Timex

Timestamp representation, computation, and conversion.

const int8_t TM_MON_DAYS()

The number of days in common years.

See also

http://oeis.org/A008685

const int16_t TM_MON_DAYS_ACCU()

The prefixsum of the number of days in common years.

See also

http://oeis.org/A061251

timex_t timex_add(const timex_t a, const timex_t b)

Adds two timestamps.

Parameters

a:First summand
b:Second summand

Return values

  • The sum of the two timestamps
timex_t timex_sub(const timex_t a, const timex_t b)

Subtracts two timestamps.

Parameters

a:The minuend
b:The subtrahend

Return values

  • The difference a - b
timex_t timex_set(uint32_t seconds, uint32_t microseconds)

Initializes a timex timestamp.

Parameters

seconds:Number of seconds to set
microseconds:Number of microseconds to set

Return values

  • The initialized timex timestamp
int timex_cmp(const timex_t a, const timex_t b)

Compares two timex timestamps.

Parameters

a:The first timestamp to compare to
b:The second timestamp to compare with

Return values

  • -1 when a is smaller
  • 0 if equal
  • 1 if a is bigger
void timex_normalize(timex_t * time)

Corrects timex structure so that microseconds < 1000000.

Parameters

time:Pointer to the timestamp to normalize

int timex_isnormalized(const timex_t * time)

Tests a timex timestamp for normalization.

Parameters

time:Pointer to the timestamp to check

Return values

  • true for a normalized timex_t
  • false otherwise
uint64_t timex_uint64(const timex_t a)

Converts a timex timestamp to a 64 bit value.

Parameters

a:The timestamp to convert

Return values

  • timex representation as uint64_t
timex_t timex_from_uint64(const uint64_t timestamp)

Converts a 64 bit value of microseconds to a timex timestamp.

Parameters

timestamp:The timestamp to convert.

Return values

  • a timex representation of an uint64 timestamp.
const char * timex_to_str(timex_t t, char * timestamp)

Converts a timex timestamp to a string.

Parameters

t:The timestamp to convert
timestamp:The output char buffer for the converted timestamp

Note

The timestamp will be normalized

Return values

  • A pointer to the string representation of the timestamp
int tm_is_leap_year(unsigned year)

Tells if a given year is a leap year in the Gregorian calendar.

Parameters

year:The year. Probably should be ≥ 1582, but needs to be ≥ 1.

Return values

  • 1 if it is a leap year, 0 if it is a common year.
int tm_doomsday(int year)

Returns the congruent weekday of the Doomsday (March 0).

Only applies for years in the Gregorian calendar.

Parameters

year:The year. Probably should be ≥ 1582, but needs to be ≥ 1.

Return values

  • The result % 7 is the weekday of the Doomsday of the given year.
void tm_get_wyday(int year, int mon, int mday, int * wday, int * yday)

Calculates the day of the year and the weekday of a given date.

Illegal dates are not catched.

Parameters

year:The year. Probably should be ≥ 1582, but needs to be ≥ 1.
mon:The month, TM_MON_JAN to TM_MON_DEC.
mday:The day in the month, 1 to 31.
wday:Returns the day of the week.
yday:Returns the day of the year (Jan 1st is 0).

void tm_fill_derived_values(struct tm * tm)

Fills in struct tm::tm_wday and struct tm::tm_yday given a date.

struct tm::tm_year, struct tm::tm_mon, and struct tm::tm_mday need to be set before you call this function.

Parameters

tm:The datum to operate on.

int tm_is_valid_date(int year, int mon, int mday)

Tests if a date is valid.

Dates before 1582-10-15 are invalid.

Parameters

year:The year.
mon:The month.
mday:The day in the month.

Return values

  • 0 iff the date is invalid.
int tm_is_valid_time(int hour, int min, int sec)

Shallow test if a time is valid.

This function accepts leap seconds at any given time, because the timezone is unknown.

Parameters

hour:The hour.
min:The minutes.
sec:The seconds.

Return values

  • 0 iff the time is invalid.
US_PER_SEC

The number of microseconds per second. 

1
(1000000U)
SEC_PER_MIN

The number of seconds per minute. 

1
(60U)
CS_PER_SEC

The number of centiseconds per second. 

1
(100U)
MS_PER_SEC

The number of milliseconds per second. 

1
(1000U)
US_PER_MS

The number of microseconds per millisecond. 

1
(1000U)
NS_PER_US

The number of nanoseconds per microsecond. 

1
(1000U)
TIMEX_MAX_STR_LEN

The maximum length of the string representation of a timex timestamp. 

1
(20)
TM_WDAY_SUN

Sunday in struct tm::tm_wday. 

1
(0)
TM_WDAY_MON

Monday in struct tm::tm_wday. 

1
(1)
TM_WDAY_TUE

Tuesday in struct tm::tm_wday. 

1
(2)
TM_WDAY_WED

Wednesday in struct tm::tm_wday. 

1
(3)
TM_WDAY_THU

Thursday in struct tm::tm_wday. 

1
(4)
TM_WDAY_FRI

Friday in struct tm::tm_wday. 

1
(5)
TM_WDAY_SAT

Saturday in struct tm::tm_wday. 

1
(6)
TM_MON_JAN

January in struct tm::tm_mon 

1
( 0)
TM_MON_FEB

February in struct tm::tm_mon 

1
( 1)
TM_MON_MAR

March in struct tm::tm_mon 

1
( 2)
TM_MON_APR

April in struct tm::tm_mon 

1
( 3)
TM_MON_MAY

May in struct tm::tm_mon 

1
( 4)
TM_MON_JUN

June in struct tm::tm_mon 

1
( 5)
TM_MON_JUL

July in struct tm::tm_mon 

1
( 6)
TM_MON_AUG

August in struct tm::tm_mon 

1
( 7)
TM_MON_SEP

September in struct tm::tm_mon 

1
( 8)
TM_MON_OCT

October in struct tm::tm_mon 

1
( 9)
TM_MON_NOV

November in struct tm::tm_mon 

1
(10)
TM_MON_DEC

December in struct tm::tm_mon 

1
(11)
struct timex_t

A timex timestamp.

Note

If a timestamp is not normalized, the number of microseconds might be > 1000000

uint32_t seconds

number of seconds

uint32_t microseconds

number of microseconds