181 lines
3.0 KiB
C
181 lines
3.0 KiB
C
/*
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* This routine converts time as follows.
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* The epoch is 0000 Jan 1 1970 GMT.
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* The argument time is in seconds since then.
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* The localtime(t) entry returns a pointer to an array
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* containing
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*
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* seconds (0-59)
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* minutes (0-59)
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* hours (0-23)
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* day of month (1-31)
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* month (0-11)
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* year-1970
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* weekday (0-6, Sun is 0)
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* day of the year
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* daylight savings flag
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*
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* The routine gets the daylight savings time from the environment.
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*
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* asctime(tvec))
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* where tvec is produced by localtime
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* returns a ptr to a character string
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* that has the ascii time in the form
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*
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* \\
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* Thu Jan 01 00:00:00 GMT 1970n0
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* 012345678901234567890123456789
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* 0 1 2
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*
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* ctime(t) just calls localtime, then asctime.
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*/
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#include <u.h>
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#include <libc.h>
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#include "zoneinfo.h"
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static char dmsize[12] =
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{
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31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
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};
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#define dysize ctimedysize
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static int dysize(int);
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static void ct_numb(char*, int);
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char*
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ctime(long t)
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{
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return asctime(localtime(t));
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}
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Tm*
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localtime(long tim)
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{
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Tinfo ti;
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Tm *ct;
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if (zonelookuptinfo(&ti, tim)!=-1) {
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ct = gmtime(tim+ti.tzoff);
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strncpy(ct->zone, ti.zone, sizeof ct->zone - 1);
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ct->zone[sizeof ct->zone-1] = 0;
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ct->tzoff = ti.tzoff;
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return ct;
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}
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return gmtime(tim);
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}
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Tm*
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gmtime(long tim)
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{
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int d0, d1;
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long hms, day;
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static Tm xtime;
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/*
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* break initial number into days
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*/
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hms = tim % 86400L;
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day = tim / 86400L;
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if(hms < 0) {
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hms += 86400L;
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day -= 1;
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}
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/*
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* generate hours:minutes:seconds
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*/
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xtime.sec = hms % 60;
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d1 = hms / 60;
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xtime.min = d1 % 60;
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d1 /= 60;
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xtime.hour = d1;
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/*
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* day is the day number.
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* generate day of the week.
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* The addend is 4 mod 7 (1/1/1970 was Thursday)
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*/
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xtime.wday = (day + 7340036L) % 7;
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/*
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* year number
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*/
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if(day >= 0)
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for(d1 = 1970; day >= dysize(d1); d1++)
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day -= dysize(d1);
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else
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for (d1 = 1970; day < 0; d1--)
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day += dysize(d1-1);
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xtime.year = d1-1900;
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xtime.yday = d0 = day;
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/*
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* generate month
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*/
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if(dysize(d1) == 366)
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dmsize[1] = 29;
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for(d1 = 0; d0 >= dmsize[d1]; d1++)
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d0 -= dmsize[d1];
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dmsize[1] = 28;
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xtime.mday = d0 + 1;
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xtime.mon = d1;
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strcpy(xtime.zone, "GMT");
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return &xtime;
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}
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char*
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asctime(Tm *t)
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{
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const char *ncp;
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static char cbuf[30];
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strcpy(cbuf, "Thu Jan 01 00:00:00 GMT 1970\n");
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ncp = &"SunMonTueWedThuFriSat"[t->wday*3];
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cbuf[0] = *ncp++;
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cbuf[1] = *ncp++;
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cbuf[2] = *ncp;
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ncp = &"JanFebMarAprMayJunJulAugSepOctNovDec"[t->mon*3];
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cbuf[4] = *ncp++;
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cbuf[5] = *ncp++;
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cbuf[6] = *ncp;
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ct_numb(cbuf+8, t->mday);
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ct_numb(cbuf+11, t->hour+100);
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ct_numb(cbuf+14, t->min+100);
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ct_numb(cbuf+17, t->sec+100);
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ncp = t->zone;
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cbuf[20] = *ncp++;
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cbuf[21] = *ncp++;
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cbuf[22] = *ncp;
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if(t->year >= 100) {
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cbuf[24] = '2';
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cbuf[25] = '0';
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}
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ct_numb(cbuf+26, t->year+100);
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return cbuf;
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}
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static
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int
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dysize(int y)
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{
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if(y%4 == 0 && (y%100 != 0 || y%400 == 0))
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return 366;
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return 365;
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}
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static
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void
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ct_numb(char *cp, int n)
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{
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cp[0] = ' ';
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if(n >= 10)
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cp[0] = (n/10)%10 + '0';
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cp[1] = n%10 + '0';
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}
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