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CLOCK(9)                   Kernel Developer's Manual                  CLOCK(9)

NAME
     days_in_month, is_leap_year, days_per_year - handy time utilities

SYNOPSIS
     #include <sys/clock.h>

     #define SECS_PER_MINUTE 60
     #define SECS_PER_HOUR 3600
     #define SECS_PER_DAY 86400
     #define DAYS_PER_COMMON_YEAR 365
     #define DAYS_PER_LEAP_YEAR 366
     #define SECS_PER_COMMON_YEAR (SECS_PER_DAY * DAYS_PER_COMMON_YEAR)
     #define SECS_PER_LEAP_YEAR (SECS_PER_DAY * DAYS_PER_LEAP_YEAR)

     static inline int
     days_in_month(int m);

     static inline int
     is_leap_year(uint64_t year);

     static inline int
     days_per_year(uint64_t year);

DESCRIPTION
     The <sys/clock.h> file provides handy time constants and static inline
     functions.

FUNCTIONS
     The days_in_month() function returns the number of days in the given
     month.  days_in_month() assumes 28 days for February.  If the input value
     is out of the valid range (1-12) then the function returns -1.

     The is_leap_year() and days_per_year() functions take as the input
     parameter a value in the Gregorian year format.

SEE ALSO
     bintime(9), boottime(9), time_second(9), time_uptime(9), todr_gettime(9)

HISTORY
     The <sys/clock.h> header with handy utilities originated from
     <dev/clock_subr.h>, which originated from <arch/hp300/hp300/clock.c>.

     The <arch/hp300/hp300/clock.c> file first appeared in NetBSD 0.8 as a set
     of hp300 time-converting functions.  <dev/clock_subr.h> first appeared in
     NetBSD 1.3 as a shared list of functions to convert between
     "year/month/day/hour/minute/second" and seconds since 1970 ("POSIX
     time").  The <sys/clock.h> file first appeared in NetBSD 8.

AUTHORS
     Kamil Rytarowski

NetBSD 10.99                   December 26, 2014                  NetBSD 10.99