Add turbocharged twin scenario and cross-platform test harness

src/solver.cpp

@@ -4,23 +4,34 @@
 
 namespace fluidsim::port {
 
-Solver::Solver(std::vector<Pipe1D>& pipes, BoundarySystem& boundaries)
+Solver::Solver(std::vector<Pipe1D> &pipes, BoundarySystem &boundaries)
     : pipes_(pipes), boundaries_(boundaries) {}
 
-void Solver::add_component(Component& component) {
-    components_.push_back(&component);
-}
+void Solver::add_component(Component &component) { components_.push_back(&component); }
 
 void Solver::step(float dt) {
-    if (dt <= 0.0f) return;
-    int substeps = std::max(minimum_substeps, 1);
-    for (const auto& pipe : pipes_) substeps = std::max(substeps, pipe.required_substeps(dt, 0.8f));
-    const float sub_dt = dt / static_cast<float>(substeps);
-    for (int i = 0; i < substeps; ++i) {
+    if (!std::isfinite(dt) || dt < 0)
+        throw std::invalid_argument("invalid solver timestep");
+    if (dt == 0)
+        return;
+    boundaries_.validate_topology();
+    const float maximum_dt = dt / static_cast<float>(std::max(minimum_substeps, 1));
+    double remaining = dt;
+    int count = 0;
+    while (remaining > double(dt) * 1e-7) {
+        float sub_dt = std::min(maximum_dt, static_cast<float>(remaining));
+        for (auto &pipe : pipes_)
+            sub_dt = std::min(sub_dt, pipe.prepare_step());
+        if (!(sub_dt > 0) || ++count > 1000000)
+            throw std::runtime_error("solver timestep failed to progress");
+        ++substep_count_;
         boundaries_.resolve(sub_dt);
-        for (auto& pipe : pipes_) pipe.advance(sub_dt);
+        for (auto &pipe : pipes_)
+            pipe.advance(sub_dt);
+        for (Component *component : components_)
+            component->update_state(sub_dt);
+        remaining -= sub_dt;
     }
-    for (Component* component : components_) component->update_state(dt);
     ++step_count_;
 }