ctime.c

File system using stacked.

/* Taken from dietlibc. */

#include <db.h>

static long int timezone;

struct tm {
  int tm_sec;			/* Seconds.	[0-60] (1 leap second) */
  int tm_min;			/* Minutes.	[0-59] */
  int tm_hour;			/* Hours.	[0-23] */
  int tm_mday;			/* Day.		[1-31] */
  int tm_mon;			/* Month.	[0-11] */
  int tm_year;			/* Year - 1900. */
  int tm_wday;			/* Day of week.	[0-6] */
  int tm_yday;			/* Days in year.[0-365]	*/
  int tm_isdst;			/* DST.		[-1/0/1]*/

  long int tm_gmtoff;		/* Seconds east of UTC.  */
  const char *tm_zone;		/* Timezone abbreviation.  */
};

#if 0
struct timezone {
  int tz_minuteswest;	/* minutes west of Greenwich */
  int tz_dsttime;	/* type of dst correction */
};
#endif


/* days per month -- nonleap! */
const short __spm[12] =
  { 0,
    (31),
    (31+28),
    (31+28+31),
    (31+28+31+30),
    (31+28+31+30+31),
    (31+28+31+30+31+30),
    (31+28+31+30+31+30+31),
    (31+28+31+30+31+30+31+31),
    (31+28+31+30+31+30+31+31+30),
    (31+28+31+30+31+30+31+31+30+31),
    (31+28+31+30+31+30+31+31+30+31+30),
  };

static const char days[] = "Sun Mon Tue Wed Thu Fri Sat ";
static const char months[] = "Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ";

static void num2str(char *c,int i) {
  c[0]=i/10+'0';
  c[1]=i%10+'0';
}

static int __isleap(int year) {
  /* every fourth year is a leap year except for century years that are
   * not divisible by 400. */
/*  return (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0)); */
  return (!(year%4) && ((year%100) || !(year%400)));
}

char *asctime_r(const struct tm *t, char *buf) {
  /* "Wed Jun 30 21:49:08 1993\n" */
  *(int*)buf=*(int*)(days+(t->tm_wday<<2));
  *(int*)(buf+4)=*(int*)(months+(t->tm_mon<<2));
  num2str(buf+8,t->tm_mday);
  if (buf[8]=='0') buf[8]=' ';
  buf[10]=' ';
  num2str(buf+11,t->tm_hour);
//  if (buf[11]=='0') buf[11]=' ';
  buf[13]=':';
  num2str(buf+14,t->tm_min);
  buf[16]=':';
  num2str(buf+17,t->tm_sec);
  buf[19]=' ';
  num2str(buf+20,(t->tm_year+1900)/100);
  num2str(buf+22,(t->tm_year+1900)%100);
  buf[24]='\n';
  return buf;
}
/* seconds per day */
#define SPD 24*60*60

struct tm *gmtime_r(const time_t *timep, struct tm *r) {
  time_t i;
  register time_t work=*timep%(SPD);
  r->tm_sec=work%60; work/=60;
  r->tm_min=work%60; r->tm_hour=work/60;
  work=*timep/(SPD);
  r->tm_wday=(4+work)%7;
  for (i=1970; ; ++i) {
    register time_t k=__isleap(i)?366:365;
    if (work>=k)
      work-=k;
    else
      break;
  }
  r->tm_year=i-1900;
  r->tm_yday=work;

  r->tm_mday=1;
  if (__isleap(i) && (work>58)) {
    if (work==59) r->tm_mday=2; /* 29.2. */
    work-=1;
  }

  for (i=11; i && (__spm[i]>work); --i) ;
  r->tm_mon=i;
  r->tm_mday+=work-__spm[i];
  return r;
}

struct tm* localtime_r(const time_t* t, struct tm* r) {
  time_t tmp;
  struct timezone tz;
  gettimeofday(0, &tz);
  timezone=tz.tz_minuteswest*60L;
  tmp=*t+timezone;
  return gmtime_r(&tmp,r);
}


char *ctime_r(const time_t *timep, char *buf) {
  	struct tm tmp;
	localtime_r(timep, &tmp);
  	asctime_r(&tmp, buf);
	return buf;
}