rem: ClearSemaphore (&_MemorySem);
add: ClearSemaphore (_MemorySem);
context: mem_init (void){	int i;	SetSemaphore (&_MemorySem);	freeListHead = &extents[0];	for (i=0; i<MAX_EXTENTS; i++)	{		extents[i].memory = NULL;		extents[i].handle = -1;		extents[i].next = &extents[i+1];		extents[i].size = 0;	}	extents[MAX_EXTENTS-1].next = NULL;	ClearSemaphore (&_MemorySem);	return TRUE;}