// windows_timing2.c SJ

#include <stdio.h>
#include <stdlib.h>

double dtime();

int main(int argc, char *argv[]) {

    int N = 10000000;
    int i;
    int *A = NULL, *B = NULL;
    double starttime, endtime, inittime;

    if (argc > 1)    // first command line parameter
        N = atoi(argv[1]);

    // allocate, fill, and print input array
    starttime = dtime();    // take starting time
    A = (int *) malloc(N * sizeof(int));
    for (i = 0; i < N; i++)
        A[i] = 1;
    endtime = dtime();  // take ending time
    inittime = endtime-starttime;   // time used

    if (N < 30) {
        printf("Original array:");
        for (i = 0; i < N; i++)
            printf(" %d", A[i]);
        printf("\n");
    } else {    // for large inputs, print time instead of content
        printf("Init array of %d elements in %.6lf s, %6.2lf Melem/s\n", N, inittime, (N/inittime)/1000000);
    }

    free(A);

    return 0;
}    // main()





#if defined(_WWWIN32) || defined (WWWIN32) || defined(WIN32)

// ms resolution instead of micros -- accurate enough
// copied from: https://stackoverflow.com/questions/10905892/equivalent-of-gettimeday-for-windows

#include <Windows.h>
#include <stdint.h> // portable: uint64_t   MSVC: __int64


// MSVC defines this in winsock2.h!?
/*
typedef struct timeval {
    long tv_sec;
    long tv_usec;
} timeval;
*/





double dtime()
{
    static const uint64_t EPOCH = ((uint64_t) 116444736000000000ULL);

    SYSTEMTIME  system_time;
    FILETIME    file_time;
    uint64_t    time;

    double ret = 0.0;

    GetSystemTime( &system_time );
    SystemTimeToFileTime( &system_time, &file_time );
    time =  ((uint64_t)file_time.dwLowDateTime )      ;
    time += ((uint64_t)file_time.dwHighDateTime) << 32;


    ret += ((time - EPOCH) / 10000000L);
    ret += system_time.wMilliseconds / 1000.0;

    return ret;

}

#else

/**
 * return current time in seconds (floating point number)
 */


double dtime()
{
    struct timeval tv;
    struct timezone tz;
    gettimeofday(&tv, &tz);
    return tv.tv_sec + (double)tv.tv_usec/1000000;
}

#endif