Quick Snip for Time Measurement

timelib.h

#include <time.h>

double TL_gettime();
int TL_checktick();

double TL_gettime()
{
    struct timespec t;
    clock_gettime(CLOCK_REALTIME, &t);
    return ( (double) t.tv_sec + (double) t.tv_nsec * 1.e-9 );
}

int TL_checktick()
{
    int i, minDelta, Delta;
    double t1, t2, timesfound[M];
    int M = 20;

    /*  Collect a sequence of M unique time values from the system. */

    for (i = 0; i < M; i++) {
        t1 = TL_gettime();
        while(((t2 = TL_gettime()) - t1) < 1.0E-6 );
        timesfound[i] = t1 = t2;
    }

    /*
     * Determine the minimum difference between these M values.
     * This result will be our estimate (in microseconds) for the
     * clock granularity.
     */

    minDelta = 1000000;
    for (i = 1; i < M; i++) {
        Delta = (int) (1.0E6 * (timesfound[i] - timesfound[i-1]));
        minDelta = MIN(minDelta, MAX(Delta, 0));
    }

    return(minDelta);
}