__ppc_get_timebase(3)

💅 __ppc_get_timebase — the PowerPC Time Base Register glow-up

okay bestie, so this page lives in section 3 of the manual (that's the library functions girlies 💖), and it's all about two little functions that let you peek at the Time Base Register on Power architecture. no cap, it's niche but it's iconic.

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🎀 NAME

__ppc_get_timebase, __ppc_get_timebase_freq — grab the current value of the Time Base Register on Power architecture, plus its frequency. periodt.

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📚 LIBRARY

Standard C library — literally just libc, link with -lc. nothing extra needed, she comes free with the standard library 🫶

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✨ SYNOPSIS

#include <sys/platform/ppc.h>

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

two functions, both returning uint64_t, both taking void. clean. minimal. ate. 💅

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🦋 DESCRIPTION

So __ppc_get_timebase() reads the current value of the Time Base Register and hands it back to you, and __ppc_get_timebase_freq() tells you the frequency at which that register is being updated. iykyk, they're a matched set 👑

now the lore: the Time Base Register is a 64-bit register that Power Architecture processors just... have. it stores a monotonically incremented value — meaning it only ever goes up, she does not backtrack — and it's updated at a system-dependent frequency, which may or may not be the same as the processor frequency. so don't go assuming they match, bestie, that's a trap 🙈

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🔥 RETURN VALUE

• __ppc_get_timebase() — returns a 64-bit unsigned integer (uint64_t) representing the current value of the Time Base Register.
• __ppc_get_timebase_freq() — returns a 64-bit unsigned integer (uint64_t) representing the frequency at which the Time Base Register gets updated.

both are 64-bit unsigned, both are exact, no funny business ⭐

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🌈 STANDARDS

GNU. that's it, that's the whole standard. she's a GNU girlie 🧚

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🕰️ HISTORY

• __ppc_get_timebase() — glibc 2.16.
• __ppc_get_timebase_freq() — glibc 2.17.

one version apart, sibling energy fr fr 🫶

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💀 EXAMPLES

okay so the program below is gonna calculate the time, in microseconds, that gets spent between two calls to __ppc_get_timebase(). it's giving benchmarking, it's giving precision, we love to see it ✨

🍓 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 = %w64u 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);
}

not me pointing out the little else branch — that's the Time Base Register overflow handler, bestie, because tb2 > tb1 is usually true but every so often the register wraps and you gotta catch it. main character energy in the form of defensive coding 💜

heads up: that overflow branch is doing the exact arithmetic shown — diff = (MAX_TB - tb2) + tb1; — don't go "fixing" it, it's the original, character for character 🙈

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👀 SEE ALSO

time(2), usleep(3)

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and that's the whole page, bestie!! slay 💖 this one came from Linux man-pages 6.20, dated 2026-02-16, and it's page __ppc_get_timebase(3). go forth and read your time base, queen 🌸👑