2 * Taken from FreeBSD src / lib / libc / stdtime / localtime.c 1.43 revision.
5 * adapted to be replacement gmtime_r.
13 #define MONSPERYEAR 12
14 #define DAYSPERNYEAR 365
15 #define DAYSPERLYEAR 366
17 #define SECSPERHOUR (60*60)
18 #define SECSPERDAY (24*60*60)
23 #define TM_WEDNESDAY 3
28 #define TM_YEAR_BASE 1900
30 #define EPOCH_YEAR 1970
31 #define EPOCH_WDAY TM_THURSDAY
33 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
35 static const int mon_lengths[2][MONSPERYEAR] = {
36 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
37 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
40 static const int year_lengths[2] = {
41 DAYSPERNYEAR, DAYSPERLYEAR
45 timesub(timep, offset, tmp)
46 const time_t * const timep;
48 struct tm * const tmp;
56 days = *timep / SECSPERDAY;
57 rem = *timep % SECSPERDAY;
63 while (rem >= SECSPERDAY) {
67 tmp->tm_hour = (int) (rem / SECSPERHOUR);
68 rem = rem % SECSPERHOUR;
69 tmp->tm_min = (int) (rem / SECSPERMIN);
71 ** A positive leap second requires a special
72 ** representation. This uses "... ??:59:60" et seq.
74 tmp->tm_sec = (int) (rem % SECSPERMIN) ;
75 tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
77 tmp->tm_wday += DAYSPERWEEK;
79 #define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
80 while (days < 0 || days >= (long) year_lengths[yleap = isleap(y)]) {
83 newy = y + days / DAYSPERNYEAR;
86 days -= (newy - y) * DAYSPERNYEAR +
87 LEAPS_THRU_END_OF(newy - 1) -
88 LEAPS_THRU_END_OF(y - 1);
91 tmp->tm_year = y - TM_YEAR_BASE;
92 tmp->tm_yday = (int) days;
93 ip = mon_lengths[yleap];
94 for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
95 days = days - (long) ip[tmp->tm_mon];
96 tmp->tm_mday = (int) (days + 1);
101 * Re-entrant version of gmtime.
103 struct tm * gmtime_r(const time_t* timep, struct tm *tm)
105 timesub(timep, 0L, tm);