FreeBSD/Linux Kernel Cross Reference
sys/dev/clock_subr.c
1 /* $NetBSD: clock_subr.c,v 1.11 2005/02/04 02:10:35 perry Exp $ */
2
3 /*
4 * Copyright (c) 1982, 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * the Systems Programming Group of the University of Utah Computer
9 * Science Department.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * from: Utah $Hdr: clock.c 1.18 91/01/21$
36 *
37 * @(#)clock.c 8.2 (Berkeley) 1/12/94
38 */
39
40 /*
41 * Copyright (c) 1988 University of Utah.
42 *
43 * This code is derived from software contributed to Berkeley by
44 * the Systems Programming Group of the University of Utah Computer
45 * Science Department.
46 *
47 * Redistribution and use in source and binary forms, with or without
48 * modification, are permitted provided that the following conditions
49 * are met:
50 * 1. Redistributions of source code must retain the above copyright
51 * notice, this list of conditions and the following disclaimer.
52 * 2. Redistributions in binary form must reproduce the above copyright
53 * notice, this list of conditions and the following disclaimer in the
54 * documentation and/or other materials provided with the distribution.
55 * 3. All advertising materials mentioning features or use of this software
56 * must display the following acknowledgement:
57 * This product includes software developed by the University of
58 * California, Berkeley and its contributors.
59 * 4. Neither the name of the University nor the names of its contributors
60 * may be used to endorse or promote products derived from this software
61 * without specific prior written permission.
62 *
63 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
64 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
65 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
66 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
67 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
68 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
69 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
70 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
71 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
72 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
73 * SUCH DAMAGE.
74 *
75 * from: Utah $Hdr: clock.c 1.18 91/01/21$
76 *
77 * @(#)clock.c 8.2 (Berkeley) 1/12/94
78 */
79
80 /*
81 * Generic routines to convert between a POSIX date
82 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
83 * Derived from arch/hp300/hp300/clock.c
84 */
85
86 #include <sys/cdefs.h>
87 __KERNEL_RCSID(0, "$NetBSD: clock_subr.c,v 1.11 2005/02/04 02:10:35 perry Exp $");
88
89 #include <sys/param.h>
90 #include <sys/systm.h>
91
92 #include <dev/clock_subr.h>
93
94 static inline int leapyear(int year);
95 #define FEBRUARY 2
96 #define days_in_year(a) (leapyear(a) ? 366 : 365)
97 #define days_in_month(a) (month_days[(a) - 1])
98
99 static const int month_days[12] = {
100 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
101 };
102
103 /*
104 * This inline avoids some unnecessary modulo operations
105 * as compared with the usual macro:
106 * ( ((year % 4) == 0 &&
107 * (year % 100) != 0) ||
108 * ((year % 400) == 0) )
109 * It is otherwise equivalent.
110 */
111 static inline int
112 leapyear(year)
113 int year;
114 {
115 int rv = 0;
116
117 if ((year & 3) == 0) {
118 rv = 1;
119 if ((year % 100) == 0) {
120 rv = 0;
121 if ((year % 400) == 0)
122 rv = 1;
123 }
124 }
125 return (rv);
126 }
127
128 time_t
129 clock_ymdhms_to_secs(dt)
130 struct clock_ymdhms *dt;
131 {
132 uint64_t secs;
133 int i, year, days;
134
135 year = dt->dt_year;
136
137 /*
138 * Compute days since start of time
139 * First from years, then from months.
140 */
141 if (year < POSIX_BASE_YEAR) return -1;
142 days = 0;
143 for (i = POSIX_BASE_YEAR; i < year; i++)
144 days += days_in_year(i);
145 if (leapyear(year) && dt->dt_mon > FEBRUARY)
146 days++;
147
148 /* Months */
149 for (i = 1; i < dt->dt_mon; i++)
150 days += days_in_month(i);
151 days += (dt->dt_day - 1);
152
153 /* Add hours, minutes, seconds. */
154 secs = (((uint64_t)days
155 * 24 + dt->dt_hour)
156 * 60 + dt->dt_min)
157 * 60 + dt->dt_sec;
158
159 if ((time_t)secs != secs) return -1;
160 return (secs);
161 }
162
163 void
164 clock_secs_to_ymdhms(secs, dt)
165 time_t secs;
166 struct clock_ymdhms *dt;
167 {
168 int mthdays[12];
169 int i, days;
170 int rsec; /* remainder seconds */
171
172 /*
173 * This function uses a local copy of month_days[]
174 * so the copy can be modified (and thread-safe).
175 * See the definition of days_in_month() above.
176 */
177 memcpy(mthdays, month_days, sizeof(mthdays));
178 #define month_days mthdays
179
180 days = secs / SECDAY;
181 rsec = secs % SECDAY;
182
183 /* Day of week (Note: 1/1/1970 was a Thursday) */
184 dt->dt_wday = (days + 4) % 7;
185
186 /* Subtract out whole years, counting them in i. */
187 for (i = POSIX_BASE_YEAR; days >= days_in_year(i); i++)
188 days -= days_in_year(i);
189 dt->dt_year = i;
190
191 /* Subtract out whole months, counting them in i. */
192 if (leapyear(i))
193 days_in_month(FEBRUARY) = 29;
194 for (i = 1; days >= days_in_month(i); i++)
195 days -= days_in_month(i);
196 dt->dt_mon = i;
197
198 /* Days are what is left over (+1) from all that. */
199 dt->dt_day = days + 1;
200
201 /* Hours, minutes, seconds are easy */
202 dt->dt_hour = rsec / 3600;
203 rsec = rsec % 3600;
204 dt->dt_min = rsec / 60;
205 rsec = rsec % 60;
206 dt->dt_sec = rsec;
207 #undef month_days
208 }
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