#include "pthread_impl.h"

#include "__lock.h"

weak_alias(__lock_fast, __lock);
weak_alias(__unlock_fast, __unlock);

void __lock_slow(volatile int *l, int current)
{
	/* A first spin lock acquisition loop, for the case of
	   medium congestion. */
	for (unsigned i = 0; i < 10; ++i) {
		if (current < 0) current -= INT_MIN + 1;
		// assertion: current >= 0
		int val = a_cas(l, current, INT_MIN + (current + 1));
		if (val == current) return;
		current = val;
	}
	// Spinning failed, so mark ourselves as being inside the CS.
	current = a_fetch_add(l, 1) + 1;
	/* The main lock acquisition loop for heavy congestion. The only
	   change to the value performed inside that loop is a successful
	   lock via the CAS that acquires the lock. */
	for (;;) {
		/* We can only go into wait, if we know that somebody holds the
		   lock and will eventually wake us up, again. */
		if (current < 0) {
			__futexwait(l, current, 1);
			current -= INT_MIN + 1;
		}
		/* assertion: current > 0, because the count
		   includes us already. */
		int val = a_cas(l, current, INT_MIN + current);
		if (val == current) return;
		current = val;
	}
}