nanosecond time on OS X

gistfile1.txt

#include <time.h>
#include <stdio.h>
#include <unistd.h>

#ifdef __MACH__
#include <mach/mach_time.h>
#define CLOCK_REALTIME 0
#define CLOCK_MONOTONIC 0
int clock_gettime(int clk_id, struct timespec *t){
    mach_timebase_info_data_t timebase;
    mach_timebase_info(&timebase);
    uint64_t time;
    time = mach_absolute_time();
    double nseconds = ((double)time * (double)timebase.numer)/((double)timebase.denom);
    double seconds = ((double)time * (double)timebase.numer)/((double)timebase.denom * 1e9);
    t->tv_sec = seconds;
    t->tv_nsec = nseconds;
    return 0;
}
#else
#include <time.h>
#endif

int main() {
    struct timespec time;
    
    for( int i = 0; i < 10; i++ ) {
        clock_gettime(0, &time);
        sleep(1);
        printf("%ld\n", time.tv_nsec);
    }

    return 0;
}

/*
$ ./test
310305432132308
310306437356865
310307438458673
310308441630063
310309445567538
310310446334440
310311448553642
310312452901376
310313458078880
310314459376329
*/