upstream/emscripten/system/lib/libc/musl/src/thread/__wait.c

#ifdef __EMSCRIPTEN__
#include <math.h>
#include <emscripten/threading.h>
#endif

#include "pthread_impl.h"

void __wait(volatile int *addr, volatile int *waiters, int val, int priv)
{
	int spins=100;
	if (priv) priv = FUTEX_PRIVATE;
	while (spins-- && (!waiters || !*waiters)) {
		if (*addr==val) a_spin();
		else return;
	}
	if (waiters) a_inc(waiters);
#ifdef __EMSCRIPTEN__
	// loop here to handle spurious wakeups from the underlying
	// emscripten_futex_wait.
	int ret = 0;
	while (*addr==val && ret == 0) {
		ret = emscripten_futex_wait((void*)addr, val, INFINITY);
	}
#else
	while (*addr==val) {
		__syscall(SYS_futex, addr, FUTEX_WAIT|priv, val, 0) != -ENOSYS
		|| __syscall(SYS_futex, addr, FUTEX_WAIT, val, 0);
	}
#endif
	if (waiters) a_dec(waiters);
}