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__PPC_GET_TIMEBASE(3)      Linux Programmer'sManual      __PPC_GET_TIMEBASE(3)
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 <sys/platform/ppc.h>
       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 fre-
       quency in which the Time Base Register is updated.
       The Time Base Register is a 64-bit register provided by Power Architec-
       ture 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 repre-
       sents 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.
EXAMPLE
       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);
       }
SEE ALSO
       time(2), usleep(3)
COLOPHON
       This  page  is  part of release 4.15 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       https://www.kernel.org/doc/man-pages/.
GNU C Library                     2017-09-15             __PPC_GET_TIMEBASE(3)