Add save/load bindings to shoulder buttons

src/sdl_input.c

@@ -68,6 +68,9 @@ static const int sdl_keycodes[nes_controller_num_buttons] = {
     SDLK_RIGHT,
 };
 
+static const int sdl_save_button = SDL_CONTROLLER_BUTTON_LEFTSHOULDER;
+static const int sdl_load_button = SDL_CONTROLLER_BUTTON_RIGHTSHOULDER;
+
 static const int sdl_buttons[nes_controller_num_buttons] = {
     SDL_CONTROLLER_BUTTON_A,
     SDL_CONTROLLER_BUTTON_B,
@@ -138,6 +141,20 @@ static int sdl_input_update(nes_Input_Reader* reader,
                 } else {
                     input->controllers[0].buttons &= ~mask;
                 }
+
+            } else if (sdl_save_button == event.cbutton.button) {
+                if (SDL_CONTROLLERBUTTONDOWN == event.type) {
+                    status = input_Result_Save;
+                } else {
+                    status = input_Result_Cancel;
+                }
+
+            } else if (sdl_load_button == event.cbutton.button) {
+                if (SDL_CONTROLLERBUTTONDOWN == event.type) {
+                    status = input_Result_Load;
+                } else {
+                    status = input_Result_Cancel;
+                }
             }
 
         } else if (SDL_CONTROLLERAXISMOTION == event.type) {