cof: added SpeedToFPS method

d2common/d2fileformats/d2cof/helpers.go

@@ -0,0 +1,16 @@
+package d2cof
+
+// SpeedToFPS returns FPS value basing on cof's speed
+func (c *COF) SpeedToFPS() float64 {
+	const (
+		baseFPS      = 25
+		speedDivisor = 256
+	)
+
+	fps := baseFPS * (float64(c.Speed) / speedDivisor)
+	if fps == 0 {
+		fps = baseFPS
+	}
+
+	return fps
+}