Алгоритм Евклида, показать время выполнения алгоритма

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
#define N1  386
#define N2  381
 
#define MIN(a,b) (((a)<(b))?(a) : (b))
#define MAX(a,b) (((a)>(b))?(a) : (b))
 
#define REPEAT_COUNT 1000000
#define REPEATOR(count, code) \
for (unsigned int indexIteration = (count); indexIteration--;){ code; }
#define TWO_VALUES_SELECTOR(variable, firstValue, secondValue) \
    (variable) = indexIteration % 2 ? (firstValue) : (secondValue);
 
double getCurrentTime() {
    clock_t time = clock();
    if (time != (clock_t)-1) {
        return ((double)time / (double)CLOCKS_PER_SEC);
    }
    return 0.; // else  
}
 
unsigned long long int f1_GCD(unsigned long long int variableN1, unsigned long long int variableN2) {
    unsigned long long int returnValue = 1;
 
    for (unsigned long long int i = 1, k = MIN(variableN1, variableN2); i <= k; i++) {
        if (!(variableN1 % i || variableN2 % i)) {
            returnValue = i;
        }
    }
 
    return returnValue;
}
 
unsigned long long int f2_GCD(unsigned long long int a, unsigned long long int b) {
    for (unsigned long long int aModB;
        aModB = a % b,
        a = b,
        b = aModB;
        );
 
    return a;
}
 
unsigned long long int f3_GCD(unsigned long long int a, unsigned long long int b) {
    if (!b) {
        return a;
    }
 
    return f3_GCD(b, a % b); // else
}
 
int main() {
    unsigned long long int vN1 = N1, vN2 = N2, a = MAX(vN1, vN2), b = MIN(vN1, vN2),
        vN1_ = vN1, vN2_ = vN2, a_ = a, b_ = b,
        returnValue;
 
    double startTime, endTime;
 
    // f1_GCD 
    startTime = getCurrentTime();
    REPEATOR(REPEAT_COUNT,
        TWO_VALUES_SELECTOR(vN1, 16, vN1_);
    TWO_VALUES_SELECTOR(vN2, 4, vN2_);
    returnValue = f1_GCD(a, b);
    )
        endTime = getCurrentTime();
    printf("f1_GCD return %d \r\nrun time: %dns\r\n\r\n",
        returnValue,
        (unsigned int)((endTime - startTime) * (double)(1000000000 / REPEAT_COUNT)));
 
    // f2_GCD 
    startTime = getCurrentTime();
    REPEATOR(REPEAT_COUNT,
        TWO_VALUES_SELECTOR(a, 16, a_);
    TWO_VALUES_SELECTOR(b, 4, b_);
    returnValue = f2_GCD(a, b);
    )
        endTime = getCurrentTime();
    printf("f2_GCD return %d \r\nrun time: %dns\r\n\r\n",
        returnValue,
        (unsigned int)((endTime - startTime) * (double)(1000000000 / REPEAT_COUNT)));
 
    // f3_GCD 
    startTime = getCurrentTime();
    REPEATOR(REPEAT_COUNT,
        TWO_VALUES_SELECTOR(a, 16, a_);
    TWO_VALUES_SELECTOR(b, 4, b_);
    returnValue = f3_GCD(a, b);
    )
        endTime = getCurrentTime();
    printf("f3_GCD return %d \r\nrun time: %dns\r\n\r\n",
        returnValue,
        (unsigned int)((endTime - startTime) * (double)(1000000000 / REPEAT_COUNT)));
 
    printf("Press any key to continue . . .");
    getchar();
    return 0;
}

using ulong = unsigned long long; // int можно не писать