TIMESPEC(3HEAD) Headers TIMESPEC(3HEAD)

NAME

timespec, timeval, TIMESPEC_TO_TIMEVAL, TIMEVAL_TO_TIMESPEC - time
structures and conversion

SYNOPSIS

#include <sys/time.h>

void
TIMESPEC_TO_TIMEVAL(struct timeval *tv, const struct timespec *ts);

void
TIMEVAL_TO_TIMESPEC(const struct timeval *tv, struct timespec *ts);

DESCRIPTION

The timeval and timespec structures are declared in the <time.h> and
<sys/time.h> headers respectively:

typedef struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* and nanoseconds */
} timespec_t;

struct timeval {
time_t tv_sec; /* seconds */
suseconds_t tv_usec; /* and microseconds */
};

In both cases, the tv_sec member represents elapsed time in whole
seconds. The tv_nsec and tv_usec members represent the rest of the
elapsed time in nanoseconds and microseconds respectively, depending on
the structure.

The TIMEVAL_TO_TIMESPEC macro can be used to convert a struct timeval
structure to a struct timespec structure, while the TIMESPEC_TO_TIMEVAL
macro works in the opposite direction.

When converting from a struct timespec to a struct timeval structure,
the tv_nsec member is truncated, losing precision. When converting
from a struct timeval to a struct timespec structure, the tv_usec
member is multiplied by 1000 to reach the precision of the target
structure. The tv_sec member is always preserved, no matter which
conversion is performed.

Note that the TIMEVAL_TO_TIMESPEC and TIMESPEC_TO_TIMEVAL macros are
non-standard but are commonly found on UNIX and UNIX-like systems.

INTERFACE STABILITY

Committed

MT-LEVEL
MT-Safe

SEE ALSO

time.h(3HEAD)

illumos December 29, 2021 illumos