What sync object should i use?

[Heinz]

Hi,

I'm looking for an object in "core.sync" whose internal counter 
can be 0 or 1 (signaled/not signaled), just like Event Objects in 
Win32 
(http://msdn.microsoft.com/en-us/library/windows/desktop/ms682396%28v=vs.85%29.aspx). 
The object must be waitable and able to notify waiters. A 
semaphore is the most similar thing but its internal counter can 
range from 0 to x. I can perfectly create and use an event under 
Win32 for my needs but i do not know their counterparts in 
FreeVSD, Linux and OSX; that's why i'm trying to use an already 
implemented object from the runtime.

This is what i'm trying to do:

void MyFunc()
{

}