gistfile1.txt

#include 
#include 
#include 
#include 

#define NCOUNT  (100000)
#define TCOUNT  (4)

volatile uint64_t u = 0;
volatile uint64_t *casvar = &u;

void *
thread(void *args) {
        volatile uint64_t val = 0;
        int i;

        for (i = 0; i < NCOUNT; i++) {
                for (;;) {
                        __atomic_load(casvar, &val, __ATOMIC_CONSUME);
                        if (__sync_val_compare_and_swap(casvar, val, val+1) == val)
                                break;
                }
        }

        return (NULL);
}

int
main(int argc, char **argv)
{
        uint64_t        i;
        pthread_t       tid[TCOUNT];
        volatile uint64_t result;

        for (i = 0; i < TCOUNT; i++)
                pthread_create(&tid[i], NULL, thread, (void *)i+10);

        for (i = 0; i < TCOUNT; i++) {
                if (pthread_join(tid[i], NULL))
                        printf("pthread_join failed %d\n", i+10);
        }

        __atomic_load(casvar, &result, __ATOMIC_CONSUME);
        if (result != TCOUNT*NCOUNT) {
                printf("womp womp %d %d\n", result, TCOUNT*NCOUNT);
                return (1);
        }
        printf("ok %d %d\n", result, TCOUNT*NCOUNT);
        return (0);
}