FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_clock.c
1 /*-
2 * Copyright (c) 1988 University of Utah.
3 * Copyright (c) 1982, 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * the Systems Programming Group of the University of Utah Computer
8 * Science Department.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * from: Utah $Hdr: clock.c 1.18 91/01/21$
35 * from: @(#)clock.c 8.2 (Berkeley) 1/12/94
36 * from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
37 * and
38 * from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
39 */
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD: releng/9.1/sys/kern/subr_clock.c 217195 2011-01-09 14:34:56Z bz $");
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/bus.h>
48 #include <sys/clock.h>
49 #include <sys/sysctl.h>
50 #include <sys/timetc.h>
51
52 int tz_minuteswest;
53 int tz_dsttime;
54
55 /*
56 * The adjkerntz and wall_cmos_clock sysctls are in the "machdep" sysctl
57 * namespace because they were misplaced there originally.
58 */
59 static int adjkerntz;
60 static int
61 sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
62 {
63 int error;
64 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
65 if (!error && req->newptr)
66 resettodr();
67 return (error);
68 }
69 SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
70 &adjkerntz, 0, sysctl_machdep_adjkerntz, "I",
71 "Local offset from UTC in seconds");
72
73 static int ct_debug;
74 SYSCTL_INT(_debug, OID_AUTO, clocktime, CTLFLAG_RW,
75 &ct_debug, 0, "Enable printing of clocktime debugging");
76
77 static int wall_cmos_clock;
78 SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock, CTLFLAG_RW,
79 &wall_cmos_clock, 0, "Enables application of machdep.adjkerntz");
80
81 /*--------------------------------------------------------------------*
82 * Generic routines to convert between a POSIX date
83 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
84 * Derived from NetBSD arch/hp300/hp300/clock.c
85 */
86
87
88 #define FEBRUARY 2
89 #define days_in_year(y) (leapyear(y) ? 366 : 365)
90 #define days_in_month(y, m) \
91 (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
92 /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
93 #define day_of_week(days) (((days) + 4) % 7)
94
95 static const int month_days[12] = {
96 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
97 };
98
99
100 /*
101 * This inline avoids some unnecessary modulo operations
102 * as compared with the usual macro:
103 * ( ((year % 4) == 0 &&
104 * (year % 100) != 0) ||
105 * ((year % 400) == 0) )
106 * It is otherwise equivalent.
107 */
108 static int
109 leapyear(int year)
110 {
111 int rv = 0;
112
113 if ((year & 3) == 0) {
114 rv = 1;
115 if ((year % 100) == 0) {
116 rv = 0;
117 if ((year % 400) == 0)
118 rv = 1;
119 }
120 }
121 return (rv);
122 }
123
124 static void
125 print_ct(struct clocktime *ct)
126 {
127 printf("[%04d-%02d-%02d %02d:%02d:%02d]",
128 ct->year, ct->mon, ct->day,
129 ct->hour, ct->min, ct->sec);
130 }
131
132 int
133 clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
134 {
135 time_t secs;
136 int i, year, days;
137
138 year = ct->year;
139
140 if (ct_debug) {
141 printf("ct_to_ts(");
142 print_ct(ct);
143 printf(")");
144 }
145
146 /* Sanity checks. */
147 if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
148 ct->day > days_in_month(year, ct->mon) ||
149 ct->hour > 23 || ct->min > 59 || ct->sec > 59 ||
150 ct->year > 2037) { /* time_t overflow */
151 if (ct_debug)
152 printf(" = EINVAL\n");
153 return (EINVAL);
154 }
155
156 /*
157 * Compute days since start of time
158 * First from years, then from months.
159 */
160 days = 0;
161 for (i = POSIX_BASE_YEAR; i < year; i++)
162 days += days_in_year(i);
163
164 /* Months */
165 for (i = 1; i < ct->mon; i++)
166 days += days_in_month(year, i);
167 days += (ct->day - 1);
168
169 /* Add hours, minutes, seconds. */
170 secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;
171
172 ts->tv_sec = secs;
173 ts->tv_nsec = ct->nsec;
174 if (ct_debug)
175 printf(" = %ld.%09ld\n", (long)ts->tv_sec, (long)ts->tv_nsec);
176 return (0);
177 }
178
179 void
180 clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
181 {
182 int i, year, days;
183 time_t rsec; /* remainder seconds */
184 time_t secs;
185
186 secs = ts->tv_sec;
187 days = secs / SECDAY;
188 rsec = secs % SECDAY;
189
190 ct->dow = day_of_week(days);
191
192 /* Subtract out whole years, counting them in i. */
193 for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
194 days -= days_in_year(year);
195 ct->year = year;
196
197 /* Subtract out whole months, counting them in i. */
198 for (i = 1; days >= days_in_month(year, i); i++)
199 days -= days_in_month(year, i);
200 ct->mon = i;
201
202 /* Days are what is left over (+1) from all that. */
203 ct->day = days + 1;
204
205 /* Hours, minutes, seconds are easy */
206 ct->hour = rsec / 3600;
207 rsec = rsec % 3600;
208 ct->min = rsec / 60;
209 rsec = rsec % 60;
210 ct->sec = rsec;
211 ct->nsec = ts->tv_nsec;
212 if (ct_debug) {
213 printf("ts_to_ct(%ld.%09ld) = ",
214 (long)ts->tv_sec, (long)ts->tv_nsec);
215 print_ct(ct);
216 printf("\n");
217 }
218 }
219
220 int
221 utc_offset(void)
222 {
223
224 return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
225 }
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