1 /* $NetBSD: clock_subr.c,v 1.7 2001/11/13 05:32:49 lukem Exp $ */ 2 3 /* 4 * Copyright (c) 1988 University of Utah. 5 * Copyright (c) 1982, 1990, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * the Systems Programming Group of the University of Utah Computer 10 * Science Department. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * from: Utah $Hdr: clock.c 1.18 91/01/21$ 41 * 42 * @(#)clock.c 8.2 (Berkeley) 1/12/94 43 */ 44 45 /* 46 * Generic routines to convert between a POSIX date 47 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec 48 * Derived from arch/hp300/hp300/clock.c 49 */ 50 51 #include <sys/cdefs.h> 52 __KERNEL_RCSID(0, "$NetBSD: clock_subr.c,v 1.7 2001/11/13 05:32:49 lukem Exp $"); 53 54 #include <sys/types.h> 55 #include <sys/systm.h> 56 57 #include <dev/clock_subr.h> 58 59 static inline int leapyear __P((int year)); 60 #define FEBRUARY 2 61 #define days_in_year(a) (leapyear(a) ? 366 : 365) 62 #define days_in_month(a) (month_days[(a) - 1]) 63 64 static const int month_days[12] = { 65 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 66 }; 67 68 /* 69 * This inline avoids some unnecessary modulo operations 70 * as compared with the usual macro: 71 * ( ((year % 4) == 0 && 72 * (year % 100) != 0) || 73 * ((year % 400) == 0) ) 74 * It is otherwise equivalent. 75 */ 76 static inline int 77 leapyear(year) 78 int year; 79 { 80 int rv = 0; 81 82 if ((year & 3) == 0) { 83 rv = 1; 84 if ((year % 100) == 0) { 85 rv = 0; 86 if ((year % 400) == 0) 87 rv = 1; 88 } 89 } 90 return (rv); 91 } 92 93 time_t 94 clock_ymdhms_to_secs(dt) 95 struct clock_ymdhms *dt; 96 { 97 time_t secs; 98 int i, year, days; 99 100 year = dt->dt_year; 101 102 /* 103 * Compute days since start of time 104 * First from years, then from months. 105 */ 106 days = 0; 107 for (i = POSIX_BASE_YEAR; i < year; i++) 108 days += days_in_year(i); 109 if (leapyear(year) && dt->dt_mon > FEBRUARY) 110 days++; 111 112 /* Months */ 113 for (i = 1; i < dt->dt_mon; i++) 114 days += days_in_month(i); 115 days += (dt->dt_day - 1); 116 117 /* Add hours, minutes, seconds. */ 118 secs = ((days 119 * 24 + dt->dt_hour) 120 * 60 + dt->dt_min) 121 * 60 + dt->dt_sec; 122 123 return (secs); 124 } 125 126 void 127 clock_secs_to_ymdhms(secs, dt) 128 time_t secs; 129 struct clock_ymdhms *dt; 130 { 131 int mthdays[12]; 132 int i, days; 133 int rsec; /* remainder seconds */ 134 135 /* 136 * This function uses a local copy of month_days[] 137 * so the copy can be modified (and thread-safe). 138 * See the definition of days_in_month() above. 139 */ 140 memcpy(mthdays, month_days, sizeof(mthdays)); 141 #define month_days mthdays 142 143 days = secs / SECDAY; 144 rsec = secs % SECDAY; 145 146 /* Day of week (Note: 1/1/1970 was a Thursday) */ 147 dt->dt_wday = (days + 4) % 7; 148 149 /* Subtract out whole years, counting them in i. */ 150 for (i = POSIX_BASE_YEAR; days >= days_in_year(i); i++) 151 days -= days_in_year(i); 152 dt->dt_year = i; 153 154 /* Subtract out whole months, counting them in i. */ 155 if (leapyear(i)) 156 days_in_month(FEBRUARY) = 29; 157 for (i = 1; days >= days_in_month(i); i++) 158 days -= days_in_month(i); 159 dt->dt_mon = i; 160 161 /* Days are what is left over (+1) from all that. */ 162 dt->dt_day = days + 1; 163 164 /* Hours, minutes, seconds are easy */ 165 dt->dt_hour = rsec / 3600; 166 rsec = rsec % 3600; 167 dt->dt_min = rsec / 60; 168 rsec = rsec % 60; 169 dt->dt_sec = rsec; 170 #undef month_days 171 } 172