adding semhosting

src/main.cpp

@@ -117,7 +117,8 @@ int main(int argc, char* argv[]) {
         // instantiate the simulator
         iss::vm_ptr vm{nullptr};
         iss::cpu_ptr cpu{nullptr};
-        std::function<void(iss::arch_if*, uint32_t, uint32_t)> semihosting_cb = &semihosting_callback<uint32_t>;
+        semihosting_callback<uint32_t> cb{}; 
+        semihosting_cb_t<uint32_t> semihosting_cb = [&cb](iss::arch_if* i, uint32_t* a0, uint32_t* a1) {cb(i,a0,a1);};
         std::string isa_opt(clim["isa"].as<std::string>());
         if(isa_opt.size() == 0 || isa_opt == "?") {
             auto list = f.get_names();