#include <stdint.h>
#include <inc/jthread.h>
#include <inc/syscall.h>
#include <inc/assert.h>

void
jthread_mutex_init(jthread_mutex_t *mu)
{
    jos_atomic_set64(mu, 0);
}

void
jthread_mutex_lock(jthread_mutex_t *mu)
{
    for (;;) {
	uint64_t cur = jos_atomic_compare_exchange64(mu, 0, 1);
	if (cur == 0)
	    break;

	jos_atomic_compare_exchange64(mu, 1, 2);
	sys_sync_wait(&mu->counter, 2, UINT64(~0));
    }
}

int
jthread_mutex_trylock(jthread_mutex_t *mu)
{
    uint64_t cur = jos_atomic_compare_exchange64(mu, 0, 1);
    if (cur == 0)
	return 0;

    return -1;
}

void
jthread_mutex_unlock(jthread_mutex_t *mu)
{
    uint64_t was = jos_atomic_compare_exchange64(mu, 1, 0);
    if (was == 0)
	panic("jthread_mutex_unlock: %p not locked", mu);

    if (was == 2) {
	jos_atomic_set64(mu, 0);
	sys_sync_wakeup(&mu->counter);
    }
}