Time

abs_time exposes monotonic and wall-clock timers behind four simple functions. On Windows it uses QueryPerformanceCounter/GetSystemTimeAsFileTime; on POSIX it uses clock_gettime. No configuration is required.

#include "abscom/abs.h"

API

Function	Description
double abs_time_now(void)	Monotonic time in seconds (safe for elapsed-time measurement).
double abs_time_wall(void)	Wall-clock time in seconds since the Unix epoch.
uint64_t abs_time_now_ns(void)	Monotonic time in nanoseconds.
uint64_t abs_time_wall_ms(void)	Wall-clock time in milliseconds.

abs_time_now is the right choice for benchmarking and measuring intervals because it never jumps (unlike wall time, which can change via NTP or manual adjustment).

Example

#include "abscom/abs.h"
#include <stdio.h>

int main(void) {
    double start = abs_time_now();

    volatile double acc = 0.0;
    for (int i = 0; i < 1000000; i++) acc += (double)i;
    ABS_UNUSED(acc);

    double elapsed = abs_time_now() - start;
    printf("loop took %.6f s\n", elapsed);
    printf("wall clock: %.3f\n", abs_time_wall());
    printf("now_ns:     %llu\n", (unsigned long long)abs_time_now_ns());
    printf("wall_ms:    %llu\n", (unsigned long long)abs_time_wall_ms());
    return 0;
}

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