#ifndef __TIME_H__
# define __TIME_H__

#ifdef __cplusplus
extern "C" {
#endif

#include <stddef.h>
#include <stdint.h>

/* Number of ticks per second in a clock_t value. This is not necessarily the
   full precision (eg. the RTC has only 128 units per second). */
#define CLOCKS_PER_SEC 1000000

/* Represent process CPU time; unit is CLOCKS_PER_SEC. */
typedef uint64_t clock_t;

/* Represent a number of seconds since 1970-01-01 00:00:00 +0000 (UTC). */
typedef int64_t time_t;

/* Broken-down time. */
struct tm {
	int tm_sec;     /* Seconds (0..60) */
	int tm_min;     /* Minutes (0..59) */
	int tm_hour;    /* Hours (0..23) */
	int tm_mday;    /* Day of month (1..31) */
	int tm_mon;     /* Month (0..11) */
	int tm_year;    /* Years since 1900 */
	int tm_wday;    /* Day of week, starting Sunday (0..6) */
	int tm_yday;    /* Day of year (0..365) */
	int tm_isdst;   /* Daylight Saving Time flag */
};

/* Returns CPU time used by the program (in number of CLOCKS_PER_SEC). */
extern clock_t clock(void);

/* Time elapsed between __start and __end, in seconds. */
double difftime(time_t __end, time_t __start);

/* Normalizes __time and returns associated timestamp.
   TODO: Currently ignores the [tm_isdst] field. */
extern time_t mktime(struct tm *__time);

/* Determine current timestamp; also set it in __timeptr if non-NULL. */
extern time_t time(time_t *__timeptr);

/* Text representation, like "Sun Sep 16 01:03:52 1973\n". The returned string
   is statically allocated and is overwritten by every call. */
extern char *asctime(const struct tm *__time);

/* Convert calendar time to asctime()'s text representation. */
extern char *ctime(const time_t *__time);

/* Convert calendar time to broken-down time as UTC. */
extern struct tm *gmtime(const time_t *__time);

/* Convert calendar time to broken-down local time.
   TODO: We don't have timezones so this always returns UTC. */
extern struct tm *localtime(const time_t *time);

/* Formats __time according to the specified format; similar to snprintf().
   TODO: %g, %G, %V (week-based year), and %U, %W (week number) are not
         supported and substituted by "??". %z and %Z output nothing. */
size_t strftime(char * restrict __s, size_t __maxsize,
	const char * restrict __format, const struct tm * restrict __time);

#ifdef __cplusplus
}
#endif

#endif /*__TIME_H__*/