diff --git a/frontend/ui/time.lua b/frontend/ui/time.lua
new file mode 100644
index 000000000..52e47021a
--- /dev/null
+++ b/frontend/ui/time.lua
@@ -0,0 +1,99 @@
+TimeVal = {
+	sec = 0,
+	usec = 0,
+}
+
+function TimeVal:new(o)
+	local o = o or {}
+	if o.sec == nil then
+		o.sec = 0
+	end
+	if o.usec == nil then
+		o.usec = 0
+	end
+	setmetatable(o, self)
+	self.__index = self
+	return o
+end
+
+
+function TimeVal:__lt(time_b)
+	if self.sec < time_b.sec then
+		return true
+	elseif self.sec > time_b.sec then
+		return false
+	else
+		-- self.sec == time_b.sec
+		if self.usec < time_b.usec then
+			return true
+		else
+			return false
+		end
+	end
+end
+
+function TimeVal:__le(time_b)
+	if self.sec < time_b.sec then
+		return true
+	elseif self.sec > time_b.sec then
+		return false
+	else
+		-- self.sec == time_b.sec
+		if self.usec > time_b.usec then
+			return false
+		else
+			return true
+		end
+	end
+end
+
+function TimeVal:__eq(time_b)
+	if self.sec == time_b.sec and self.usec == time_b.usec then
+		return true
+	else
+		return false
+	end
+end
+
+function TimeVal:__sub(time_b)
+	diff = TimeVal:new{}
+
+	diff.sec = self.sec - time_b.sec
+	diff.usec = self.usec - time_b.usec
+
+	if diff.sec < 0 and diff.usec > 0 then
+		diff.sec = diff.sec + 1
+		diff.usec = diff.usec - 1000000
+	elseif diff.sec > 0 and diff.usec < 0 then
+		diff.sec = diff.sec - 1
+		diff.usec = diff.usec + 1000000
+	end
+
+	return diff
+end
+
+function TimeVal:__add(time_b)
+	sum = TimeVal:new{}
+
+	sum.sec = self.sec + time_b.sec
+	sum.usec = self.usec + time_b.usec
+	if sum.usec > 1000000 then
+		sum.usec = sum.sec - 1000000
+		sum.sec = sum.sec + 1
+	end
+
+	if sum.sec < 0 and sum.usec > 0 then
+		sum.sec = sum.sec + 1
+		sum.usec = sum.usec - 1000000
+	elseif sum.sec > 0 and sum.usec < 0 then
+		sum.sec = sum.sec - 1
+		sum.usec = sum.usec + 1000000
+	end
+
+	return sum
+end
+
+function TimeVal:now()
+	local sec, usec = util.gettime()
+	return TimeVal:new{sec = sec, usec = usec}
+end