Replace Python numerical kernels with native C execution

native/include/kernels.h

@@ -0,0 +1,37 @@
+#ifndef NATIVE_KERNELS_H
+#define NATIVE_KERNELS_H
+typedef struct { double p, T, rho, u, h; } NativeGas;
+typedef struct {
+    int velocity_index;
+    double lower, upper;
+    double lower_restitution, upper_restitution, lower_threshold, upper_threshold;
+} NativeStop;
+/* Constants are emitted per medium instance by the model compiler. */
+typedef struct { int real_helium; double R, cp, Tref, slope, mu, muT, S; } NativeMedium;
+int native_medium_init(const NativeMedium *, double p, double T, double V, int legacy_ideal_initial, double *mU);
+double native_density(const NativeMedium *, double p, double T);
+double native_temperature_ph(const NativeMedium *, double p, double h);
+double native_viscosity(const NativeMedium *, double T, int diagnostic);
+int native_medium_gas(const NativeMedium *, double m, double U, double V, NativeGas *);
+int native_medium_orifice(const NativeMedium *, double p1, double p2, double h1, double h2,
+                          double cq_area, double opening, double *q, double *cm, double *v);
+double native_pipe_flow(const NativeMedium *, double p1, double p2, double T,
+                        double diameter, double length, double roughness, int kind);
+void native_pipe_diagnostics(const NativeMedium *, double q, double p, double T,
+                             double diameter, double length, double roughness,
+                             int diagnostic, double *result);
+double native_limit_force(double penetration, double velocity, double stiffness,
+                          double damping, double depth, int signed_force);
+int native_gas_init(double p, double T, double volume, double *mU);
+int native_gas(double m, double U, double volume, NativeGas *gas);
+int native_orifice(double p1, double p2, double h1, double h2,
+                   double cq_area, double opening, double *flow,
+                   double *cm, double *velocity);
+double native_contact(double penetration, double velocity, double stiffness,
+                      double damping, double pdis, int signed_force);
+void native_stop_motion(double x, double v, double lower, double upper,
+                        double *acceleration, double *velocity);
+double native_signal(double t, double start, int stages, int cyclic, const double *data);
+double native_signal_break(double t, double end, double start, int stages,
+                           int cyclic, const double *data);
+#endif

native/include/runtime.h

@@ -0,0 +1,34 @@
+#ifndef NATIVE_RUNTIME_H
+#define NATIVE_RUNTIME_H
+#include "model.h"
+#include <stddef.h>
+typedef struct {
+    double start, stop, sample_step, max_step, rtol, timeout;
+    int bdf, record_samples;
+    const char *cancel_path;
+} NativeOptions;
+typedef struct {
+    NativeOptions options;
+    double *times, *states;
+    size_t count, capacity, sample_index;
+    double final_time, final_state[NSTATES];
+    double wall_start, cpu_start, solve_seconds, solve_cpu_seconds, last_progress;
+    double max_accepted_step;
+    unsigned long nfev, accepted, rejected, events, starts, njev, nlu;
+    int status; /* 0 completed, 1 cancelled, 2 failed */
+    const char *message;
+} NativeRun;
+typedef int (*NativeDense)(void *context, double t, double *state);
+double native_wall_time(void);
+double native_cpu_time(void);
+int native_poll(NativeRun *run, double time);
+int native_rhs(NativeRun *run, double t, const double *y, double *dy);
+int native_append(NativeRun *run, double t, const double *y);
+int native_accept(NativeRun *run, double t, double next, const double *old,
+                  const double *trial, NativeDense dense, void *context,
+                  double *accepted_time, double *accepted_state);
+int native_rk45(NativeRun *run);
+int native_bdf(NativeRun *run);
+int native_solve(NativeRun *run);
+void native_run_free(NativeRun *run);
+#endif