timertests

//
// clang -O2 -march=native timetest.c -o timetest
//

#include <time.h>
#include <stdint.h>
#include <stdio.h>
#include <limits.h>

static long diff_nano(struct timespec *start, struct timespec *end) {
    return ((end->tv_sec * (1000000000)) + (end->tv_nsec)) - ((start->tv_sec * 1000000000) + (start->tv_nsec));
}

int main(int argc, char **argv) {
    struct timespec start, now, delay_time;
    long t;

    delay_time.tv_sec = 0;
    delay_time.tv_nsec = 9000000;       // 9ms

    long lowest = LONG_MAX;
    long highest = 0;
    long tt = 0;

    volatile uint64_t a[4096];

    clock_gettime(CLOCK_MONOTONIC_RAW, &start);
    while(1) {

        //
        // DO THE STUFF
        //
        for(size_t i = 0; i < 4096; ++i) {
            a[i]++;
        }


        //
        // NOTE(peter): Wait for 10ms
        //
        clock_nanosleep(CLOCK_MONOTONIC_RAW, 0, &delay_time, 0);    // 9ms
        clock_gettime(CLOCK_MONOTONIC_RAW, &now);
        while(diff_nano(&start, &now) < 10000000) {                         // remaining 1ms
            clock_gettime(CLOCK_MONOTONIC_RAW, &now);
        }
        t = diff_nano(&start, &now);
        start.tv_sec = now.tv_sec;
        start.tv_nsec = now.tv_nsec;

        // NOTE(peter): Print result on change
        if(t < lowest) {
            lowest = t;
            printf("%ld ns (l: %ld  h: %ld)\n", t, lowest, highest);
        }
        if(t > highest) {
            highest = t;
            printf("%ld ns (l: %ld  h: %ld)\n", t, lowest, highest);
        }

        // NOTE(peter): Print result every 100 frames...
        if(tt++ == 100) {
            printf("%ld ns (l: %ld  h: %ld)\n", t, lowest, highest);
            tt = 0;
        }
    }

    return 0;
}