TIMEVAL
Section: Misc. Reference Manual Pages (3bsd)Index Return to Main Contents
BSD mandoc
NAME
timeval timespec - time structuresLIBRARY
Lb libbsdSYNOPSIS
In sys/time.h (See libbsd(7) for include usage.) Ft void Fn TIMEVAL_TO_TIMESPEC struct timeval *tv struct timespec *ts Ft void Fn TIMESPEC_TO_TIMEVAL struct timeval *tv struct timespec *tsDESCRIPTION
The In sys/time.h header, included by In time.h , defines various structures related to time and timers.-
The following structure is used by
gettimeofday(2),
among others:
struct timeval { time_t tv_sec; suseconds_t tv_usec; };
The tv_sec member represents the elapsed time, in whole seconds. The tv_usec member captures rest of the elapsed time, represented as the number of microseconds.
-
The following structure is used by
nanosleep(2),
among others:
struct timespec { time_t tv_sec; long tv_nsec; };
The tv_sec member is again the elapsed time in whole seconds. The tv_nsec member represents the rest of the elapsed time in nanoseconds.
A microsecond is equal to one millionth of a second, 1000 nanoseconds, or 1/1000 milliseconds. To ease the conversions, the macros Fn TIMEVAL_TO_TIMESPEC and Fn TIMESPEC_TO_TIMEVAL can be used to convert between struct timeval and struct timespec
EXAMPLES
It can be stressed that the traditional UNIX timeval and timespec structures represent elapsed time, measured by the system clock. The following sketch implements a function suitable for use in a context where the timespec structure is required for a conditional timeout:static void example(struct timespec *spec, time_t minutes) { struct timeval elapsed; (void)gettimeofday(&elapsed, NULL); _DIAGASSERT(spec != NULL); TIMEVAL_TO_TIMESPEC(&elapsed, spec); /* Add the offset for timeout in minutes. */ spec->tv_sec = spec->tv_sec + minutes * 60; }
A better alternative would use the more precise clock_gettime2.
SEE ALSO
timeradd(3bsd)
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Time: 04:45:47 GMT, September 16, 2022
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