Core/ST: Undo savestate load

Implemented in core among with its accompanying part in the view.

core/memory/savestates.h

@@ -78,7 +78,7 @@ namespace Savestates
      * \brief Executes a savestate operation to a path
      * \param path The savestate's path
      * \param job The job to set
-     * \param callback The callback to call when the operation is complete. Can be null.
+     * \param callback The callback to call when the operation is complete.
      * \param ignore_warnings Whether warnings, such as those about ROM compatibility, shouldn't be shown.
      * \warning The operation won't complete immediately. Must be called via AsyncExecutor unless calls are originating from the emu thread.
      */
@@ -88,7 +88,7 @@ namespace Savestates
      * \brief Executes a savestate operation to a slot
      * \param slot The slot to construct the savestate path with.
      * \param job The job to set
-     * \param callback The callback to call when the operation is complete. Can be null.
+     * \param callback The callback to call when the operation is complete.
 	 * \param ignore_warnings Whether warnings, such as those about ROM compatibility, shouldn't be shown.
      * \warning The operation won't complete immediately. Must be called via AsyncExecutor unless calls are originating from the emu thread.
      */
@@ -98,9 +98,15 @@ namespace Savestates
      * Executes a savestate operation in-memory.
      * \param buffer The buffer to use for the operation. Can be empty if the <see cref="job"/> is <see cref="e_st_job::save"/>.
      * \param job The job to set.
-     * \param callback The callback to call when the operation is complete. Can be null.
+     * \param callback The callback to call when the operation is complete.
 	 * \param ignore_warnings Whether warnings, such as those about ROM compatibility, shouldn't be shown.
      * \warning The operation won't complete immediately. Must be called via AsyncExecutor unless calls are originating from the emu thread.
      */
     void do_memory(const std::vector<uint8_t>& buffer, Job job, const t_savestate_callback& callback = nullptr, bool ignore_warnings = false);
+
+    /**
+     * Gets the undo savestate buffer. Will be empty will no undo savestate is available.
+     */
+    std::vector<uint8_t> get_undo_savestate();
+
 }

shared/Config.cpp

@@ -176,6 +176,11 @@ t_config get_default_config()
 		.down_cmd = Action::LoadAs,
 	};
 
+	config.undo_load_state_hotkey = {
+		.identifier = L"Undo load state",
+		.down_cmd = Action::UndoLoadState,
+	};
+
 	config.save_to_slot_1_hotkey = {
 		.identifier = L"Save to slot 1",
 		.down_cmd = Action::SaveSlot1,
@@ -578,6 +583,7 @@ mINI::INIStructure handle_config_ini(bool is_reading, mINI::INIStructure ini)
 	HANDLE_P_VALUE(piano_roll_constrain_edit_to_column)
 	HANDLE_P_VALUE(piano_roll_undo_stack_size)
 	HANDLE_P_VALUE(piano_roll_keep_selection_visible)
+	HANDLE_P_VALUE(st_undo_load)
 	HANDLE_P_VALUE(use_summercart)
 	HANDLE_P_VALUE(wii_vc_emulation)
 	HANDLE_P_VALUE(is_float_exception_propagation_enabled)

shared/Config.hpp

@@ -45,6 +45,7 @@ enum class Action
     LoadSlot,
     SaveAs,
     LoadAs,
+    UndoLoadState,
     SaveSlot1,
     SaveSlot2,
     SaveSlot3,
@@ -168,6 +169,7 @@ typedef struct Config
     t_hotkey load_current_hotkey;
     t_hotkey save_as_hotkey;
     t_hotkey load_as_hotkey;
+    t_hotkey undo_load_state_hotkey;
     t_hotkey save_to_slot_1_hotkey;
     t_hotkey save_to_slot_2_hotkey;
     t_hotkey save_to_slot_3_hotkey;
@@ -488,6 +490,11 @@ typedef struct Config
     /// </summary>
     int32_t piano_roll_keep_selection_visible;
 
+	/// <summary>
+	/// Whether undo savestate load functionality is enabled.
+	/// </summary>
+	int32_t st_undo_load = 1;
+
     /// <summary>
     /// SD card emulation
     /// </summary>

view/gui/FrontendService.cpp

@@ -200,6 +200,9 @@ void FrontendService::set_default_hotkey_keys(t_config* config)
     config->load_as_hotkey.key = 'M';
     config->load_as_hotkey.ctrl = true;
 
+	config->undo_load_state_hotkey.key = 'Z';
+	config->undo_load_state_hotkey.ctrl = true;
+
     config->save_to_slot_1_hotkey.key = '1';
     config->save_to_slot_1_hotkey.shift = true;
 

view/gui/Main.cpp

@@ -135,6 +135,7 @@ const std::map<Action, int> ACTION_ID_MAP = {
     {Action::LoadSlot, IDM_LOAD_SLOT},
     {Action::SaveAs, IDM_SAVE_STATE_AS},
     {Action::LoadAs, IDM_LOAD_STATE_AS},
+    {Action::UndoLoadState, IDM_UNDO_LOAD_STATE},
     {Action::SaveSlot1, (ID_SAVE_1 - 1) + 1},
     {Action::SaveSlot2, (ID_SAVE_1 - 1) + 2},
     {Action::SaveSlot3, (ID_SAVE_1 - 1) + 3},
@@ -1328,6 +1329,7 @@ LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)
             EnableMenuItem(g_main_menu, IDM_LOAD_SLOT, emu_launched ? MF_ENABLED : MF_GRAYED);
             EnableMenuItem(g_main_menu, IDM_SAVE_STATE_AS, emu_launched ? MF_ENABLED : MF_GRAYED);
             EnableMenuItem(g_main_menu, IDM_LOAD_STATE_AS, emu_launched ? MF_ENABLED : MF_GRAYED);
+            EnableMenuItem(g_main_menu, IDM_UNDO_LOAD_STATE, (emu_launched && g_config.st_undo_load) ? MF_ENABLED : MF_GRAYED);
             for (int i = IDM_SELECT_1; i < IDM_SELECT_10; ++i)
             {
                 EnableMenuItem(g_main_menu, i, emu_launched ? MF_ENABLED : MF_GRAYED);
@@ -1771,6 +1773,39 @@ LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)
                     });
                 }
                 break;
+            case IDM_UNDO_LOAD_STATE:
+	            {
+            		++g_vr_wait_before_input_poll;
+            		AsyncExecutor::invoke_async([=]
+					{
+						--g_vr_wait_before_input_poll;
+
+            			auto buf = Savestates::get_undo_savestate();
+
+						if (buf.empty())
+						{
+							Statusbar::post(L"No load to undo");
+							return;
+						}
+
+						Savestates::do_memory(buf, Savestates::Job::Load, [](const CoreResult result, auto)
+						{
+							if (result == CoreResult::Ok)
+							{
+								Statusbar::post(L"Undid load");
+								return;
+							}
+
+							if (result == CoreResult::ST_Cancelled)
+							{
+								return;
+							}
+
+							Statusbar::post(L"Failed to undo load");
+						});
+					});
+	            }
+            	break;
             case IDM_START_MOVIE_RECORDING:
                 {
                     BetterEmulationLock lock;

view/gui/features/ConfigDialog.cpp

@@ -1038,6 +1038,13 @@ void get_config_listview_items(std::vector<t_options_group>& groups, std::vector
                 return emu_launched;
             },
         },
+    	t_options_item{
+    		.group_id = core_group.id,
+			.name = L"Undo Savestate Load",
+			.tooltip = L"Whether undo savestate load functionality is enabled.",
+			.data = &g_config.st_undo_load,
+			.type = t_options_item::Type::Bool,
+		},
         t_options_item{
             .group_id = core_group.id,
             .name = L"Counter Factor",

view/resource.h

@@ -505,6 +505,7 @@
 #define IDC_SEEKER_SUBTEXT              40091
 #define IDC_VERSION_TEXT                40092
 #define IDC_PLUGIN_WARNING              40093
+#define IDM_UNDO_LOAD_STATE             40094
 #define IDC_STATIC                      -1
 
 // Next default values for new objects

view/rsrc.rc

@@ -67,6 +67,7 @@ BEGIN
         MENUITEM "Load State",                  IDM_LOAD_SLOT, GRAYED
         MENUITEM "&Save State As...",           IDM_SAVE_STATE_AS, GRAYED
         MENUITEM "&Load State As...",           IDM_LOAD_STATE_AS, GRAYED
+        MENUITEM "Undo Load State",             IDM_UNDO_LOAD_STATE, GRAYED
         MENUITEM SEPARATOR
         POPUP "Current Save S&tate"
         BEGIN