40 lines
935 B
C
40 lines
935 B
C
#include <time.h>
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static int monthsize[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
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#define SECS_DAY 24*60L*60L
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#define YEARSIZE(year) ((year) % 4 ? 365 : 366)
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struct tm *
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gmtime(clock)
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long *clock;
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{
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unsigned long cl = *clock;
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long dayclock, dayno;
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struct tm tm_buf;
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register struct tm *pbuf = &tm_buf;
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register int *months = monthsize;
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int year = 1970;
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dayclock = cl % SECS_DAY;
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dayno = cl / SECS_DAY;
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pbuf->tm_sec = dayclock % 60;
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pbuf->tm_min = (dayclock % 3600) / 60;
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pbuf->tm_hour = dayclock / 3600;
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pbuf->tm_wday = (dayno + 4) % 7; /* day 0 was a thursday */
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while (dayno >= YEARSIZE(year)) {
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dayno -= YEARSIZE(year);
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year++;
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}
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pbuf->tm_year = year;
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pbuf->tm_yday = dayno;
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pbuf->tm_isdst = 0;
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if (YEARSIZE(year) == 366) monthsize[1] = 29;
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while (dayno - *months >= 0) dayno -= *months++;
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pbuf->tm_mday = dayno + 1;
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pbuf->tm_mon = months - monthsize;
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monthsize[1] = 28;
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return pbuf;
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}
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