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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | STANDARDS | HISTORY | EXAMPLES | SEE ALSO | COLOPHON |
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__ppc_get_timebase(3) Library Functions Manual __ppc_get_timebase(3)
__ppc_get_timebase, __ppc_get_timebase_freq - get the current
value of the Time Base Register on Power architecture and its
frequency.
Standard C library (libc, -lc)
#include <sys/platform/ppc.h>
uint64_t __ppc_get_timebase(void);
uint64_t __ppc_get_timebase_freq(void);
__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.
__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.
GNU.
__ppc_get_timebase()
glibc 2.16.
__ppc_get_timebase_freq()
glibc 2.17.
The following program will calculate the time, in microseconds,
spent between two calls to __ppc_get_timebase().
Program source
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/platform/ppc.h>
/* Maximum value of the Time Base Register: 2^60 - 1.
Source: POWER ISA. */
#define MAX_TB 0xFFFFFFFFFFFFFFF
int
main(void)
{
uint64_t tb1, tb2, diff;
uint64_t freq;
freq = __ppc_get_timebase_freq();
printf("Time Base frequency = %"PRIu64" Hz\n", freq);
tb1 = __ppc_get_timebase();
// Do some stuff...
tb2 = __ppc_get_timebase();
if (tb2 > tb1) {
diff = tb2 - tb1;
} else {
/* Treat Time Base Register overflow. */
diff = (MAX_TB - tb2) + tb1;
}
printf("Elapsed time = %1.2f usecs\n",
(double) diff * 1000000 / freq);
exit(EXIT_SUCCESS);
}
time(2), usleep(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
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⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
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2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
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man-pages@man7.org
Linux man-pages 6.9.1 2024-06-15 __ppc_get_timebase(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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