 days_in_month(FEBRUARY) = 29;
 193         for (i = 1; days >= days_in_month(i); i++)
 194                 days -= days_in_month(i);
 195         dt->dt_mon = i;
 196
 197         /* Days are what is left over (+1) from all that. */
 198         dt->dt_day = days + 1;
 199
 200         /* Hours, minutes, seconds are easy */
 201         dt->dt_hour = rsec / 3600;
 202         rsec = rsec % 3600;
 203         dt->dt_min  = rsec / 60;
 204         rsec = rsec % 60;
 205         dt->dt_sec  = rsec;
 206 #undef month_days
 207 }