tm2sec.c - 9base - revived minimalist port of Plan 9 userland to Unix
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tm2sec.c (1900B)
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1 #include <u.h>
2 #include <libc.h>
3
4 #include "zoneinfo.h"
5
6 #define SEC2MIN 60L
7 #define SEC2HOUR (60L*SEC2MIN)
8 #define SEC2DAY (24L*SEC2HOUR)
9
10 /*
11 * days per month plus days/year
12 */
13 static int dmsize[] =
14 {
15 365, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
16 };
17 static int ldmsize[] =
18 {
19 366, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
20 };
21
22 /*
23 * return the days/month for the given year
24 */
25 static int *
26 yrsize(int y)
27 {
28 if((y%4) == 0 && ((y%100) != 0 || (y%400) == 0))
29 return ldmsize;
30 else
31 return dmsize;
32 }
33
34 /*
35 * compute seconds since Jan 1 1970 GMT
36 * and convert to our timezone.
37 */
38 long
39 tm2sec(Tm *tm)
40 {
41 Tinfo ti0, ti1, *ti;
42 long secs;
43 int i, yday, year, *d2m;
44
45 secs = 0;
46
47 /*
48 * seconds per year
49 */
50 year = tm->year + 1900;
51 for(i = 1970; i < year; i++){
52 d2m = yrsize(i);
53 secs += d2m[0] * SEC2DAY;
54 }
55
56 /*
57 * if mday is set, use mon and mday to compute yday
58 */
59 if(tm->mday){
60 yday = 0;
61 d2m = yrsize(year);
62 for(i=0; i<tm->mon; i++)
63 yday += d2m[i+1];
64 yday += tm->mday-1;
65 }else{
66 yday = tm->yday;
67 }
68 secs += yday * SEC2DAY;
69
70 /*
71 * hours, minutes, seconds
72 */
73 secs += tm->hour * SEC2HOUR;
74 secs += tm->min * SEC2MIN;
75 secs += tm->sec;
76
77 /*
78 * Assume the local time zone if zone is not GMT
79 */
80 if(strcmp(tm->zone, "GMT") != 0) {
81 i = zonelookuptinfo(&ti0, secs);
82 ti = &ti0;
83 if (i != -1)
84 if (ti->tzoff!=0) {
85 /*
86 * to what local time period `secs' belongs?
87 */
88 if (ti->tzoff>0) {
89 /*
90 * east of GMT; check previous local time transition
91 */
92 if (ti->t+ti->tzoff > secs)
93 if (zonetinfo(&ti1, i-1)!=-1)
94 ti = &ti1;
95 } else
96 /*
97 * west of GMT; check next local time transition
98 */
99 if (zonetinfo(&ti1, i+1))
100 if (ti1.t+ti->tzoff < secs)
101 ti = &ti1;
102 // fprint(2, "tt: %ld+%d %ld\n", (long)ti->t, ti->tzoff, (long)secs);
103 secs -= ti->tzoff;
104 }
105 }
106
107 if(secs < 0)
108 secs = 0;
109 return secs;
110 }