getclock(3) Library Functions Manual getclock(3)
NAME
getclock - Gets current value of system-wide clock.
LIBRARY
Standard C Library (libc.a)
SYNOPSIS
#include <sys/timers.h>
int getclock( int clktyp, struct timespec *tp) ;
PARAMETERS
Identifies a system-wide clock. Points to a timespec structure space where the current value of the system-wide clock is stored.
DESCRIPTION
The getclock() function sets the current value of the clock specified by clktyp into the location pointed to by the tp parameter.
The clktyp parameter is given as a symbolic constant name, as defined in the sys/timers.h include file. Only the TIMEOFDAY symbolic con-
stant, which specifies the normal time-of-day clock to access for system-wide time, is supported.
For the clock specified by TIMEOFDAY, the value returned by this function is the elapsed time since the epoch. The epoch is referenced to
00:00:00 CUT (Coordinated Universal Time) 1 Jan 1970.
The getclock() function returns a timespec structure, which is defined in the sys/timers.h header file. It has the following members:
time_t tv_sec Elapsed time in seconds since the epoch
long tv_nsec Elapsed time as a fraction of a second since
the epoch (expressed in nanoseconds)
The time interval expressed by the members of this structure is ((tv_sec * 10^9) + (tv_nsec)) nanoseconds.
NOTES
Trial use
RETURN VALUES
Upon successful completion, the getclock() function returns a value of 0 (zero). Otherwise, getclock() returns a value of -1 and sets
errno to indicate the error.
ERRORS
If the getclock() function fails, errno is to one of the following values: The clktyp parameter does not specify a known system-wide clock.
An error occurred when the system-wide clock specified by the clktyp parameter was accessed.
RELATED INFORMATION
Functions: gettimeofday(2), gettimer(3), setclock(3), time(3) delim off
getclock(3)