Io: Account for free space on the host device.

Core/HW/MemoryStick.cpp

@@ -15,6 +15,7 @@
 // Official git repository and contact information can be found at
 // https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
 
+#include <algorithm>
 #include "Common/Serialize/Serializer.h"
 #include "Common/Serialize/SerializeFuncs.h"
 #include "Core/CoreTiming.h"
@@ -71,18 +72,20 @@ u64 MemoryStick_SectorSize() {
 }
 
 u64 MemoryStick_FreeSpace() {
+	u64 realFreeSpace = pspFileSystem.FreeSpace("ms0:/");
+
 	// Cap the memory stick size to avoid math errors when old games get sizes that were
-	// hard to imagine back then.
+	// 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;
-	u64 usedSpace = pspFileSystem.getDirSize("ms0:/PSP/SAVEDATA/");// Assume the memory stick is only used to store savedata.
-	u64 freeSpace;
-	if (usedSpace >= memStickSize)
-		freeSpace = 0;
-	else
-		freeSpace = memStickSize - usedSpace;
-
-	return freeSpace;
+	// 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;
+	}
+
+	return std::min(simulatedFreeSpace, realFreeSpace);
 }
 
 void MemoryStick_SetFatState(MemStickFatState state) {