silly dictNextPower test

gistfile1.c

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <time.h>
#include <math.h>

#define DICT_HT_INITIAL_SIZE 4

static unsigned long _dictNextPowerNew(unsigned long size)
{
    if (size >= LONG_MAX) return LONG_MAX;
    
    if (size <= DICT_HT_INITIAL_SIZE){
        return DICT_HT_INITIAL_SIZE;
    }
    else{
        while(size & (size-1)){
            size |= size-1;
            size++;
        }
        return size;
    }
}

static unsigned long _dictNextPowerOld(unsigned long size)
{
    unsigned long i = DICT_HT_INITIAL_SIZE;

    if (size >= LONG_MAX) return LONG_MAX;
    while(1) {
        if (i >= size)
            return i;
        i *= 2;
    }
}

int main(int argc, const char **argv) {
    unsigned long n2, i, j;
    unsigned long long v;
    double tm1, tm2, tmnew, tmold;

    if (argc < 2) {
        fprintf(stderr, "Pass iterations!\n");
        exit(1);
    }

    long n = strtol(argv[1], NULL, 10);

    for (i = 1000000; i <= n; i += 500000) {
        n2 = 3;
        v = 0;

        tm1 = clock();
        for (j = 0; j < i; j++) {
            v += _dictNextPowerOld(n2);

            if (v >= LONG_MAX) {
                n2 = 3;
            } else {
                n2++;
            }
        }
        tm2 = clock();

        tmold = ((double)tm2-tm1)/CLOCKS_PER_SEC;

        n2 = 3;
        v = 0;

        tm1 = clock();
        for (j = 0; j < i; j++) {
            v += _dictNextPowerNew(n2);
            
            if (v >= LONG_MAX) {
                n2 = 3;
            } else {
                n2++;
            }
        } 
        tm2 = clock();
    
        tmnew = ((double)tm2 - tm1)/CLOCKS_PER_SEC;

        printf("%lu => old=%f; new=%f [%s faster by %f]\n", i, tmold, tmnew,
            tmold > tmnew ? "new" : "old", fabs(tmold-tmnew));

    }
}