Lua bindings now work(tm)

include/lua.hpp

@@ -2,6 +2,13 @@
 #include "helpers.hpp"
 #include "memory.hpp"
 
+// The kinds of events that can cause a Lua call.
+// Frame: Call program on frame end
+// TODO: Add more
+enum class LuaEvent {
+	Frame,
+};
+
 #ifdef PANDA3DS_ENABLE_LUA
 extern "C" {
 #include <lauxlib.h>
@@ -14,6 +21,9 @@ extern "C" {
 class LuaManager {
 	lua_State* L = nullptr;
 	bool initialized = false;
+	bool haveScript = false;
+
+	void signalEventInternal(LuaEvent e);
 
   public:
 	// For Lua we must have some global pointers to our emulator objects to use them in script code via thunks. See the thunks in lua.cpp as an
@@ -27,6 +37,11 @@ class LuaManager {
 	void initializeThunks();
 	void loadFile(const char* path);
 	void reset();
+	void signalEvent(LuaEvent e) {
+		if (haveScript) [[unlikely]] {
+			signalEventInternal(e);
+		}
+	}
 };
 
 #elif  // Lua not enabled, Lua manager does nothing
@@ -38,5 +53,6 @@ class LuaManager {
 	void initialize() {}
 	void loadFile(const char* path) {}
 	void reset() {}
+	void signalEvent(LuaEvent e) {}
 };
 #endif

src/emulator.cpp

@@ -82,7 +82,6 @@ Emulator::Emulator()
 		}
 	}
 
-	lua.initialize();
 	reset(ReloadOption::NoReload);
 }
 
@@ -414,6 +413,7 @@ void Emulator::runFrame() {
 	if (running) {
 		cpu.runFrame(); // Run 1 frame of instructions
 		gpu.display();  // Display graphics
+		lua.signalEvent(LuaEvent::Frame);
 
 		// Send VBlank interrupts
 		ServiceManager& srv = kernel.getServiceManager();

src/lua.cpp

@@ -14,27 +14,54 @@ void LuaManager::initialize() {
 	initializeThunks();
 
 	initialized = true;
+	haveScript = false;
 }
 
 void LuaManager::close() {
 	if (initialized) {
 		lua_close(L);
 		initialized = false;
+		haveScript = false;
 		L = nullptr;
 	}
 }
 
 void LuaManager::loadFile(const char* path) {
+	// Initialize Lua if it has not been initialized
+	if (!initialized) {
+		initialize();
+	}
+
+	// If init failed, don't execute
+	if (!initialized) {
+		printf("Lua initialization failed, file won't run\n");
+		haveScript = false;
+
+		return;
+	}
+
 	int status = luaL_loadfile(L, path);  // load Lua script
 	int ret = lua_pcall(L, 0, 0, 0);      // tell Lua to run the script
 
 	if (ret != 0) {
+		haveScript = false;
 		fprintf(stderr, "%s\n", lua_tostring(L, -1));  // tell us what mistake we made
+	} else {
+		haveScript = true;
 	}
 }
 
+void LuaManager::signalEventInternal(LuaEvent e) {
+	lua_getglobal(L, "eventHandler"); // We want to call the event handler
+	lua_pushnumber(L, static_cast<int>(e)); // Push event type
+
+	// Call the function with 1 argument and 0 outputs, without an error handler
+	lua_pcall(L, 1, 0, 0);
+}
+
 void LuaManager::reset() {
 	// Reset scripts
+	haveScript = false;
 }
 
 // Initialize C++ thunks for Lua code to call here
@@ -62,15 +89,53 @@ MAKE_MEMORY_FUNCTIONS(32)
 MAKE_MEMORY_FUNCTIONS(64)
 #undef MAKE_MEMORY_FUNCTIONS
 
+// clang-format off
+static constexpr luaL_Reg functions[] = {
+	{ "__read8", read8Thunk },
+	{ "__read16", read16Thunk },
+	{ "__read32", read32Thunk },
+	{ "__read64", read64Thunk },
+	{ "__write8", write8Thunk} ,
+	{ "__write16", write16Thunk },
+	{ "__write32", write32Thunk },
+	{ "__write64", write64Thunk },
+	{ nullptr, nullptr },
+};
+// clang-format on
+
 void LuaManager::initializeThunks() {
-	lua_register(L, "read8", read8Thunk);
-	lua_register(L, "read16", read16Thunk);
-	lua_register(L, "read32", read32Thunk);
-	lua_register(L, "read64", read64Thunk);
-	lua_register(L, "write8", write8Thunk);
-	lua_register(L, "write16", write16Thunk);
-	lua_register(L, "write32", write32Thunk);
-	lua_register(L, "write64", write64Thunk);
+	static const char* runtimeInit = R"(
+	Pand = {
+		read8 = function(addr) return GLOBALS.__read8(addr) end,
+		read16 = function(addr) return GLOBALS.__read16(addr) end,
+		read32 = function(addr) return GLOBALS.__read32(addr) end,
+		read64 = function(addr) return GLOBALS.__read64(addr) end,
+		write8 = function(addr, value) GLOBALS.__write8(addr, value) end,
+		write16 = function(addr, value) GLOBALS.__write16(addr, value) end,
+		write32 = function(addr, value) GLOBALS.__write32(addr, value) end,
+		write64 = function(addr, value) GLOBALS.__write64(addr, value) end,
+		Frame = __Frame,
+	}
+)";
+
+	auto addIntConstant = [&]<typename T>(T x, const char* name) {
+		lua_pushinteger(L, (int)x);
+		lua_setglobal(L, name);
+	};
+
+	luaL_register(L, "GLOBALS", functions);
+	addIntConstant(LuaEvent::Frame, "__Frame");
+
+	// Call our Lua runtime initialization before any Lua script runs
+	luaL_loadstring(L, runtimeInit);
+	int ret = lua_pcall(L, 0, 0, 0);  // tell Lua to run the script
+
+	if (ret != 0) {
+		initialized = false;
+		fprintf(stderr, "%s\n", lua_tostring(L, -1));  // Init should never fail!
+	} else {
+		initialized = true;
+	}
 }
 
 #endif