__PPC_GET_TIMEBASE

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
VERSIONS
CONFORMING TO
EXAMPLES
SEE ALSO
COLOPHON

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NAME

__ppc_get_timebase, __ppc_get_timebase_freq − get the current value
of the Time Base Register on Power architecture and its frequency.

SYNOPSIS

#include

uint64_t __ppc_get_timebase(void)

uint64_t __ppc_get_timebase_freq(void);

DESCRIPTION

__ppc_get_timebase() reads the current value of the Time Base Register and returns its value, while __ppc_get_timebase_freq() returns the frequency in which the Time Base Register is updated.

The Time Base Register is a 64-bit register provided by Power Architecture processors. It stores a monotonically incremented value that is updated at a system-dependent frequency that may be different from the processor frequency.

RETURN VALUE

__ppc_get_timebase() returns a 64-bit unsigned integer that represents the current value of the Time Base Register.

__ppc_get_timebase_freq() returns a 64-bit unsigned integer that represents the frequency at which the Time Base Register is updated.

VERSIONS

GNU C Library support for __ppc_get_timebase() has been provided since version 2.16 and __ppc_get_timebase_freq() has been available since version 2.17.

CONFORMING TO

Both functions are nonstandard GNU extensions.

EXAMPLES

The following program will calculate the time, in microseconds, spent between two calls to __ppc_get_timebase().

Program source
#include
#include
#include
#include
#include

/* Maximum value of the Time Base Register: 2^60 − 1.
Source: POWER ISA. bodies/ usr/
#define MAX_TB 0xFFFFFFFFFFFFFFF

int
main(void)
{
uint64_t tb1, tb2, diff;

uint64_t freq = __ppc_get_timebase_freq();
printf(“Time Base frequency = %”PRIu64″ Hzn”, freq);

tb1 = __ppc_get_timebase();

// Do some stuff…

tb2 = __ppc_get_timebase();

if (tb2 > tb1) {
diff = tb2 − tb1;
} else {
/bin /boot /dead.letter /dev /etc /home /initrd /lib /lib64 /lost+found /media /mnt /opt /proc /release-notes.html /release-notes.txt /root /run /sbin /srv /sys /tmp /usr /var Treat Time Base Register overflow. bodies/ usr/
diff = (MAX_TB − tb2) + tb1;
}

printf(“Elapsed time = %1.2f usecsn”,
(double) diff bodies manpages.csv script_extrae_body.sh script.sh usr 1000000 / freq );

exit(EXIT_SUCCESS);
}

SEE ALSO

time(2), usleep(3)

COLOPHON

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