#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <inttypes.h>

static uint64_t rdtsc(void)
{
        uint32_t lo, hi;
        asm volatile("lfence; rdtsc" : "=a" (lo), "=d" (hi));
        return ((uint64_t) hi << 32) | lo;
}

int main(int argc, char **argv)
{
        int s, khz;
        uint64_t tsc1, tsc2, delta;
        double tsc_s, error;

        if (argc < 3) {
                printf("Usage: %s <sleep seconds> <cpu khz>\n", argv[0]);
                exit(1);
        }

        s = atoi(argv[1]);

        khz = atoi(argv[2]);
        if (khz == 0) {
                printf("cpu khz must be larger than 0\n");
                exit(1);
        }

        tsc1 = rdtsc();
        sleep(s);
        tsc2 = rdtsc();

        delta = tsc2 - tsc1;
        tsc_s = delta / khz / 1000.0;
        error = (tsc_s - s) * 100.0 / s;

        printf("tsc1  = %" PRIu64 ", "
               "tsc2  = %" PRIu64 ", "
               "delta = %lf s, error = %lf\n",
               tsc1, tsc2, tsc_s, error);

        exit(0);
}