MemoryCard: Use constants for address and offset mask

And sanitize them on state load.

src/core/memory_card.cpp

@@ -77,6 +77,12 @@ bool MemoryCard::DoState(StateWrapper& sw)
   sw.Do(&m_data);
   sw.Do(&m_changed);
 
+  if (sw.IsReading())
+  {
+    m_address &= ADDRESS_MASK;
+    m_sector_offset &= OFFSET_MASK;
+  }
+
   return !sw.HasError();
 }
 
@@ -126,7 +132,7 @@ bool MemoryCard::Transfer(const u8 data_in, u8* data_out)
   {                                                                                                                    \
     *data_out = 0x00;                                                                                                  \
     ack = true;                                                                                                        \
-    m_address = ((m_address & u16(0x00FF)) | (ZeroExtend16(data_in) << 8)) & 0x3FF;                                    \
+    m_address = ((m_address & u16(0x00FF)) | (ZeroExtend16(data_in) << 8)) & ADDRESS_MASK;                             \
     m_state = next_state;                                                                                              \
   }                                                                                                                    \
   break;
@@ -136,7 +142,7 @@ bool MemoryCard::Transfer(const u8 data_in, u8* data_out)
   {                                                                                                                    \
     *data_out = m_last_byte;                                                                                           \
     ack = true;                                                                                                        \
-    m_address = ((m_address & u16(0xFF00)) | ZeroExtend16(data_in)) & 0x3FF;                                           \
+    m_address = ((m_address & u16(0xFF00)) | ZeroExtend16(data_in)) & ADDRESS_MASK;                                    \
     m_sector_offset = 0;                                                                                               \
     m_state = next_state;                                                                                              \
   }                                                                                                                    \

src/core/memory_card.h

@@ -41,11 +41,11 @@ public:
   void Format();
 
 private:
-  enum : u32
+  static constexpr u16 ADDRESS_MASK = 0x3FF;
-  {
+  static constexpr u8 OFFSET_MASK = 0x7F;
-    // save in three seconds, that should be long enough for everything to finish writing
+
-    SAVE_DELAY_IN_SECONDS = 5,
+  // save in three seconds, that should be long enough for everything to finish writing
-  };
+  static constexpr u32 SAVE_DELAY_IN_SECONDS = 5;
 
   union FLAG
   {