3DS: Expose late thread flush as "loose sync"

CHANGES

@@ -4,6 +4,7 @@ Features:
  - Custom border support
  - New option to lock the maximum frame size
  - Memory access and information logging
+ - 3DS: Add faster "loose" sync mode, default enabled
  - Scripting: New `input` API for getting raw keyboard/mouse/controller state
  - Scripting: New `storage` API for saving data for a script, e.g. settings
  - Scripting: New `image` and `canvas` APIs for drawing images and displaying on-screen

src/feature/gui/gui-runner.c

@@ -702,6 +702,7 @@ void mGUIRun(struct mGUIRunner* runner, const char* path) {
 		mCoreConfigGetIntValue(&runner->config, "showOSD", &showOSD);
 		mCoreConfigGetIntValue(&runner->config, "mute", &mute);
 		mCoreConfigGetIntValue(&runner->config, "fastForwardMute", &fastForwardMute);
+		runner->core->reloadConfigOption(runner->core, "threadedVideo.flushScanline", &runner->config);
 #ifdef M_CORE_GB
 		if (runner->core->platform(runner->core) == mPLATFORM_GB) {
 			runner->core->reloadConfigOption(runner->core, "gb.pal", &runner->config);

src/platform/3ds/main.c

@@ -273,6 +273,7 @@ static void _resetCamera(struct m3DSImageSource* imageSource) {
 static void _setup(struct mGUIRunner* runner) {
 	if (core2) {
 		mCoreConfigSetDefaultIntValue(&runner->config, "threadedVideo", 1);
+		mCoreConfigSetDefaultIntValue(&runner->config, "threadedVideo.flushScanline", 0);
 		mCoreLoadForeignConfig(runner->core, &runner->config);
 	}
 
@@ -968,6 +969,22 @@ int main(int argc, char* argv[]) {
 			{ .id = 0 }
 		},
 		.configExtra = (struct GUIMenuItem[]) {
+#ifdef M_CORE_GBA
+			{
+				.title = "Sync",
+				.data = GUI_V_S("threadedVideo.flushScanline"),
+				.state = 0,
+				.validStates = (const char*[]) {
+					"Loose (faster, can tear)", "Strict (slower, less input lag)"
+				},
+				.stateMappings = (const struct GUIVariant[]) {
+					GUI_V_I(0),
+					GUI_V_I(-1),
+				},
+				.nStates = 2
+			},
+#endif
+
 			{
 				.title = "Screen mode",
 				.data = GUI_V_S("screenMode"),