Fix save/load states in Emscripten build (#2470)

* Fix save/load states in Emscripten build
* Simplified Emscripten integration points
* Moved standalone JS functions to be static member functions of running_machine
* Improved Emscripten main loop
* Use convenience functions for cleaner code

As an added bonus, this now allows for proper shutdown of the running machine when running in the Emscripten environment - previously, attempts to exit the program were just being ignored.

scripts/resources/emscripten/emscripten_post.js

@@ -1,8 +1,8 @@
 // MAME-JavaScript function mappings
 var JSMAME = JSMAME || {};
-JSMAME.get_machine = Module.cwrap('_Z14js_get_machinev', 'number');
+JSMAME.get_machine = Module.cwrap('_ZN15running_machine30emscripten_get_running_machineEv', 'number');
-JSMAME.get_ui = Module.cwrap('_Z9js_get_uiv', 'number');
+JSMAME.get_ui = Module.cwrap('_ZN15running_machine17emscripten_get_uiEv', 'number');
-JSMAME.get_sound = Module.cwrap('_Z12js_get_soundv', 'number');
+JSMAME.get_sound = Module.cwrap('_ZN15running_machine20emscripten_get_soundEv', 'number');
 JSMAME.ui_set_show_fps = Module.cwrap('_ZN15mame_ui_manager12set_show_fpsEb', '', ['number', 'number']);
 JSMAME.ui_get_show_fps = Module.cwrap('_ZNK15mame_ui_manager8show_fpsEv', 'number', ['number']);
 JSMAME.sound_manager_mute = Module.cwrap('_ZN13sound_manager4muteEbh', '', ['number', 'number', 'number']);

scripts/src/main.lua

@@ -157,7 +157,7 @@ end
 				.. " -s TOTAL_MEMORY=268435456"
 				.. " -s DISABLE_EXCEPTION_CATCHING=2"
 				.. " -s EXCEPTION_CATCHING_WHITELIST='[\"__ZN15running_machine17start_all_devicesEv\",\"__ZN12cli_frontend7executeEiPPc\"]'"
-				.. " -s EXPORTED_FUNCTIONS=\"['_main', '_malloc', '__Z14js_get_machinev', '__Z9js_get_uiv', '__Z12js_get_soundv', '__ZN15mame_ui_manager12set_show_fpsEb', '__ZNK15mame_ui_manager8show_fpsEv', '__ZN13sound_manager4muteEbh', '_SDL_PauseAudio', '_SDL_SendKeyboardKey']\""
+				.. " -s EXPORTED_FUNCTIONS=\"['_main', '_malloc', '__ZN15running_machine30emscripten_get_running_machineEv', '__ZN15running_machine17emscripten_get_uiEv', '__ZN15running_machine20emscripten_get_soundEv', '__ZN15mame_ui_manager12set_show_fpsEb', '__ZNK15mame_ui_manager8show_fpsEv', '__ZN13sound_manager4muteEbh', '_SDL_PauseAudio', '_SDL_SendKeyboardKey']\""
 				.. " --pre-js " .. _MAKE.esc(MAME_DIR) .. "src/osd/modules/sound/js_sound.js"
 				.. " --post-js " .. _MAKE.esc(MAME_DIR) .. "scripts/resources/emscripten/emscripten_post.js"
 				.. " --embed-file " .. _MAKE.esc(MAME_DIR) .. "bgfx/chains@bgfx/chains"

src/emu/machine.cpp

@@ -89,8 +89,6 @@
 
 #if defined(EMSCRIPTEN)
 #include <emscripten.h>
-
-void js_set_main_loop(running_machine * machine);
 #endif
 
 
@@ -342,17 +340,18 @@ int running_machine::run(bool quiet)
 
 		export_http_api();
 
-		// run the CPUs until a reset or exit
 		m_hard_reset_pending = false;
+
+#if defined(EMSCRIPTEN)
+		// break out to our async javascript loop and halt
+		emscripten_set_running_machine(this);
+#endif
+
+		// run the CPUs until a reset or exit
 		while ((!m_hard_reset_pending && !m_exit_pending) || m_saveload_schedule != saveload_schedule::NONE)
 		{
 			g_profiler.start(PROFILER_EXTRA);
 
-#if defined(EMSCRIPTEN)
-			// break out to our async javascript loop and halt
-			js_set_main_loop(this);
-#endif
-
 			// execute CPUs if not paused
 			if (!m_paused)
 				m_scheduler.timeslice();
@@ -422,7 +421,6 @@ int running_machine::run(bool quiet)
 	return error;
 }
 
-
 //-------------------------------------------------
 //  schedule_exit - schedule a clean exit
 //-------------------------------------------------
@@ -1316,41 +1314,71 @@ device_memory_interface::space_config_vector dummy_space_device::memory_space_co
 
 #if defined(EMSCRIPTEN)
 
-static running_machine * jsmess_machine;
+running_machine * running_machine::emscripten_running_machine;
 
-void js_main_loop()
+void running_machine::emscripten_main_loop()
 {
-	if (jsmess_machine->paused()) {
+	running_machine *machine = emscripten_running_machine;
-		jsmess_machine->video().frame_update();
+
-		return;
+	g_profiler.start(PROFILER_EXTRA);
+
+	// execute CPUs if not paused
+	if (!machine->m_paused)
+	{
+		device_scheduler * scheduler;
+		scheduler = &(machine->scheduler());
+
+		// Emscripten will call this function at 60Hz, so step the simulation
+		// forward for the amount of time that has passed since the last frame
+		const attotime frametime(0,HZ_TO_ATTOSECONDS(60));
+		const attotime stoptime(scheduler->time() + frametime);
+
+		while (!machine->m_paused && !machine->scheduled_event_pending() && scheduler->time() < stoptime)
+		{
+			scheduler->timeslice();
+			// handle save/load
+			if (machine->m_saveload_schedule != saveload_schedule::NONE)
+			{
+				machine->handle_saveload();
+				break;
+			}
+		}
+	}
+	// otherwise, just pump video updates through
+	else
+		machine->m_video->frame_update();
+
+	// cancel the emscripten loop if the system has been told to exit
+	if (machine->exit_pending())
+	{
+		emscripten_cancel_main_loop();
 	}
 
-	device_scheduler * scheduler;
+	g_profiler.stop();
-	scheduler = &(jsmess_machine->scheduler());
-	attotime stoptime(scheduler->time() + attotime(0,HZ_TO_ATTOSECONDS(60)));
-	while (scheduler->time() < stoptime) {
-		scheduler->timeslice();
-	}
 }
 
-void js_set_main_loop(running_machine * machine) {
+void running_machine::emscripten_set_running_machine(running_machine *machine)
-	jsmess_machine = machine;
+{
+	emscripten_running_machine = machine;
 	EM_ASM (
 		JSMESS.running = true;
 	);
-	emscripten_set_main_loop(&js_main_loop, 0, 1);
+	emscripten_set_main_loop(&(emscripten_main_loop), 0, 1);
 }
 
-running_machine * js_get_machine() {
+running_machine * running_machine::emscripten_get_running_machine()
-	return jsmess_machine;
+{
+	return emscripten_running_machine;
 }
 
-ui_manager * js_get_ui() {
+ui_manager * running_machine::emscripten_get_ui()
-	return &(jsmess_machine->ui());
+{
+	return &(emscripten_running_machine->ui());
 }
 
-sound_manager * js_get_sound() {
+sound_manager * running_machine::emscripten_get_sound()
-	return &(jsmess_machine->sound());
+{
+	return &(emscripten_running_machine->sound());
 }
 
 #endif /* defined(EMSCRIPTEN) */

src/emu/machine.h

@@ -396,6 +396,17 @@ private:
 
 	// configuration state
 	dummy_space_device m_dummy_space;
+
+#if defined(EMSCRIPTEN)
+private:
+	static running_machine *emscripten_running_machine;
+	static void emscripten_main_loop();
+public:
+	static void emscripten_set_running_machine(running_machine *machine);
+	static running_machine * emscripten_get_running_machine();
+	static ui_manager * emscripten_get_ui();
+	static sound_manager * emscripten_get_sound();
+#endif
 };