1 /* $NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej 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/types.h> 52 #include <sys/systm.h> 53 54 #include <dev/clock_subr.h> 55 56 static inline int leapyear __P((int year)); 57 #define FEBRUARY 2 58 #define days_in_year(a) (leapyear(a) ? 366 : 365) 59 #define days_in_month(a) (month_days[(a) - 1]) 60 61 static const int month_days[12] = { 62 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 63 }; 64 65 /* 66 * This inline avoids some unnecessary modulo operations 67 * as compared with the usual macro: 68 * ( ((year % 4) == 0 && 69 * (year % 100) != 0) || 70 * ((year % 400) == 0) ) 71 * It is otherwise equivalent. 72 */ 73 static inline int 74 leapyear(year) 75 int year; 76 { 77 int rv = 0; 78 79 if ((year & 3) == 0) { 80 rv = 1; 81 if ((year % 100) == 0) { 82 rv = 0; 83 if ((year % 400) == 0) 84 rv = 1; 85 } 86 } 87 return (rv); 88 } 89 90 time_t 91 clock_ymdhms_to_secs(dt) 92 struct clock_ymdhms *dt; 93 { 94 time_t secs; 95 int i, year, days; 96 97 year = dt->dt_year; 98 99 /* 100 * Compute days since start of time 101 * First from years, then from months. 102 */ 103 days = 0; 104 for (i = POSIX_BASE_YEAR; i < year; i++) 105 days += days_in_year(i); 106 if (leapyear(year) && dt->dt_mon > FEBRUARY) 107 days++; 108 109 /* Months */ 110 for (i = 1; i < dt->dt_mon; i++) 111 days += days_in_month(i); 112 days += (dt->dt_day - 1); 113 114 /* Add hours, minutes, seconds. */ 115 secs = ((days 116 * 24 + dt->dt_hour) 117 * 60 + dt->dt_min) 118 * 60 + dt->dt_sec; 119 120 return (secs); 121 } 122 123 void 124 clock_secs_to_ymdhms(secs, dt) 125 time_t secs; 126 struct clock_ymdhms *dt; 127 { 128 int mthdays[12]; 129 int i, days; 130 int rsec; /* remainder seconds */ 131 132 /* 133 * This function uses a local copy of month_days[] 134 * so the copy can be modified (and thread-safe). 135 * See the definition of days_in_month() above. 136 */ 137 memcpy(mthdays, month_days, sizeof(mthdays)); 138 #define month_days mthdays 139 140 days = secs / SECDAY; 141 rsec = secs % SECDAY; 142 143 /* Day of week (Note: 1/1/1970 was a Thursday) */ 144 dt->dt_wday = (days + 4) % 7; 145 146 /* Subtract out whole years, counting them in i. */ 147 for (i = POSIX_BASE_YEAR; days >= days_in_year(i); i++) 148 days -= days_in_year(i); 149 dt->dt_year = i; 150 151 /* Subtract out whole months, counting them in i. */ 152 if (leapyear(i)) 153 days_in_month(FEBRUARY) = 29; 154 for (i = 1; days >= days_in_month(i); i++) 155 days -= days_in_month(i); 156 dt->dt_mon = i; 157 158 /* Days are what is left over (+1) from all that. */ 159 dt->dt_day = days + 1; 160 161 /* Hours, minutes, seconds are easy */ 162 dt->dt_hour = rsec / 3600; 163 rsec = rsec % 3600; 164 dt->dt_min = rsec / 60; 165 rsec = rsec % 60; 166 dt->dt_sec = rsec; 167 #undef month_days 168 } 169