add c test program

Author: baggepinnen

examples/juliac/juliac_pid.jl

@@ -46,5 +46,5 @@ end
 
 # compile using something like
 # cd(@__DIR__)
-# run(`julia +nightly --project --experimental /home/fredrikb/repos/julia/contrib/juliac.jl --output-lib juliac_pid --trim=unsafe-warn --compile-ccallable juliac_pid.jl`)
+# run(`/home/fredrikb/repos/julia/julia --project --experimental /home/fredrikb/repos/julia/contrib/juliac.jl --output-lib juliac_pid --experimental --trim=unsafe-warn --compile-ccallable juliac_pid.jl`)
 # run(`ls -ltrh`) # marvel at the smallness of the binary

examples/juliac/test_juliac_pid.c

@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <dlfcn.h>
+#include <julia.h>
+
+// Define the type of the function calculate_control
+typedef double (*calculate_control_t)(double r, double y, double uff);
+
+int main() {
+    jl_init();
+
+    const char *lib_path = "/home/fredrikb/.julia/dev/DiscretePIDs/examples/juliac/juliac_pid.so";
+
+    // Load the shared library
+    printf("Loading juliac_pid.so\n");
+    void *lib_handle = dlopen(lib_path, RTLD_LAZY);
+    if (!lib_handle) {
+        fprintf(stderr, "Error: Unable to load library %s\n", dlerror());
+        exit(EXIT_FAILURE);
+    }
+    printf("Loaded juliac_pid.so\n");
+
+    // Locate the calculate_control function
+    printf("Finding calculate_control!\n");
+    calculate_control_t calculate_control = (calculate_control_t)dlsym(lib_handle, "calculate_control!");
+    char *error = dlerror();
+    if (error != NULL) {
+        fprintf(stderr, "Error: Unable to find symbol calculate_control!: %s\n", error);
+        dlclose(lib_handle);
+        exit(EXIT_FAILURE);
+    }
+    printf("Found calculate_control!\n");
+
+    // Call the function
+    double r = 0.0, y = 0.0, uff = 0.0;
+    double result = calculate_control(r, y, uff);
+    printf("calculate_control! returned: %f\n", result);
+
+    // Close the library
+    dlclose(lib_handle);
+
+    jl_atexit_hook(0);
+    return 0;
+}
+
+
+// export LD_LIBRARY_PATH=/home/fredrikb/repos/julia/usr/lib:$LD_LIBRARY_PATH
+// gcc -o pid_program test_juliac_pid.c -I /home/fredrikb/repos/julia/usr/include/julia -L/home/fredrikb/repos/julia/usr/lib -ljulia -ldl