#define _POSIX_C_SOURCE 199309L

#include <stdio.h>

#include <stdlib.h>

#include <time.h>

struct unaligned {

char a;

int b;

} __attribute__((packed));

struct aligned {

int b;

char a;

} __attribute__((packed));

int unaligned (struct unaligned *f) {

f->a = (char)rand();

return f->b;

}

int aligned (struct aligned *f) {

int b = f->b;

f->a = (char)rand();

return b;

}

int main (void) {

struct aligned a;

struct unaligned u;

struct timespec s, e;

double delta;

clock_gettime(CLOCK_MONOTONIC, &s);

e.tv_sec = s.tv_sec;

while (s.tv_sec == e.tv_sec)

clock_gettime(CLOCK_MONOTONIC, &e);

clock_gettime(CLOCK_MONOTONIC, &s);

int i = 0;

for (e.tv_sec = s.tv_sec; e.tv_sec == s.tv_sec; i++) {

u.b = (int)rand();

printf("%d\n", unaligned(&u));

clock_gettime(CLOCK_MONOTONIC, &e);

}

delta = (double)(e.tv_sec - s.tv_sec) + (double)(e.tv_nsec - s.tv_nsec) / 1000000;

fprintf(stderr, "unaligned = %d iterations in %lf seconds (%lf iterations per second)\n",

i, delta, i / delta);

clock_gettime(CLOCK_MONOTONIC, &s);

e.tv_sec = s.tv_sec;

while (s.tv_sec == e.tv_sec)

clock_gettime(CLOCK_MONOTONIC, &e);

clock_gettime(CLOCK_MONOTONIC, &s);

i = 0;

for (e.tv_sec = s.tv_sec; e.tv_sec == s.tv_sec; i++) {

a.b = (int)rand();

printf("%d\n", aligned(&a));

clock_gettime(CLOCK_MONOTONIC, &e);

}

delta = (double)(e.tv_sec - s.tv_sec) + (double)(e.tv_nsec - s.tv_nsec) / 1000000;

fprintf(stderr, "aligned = %d iterations in %lf seconds (%f iterations per second)\n",

i, delta, i / delta);

return 0;

}