kern

view src/klibc/time.c @ 62:38f768da2f31

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added a comment in the tss showing the interesting bits
author John Tsiombikas <nuclear@member.fsf.org>
date Wed, 17 Aug 2011 05:39:39 +0300
parents 92297f65aaef
children
line source
1 #include <stdio.h>
2 #include "time.h"
3 #include "rtc.h"
4 #include "timer.h"
5 #include "config.h"
6
7 #define MINSEC 60
8 #define HOURSEC (60 * MINSEC)
9 #define DAYSEC (24 * HOURSEC)
10 #define YEARDAYS(x) (is_leap_year(x) ? 366 : 365)
11
12 /* 1-1-1970 was a thursday */
13 #define EPOCH_WDAY 4
14
15 static int is_leap_year(int yr);
16
17 static int mdays[2][12] = {
18 {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
19 {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
20 };
21
22 static char *wday[] = {
23 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
24 };
25 static char *mon[] = {
26 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
27 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
28 };
29
30
31 time_t time(time_t *tp)
32 {
33 time_t res = start_time + nticks / TICK_FREQ_HZ;
34
35 if(tp) *tp = res;
36 return res;
37 }
38
39 char *asctime(struct tm *tm)
40 {
41 static char buf[64];
42 return asctime_r(tm, buf);
43 }
44
45 char *asctime_r(struct tm *tm, char *buf)
46 {
47 sprintf(buf, "%s %s %d %02d:%02d:%02d %d\n", wday[tm->tm_wday],
48 mon[tm->tm_mon], tm->tm_mday, tm->tm_hour, tm->tm_min,
49 tm->tm_sec, tm->tm_year + 1900);
50 return buf;
51 }
52
53 time_t mktime(struct tm *tm)
54 {
55 int i, num_years = tm->tm_year - 70;
56 int year = 1970;
57 int days = day_of_year(tm->tm_year + 1900, tm->tm_mon, tm->tm_mday - 1);
58
59 /* set correct yearday */
60 tm->tm_yday = days;
61
62 for(i=0; i<num_years; i++) {
63 days += YEARDAYS(year++);
64 }
65
66 /* set wday correctly */
67 tm->tm_wday = (days + EPOCH_WDAY) % 7;
68
69 return (time_t)days * DAYSEC + tm->tm_hour * HOURSEC +
70 tm->tm_min * MINSEC + tm->tm_sec;
71 }
72
73 struct tm *gmtime(time_t *tp)
74 {
75 static struct tm tm;
76 return gmtime_r(tp, &tm);
77 }
78
79 struct tm *gmtime_r(time_t *tp, struct tm *tm)
80 {
81 int year, days, leap, yrdays;
82 time_t t;
83
84 year = 1970;
85 days = *tp / DAYSEC;
86 t = *tp % DAYSEC;
87
88 tm->tm_wday = (days + EPOCH_WDAY) % 7;
89
90 while(days >= (yrdays = YEARDAYS(year))) {
91 days -= yrdays;
92 year++;
93 }
94 tm->tm_year = year - 1900;
95 tm->tm_yday = days;
96
97 leap = is_leap_year(year);
98 tm->tm_mon = 0;
99 while(days >= mdays[leap][tm->tm_mon]) {
100 days -= mdays[leap][tm->tm_mon++];
101 }
102
103 tm->tm_mday = days + 1;
104
105 tm->tm_hour = t / HOURSEC;
106 t %= HOURSEC;
107 tm->tm_min = t / MINSEC;
108 tm->tm_sec = t % MINSEC;
109 return tm;
110 }
111
112 int day_of_year(int year, int mon, int day)
113 {
114 int i, yday, leap;
115
116 leap = is_leap_year(year) ? 1 : 0;
117 yday = day;
118
119 for(i=0; i<mon; i++) {
120 yday += mdays[leap][i];
121 }
122 return yday;
123 }
124
125 static int is_leap_year(int yr)
126 {
127 /* exceptions first */
128 if(yr % 400 == 0) {
129 return 1;
130 }
131 if(yr % 100 == 0) {
132 return 0;
133 }
134 /* standard case */
135 return yr % 4 == 0;
136 }