apps/plugins/lua/gmtime.c

   1 #include <time.h>
   2
   3 /* seconds per day */
   4 #define SPD 24*60*60
   5
   6 /* days per month -- nonleap! */
   7 const short __spm[13] =
   8   { 0,
   9     (31),
  10     (31+28),
  11     (31+28+31),
  12     (31+28+31+30),
  13     (31+28+31+30+31),
  14     (31+28+31+30+31+30),
  15     (31+28+31+30+31+30+31),
  16     (31+28+31+30+31+30+31+31),
  17     (31+28+31+30+31+30+31+31+30),
  18     (31+28+31+30+31+30+31+31+30+31),
  19     (31+28+31+30+31+30+31+31+30+31+30),
  20     (31+28+31+30+31+30+31+31+30+31+30+31),
  21   };
  22
  23 static inline int isleap(int year) {
  24   /* every fourth year is a leap year except for century years that are
  25    * not divisible by 400. */
  26 /*  return (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0)); */
  27   return (!(year%4) && ((year%100) || !(year%400)));
  28 }
  29
  30 struct tm *gmtime(const time_t *timep) {
  31   static struct tm r;
  32   time_t i;
  33   register time_t work=*timep%(SPD);
  34   r.tm_sec=work%60; work/=60;
  35   r.tm_min=work%60; r.tm_hour=work/60;
  36   work=*timep/(SPD);
  37   r.tm_wday=(4+work)%7;
  38   for (i=1970; ; ++i) {
  39     register time_t k=isleap(i)?366:365;
  40     if (work>=k)
  41       work-=k;
  42     else
  43       break;
  44   }
  45   r.tm_year=i-1900;
  46   r.tm_yday=work;
  47
  48   r.tm_mday=1;
  49   if (isleap(i) && (work>58)) {
  50     if (work==59) r.tm_mday=2; /* 29.2. */
  51     work-=1;
  52   }
  53
  54   for (i=11; i && (__spm[i]>work); --i) ;
  55   r.tm_mon=i;
  56   r.tm_mday+=work-__spm[i];
  57   return &r;
  58 }