Io: Track initial free space for compat flag.

This seems to be necessary for Assassin's Creed.  See hrydgard#12761.

Core/Compatibility.cpp

@@ -72,6 +72,7 @@ void Compatibility::CheckSettings(IniFile &iniFile, const std::string &gameID) {
 	CheckSetting(iniFile, gameID, "ForceSoftwareRenderer", &flags_.ForceSoftwareRenderer);
 	CheckSetting(iniFile, gameID, "DarkStalkersPresentHack", &flags_.DarkStalkersPresentHack);
 	CheckSetting(iniFile, gameID, "ReportSmallMemstick", &flags_.ReportSmallMemstick);
+	CheckSetting(iniFile, gameID, "MemstickFixedFree", &flags_.MemstickFixedFree);
 	CheckSetting(iniFile, gameID, "DateLimited", &flags_.DateLimited);
 }
 

Core/Compatibility.h

@@ -70,6 +70,7 @@ struct CompatFlags {
 	bool ForceSoftwareRenderer;
 	bool DarkStalkersPresentHack;
 	bool ReportSmallMemstick;
+	bool MemstickFixedFree;
 	bool DateLimited;
 };
 

Core/HLE/sceIo.cpp

@@ -621,8 +621,6 @@ static void __IoVblank() {
 }
 
 void __IoInit() {
-	MemoryStick_Init();
-
 	asyncNotifyEvent = CoreTiming::RegisterEvent("IoAsyncNotify", __IoAsyncNotify);
 	syncNotifyEvent = CoreTiming::RegisterEvent("IoSyncNotify", __IoSyncNotify);
 
@@ -663,6 +661,7 @@ void __IoInit() {
 
 	__KernelRegisterWaitTypeFuncs(WAITTYPE_ASYNCIO, __IoAsyncBeginCallback, __IoAsyncEndCallback);
 
+	MemoryStick_Init();
 	lastMemStickState = MemoryStick_State();
 	lastMemStickFatState = MemoryStick_FatState();
 	__DisplayListenVblank(__IoVblank);

Core/HW/MemoryStick.cpp

@@ -29,12 +29,13 @@ static MemStickState memStickState;
 static MemStickFatState memStickFatState;
 static bool memStickNeedsAssign = false;
 static u64 memStickInsertedAt = 0;
+static uint64_t memstickInitialFree = 0;
 
 const u64 normalMemstickSize = 9ULL * 1024 * 1024 * 1024;
 const u64 smallMemstickSize = 1ULL * 1024 * 1024 * 1024;
 
 void MemoryStick_DoState(PointerWrap &p) {
-	auto s = p.Section("MemoryStick", 1, 4);
+	auto s = p.Section("MemoryStick", 1, 5);
 	if (!s)
 		return;
 
@@ -47,6 +48,9 @@ void MemoryStick_DoState(PointerWrap &p) {
 		u64 memStickSize = normalMemstickSize;
 		Do(p, memStickSize);
 	}
+	if (s >= 5) {
+		Do(p, memstickInitialFree);
+	}
 
 	if (s >= 3) {
 		Do(p, memStickNeedsAssign);
@@ -72,18 +76,26 @@ u64 MemoryStick_SectorSize() {
 }
 
 u64 MemoryStick_FreeSpace() {
+	const CompatFlags &flags = PSP_CoreParameter().compat.flags();
 	u64 realFreeSpace = pspFileSystem.FreeSpace("ms0:/");
 
 	// Cap the memory stick size to avoid math errors when old games get sizes that were
 	// not planned for back then (even though 2GB cards were available.)
 	// We have a compat setting to make it even smaller for Harry Potter : Goblet of Fire, see #13266.
-	const u64 memStickSize = PSP_CoreParameter().compat.flags().ReportSmallMemstick ? smallMemstickSize : (u64)g_Config.iMemStickSizeGB * 1024 * 1024 * 1024;
+	const u64 memStickSize = flags.ReportSmallMemstick ? smallMemstickSize : (u64)g_Config.iMemStickSizeGB * 1024 * 1024 * 1024;
 	// Assume the memory stick is only used to store savedata.
 	u64 usedSpace = pspFileSystem.getDirSize("ms0:/PSP/SAVEDATA/");
 	u64 simulatedFreeSpace = 0;
 	if (usedSpace < memStickSize) {
 		simulatedFreeSpace = memStickSize - usedSpace;
 	}
+	if (flags.MemstickFixedFree) {
+		// Assassin's Creed: Bloodlines fails to save if free space changes incorrectly during game.
+		realFreeSpace = 0;
+		if (usedSpace <= memstickInitialFree) {
+			realFreeSpace = memstickInitialFree - usedSpace;
+		}
+	}
 
 	return std::min(simulatedFreeSpace, realFreeSpace);
 }
@@ -119,4 +131,5 @@ void MemoryStick_Init() {
 	}
 
 	memStickNeedsAssign = false;
+	memstickInitialFree = pspFileSystem.FreeSpace("ms0:/") + pspFileSystem.getDirSize("ms0:/PSP/SAVEDATA/");
 }

assets/compat.ini

@@ -784,6 +784,12 @@ ULJM05225 = true
 CPCS01043 = true
 ULUS10062 = true
 
+[MemstickFixedFree]
+ULJM05571 = true
+ULES01367 = true
+NPEH00029 = true
+ULUS10455 = true
+
 [DateLimited]
 # Car Jack Streets - issue #12698
 NPUZ00043 = true