#include <stdio.h>
#include <threads.h>
#include <stdatomic.h>

#include "librace.h"

#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 {
	atomic_int lock;
} rwlock_t;

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

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

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

rwlock_t mylock;
int shareddata;

static void a(void *obj) {
	int i;
	for(i = 0; i < PROBLEMSIZE; i++) {
		if (write_trylock(&mylock)) {
			write_unlock(&mylock);
		}
	}
}

int user_main(int argc, char **argv)
{
	thrd_t t1, t2;
	atomic_init(&mylock.lock, RW_LOCK_BIAS);

	thrd_create(&t1, (thrd_start_t)&a, NULL);
	thrd_create(&t2, (thrd_start_t)&a, NULL);

	thrd_join(t1);
	thrd_join(t2);

	return 0;
}