new fps counter

code/queue.lua

@@ -0,0 +1,74 @@
+Queue = {}
+
+function Queue:New()
+	local o = {head = nil, tail = nil}
+
+	setmetatable(o, self)
+	self.__index = self
+	return o
+end
+
+function Queue:Enqueue(item)
+	local elem = {item  = item}
+	if self.head == nil then
+		self.head = elem
+		self.tail = elem
+		return
+	end
+
+	elem.next = self.head
+	elem.next.prev = elem
+	self.head = elem
+	return
+end
+
+function Queue:Empty()
+	return self.tail == nil
+end
+
+function Queue:Dequeue()
+	if self:Empty() then
+		return nil
+	end
+
+	local newtail = self.tail.prev
+	local item = self.tail.item
+	if newtail then
+		newtail.next = nil
+	end
+	self.tail = newtail
+	return item
+end
+
+local tq1 = Queue:New()
+tq1:Enqueue(5)
+assert(tq1.head.item == 5)
+assert(tq1:Dequeue() == 5)
+
+-- queue that keeps a rolling tally of its arguments
+AvgQueue = {}
+
+function AvgQueue:New(n, initial)
+	local o = {}
+
+	o.n = n
+	o.queue = Queue:New()
+	o.avg = initial
+
+
+	local x = initial / n
+	for _ = 1,n do
+		o.queue:Enqueue(x)
+	end
+
+	setmetatable(o, self)
+	self.__index = self
+	return o
+end
+
+function AvgQueue:Push(item)
+	local x = item/self.n
+	self.avg = self.avg + x - self.queue:Dequeue()
+	self.queue:Enqueue(x)
+	return self.avg
+end