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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 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. 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 ", 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 ", (double) diff * 1000000 / freq ); exit(EXIT_SUCCESS); } SEE ALSO
time(2), usleep(3) GNU C Library 2019-03-06 __PPC_GET_TIMEBASE(3)
