add Chapter17

Chapter17/fsm/util/inc/units.hpp

@@ -0,0 +1,33 @@
+#pragma once
+
+namespace units 
+{
+    template<typename T, typename ST>
+    class unit {
+    private:
+	    T val_; 
+    public:
+	    explicit unit(T val) : val_(val){}
+	    [[nodiscard]] T get() const {return val_;}
+        [[nodiscard]] T get_mili() const {return 1e3 * val_;}
+
+        constexpr T operator/(const unit& second) const{
+            return val_ / second.get();
+        }
+
+        constexpr unit operator*(const T& second) const{
+            return unit(val_ * second);
+        }
+
+        constexpr unit operator/(const T& second) const{
+            return unit(val_ / second);
+        }
+    };
+
+    using voltage = unit<float, struct the_voltage>;
+    using resistance = unit<float, struct the_resistance>;
+
+    voltage operator""_V(long double volts);
+
+    resistance operator""_Ohm(long double ohms);
+};