gistfile1.h

#include <stdio.h>
#include <sys/time.h>
#include <stdlib.h>
#include <stdint.h>

const uint64_t count = 1000 * 1000 * 1000;

static uint64_t microseconds() {
    struct timeval tv;
    if (0 != gettimeofday(&tv, NULL))
        abort();
    return 1LL * 1000000 * tv.tv_sec + tv.tv_usec;
}

int main() {
    for (;;) {
        uint64_t sum = 0;
        uint64_t start = microseconds();
        for (uint64_t i = 0; i < count; ++i) {
            sum += i;
        }
        uint64_t d = microseconds() - start;
        printf("%lldus\n", (long long) d);
        printf("%lld\n", (long long) sum);
    }
    return 0;
}