Annotation of sys/kern/clock_subr.c, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: clock_subr.c,v 1.2 2006/11/14 18:00:27 jmc Exp $ */
! 2: /* $NetBSD: clock_subr.c,v 1.3 1997/03/15 18:11:16 is Exp $ */
! 3:
! 4: /*
! 5: * Copyright (c) 1988 University of Utah.
! 6: * Copyright (c) 1982, 1990, 1993
! 7: * The Regents of the University of California. All rights reserved.
! 8: *
! 9: * This code is derived from software contributed to Berkeley by
! 10: * the Systems Programming Group of the University of Utah Computer
! 11: * Science Department.
! 12: *
! 13: * Redistribution and use in source and binary forms, with or without
! 14: * modification, are permitted provided that the following conditions
! 15: * are met:
! 16: * 1. Redistributions of source code must retain the above copyright
! 17: * notice, this list of conditions and the following disclaimer.
! 18: * 2. Redistributions in binary form must reproduce the above copyright
! 19: * notice, this list of conditions and the following disclaimer in the
! 20: * documentation and/or other materials provided with the distribution.
! 21: * 3. Neither the name of the University nor the names of its contributors
! 22: * may be used to endorse or promote products derived from this software
! 23: * without specific prior written permission.
! 24: *
! 25: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 26: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 27: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 28: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 29: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 30: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 31: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 32: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 33: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 34: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 35: * SUCH DAMAGE.
! 36: *
! 37: * from: Utah $Hdr: clock.c 1.18 91/01/21$
! 38: *
! 39: * @(#)clock.c 8.2 (Berkeley) 1/12/94
! 40: */
! 41:
! 42: /*
! 43: * Generic routines to convert between a POSIX date
! 44: * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
! 45: * Derived from arch/hp300/hp300/clock.c
! 46: */
! 47:
! 48: #include <sys/types.h>
! 49: #include <sys/systm.h>
! 50:
! 51: #include <dev/clock_subr.h>
! 52:
! 53: static inline int leapyear(int year);
! 54: #define FEBRUARY 2
! 55: #define days_in_year(a) (leapyear(a) ? 366 : 365)
! 56: #define days_in_month(a) (month_days[(a) - 1])
! 57:
! 58: static const int month_days[12] = {
! 59: 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
! 60: };
! 61:
! 62: /*
! 63: * This inline avoids some unnecessary modulo operations
! 64: * as compared with the usual macro:
! 65: * ( ((year % 4) == 0 &&
! 66: * (year % 100) != 0) ||
! 67: * ((year % 400) == 0) )
! 68: * It is otherwise equivalent.
! 69: */
! 70: static inline int
! 71: leapyear(int year)
! 72: {
! 73: int rv = 0;
! 74:
! 75: if ((year & 3) == 0) {
! 76: rv = 1;
! 77: if ((year % 100) == 0) {
! 78: rv = 0;
! 79: if ((year % 400) == 0)
! 80: rv = 1;
! 81: }
! 82: }
! 83: return (rv);
! 84: }
! 85:
! 86: time_t
! 87: clock_ymdhms_to_secs(struct clock_ymdhms *dt)
! 88: {
! 89: time_t secs;
! 90: int i, year, days;
! 91:
! 92: year = dt->dt_year;
! 93:
! 94: /*
! 95: * Compute days since start of time.
! 96: * First from years, then from months.
! 97: */
! 98: days = 0;
! 99: for (i = POSIX_BASE_YEAR; i < year; i++)
! 100: days += days_in_year(i);
! 101: if (leapyear(year) && dt->dt_mon > FEBRUARY)
! 102: days++;
! 103:
! 104: /* Months */
! 105: for (i = 1; i < dt->dt_mon; i++)
! 106: days += days_in_month(i);
! 107: days += (dt->dt_day - 1);
! 108:
! 109: /* Add hours, minutes, seconds. */
! 110: secs = ((days
! 111: * 24 + dt->dt_hour)
! 112: * 60 + dt->dt_min)
! 113: * 60 + dt->dt_sec;
! 114:
! 115: return (secs);
! 116: }
! 117:
! 118: /* This function uses a copy of month_days[] */
! 119: #undef days_in_month
! 120: #define days_in_month(a) (mthdays[(a) - 1])
! 121:
! 122: void
! 123: clock_secs_to_ymdhms(time_t secs, struct clock_ymdhms *dt)
! 124: {
! 125: int mthdays[12];
! 126: int i, days;
! 127: int rsec; /* remainder seconds */
! 128:
! 129: bcopy(month_days, mthdays, sizeof(mthdays));
! 130:
! 131: days = secs / SECDAY;
! 132: rsec = secs % SECDAY;
! 133:
! 134: /* Day of week (Note: 1/1/1970 was a Thursday) */
! 135: dt->dt_wday = (days + 4) % 7;
! 136:
! 137: /* Subtract out whole years, counting them in i. */
! 138: for (i = POSIX_BASE_YEAR; days >= days_in_year(i); i++)
! 139: days -= days_in_year(i);
! 140: dt->dt_year = i;
! 141:
! 142: /* Subtract out whole months, counting them in i. */
! 143: if (leapyear(i))
! 144: days_in_month(FEBRUARY) = 29;
! 145: for (i = 1; days >= days_in_month(i); i++)
! 146: days -= days_in_month(i);
! 147: dt->dt_mon = i;
! 148:
! 149: /* Days are what is left over (+1) from all that. */
! 150: dt->dt_day = days + 1;
! 151:
! 152: /* Hours, minutes, seconds are easy */
! 153: dt->dt_hour = rsec / 3600;
! 154: rsec = rsec % 3600;
! 155: dt->dt_min = rsec / 60;
! 156: rsec = rsec % 60;
! 157: dt->dt_sec = rsec;
! 158: }
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