1 /* $NetBSD: clock_subr.c,v 1.16 2011/02/08 20:20:26 rmind 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. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * from: Utah $Hdr: clock.c 1.18 91/01/21$ 37 * 38 * @(#)clock.c 8.2 (Berkeley) 1/12/94 39 */ 40 41 /* 42 * Generic routines to convert between a POSIX date 43 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec 44 * Derived from arch/hp300/hp300/clock.c 45 */ 46 47 #include <sys/cdefs.h> 48 __KERNEL_RCSID(0, "$NetBSD: clock_subr.c,v 1.16 2011/02/08 20:20:26 rmind Exp $"); 49 50 #include <sys/param.h> 51 #include <sys/systm.h> 52 53 #include <dev/clock_subr.h> 54 55 static inline int leapyear(int year); 56 #define FEBRUARY 2 57 #define days_in_year(a) (leapyear(a) ? 366 : 365) 58 #define days_in_month(a) (month_days[(a) - 1]) 59 60 static const int month_days[12] = { 61 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 62 }; 63 64 /* 65 * This inline avoids some unnecessary modulo operations 66 * as compared with the usual macro: 67 * ( ((year % 4) == 0 && 68 * (year % 100) != 0) || 69 * ((year % 400) == 0) ) 70 * It is otherwise equivalent. 71 */ 72 static inline int 73 leapyear(int year) 74 { 75 int rv = 0; 76 77 if ((year & 3) == 0) { 78 rv = 1; 79 if ((year % 100) == 0) { 80 rv = 0; 81 if ((year % 400) == 0) 82 rv = 1; 83 } 84 } 85 return rv; 86 } 87 88 time_t 89 clock_ymdhms_to_secs(struct clock_ymdhms *dt) 90 { 91 uint64_t secs; 92 int i, year, days; 93 94 year = dt->dt_year; 95 96 /* 97 * Compute days since start of time 98 * First from years, then from months. 99 */ 100 if (year < POSIX_BASE_YEAR) 101 return -1; 102 days = 0; 103 for (i = POSIX_BASE_YEAR; i < year; i++) 104 days += days_in_year(i); 105 if (leapyear(year) && dt->dt_mon > FEBRUARY) 106 days++; 107 108 /* Months */ 109 for (i = 1; i < dt->dt_mon; i++) 110 days += days_in_month(i); 111 days += (dt->dt_day - 1); 112 113 /* Add hours, minutes, seconds. */ 114 secs = (((uint64_t)days 115 * 24 + dt->dt_hour) 116 * 60 + dt->dt_min) 117 * 60 + dt->dt_sec; 118 119 if ((time_t)secs != secs) 120 return -1; 121 return secs; 122 } 123 124 void 125 clock_secs_to_ymdhms(time_t secs, struct clock_ymdhms *dt) 126 { 127 int mthdays[12]; 128 int i; 129 time_t days; 130 time_t 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