`__ppc_get_timebase_freq` ( 3 )

получить текущее значение (get the current value)

Имя (Name)

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

Синопсис (Synopsis)

#include <sys/platform/ppc.h>

uint64_t __ppc_get_timebase(void); uint64_t __ppc_get_timebase_freq(void);

Описание (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.

Возвращаемое значение (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.

Версии (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.

Стандарты (Conforming to)

Both functions are nonstandard GNU extensions.

Примеры (Examples)

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 = __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);
       }

Смотри также (See also)

time(2), usleep(3)

Исходный текст на man7.org

__ppc_get_timebase_freq ( 3 )