Add turbocharged twin scenario and cross-platform test harness

tools/two_stroke_benchmark.cpp

@@ -0,0 +1,37 @@
+#include "FluidSim/TwoStrokeScenario.hpp"
+#include <chrono>
+#include <iostream>
+
+using namespace fluidsim::port;
+int main() {
+    std::cout << "exhaust,rpm,shaft_kW,shaft_Nm,firings_per_revolution,repairs,wall_seconds\n";
+    for (auto exhaust : {TwoStrokeExhaust::Straight, TwoStrokeExhaust::Racing}) {
+        for (float rpm : {6000.f, 8000.f, 10000.f, 12000.f, 14000.f, 17000.f}) {
+            TwoStrokeConfig config;
+            config.exhaust = exhaust;
+            TwoStrokeScenario s(44100, config);
+            s.set_throttle(1);
+            const auto start = std::chrono::steady_clock::now();
+            double torque = 0, power = 0;
+            std::uint64_t initial_firings = 0;
+            // An ideal absorbing/motoring dyno imposes speed, exchanging shaft
+            // work externally. It never changes gas energy or adds combustion.
+            for (int i = 0; i < 44100; ++i) {
+                s.crankshaft.omega = rpm * 2 * pi / 60;
+                s.process();
+                if (i == 22049) initial_firings = s.cylinder.combustion_count();
+                if (i >= 22050) {
+                    torque += s.crankshaft.average_torque / 22050;
+                    power += s.crankshaft.average_power / (22050 * 1000.f);
+                }
+            }
+            unsigned long long repairs = 0;
+            for (const auto& pipe : s.pipes) repairs += pipe.positivity_repairs;
+            const double wall = std::chrono::duration<double>(std::chrono::steady_clock::now()-start).count();
+            std::cout << (exhaust == TwoStrokeExhaust::Racing ? "racing" : "straight") << ',' << rpm
+                      << ',' << power << ',' << torque << ','
+                      << (s.cylinder.combustion_count()-initial_firings) / (rpm / 120)
+                      << ',' << repairs << ',' << wall << std::endl;
+        }
+    }
+}