init commit

engine/transmission.cpp

@@ -0,0 +1,25 @@
+#include "transmission.h"
+
+void Transmission::set_gear(int gear) {
+    if (gear >= 0 && gear <= kNumGears) {
+        m_gear = gear;
+    }
+}
+
+int Transmission::gear() const {
+    return m_gear;
+}
+
+double Transmission::ratio() const {
+    return kGearRatios[m_gear] * kFinalDrive;
+}
+
+double Transmission::output_torque_nm(double engine_torque_nm) const {
+    if (m_gear == 0) return 0.0; // neutral: nothing reaches the wheels
+    return engine_torque_nm * ratio();
+}
+
+double Transmission::reflected_engine_rpm(double wheel_rpm) const {
+    if (m_gear == 0) return 0.0; // decoupled in neutral
+    return wheel_rpm * ratio();
+}