kernel/mktime.c

   1 #include <time.h>
   2
   3
   4 #define MINUTE 60
   5 #define HOUR (60*MINUTE)
   6 #define DAY (24*HOUR)
   7 #define YEAR (365*DAY)
   8
   9 /* interestingly, we assume leap-years */
  10 static int month[12] = {
  11         0,
  12         DAY*(31),
  13         DAY*(31+28),
  14         DAY*(31+28+31),
  15         DAY*(31+28+31+30),
  16         DAY*(31+28+31+30+31),
  17         DAY*(31+28+31+30+31+30),
  18         DAY*(31+28+31+30+31+30+31),
  19         DAY*(31+28+31+30+31+30+31+31),
  20         DAY*(31+28+31+30+31+30+31+31+30),
  21         DAY*(31+28+31+30+31+30+31+31+30+31),
  22         DAY*(31+28+31+30+31+30+31+31+30+31+30)
  23 };
  24
  25 long kernel_mktime(struct tm * tm)
  26 {
  27         long res;
  28         int year;
  29         int leap;
  30
  31         year = tm->tm_year - 1;
  32         leap = ((tm->tm_year % 4)?0:((tm->tm_year % 100)?0:1));
  33
  34         res = YEAR*year + DAY*(year/4);
  35         res += month[tm->tm_mon];
  36
  37         if (tm->tm_mon>1 && leap)
  38                 res += DAY;
  39         res += DAY*(tm->tm_mday-1);
  40         res += HOUR*tm->tm_hour;
  41         res += MINUTE*tm->tm_min;
  42         res += tm->tm_sec;
  43         return res;
  44 }