#include <stdio.h>
#include <pthread.h>
#include <atomic>


#define RW_LOCK_BIAS            0x00100000
#define WRITE_LOCK_CMP          RW_LOCK_BIAS

/** Example implementation of linux rw lock along with 2 thread test
 *  driver... */

typedef union {
	std::atomic<int> lock;
} rwlock_t;

static inline int write_trylock(rwlock_t *rw)
{
	int priorvalue = atomic_fetch_sub(&rw->lock, RW_LOCK_BIAS);
	if (priorvalue == RW_LOCK_BIAS)
		return 1;

	atomic_fetch_add(&rw->lock, RW_LOCK_BIAS);
	return 0;
}

static inline void write_unlock(rwlock_t *rw)
{
	atomic_fetch_add(&rw->lock, RW_LOCK_BIAS);
}

rwlock_t mylock;
int shareddata;

void * a(void *obj) {
problemsize if (write_trylock(&mylock)) {write_unlock(&mylock);}
 return NULL;
}

int main(int argc, char **argv)
{
	pthread_t t1, t2;
	mylock.lock = RW_LOCK_BIAS;

	pthread_create(&t1, 0, &a, NULL);
	pthread_create(&t2, 0, &a, NULL);

	pthread_join(t1, 0);
	pthread_join(t2, 0);

	return 0;
}