SCI: Fix auto-saving in the fan-made Cascade Quest

Script patch to change the fixed slot 999 to fixed slot 99 in the
game scripts and additional code for kSaveGame, that checks for
Cascade Quest + slot 99 and will then use ScummVM slot 0, which
is our auto-save slot.

Fixes bug #7007

Also added the game name to the other fan-made script patch.

2 files changed, 70 insertions, 19 deletions

diff --git a/engines/sci/engine/kfile.cpp b/engines/sci/engine/kfile.cpp
index 335763a35f..d604bb85d0 100644
--- a/engines/sci/engine/kfile.cpp
+++ b/engines/sci/engine/kfile.cpp
@@ -806,25 +806,47 @@ reg_t kSaveGame(EngineState *s, int argc, reg_t *argv) {
 				return NULL_REG;
 		} else if (virtualId < SAVEGAMEID_OFFICIALRANGE_START) {
 			// virtualId is low, we assume that scripts expect us to create new slot
-			if (g_sci->getGameId() == GID_JONES) {
+			switch (g_sci->getGameId()) {
+			case GID_JONES:
 				// Jones has one save slot only
 				savegameId = 0;
-			} else if (virtualId == s->_lastSaveVirtualId) {
-				// if last virtual id is the same as this one, we assume that caller wants to overwrite last save
-				savegameId = s->_lastSaveNewId;
-			} else {
-				uint savegameNr;
-				// savegameId is in lower range, scripts expect us to create a new slot
-				for (savegameId = SAVEGAMESLOT_FIRST; savegameId <= SAVEGAMESLOT_LAST; savegameId++) {
-					for (savegameNr = 0; savegameNr < saves.size(); savegameNr++) {
-						if (savegameId == saves[savegameNr].id)
+				break;
+			case GID_FANMADE: {
+				// Fanmade game, try to identify the game
+				const char *gameName = g_sci->getGameObjectName();
+
+				if (strcmp(gameName, "CascadeQuest") == 0) {
+					// Cascade Quest calls us directly to auto-save and uses slot 99,
+					//  put that save into slot 0 (ScummVM auto-save slot) see bug #7007
+					if (virtualId == (SAVEGAMEID_OFFICIALRANGE_START - 1)) {
+						savegameId = 0;
+					}
+				}
+				break;
+			}
+			default:
+				break;
+			}
+
+			if (savegameId < 0) {
+				// savegameId not set yet
+				if (virtualId == s->_lastSaveVirtualId) {
+					// if last virtual id is the same as this one, we assume that caller wants to overwrite last save
+					savegameId = s->_lastSaveNewId;
+				} else {
+					uint savegameNr;
+					// savegameId is in lower range, scripts expect us to create a new slot
+					for (savegameId = SAVEGAMESLOT_FIRST; savegameId <= SAVEGAMESLOT_LAST; savegameId++) {
+						for (savegameNr = 0; savegameNr < saves.size(); savegameNr++) {
+							if (savegameId == saves[savegameNr].id)
+								break;
+						}
+						if (savegameNr == saves.size()) // Slot not found, seems to be good to go
 							break;
 					}
-					if (savegameNr == saves.size()) // Slot not found, seems to be good to go
-						break;
+					if (savegameId > SAVEGAMESLOT_LAST)
+						error("kSavegame: no more savegame slots available");
 				}
-				if (savegameId > SAVEGAMESLOT_LAST)
-					error("kSavegame: no more savegame slots available");
 			}
 		} else {
 			error("kSaveGame: invalid savegameId used");
diff --git a/engines/sci/engine/script_patches.cpp b/engines/sci/engine/script_patches.cpp
index b1603266d8..9592b212b5 100644
--- a/engines/sci/engine/script_patches.cpp
+++ b/engines/sci/engine/script_patches.cpp
@@ -379,12 +379,40 @@ static const SciScriptPatcherEntry ecoquest2Signatures[] = {
 };
 
 // ===========================================================================
+// Fan-made games
+// Attention: Try to make script patches as specific as possible
+
+// CascadeQuest::autosave in script 994 is called various times to auto-save the game.
+// The script use a fixed slot "999" for this purpose. This doesn't work in ScummVM, because we do not let
+//  scripts save directly into specific slots, but instead use virtual slots / detect scripts wanting to
+//  create a new slot.
+//
+// For this game we patch the code to use slot 99 instead. kSaveGame also checks for Cascade Quest,
+//  will then check, if slot 99 is asked for and will then use the actual slot 0, which is the official
+//  ScummVM auto-save slot.
+//
+// Responsible method: CascadeQuest::autosave
+// Fixes bug: #7007
+static const uint16 fanmadeSignatureCascadeQuestFixAutoSaving[] = {
+	SIG_MAGICDWORD,
+	0x38, SIG_UINT16(0x03e7),        // pushi 3E7 (999d) -> save game slot 999
+	0x74, SIG_UINT16(0x06f8),        // lofss "AutoSave"
+	0x89, 0x1e,                      // lsg global[1E]
+	0x43, 0x2d, 0x08,                // callk SaveGame
+	SIG_END
+};
+
+static const uint16 fanmadePatchCascadeQuestFixAutoSaving[] = {
+	0x38, PATCH_UINT16((SAVEGAMEID_OFFICIALRANGE_START - 1)), // fix slot
+	PATCH_END
+};
+
 // EventHandler::handleEvent in Demo Quest has a bug, and it jumps to the
 // wrong address when an incorrect word is typed, therefore leading to an
 // infinite loop. This script bug was not apparent in SSCI, probably because
 // event handling was slightly different there, so it was never discovered.
 // Fixes bug: #5120
-static const uint16 fanmadeSignatureInfiniteLoop[] = {
+static const uint16 fanmadeSignatureDemoQuestInfiniteLoop[] = {
 	0x38, SIG_UINT16(0x004c),        // pushi 004c
 	0x39, 0x00,                      // pushi 00
 	0x87, 0x01,                      // lap 01
@@ -395,15 +423,16 @@ static const uint16 fanmadeSignatureInfiniteLoop[] = {
 	SIG_END
 };
 
-static const uint16 fanmadePatchInfiniteLoop[] = {
+static const uint16 fanmadePatchDemoQuestInfiniteLoop[] = {
 	PATCH_ADDTOOFFSET(+10),
-	0x30, SIG_UINT16(0x0032),        // bnt 0032  [06a8] --> pushi 004c
+	0x30, PATCH_UINT16(0x0032),      // bnt 0032  [06a8] --> pushi 004c
 	PATCH_END
 };
 
-//          script, description,                                      signature                     patch
+//          script, description,                                      signature                                  patch
 static const SciScriptPatcherEntry fanmadeSignatures[] = {
-	{  true,   999, "infinite loop on typo",                       1, fanmadeSignatureInfiniteLoop, fanmadePatchInfiniteLoop },
+	{  true,   994, "Cascade Quest: fix auto-saving",              1, fanmadeSignatureCascadeQuestFixAutoSaving, fanmadePatchCascadeQuestFixAutoSaving },
+	{  true,   999, "Demo Quest: infinite loop on typo",           1, fanmadeSignatureDemoQuestInfiniteLoop,     fanmadePatchDemoQuestInfiniteLoop },
 	SCI_SIGNATUREENTRY_TERMINATOR
 };