Time

Standard system time functions. More...

Collaboration diagram for Time:

Classes
struct	tm

Macros
#define	TZ_LEN   6
#define	SECONDS_PER_MINUTE   (60)
#define	MINUTES_PER_HOUR   (60)
#define	SECONDS_PER_HOUR   (SECONDS_PER_MINUTE * MINUTES_PER_HOUR)
#define	HOURS_PER_DAY   (24)
#define	MINUTES_PER_DAY   (HOURS_PER_DAY * MINUTES_PER_HOUR)
#define	SECONDS_PER_DAY   (MINUTES_PER_DAY * SECONDS_PER_MINUTE)
#define	TZ_LEN   6
#define	SECONDS_PER_MINUTE   (60)
#define	MINUTES_PER_HOUR   (60)
#define	SECONDS_PER_HOUR   (SECONDS_PER_MINUTE * MINUTES_PER_HOUR)
#define	HOURS_PER_DAY   (24)
#define	MINUTES_PER_DAY   (HOURS_PER_DAY * MINUTES_PER_HOUR)
#define	SECONDS_PER_DAY   (MINUTES_PER_DAY * SECONDS_PER_MINUTE)

Functions
int	strftime (char *s, size_t maxsize, const char *format, const struct tm *tm_p)
struct tm *	localtime (const time_t *timep)
struct tm *	gmtime (const time_t *timep)
time_t	mktime (struct tm *tb)
time_t	time (time_t *tloc) noexcept
double	difftime (time_t end, time_t beginning) noexcept
uint16_t	time_ms (time_t *t_utc, uint16_t *out_ms)
time_t	time_start_of_today (void)

Detailed Description

Standard system time functions.

This module contains standard time functions and formatters for printing. Note that Pebble now supports both local time and UTC time (including timezones and daylight savings time). Most of these functions are part of the C standard library which is documented at https://sourceware.org/newlib/libc.html#Timefns

Function Documentation

difftime()

double difftime ( time_t  end, time_t  beginning  )

noexcept

Obtain the number of seconds elapsed between beginning and end represented as a double.

Parameters

end	A time_t variable representing some number of seconds since epoch, January 1st 1970
beginning	A time_t variable representing some number of seconds since epoch, January 1st 1970. Note that end should be greater than beginning, but this is not enforced.

Returns

The number of seconds elapsed between beginning and end.

Note

Pebble uses software floating point emulation. Including this function which returns a double will significantly increase the size of your binary. We recommend directly subtracting both timestamps to calculate a time difference.

int difference = ts1 - ts2;

gmtime()

struct tm * gmtime

(

const time_t *

timep

)

convert the time value pointed at by clock to a struct tm which contains the time expressed in Coordinated Universal Time (UTC)

Parameters

timep

A pointer to an object of type time_t that contains a time value

Returns

A pointer to a struct tm containing Coordinated Universal Time (UTC)

localtime()

struct tm * localtime

(

const time_t *

timep

)

convert the time value pointed at by clock to a struct tm which contains the time adjusted for the local timezone

Parameters

timep

A pointer to an object of type time_t that contains a time value

Returns

A pointer to a struct tm containing the broken out time value adjusted for the local timezone

mktime()

time_t mktime

(

struct tm *

tb

)

convert the broken-down time structure to a timestamp expressed in Coordinated Universal Time (UTC)

Parameters

tb	A pointer to an object of type tm that contains broken-down time

Returns

The number of seconds since epoch, January 1st 1970

strftime()

int strftime	(	char *	s,
		size_t	maxsize,
		const char *	format,
		const struct tm *	tm_p
	)

Format the time value at tm according to fmt and place the result in a buffer s of size max

Parameters

s	A preallocation char array of size max
maxsize	the size of the array s
format	a formatting string
tm_p	A pointer to a struct tm containing a broken out time value

Returns

The number of bytes placed in the array s, not including the null byte, 0 if the value does not fit.

time()

time_t time ( time_t *  tloc )

noexcept

Obtain the number of seconds since epoch. Note that the epoch is not adjusted for Timezones and Daylight Savings.

Parameters

tloc	Optionally points to an address of a time_t variable to store the time in. If you only want to use the return value, you may pass NULL into tloc instead

Returns

The number of seconds since epoch, January 1st 1970

time_ms()

uint16_t time_ms	(	time_t *	t_utc,
		uint16_t *	out_ms
	)

Obtain the number of seconds and milliseconds part since the epoch. This is a non-standard C function provided for convenience.

Parameters

tloc	Optionally points to an address of a time_t variable to store the time in. You may pass NULL into tloc if you don't need a time_t variable to be set with the seconds since the epoch
out_ms	Optionally points to an address of a uint16_t variable to store the number of milliseconds since the last second in. If you only want to use the return value, you may pass NULL into out_ms instead

Returns

The number of milliseconds since the last second

time_start_of_today()

time_t time_start_of_today

(

void

)

Return the UTC time that corresponds to the start of today (midnight).

Returns

the UTC time corresponding to the start of today (midnight)