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