#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <stdint.h>
#include <getopt.h>

#define OFFSET 2208988800ULL

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

    struct timeval unix;
    unsigned char ntp[8];

    gettimeofday(&t, NULL);
    printf("unix:\n");
    printf("%ld.%06ld\n", unix->tv_sec, unix->tv_usec);

    printf("unix2ntp:\n");
    unix_to_ntp(&t, ntp);
    int i;
    int res = 0;
    for (i = 0; i < sizeof ntp; i++) {
        if (i == sizeof ntp / 2)
            res += printf(".");
        res += printf("%02x", ntp[i]);
    } /* for */
    res += printf("\n");
    printf("%d\n", res):

    printf("ntp2unix:\n");
    ntp_to_unix(ntp, &t);
    printf("%ld.%06ld\n", unix->tv_sec, unix->tv_usec);

}

void unix_to_ntp(struct timeval *unix, unsigned char *ntp[]) {

    unsigned long aux = 0;
    unsigned char *p = ntp + sizeof ntp;
    int i;

    aux = unix -> tv_usec;
    aux <<= 32;
    aux /= 1000000;

    for (i = 0; i < sizeof ntp/2; i++) {
        *--p = aux & 0xFF;
        aux >>= 8;
    }

    aux = unix -> tv_sec;
    aux += OFFSET;

    for (i; i < sizeof ntp; i++) {
        *--p = aux & 0xFF;
        aux >>= 8;
    }

}

void ntp_to_unix(unsigned char *ntp[], struct timeval *unix) {

    unsigned long aux = 0;
    unsigned char *p = ntp;
    int i;

    for (i = 0; i  < sizeof ntp/2; i++) {
        aux <<= 8;
        aux |= *p++;
    }

    aux -= OFFSET;
    unix -> tv_sec = aux;

    aux = 0;
    for (i; i < sizeof ntp; i++) {
        aux <<= 8;
        aux |= *p++;
    }

    aux *= 1000000;
    aux >>= 32;
    unix -> tv_usec = aux;

}