Move NDSCart-related global state into objects (#1871)

* Move NDSCart-related global state into objects

- RAII will now do the heavy lifting
- Mark some methods as const or noexcept

* Move GBACart-related global state into objects (#1870)

- RAII will now do the heavy lifting
- Mark some methods as const or noexcept
- Once the `NDS` object is finalized, most of these `assert`s can go away

* Make AREngine::RunCheat public (#1872)

- I use it directly in melonDS DS to apply single cheats without using ARCodeFile
- Before the AREngine refactor I could just redeclare the function in my code
- Now I can't

7 files changed, 329 insertions, 327 deletions

diff --git a/src/ARMJIT_Memory.cpp b/src/ARMJIT_Memory.cpp
index b1673ab..095fb30 100644
--- a/src/ARMJIT_Memory.cpp
+++ b/src/ARMJIT_Memory.cpp
@@ -1248,6 +1248,11 @@ T VRAMRead(u32 addr)
     }
 }
 
+u32 NDSCartSlot_ReadROMData()
+{ // TODO: Add a NDS* parameter, when NDS* is eventually implemented
+    return NDS::NDSCartSlot->ReadROMData();
+}
+
 void* GetFuncForAddr(ARM* cpu, u32 addr, bool store, int size)
 {
     if (cpu->Num == 0)
@@ -1256,7 +1261,7 @@ void* GetFuncForAddr(ARM* cpu, u32 addr, bool store, int size)
         {
         case 0x04000000:
             if (!store && size == 32 && addr == 0x04100010 && NDS::ExMemCnt[0] & (1<<11))
-                return (void*)NDSCart::ReadROMData;
+                return (void*)NDSCartSlot_ReadROMData;
 
             /*
                 unfortunately we can't map GPU2D this way
diff --git a/src/DSi.cpp b/src/DSi.cpp
index 8ea26c5..bf7748e 100644
--- a/src/DSi.cpp
+++ b/src/DSi.cpp
@@ -193,7 +193,7 @@ void Reset()
     SCFG_Clock7 = 0x0187;
     SCFG_EXT[0] = 0x8307F100;
     SCFG_EXT[1] = 0x93FFFB06;
-    SCFG_MC = 0x0010 | (~((u32)(NDSCart::Cart != nullptr))&1);//0x0011;
+    SCFG_MC = 0x0010 | (~((u32)(NDS::NDSCartSlot->GetCart() != nullptr))&1);//0x0011;
     SCFG_RST = 0;
 
     DSP->SetRstLine(false);
@@ -310,13 +310,13 @@ void DecryptModcryptArea(u32 offset, u32 size, u8* iv)
     if ((offset == 0) || (size == 0))
         return;
 
-    const NDSHeader& header = NDSCart::Cart->GetHeader();
+    const NDSHeader& header = NDS::NDSCartSlot->GetCart()->GetHeader();
 
     if ((header.DSiCryptoFlags & (1<<4)) ||
         (header.AppFlags & (1<<7)))
     {
         // dev key
-        const u8* cartrom = NDSCart::Cart->GetROM();
+        const u8* cartrom = NDS::NDSCartSlot->GetCart()->GetROM();
         memcpy(key, &cartrom[0], 16);
     }
     else
@@ -403,9 +403,9 @@ void DecryptModcryptArea(u32 offset, u32 size, u8* iv)
 void SetupDirectBoot()
 {
     bool dsmode = false;
-    NDSHeader& header = NDSCart::Cart->GetHeader();
-    const u8* cartrom = NDSCart::Cart->GetROM();
-    u32 cartid = NDSCart::Cart->ID();
+    NDSHeader& header = NDS::NDSCartSlot->GetCart()->GetHeader();
+    const u8* cartrom = NDS::NDSCartSlot->GetCart()->GetROM();
+    u32 cartid = NDS::NDSCartSlot->GetCart()->ID();
     DSi_TSC* tsc = (DSi_TSC*)NDS::SPI->GetTSC();
 
     // TODO: add controls for forcing DS or DSi mode?
@@ -594,7 +594,7 @@ void SetupDirectBoot()
     if (header.ARM9ROMOffset >= 0x4000 && header.ARM9ROMOffset < 0x8000)
     {
         u8 securearea[0x800];
-        NDSCart::DecryptSecureArea(securearea);
+        NDS::NDSCartSlot->DecryptSecureArea(securearea);
 
         for (u32 i = 0; i < 0x800; i+=4)
         {
@@ -1289,7 +1289,7 @@ void Set_SCFG_MC(u32 val)
 
     if ((oldslotstatus == 0x0) && ((SCFG_MC & 0xC) == 0x4))
     {
-        NDSCart::ResetCart();
+        NDS::NDSCartSlot->ResetCart();
     }
 }
 
diff --git a/src/NDS.cpp b/src/NDS.cpp
index 8eca715..7935929 100644
--- a/src/NDS.cpp
+++ b/src/NDS.cpp
@@ -183,6 +183,7 @@ class SPU* SPU;
 class SPIHost* SPI;
 class RTC* RTC;
 class Wifi* Wifi;
+std::unique_ptr<NDSCart::NDSCartSlot> NDSCartSlot;
 std::unique_ptr<GBACart::GBACartSlot> GBACartSlot;
 class AREngine* AREngine;
 
@@ -227,9 +228,8 @@ bool Init()
     SPI = new class SPIHost();
     RTC = new class RTC();
     Wifi = new class Wifi();
+    NDSCartSlot = std::make_unique<NDSCart::NDSCartSlot>();
     GBACartSlot = std::make_unique<GBACart::GBACartSlot>();
-
-    if (!NDSCart::Init()) return false;
     if (!GPU::Init()) return false;
 
     if (!DSi::Init()) return false;
@@ -259,7 +259,7 @@ void DeInit()
     delete RTC; RTC = nullptr;
     delete Wifi; Wifi = nullptr;
 
-    NDSCart::DeInit();
+    NDSCartSlot = nullptr;
     GBACartSlot = nullptr;
     GPU::DeInit();
 
@@ -405,7 +405,7 @@ bool NeedsDirectBoot()
 
 void SetupDirectBoot(const std::string& romname)
 {
-    const NDSHeader& header = NDSCart::Cart->GetHeader();
+    const NDSHeader& header = NDSCartSlot->GetCart()->GetHeader();
 
     if (ConsoleType == 1)
     {
@@ -413,8 +413,8 @@ void SetupDirectBoot(const std::string& romname)
     }
     else
     {
-        u32 cartid = NDSCart::Cart->ID();
-        const u8* cartrom = NDSCart::Cart->GetROM();
+        u32 cartid = NDSCartSlot->GetCart()->ID();
+        const u8* cartrom = NDSCartSlot->GetCart()->GetROM();
         MapSharedWRAM(3);
 
         // setup main RAM data
@@ -447,7 +447,7 @@ void SetupDirectBoot(const std::string& romname)
         if (header.ARM9ROMOffset >= 0x4000 && header.ARM9ROMOffset < 0x8000)
         {
             u8 securearea[0x800];
-            NDSCart::DecryptSecureArea(securearea);
+            NDSCartSlot->DecryptSecureArea(securearea);
 
             for (u32 i = 0; i < 0x800; i+=4)
             {
@@ -500,7 +500,7 @@ void SetupDirectBoot(const std::string& romname)
         ARM9->CP15Write(0x911, 0x00000020);
     }
 
-    NDSCart::SetupDirectBoot(romname);
+    NDSCartSlot->SetupDirectBoot(romname);
 
     ARM9->R[12] = header.ARM9EntryAddress;
     ARM9->R[13] = 0x03002F7C;
@@ -526,7 +526,7 @@ void SetupDirectBoot(const std::string& romname)
     // checkme
     RCnt = 0x8000;
 
-    NDSCart::SPICnt = 0x8000;
+    NDSCartSlot->SetSPICnt(0x8000);
 
     SPU->SetBias(0x200);
 
@@ -644,7 +644,7 @@ void Reset()
     KeyCnt[1] = 0;
     RCnt = 0;
 
-    NDSCart::Reset();
+    NDSCartSlot->Reset();
     GBACartSlot->Reset();
     GPU::Reset();
     SPU->Reset();
@@ -845,7 +845,7 @@ bool DoSavestate(Savestate* file)
     ARM9->DoSavestate(file);
     ARM7->DoSavestate(file);
 
-    NDSCart::DoSavestate(file);
+    NDSCartSlot->DoSavestate(file);
     if (ConsoleType == 0)
         GBACartSlot->DoSavestate(file);
     GPU::DoSavestate(file);
@@ -885,11 +885,11 @@ void SetConsoleType(int type)
 
 bool LoadCart(const u8* romdata, u32 romlen, const u8* savedata, u32 savelen)
 {
-    if (!NDSCart::LoadROM(romdata, romlen))
+    if (!NDSCartSlot->LoadROM(romdata, romlen))
         return false;
 
     if (savedata && savelen)
-        NDSCart::LoadSave(savedata, savelen);
+        NDSCartSlot->LoadSave(savedata, savelen);
 
     return true;
 }
@@ -897,17 +897,17 @@ bool LoadCart(const u8* romdata, u32 romlen, const u8* savedata, u32 savelen)
 void LoadSave(const u8* savedata, u32 savelen)
 {
     if (savedata && savelen)
-        NDSCart::LoadSave(savedata, savelen);
+        NDSCartSlot->LoadSave(savedata, savelen);
 }
 
 void EjectCart()
 {
-    NDSCart::EjectCart();
+    NDSCartSlot->EjectCart();
 }
 
 bool CartInserted()
 {
-    return NDSCart::Cart != nullptr;
+    return NDSCartSlot->GetCart() != nullptr;
 }
 
 bool LoadGBACart(const u8* romdata, u32 romlen, const u8* savedata, u32 savelen)
@@ -1741,9 +1741,9 @@ void MonitorARM9Jump(u32 addr)
     // checkme: can the entrypoint addr be THUMB?
     // also TODO: make it work in DSi mode
 
-    if ((!RunningGame) && NDSCart::Cart)
+    if ((!RunningGame) && NDSCartSlot->GetCart())
     {
-        const NDSHeader& header = NDSCart::Cart->GetHeader();
+        const NDSHeader& header = NDSCartSlot->GetCart()->GetHeader();
         if (addr == header.ARM9EntryAddress)
         {
             Log(LogLevel::Info, "Game is now booting\n");
@@ -3035,40 +3035,40 @@ u8 ARM9IORead8(u32 addr)
 
     case 0x040001A2:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ReadSPIData();
+            return NDSCartSlot->ReadSPIData();
         return 0;
 
     case 0x040001A8:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[0];
+            return NDSCartSlot->GetROMCommand(0);
         return 0;
     case 0x040001A9:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[1];
+            return NDSCartSlot->GetROMCommand(1);
         return 0;
     case 0x040001AA:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[2];
+            return NDSCartSlot->GetROMCommand(2);
         return 0;
     case 0x040001AB:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[3];
+            return NDSCartSlot->GetROMCommand(3);
         return 0;
     case 0x040001AC:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[4];
+            return NDSCartSlot->GetROMCommand(4);
         return 0;
     case 0x040001AD:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[5];
+            return NDSCartSlot->GetROMCommand(5);
         return 0;
     case 0x040001AE:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[6];
+            return NDSCartSlot->GetROMCommand(6);
         return 0;
     case 0x040001AF:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[7];
+            return NDSCartSlot->GetROMCommand(7);
         return 0;
 
     case 0x04000208: return IME[0];
@@ -3182,32 +3182,32 @@ u16 ARM9IORead16(u32 addr)
 
     case 0x040001A0:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::SPICnt;
+            return NDSCartSlot->GetSPICnt();
         return 0;
     case 0x040001A2:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ReadSPIData();
+            return NDSCartSlot->ReadSPIData();
         return 0;
 
     case 0x040001A8:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[0] |
-                  (NDSCart::ROMCommand[1] << 8);
+            return NDSCartSlot->GetROMCommand(0) |
+                  (NDSCartSlot->GetROMCommand(1) << 8);
         return 0;
     case 0x040001AA:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[2] |
-                  (NDSCart::ROMCommand[3] << 8);
+            return NDSCartSlot->GetROMCommand(2) |
+                  (NDSCartSlot->GetROMCommand(3) << 8);
         return 0;
     case 0x040001AC:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[4] |
-                  (NDSCart::ROMCommand[5] << 8);
+            return NDSCartSlot->GetROMCommand(4) |
+                  (NDSCartSlot->GetROMCommand(5) << 8);
         return 0;
     case 0x040001AE:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[6] |
-                  (NDSCart::ROMCommand[7] << 8);
+            return NDSCartSlot->GetROMCommand(6) |
+                  (NDSCartSlot->GetROMCommand(7) << 8);
         return 0;
 
     case 0x04000204: return ExMemCnt[0];
@@ -3316,26 +3316,26 @@ u32 ARM9IORead32(u32 addr)
 
     case 0x040001A0:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::SPICnt | (NDSCart::ReadSPIData() << 16);
+            return NDSCartSlot->GetSPICnt() | (NDSCartSlot->ReadSPIData() << 16);
         return 0;
     case 0x040001A4:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCnt;
+            return NDSCartSlot->GetROMCnt();
         return 0;
 
     case 0x040001A8:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[0] |
-                  (NDSCart::ROMCommand[1] << 8) |
-                  (NDSCart::ROMCommand[2] << 16) |
-                  (NDSCart::ROMCommand[3] << 24);
+            return NDSCartSlot->GetROMCommand(0) |
+                  (NDSCartSlot->GetROMCommand(1) << 8) |
+                  (NDSCartSlot->GetROMCommand(2) << 16) |
+                  (NDSCartSlot->GetROMCommand(3) << 24);
         return 0;
     case 0x040001AC:
         if (!(ExMemCnt[0] & (1<<11)))
-            return NDSCart::ROMCommand[4] |
-                  (NDSCart::ROMCommand[5] << 8) |
-                  (NDSCart::ROMCommand[6] << 16) |
-                  (NDSCart::ROMCommand[7] << 24);
+            return NDSCartSlot->GetROMCommand(4) |
+                  (NDSCartSlot->GetROMCommand(5) << 8) |
+                  (NDSCartSlot->GetROMCommand(6) << 16) |
+                  (NDSCartSlot->GetROMCommand(7) << 24);
         return 0;
 
     case 0x04000208: return IME[0];
@@ -3386,7 +3386,7 @@ u32 ARM9IORead32(u32 addr)
             return IPCFIFO7.Peek();
 
     case 0x04100010:
-        if (!(ExMemCnt[0] & (1<<11))) return NDSCart::ReadROMData();
+        if (!(ExMemCnt[0] & (1<<11))) return NDSCartSlot->ReadROMData();
         return 0;
 
     case 0x04004000:
@@ -3441,25 +3441,25 @@ void ARM9IOWrite8(u32 addr, u8 val)
 
     case 0x040001A0:
         if (!(ExMemCnt[0] & (1<<11)))
-            NDSCart::WriteSPICnt((NDSCart::SPICnt & 0xFF00) | val);
+            NDSCartSlot->WriteSPICnt((NDSCartSlot->GetSPICnt() & 0xFF00) | val);
         return;
     case 0x040001A1:
         if (!(ExMemCnt[0] & (1<<11)))
-            NDSCart::WriteSPICnt((NDSCart::SPICnt & 0x00FF) | (val << 8));
+            NDSCartSlot->WriteSPICnt((NDSCartSlot->GetSPICnt() & 0x00FF) | (val << 8));
         return;
     case 0x040001A2:
         if (!(ExMemCnt[0] & (1<<11)))
-            NDSCart::WriteSPIData(val);
+            NDSCartSlot->WriteSPIData(val);
         return;
 
-    case 0x040001A8: if (!(ExMemCnt[0] & (1<<11))) NDSCart::ROMCommand[0] = val; return;
-    case 0x040001A9: if (!(ExMemCnt[0] & (1<<11))) NDSCart::ROMCommand[1] = val; return;
-    case 0x040001AA: if (!(ExMemCnt[0] & (1<<11))) NDSCart::ROMCommand[2] = val; return;
-    case 0x040001AB: if (!(ExMemCnt[0] & (1<<11))) NDSCart::ROMCommand[3] = val; return;
-    case 0x040001AC: if (!(ExMemCnt[0] & (1<<11))) NDSCart::ROMCommand[4] = val; return;
-    case 0x040001AD: if (!(ExMemCnt[0] & (1<<11))) NDSCart::ROMCommand[5] = val; return;
-    case 0x040001AE: if (!(ExMemCnt[0] & (1<<11))) NDSCart::ROMCommand[6] = val; return;
-    case 0x040001AF: if (!(ExMemCnt[0] & (1<<11))) NDSCart::ROMCommand[7] = val; return;
+    case 0x040001A8: if (!(ExMemCnt[0] & (1<<11))) NDSCartSlot->SetROMCommand(0, val); return;
+    case 0x040001A9: if (!(ExMemCnt[0] & (1<<11))) NDSCartSlot->SetROMCommand(1, val); return;
+    case 0x040001AA: if (!(ExMemCnt[0] & (1<<11))) NDSCartSlot->SetROMCommand(2, val); return;
+    case 0x040001AB: if (!(ExMemCnt[0] & (1<<11))) NDSCartSlot->SetROMCommand(3, val); return;
+    case 0x040001AC: if (!(ExMemCnt[0] & (1<<11))) NDSCartSlot->SetROMCommand(4, val); return;
+    case 0x040001AD: if (!(ExMemCnt[0] & (1<<11))) NDSCartSlot->SetROMCommand(5, val); return;
+    case 0x040001AE: if (!(ExMemCnt[0] & (1<<11))) NDSCartSlot->SetROMCommand(6, val); return;
+    case 0x040001AF: if (!(ExMemCnt[0] & (1<<11))) NDSCartSlot->SetROMCommand(7, val); return;
 
     case 0x04000208: IME[0] = val & 0x1; UpdateIRQ(0); return;
 
@@ -3574,39 +3574,39 @@ void ARM9IOWrite16(u32 addr, u16 val)
 
     case 0x040001A0:
         if (!(ExMemCnt[0] & (1<<11)))
-            NDSCart::WriteSPICnt(val);
+            NDSCartSlot->WriteSPICnt(val);
         return;
     case 0x040001A2:
         if (!(ExMemCnt[0] & (1<<11)))
-            NDSCart::WriteSPIData(val & 0xFF);
+            NDSCartSlot->WriteSPIData(val & 0xFF);
         return;
 
     case 0x040001A8:
         if (!(ExMemCnt[0] & (1<<11)))
         {
-            NDSCart::ROMCommand[0] = val & 0xFF;
-            NDSCart::ROMCommand[1] = val >> 8;
+            NDSCartSlot->SetROMCommand(0, val & 0xFF);
+            NDSCartSlot->SetROMCommand(1, val >> 8);
         }
         return;
     case 0x040001AA:
         if (!(ExMemCnt[0] & (1<<11)))
         {
-            NDSCart::ROMCommand[2] = val & 0xFF;
-            NDSCart::ROMCommand[3] = val >> 8;
+            NDSCartSlot->SetROMCommand(2, val & 0xFF);
+            NDSCartSlot->SetROMCommand(3, val >> 8);
         }
         return;
     case 0x040001AC:
         if (!(ExMemCnt[0] & (1<<11)))
         {
-            NDSCart::ROMCommand[4] = val & 0xFF;
-            NDSCart::ROMCommand[5] = val >> 8;
+            NDSCartSlot->SetROMCommand(4, val & 0xFF);
+            NDSCartSlot->SetROMCommand(5, val >> 8);
         }
         return;
     case 0x040001AE:
         if (!(ExMemCnt[0] & (1<<11)))
         {
-            NDSCart::ROMCommand[6] = val & 0xFF;
-            NDSCart::ROMCommand[7] = val >> 8;
+            NDSCartSlot->SetROMCommand(6, val & 0xFF);
+            NDSCartSlot->SetROMCommand(7, val >> 8);
         }
         return;
 
@@ -3760,31 +3760,31 @@ void ARM9IOWrite32(u32 addr, u32 val)
     case 0x040001A0:
         if (!(ExMemCnt[0] & (1<<11)))
         {
-            NDSCart::WriteSPICnt(val & 0xFFFF);
-            NDSCart::WriteSPIData((val >> 16) & 0xFF);
+            NDSCartSlot->WriteSPICnt(val & 0xFFFF);
+            NDSCartSlot->WriteSPIData((val >> 16) & 0xFF);
         }
         return;
     case 0x040001A4:
         if (!(ExMemCnt[0] & (1<<11)))
-            NDSCart::WriteROMCnt(val);
+            NDSCartSlot->WriteROMCnt(val);
         return;
 
     case 0x040001A8:
         if (!(ExMemCnt[0] & (1<<11)))
         {
-            NDSCart::ROMCommand[0] = val & 0xFF;
-            NDSCart::ROMCommand[1] = (val >> 8) & 0xFF;
-            NDSCart::ROMCommand[2] = (val >> 16) & 0xFF;
-            NDSCart::ROMCommand[3] = val >> 24;
+            NDSCartSlot->SetROMCommand(0, val & 0xFF);
+            NDSCartSlot->SetROMCommand(1, (val >> 8) & 0xFF);
+            NDSCartSlot->SetROMCommand(2, (val >> 16) & 0xFF);
+            NDSCartSlot->SetROMCommand(3, val >> 24);
         }
         return;
     case 0x040001AC:
         if (!(ExMemCnt[0] & (1<<11)))
         {
-            NDSCart::ROMCommand[4] = val & 0xFF;
-            NDSCart::ROMCommand[5] = (val >> 8) & 0xFF;
-            NDSCart::ROMCommand[6] = (val >> 16) & 0xFF;
-            NDSCart::ROMCommand[7] = val >> 24;
+            NDSCartSlot->SetROMCommand(4, val & 0xFF);
+            NDSCartSlot->SetROMCommand(5, (val >> 8) & 0xFF);
+            NDSCartSlot->SetROMCommand(6, (val >> 16) & 0xFF);
+            NDSCartSlot->SetROMCommand(7, val >> 24);
         }
         return;
 
@@ -3830,7 +3830,7 @@ void ARM9IOWrite32(u32 addr, u32 val)
         return;
 
     case 0x04100010:
-        if (!(ExMemCnt[0] & (1<<11)))  NDSCart::WriteROMData(val);
+        if (!(ExMemCnt[0] & (1<<11)))  NDSCartSlot->WriteROMData(val);
         return;
 
     // NO$GBA debug register "String Out (raw)"
@@ -3899,40 +3899,40 @@ u8 ARM7IORead8(u32 addr)
 
     case 0x040001A2:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ReadSPIData();
+            return NDSCartSlot->ReadSPIData();
         return 0;
 
     case 0x040001A8:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[0];
+            return NDSCartSlot->GetROMCommand(0);
         return 0;
     case 0x040001A9:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[1];
+            return NDSCartSlot->GetROMCommand(1);
         return 0;
     case 0x040001AA:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[2];
+            return NDSCartSlot->GetROMCommand(2);
         return 0;
     case 0x040001AB:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[3];
+            return NDSCartSlot->GetROMCommand(3);
         return 0;
     case 0x040001AC:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[4];
+            return NDSCartSlot->GetROMCommand(4);
         return 0;
     case 0x040001AD:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[5];
+            return NDSCartSlot->GetROMCommand(5);
         return 0;
     case 0x040001AE:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[6];
+            return NDSCartSlot->GetROMCommand(6);
         return 0;
     case 0x040001AF:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[7];
+            return NDSCartSlot->GetROMCommand(7);
         return 0;
 
     case 0x040001C2: return SPI->ReadData();
@@ -3999,28 +3999,28 @@ u16 ARM7IORead16(u32 addr)
             return val;
         }
 
-    case 0x040001A0: if (ExMemCnt[0] & (1<<11)) return NDSCart::SPICnt;        return 0;
-    case 0x040001A2: if (ExMemCnt[0] & (1<<11)) return NDSCart::ReadSPIData(); return 0;
+    case 0x040001A0: if (ExMemCnt[0] & (1<<11)) return NDSCartSlot->GetSPICnt();   return 0;
+    case 0x040001A2: if (ExMemCnt[0] & (1<<11)) return NDSCartSlot->ReadSPIData(); return 0;
 
     case 0x040001A8:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[0] |
-                  (NDSCart::ROMCommand[1] << 8);
+            return NDSCartSlot->GetROMCommand(0) |
+                  (NDSCartSlot->GetROMCommand(1) << 8);
         return 0;
     case 0x040001AA:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[2] |
-                  (NDSCart::ROMCommand[3] << 8);
+            return NDSCartSlot->GetROMCommand(2) |
+                  (NDSCartSlot->GetROMCommand(3) << 8);
         return 0;
     case 0x040001AC:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[4] |
-                  (NDSCart::ROMCommand[5] << 8);
+            return NDSCartSlot->GetROMCommand(4) |
+                  (NDSCartSlot->GetROMCommand(5) << 8);
         return 0;
     case 0x040001AE:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[6] |
-                  (NDSCart::ROMCommand[7] << 8);
+            return NDSCartSlot->GetROMCommand(6) |
+                  (NDSCartSlot->GetROMCommand(7) << 8);
         return 0;
 
     case 0x040001C0: return SPI->ReadCnt();
@@ -4083,26 +4083,26 @@ u32 ARM7IORead32(u32 addr)
 
     case 0x040001A0:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::SPICnt | (NDSCart::ReadSPIData() << 16);
+            return NDSCartSlot->GetSPICnt() | (NDSCartSlot->ReadSPIData() << 16);
         return 0;
     case 0x040001A4:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCnt;
+            return NDSCartSlot->GetROMCnt();
         return 0;
 
     case 0x040001A8:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[0] |
-                  (NDSCart::ROMCommand[1] << 8) |
-                  (NDSCart::ROMCommand[2] << 16) |
-                  (NDSCart::ROMCommand[3] << 24);
+            return NDSCartSlot->GetROMCommand(0) |
+                  (NDSCartSlot->GetROMCommand(1) << 8) |
+                  (NDSCartSlot->GetROMCommand(2) << 16) |
+                  (NDSCartSlot->GetROMCommand(3) << 24);
         return 0;
     case 0x040001AC:
         if (ExMemCnt[0] & (1<<11))
-            return NDSCart::ROMCommand[4] |
-                  (NDSCart::ROMCommand[5] << 8) |
-                  (NDSCart::ROMCommand[6] << 16) |
-                  (NDSCart::ROMCommand[7] << 24);
+            return NDSCartSlot->GetROMCommand(4) |
+                  (NDSCartSlot->GetROMCommand(5) << 8) |
+                  (NDSCartSlot->GetROMCommand(6) << 16) |
+                  (NDSCartSlot->GetROMCommand(7) << 24);
         return 0;
 
     case 0x040001C0:
@@ -4137,7 +4137,7 @@ u32 ARM7IORead32(u32 addr)
             return IPCFIFO9.Peek();
 
     case 0x04100010:
-        if (ExMemCnt[0] & (1<<11)) return NDSCart::ReadROMData();
+        if (ExMemCnt[0] & (1<<11)) return NDSCartSlot->ReadROMData();
         return 0;
     }
 
@@ -4177,26 +4177,26 @@ void ARM7IOWrite8(u32 addr, u8 val)
     case 0x040001A0:
         if (ExMemCnt[0] & (1<<11))
         {
-            NDSCart::WriteSPICnt((NDSCart::SPICnt & 0xFF00) | val);
+            NDSCartSlot->WriteSPICnt((NDSCartSlot->GetSPICnt() & 0xFF00) | val);
         }
         return;
     case 0x040001A1:
         if (ExMemCnt[0] & (1<<11))
-            NDSCart::WriteSPICnt((NDSCart::SPICnt & 0x00FF) | (val << 8));
+            NDSCartSlot->WriteSPICnt((NDSCartSlot->GetSPICnt() & 0x00FF) | (val << 8));
         return;
     case 0x040001A2:
         if (ExMemCnt[0] & (1<<11))
-            NDSCart::WriteSPIData(val);
+            NDSCartSlot->WriteSPIData(val);
         return;
 
-    case 0x040001A8: if (ExMemCnt[0] & (1<<11)) NDSCart::ROMCommand[0] = val; return;
-    case 0x040001A9: if (ExMemCnt[0] & (1<<11)) NDSCart::ROMCommand[1] = val; return;
-    case 0x040001AA: if (ExMemCnt[0] & (1<<11)) NDSCart::ROMCommand[2] = val; return;
-    case 0x040001AB: if (ExMemCnt[0] & (1<<11)) NDSCart::ROMCommand[3] = val; return;
-    case 0x040001AC: if (ExMemCnt[0] & (1<<11)) NDSCart::ROMCommand[4] = val; return;
-    case 0x040001AD: if (ExMemCnt[0] & (1<<11)) NDSCart::ROMCommand[5] = val; return;
-    case 0x040001AE: if (ExMemCnt[0] & (1<<11)) NDSCart::ROMCommand[6] = val; return;
-    case 0x040001AF: if (ExMemCnt[0] & (1<<11)) NDSCart::ROMCommand[7] = val; return;
+    case 0x040001A8: if (ExMemCnt[0] & (1<<11)) NDSCartSlot->SetROMCommand(0, val); return;
+    case 0x040001A9: if (ExMemCnt[0] & (1<<11)) NDSCartSlot->SetROMCommand(1, val); return;
+    case 0x040001AA: if (ExMemCnt[0] & (1<<11)) NDSCartSlot->SetROMCommand(2, val); return;
+    case 0x040001AB: if (ExMemCnt[0] & (1<<11)) NDSCartSlot->SetROMCommand(3, val); return;
+    case 0x040001AC: if (ExMemCnt[0] & (1<<11)) NDSCartSlot->SetROMCommand(4, val); return;
+    case 0x040001AD: if (ExMemCnt[0] & (1<<11)) NDSCartSlot->SetROMCommand(5, val); return;
+    case 0x040001AE: if (ExMemCnt[0] & (1<<11)) NDSCartSlot->SetROMCommand(6, val); return;
+    case 0x040001AF: if (ExMemCnt[0] & (1<<11)) NDSCartSlot->SetROMCommand(7, val); return;
 
     case 0x040001C2:
         SPI->WriteData(val);
@@ -4287,39 +4287,39 @@ void ARM7IOWrite16(u32 addr, u16 val)
 
     case 0x040001A0:
         if (ExMemCnt[0] & (1<<11))
-            NDSCart::WriteSPICnt(val);
+            NDSCartSlot->WriteSPICnt(val);
         return;
     case 0x040001A2:
         if (ExMemCnt[0] & (1<<11))
-            NDSCart::WriteSPIData(val & 0xFF);
+            NDSCartSlot->WriteSPIData(val & 0xFF);
         return;
 
     case 0x040001A8:
         if (ExMemCnt[0] & (1<<11))
         {
-            NDSCart::ROMCommand[0] = val & 0xFF;
-            NDSCart::ROMCommand[1] = val >> 8;
+            NDSCartSlot->SetROMCommand(0, val & 0xFF);
+            NDSCartSlot->SetROMCommand(1, val >> 8);
         }
         return;
     case 0x040001AA:
         if (ExMemCnt[0] & (1<<11))
         {
-            NDSCart::ROMCommand[2] = val & 0xFF;
-            NDSCart::ROMCommand[3] = val >> 8;
+            NDSCartSlot->SetROMCommand(2, val & 0xFF);
+            NDSCartSlot->SetROMCommand(3, val >> 8);
         }
         return;
     case 0x040001AC:
         if (ExMemCnt[0] & (1<<11))
         {
-            NDSCart::ROMCommand[4] = val & 0xFF;
-            NDSCart::ROMCommand[5] = val >> 8;
+            NDSCartSlot->SetROMCommand(4, val & 0xFF);
+            NDSCartSlot->SetROMCommand(5, val >> 8);
         }
         return;
     case 0x040001AE:
         if (ExMemCnt[0] & (1<<11))
         {
-            NDSCart::ROMCommand[6] = val & 0xFF;
-            NDSCart::ROMCommand[7] = val >> 8;
+            NDSCartSlot->SetROMCommand(6, val & 0xFF);
+            NDSCartSlot->SetROMCommand(7, val >> 8);
         }
         return;
 
@@ -4448,31 +4448,31 @@ void ARM7IOWrite32(u32 addr, u32 val)
     case 0x040001A0:
         if (ExMemCnt[0] & (1<<11))
         {
-            NDSCart::WriteSPICnt(val & 0xFFFF);
-            NDSCart::WriteSPIData((val >> 16) & 0xFF);
+            NDSCartSlot->WriteSPICnt(val & 0xFFFF);
+            NDSCartSlot->WriteSPIData((val >> 16) & 0xFF);
         }
         return;
     case 0x040001A4:
         if (ExMemCnt[0] & (1<<11))
-            NDSCart::WriteROMCnt(val);
+            NDSCartSlot->WriteROMCnt(val);
         return;
 
     case 0x040001A8:
         if (ExMemCnt[0] & (1<<11))
         {
-            NDSCart::ROMCommand[0] = val & 0xFF;
-            NDSCart::ROMCommand[1] = (val >> 8) & 0xFF;
-            NDSCart::ROMCommand[2] = (val >> 16) & 0xFF;
-            NDSCart::ROMCommand[3] = val >> 24;
+            NDSCartSlot->SetROMCommand(0, val & 0xFF);
+            NDSCartSlot->SetROMCommand(1, (val >> 8) & 0xFF);
+            NDSCartSlot->SetROMCommand(2, (val >> 16) & 0xFF);
+            NDSCartSlot->SetROMCommand(3, val >> 24);
         }
         return;
     case 0x040001AC:
         if (ExMemCnt[0] & (1<<11))
         {
-            NDSCart::ROMCommand[4] = val & 0xFF;
-            NDSCart::ROMCommand[5] = (val >> 8) & 0xFF;
-            NDSCart::ROMCommand[6] = (val >> 16) & 0xFF;
-            NDSCart::ROMCommand[7] = val >> 24;
+            NDSCartSlot->SetROMCommand(4, val & 0xFF);
+            NDSCartSlot->SetROMCommand(5, (val >> 8) & 0xFF);
+            NDSCartSlot->SetROMCommand(6, (val >> 16) & 0xFF);
+            NDSCartSlot->SetROMCommand(7, val >> 24);
         }
         return;
 
@@ -4504,7 +4504,7 @@ void ARM7IOWrite32(u32 addr, u32 val)
         return;
 
     case 0x04100010:
-        if (ExMemCnt[0] & (1<<11))  NDSCart::WriteROMData(val);
+        if (ExMemCnt[0] & (1<<11))  NDSCartSlot->WriteROMData(val);
         return;
     }
 
diff --git a/src/NDS.h b/src/NDS.h
index 1805437..127510d 100644
--- a/src/NDS.h
+++ b/src/NDS.h
@@ -26,6 +26,7 @@
 #include "Platform.h"
 #include "Savestate.h"
 #include "types.h"
+#include "NDSCart.h"
 #include "GBACart.h"
 
 // when touching the main loop/timing code, pls test a lot of shit
@@ -259,6 +260,7 @@ extern class SPU* SPU;
 extern class SPIHost* SPI;
 extern class RTC* RTC;
 extern class Wifi* Wifi;
+extern std::unique_ptr<NDSCart::NDSCartSlot> NDSCartSlot;
 extern std::unique_ptr<GBACart::GBACartSlot> GBACartSlot;
 extern class AREngine* AREngine;
 
diff --git a/src/NDSCart.cpp b/src/NDSCart.cpp
index 4c6efdd..bf2b791 100644
--- a/src/NDSCart.cpp
+++ b/src/NDSCart.cpp
@@ -41,36 +41,12 @@ enum
 
 // SRAM TODO: emulate write delays???
 
-u16 SPICnt;
-u32 ROMCnt;
-
-u8 SPIData;
-u32 SPIDataPos;
-bool SPIHold;
-
-u8 ROMCommand[8];
-u32 ROMData;
-
-u8 TransferData[0x4000];
-u32 TransferPos;
-u32 TransferLen;
-u32 TransferDir;
-u8 TransferCmd[8];
-
-std::unique_ptr<CartCommon> Cart;
-
-u32 Key1_KeyBuf[0x412];
-
-u64 Key2_X;
-u64 Key2_Y;
-
-
 u32 ByteSwap(u32 val)
 {
     return (val >> 24) | ((val >> 8) & 0xFF00) | ((val << 8) & 0xFF0000) | (val << 24);
 }
 
-void Key1_Encrypt(u32* data)
+void NDSCartSlot::Key1_Encrypt(u32* data) noexcept
 {
     u32 y = data[0];
     u32 x = data[1];
@@ -91,7 +67,7 @@ void Key1_Encrypt(u32* data)
     data[1] = y ^ Key1_KeyBuf[0x11];
 }
 
-void Key1_Decrypt(u32* data)
+void NDSCartSlot::Key1_Decrypt(u32* data) noexcept
 {
     u32 y = data[0];
     u32 x = data[1];
@@ -112,7 +88,7 @@ void Key1_Decrypt(u32* data)
     data[1] = y ^ Key1_KeyBuf[0x0];
 }
 
-void Key1_ApplyKeycode(u32* keycode, u32 mod)
+void NDSCartSlot::Key1_ApplyKeycode(u32* keycode, u32 mod) noexcept
 {
     Key1_Encrypt(&keycode[1]);
     Key1_Encrypt(&keycode[0]);
@@ -131,7 +107,7 @@ void Key1_ApplyKeycode(u32* keycode, u32 mod)
     }
 }
 
-void Key1_LoadKeyBuf(bool dsi, bool externalBios, u8 *bios, u32 biosLength)
+void NDSCartSlot::Key1_LoadKeyBuf(bool dsi, bool externalBios, u8 *bios, u32 biosLength) noexcept
 {
     if (externalBios)
     {
@@ -146,19 +122,19 @@ void Key1_LoadKeyBuf(bool dsi, bool externalBios, u8 *bios, u32 biosLength)
         }
         else
         {
-            memcpy(Key1_KeyBuf, bios + (dsi ? 0xC6D0 : 0x0030), 0x1048);
+            memcpy(Key1_KeyBuf.data(), bios + (dsi ? 0xC6D0 : 0x0030), sizeof(Key1_KeyBuf));
             Platform::Log(LogLevel::Debug, "NDSCart: Initialized Key1_KeyBuf from memory\n");
         }
     }
     else
     {
         // well
-        memset(Key1_KeyBuf, 0, 0x1048);
+        memset(Key1_KeyBuf.data(), 0, sizeof(Key1_KeyBuf));
         Platform::Log(LogLevel::Debug, "NDSCart: Initialized Key1_KeyBuf to zero\n");
     }
 }
 
-void Key1_InitKeycode(bool dsi, u32 idcode, u32 level, u32 mod, u8 *bios, u32 biosLength)
+void NDSCartSlot::Key1_InitKeycode(bool dsi, u32 idcode, u32 level, u32 mod, u8 *bios, u32 biosLength) noexcept
 {
     Key1_LoadKeyBuf(dsi, Platform::GetConfigBool(Platform::ExternalBIOSEnable), bios, biosLength);
 
@@ -174,7 +150,7 @@ void Key1_InitKeycode(bool dsi, u32 idcode, u32 level, u32 mod, u8 *bios, u32 bi
 }
 
 
-void Key2_Encrypt(u8* data, u32 len)
+void NDSCartSlot::Key2_Encrypt(u8* data, u32 len) noexcept
 {
     for (u32 i = 0; i < len; i++)
     {
@@ -260,7 +236,7 @@ void CartCommon::LoadSave(const u8* savedata, u32 savelen)
 {
 }
 
-int CartCommon::ROMCommandStart(u8* cmd, u8* data, u32 len)
+int CartCommon::ROMCommandStart(NDSCart::NDSCartSlot& cartslot, u8* cmd, u8* data, u32 len)
 {
     if (CmdEncMode == 0)
     {
@@ -289,7 +265,7 @@ int CartCommon::ROMCommandStart(u8* cmd, u8* data, u32 len)
 
         case 0x3C:
             CmdEncMode = 1;
-            Key1_InitKeycode(false, *(u32*)&ROM[0xC], 2, 2, NDS::ARM7BIOS, sizeof(NDS::ARM7BIOS));
+            cartslot.Key1_InitKeycode(false, *(u32*)&ROM[0xC], 2, 2, NDS::ARM7BIOS, sizeof(NDS::ARM7BIOS));
             DSiMode = false;
             return 0;
 
@@ -297,7 +273,7 @@ int CartCommon::ROMCommandStart(u8* cmd, u8* data, u32 len)
             if (IsDSi)
             {
                 CmdEncMode = 1;
-                Key1_InitKeycode(true, *(u32*)&ROM[0xC], 1, 2, DSi::ARM7iBIOS, sizeof(DSi::ARM7iBIOS));
+                cartslot.Key1_InitKeycode(true, *(u32*)&ROM[0xC], 1, 2, DSi::ARM7iBIOS, sizeof(DSi::ARM7iBIOS));
                 DSiMode = true;
             }
             return 0;
@@ -314,7 +290,7 @@ int CartCommon::ROMCommandStart(u8* cmd, u8* data, u32 len)
         u8 cmddec[8];
         *(u32*)&cmddec[0] = ByteSwap(*(u32*)&cmd[4]);
         *(u32*)&cmddec[4] = ByteSwap(*(u32*)&cmd[0]);
-        Key1_Decrypt((u32*)cmddec);
+        cartslot.Key1_Decrypt((u32*)cmddec);
         u32 tmp = ByteSwap(*(u32*)&cmddec[4]);
         *(u32*)&cmddec[4] = ByteSwap(*(u32*)&cmddec[0]);
         *(u32*)&cmddec[0] = tmp;
@@ -518,9 +494,9 @@ void CartRetail::LoadSave(const u8* savedata, u32 savelen)
     Platform::WriteNDSSave(savedata, len, 0, len);
 }
 
-int CartRetail::ROMCommandStart(u8* cmd, u8* data, u32 len)
+int CartRetail::ROMCommandStart(NDSCart::NDSCartSlot& cartslot, u8* cmd, u8* data, u32 len)
 {
-    if (CmdEncMode != 2) return CartCommon::ROMCommandStart(cmd, data, len);
+    if (CmdEncMode != 2) return CartCommon::ROMCommandStart(cartslot, cmd, data, len);
 
     switch (cmd[0])
     {
@@ -541,7 +517,7 @@ int CartRetail::ROMCommandStart(u8* cmd, u8* data, u32 len)
         return 0;
 
     default:
-        return CartCommon::ROMCommandStart(cmd, data, len);
+        return CartCommon::ROMCommandStart(cartslot, cmd, data, len);
     }
 }
 
@@ -922,9 +898,9 @@ void CartRetailNAND::LoadSave(const u8* savedata, u32 savelen)
     BuildSRAMID();
 }
 
-int CartRetailNAND::ROMCommandStart(u8* cmd, u8* data, u32 len)
+int CartRetailNAND::ROMCommandStart(NDSCart::NDSCartSlot& cartslot, u8* cmd, u8* data, u32 len)
 {
-    if (CmdEncMode != 2) return CartCommon::ROMCommandStart(cmd, data, len);
+    if (CmdEncMode != 2) return CartCommon::ROMCommandStart(cartslot, cmd, data, len);
 
     switch (cmd[0])
     {
@@ -1054,7 +1030,7 @@ int CartRetailNAND::ROMCommandStart(u8* cmd, u8* data, u32 len)
         return 0;
 
     default:
-        return CartRetail::ROMCommandStart(cmd, data, len);
+        return CartRetail::ROMCommandStart(cartslot, cmd, data, len);
     }
 }
 
@@ -1272,9 +1248,9 @@ void CartHomebrew::DoSavestate(Savestate* file)
     CartCommon::DoSavestate(file);
 }
 
-int CartHomebrew::ROMCommandStart(u8* cmd, u8* data, u32 len)
+int CartHomebrew::ROMCommandStart(NDSCart::NDSCartSlot& cartslot, u8* cmd, u8* data, u32 len)
 {
-    if (CmdEncMode != 2) return CartCommon::ROMCommandStart(cmd, data, len);
+    if (CmdEncMode != 2) return CartCommon::ROMCommandStart(cartslot, cmd, data, len);
 
     switch (cmd[0])
     {
@@ -1305,7 +1281,7 @@ int CartHomebrew::ROMCommandStart(u8* cmd, u8* data, u32 len)
         return 1;
 
     default:
-        return CartCommon::ROMCommandStart(cmd, data, len);
+        return CartCommon::ROMCommandStart(cartslot, cmd, data, len);
     }
 }
 
@@ -1471,32 +1447,29 @@ void CartHomebrew::ReadROM_B7(u32 addr, u32 len, u8* data, u32 offset)
 
 
 
-bool Init()
+NDSCartSlot::NDSCartSlot() noexcept
 {
-    NDS::RegisterEventFunc(NDS::Event_ROMTransfer, ROMTransfer_PrepareData, ROMPrepareData);
-    NDS::RegisterEventFunc(NDS::Event_ROMTransfer, ROMTransfer_End, ROMEndTransfer);
-    NDS::RegisterEventFunc(NDS::Event_ROMSPITransfer, 0, SPITransferDone);
-
-    Cart = nullptr;
-
-    return true;
+    NDS::RegisterEventFunc(NDS::Event_ROMTransfer, ROMTransfer_PrepareData, MemberEventFunc(NDSCartSlot, ROMPrepareData));
+    NDS::RegisterEventFunc(NDS::Event_ROMTransfer, ROMTransfer_End, MemberEventFunc(NDSCartSlot, ROMEndTransfer));
+    NDS::RegisterEventFunc(NDS::Event_ROMSPITransfer, 0, MemberEventFunc(NDSCartSlot, SPITransferDone));
+    // All fields are default-constructed because they're listed as such in the class declaration
 }
 
-void DeInit()
+NDSCartSlot::~NDSCartSlot() noexcept
 {
-    Cart = nullptr;
-
     NDS::UnregisterEventFunc(NDS::Event_ROMTransfer, ROMTransfer_PrepareData);
     NDS::UnregisterEventFunc(NDS::Event_ROMTransfer, ROMTransfer_End);
     NDS::UnregisterEventFunc(NDS::Event_ROMSPITransfer, 0);
+
+    // Cart is cleaned up automatically because it's a unique_ptr
 }
 
-void Reset()
+void NDSCartSlot::Reset() noexcept
 {
     ResetCart();
 }
 
-void DoSavestate(Savestate* file)
+void NDSCartSlot::DoSavestate(Savestate* file) noexcept
 {
     file->Section("NDSC");
 
@@ -1507,14 +1480,14 @@ void DoSavestate(Savestate* file)
     file->Var32(&SPIDataPos);
     file->Bool32(&SPIHold);
 
-    file->VarArray(ROMCommand, 8);
+    file->VarArray(ROMCommand.data(), sizeof(ROMCommand));
     file->Var32(&ROMData);
 
-    file->VarArray(TransferData, 0x4000);
+    file->VarArray(TransferData.data(), sizeof(TransferData));
     file->Var32(&TransferPos);
     file->Var32(&TransferLen);
     file->Var32(&TransferDir);
-    file->VarArray(TransferCmd, 8);
+    file->VarArray(TransferCmd.data(), sizeof(TransferCmd));
 
     // cart inserted/len/ROM/etc should be already populated
     // savestate should be loaded after the right game is loaded
@@ -1589,7 +1562,7 @@ bool ReadROMParams(u32 gamecode, ROMListEntry* params)
 }
 
 
-void DecryptSecureArea(u8* out)
+void NDSCartSlot::DecryptSecureArea(u8* out) noexcept
 {
     const NDSHeader& header = Cart->GetHeader();
     const u8* cartrom = Cart->GetROM();
@@ -1741,7 +1714,7 @@ std::unique_ptr<CartCommon> ParseROM(const u8* romdata, u32 romlen)
     return cart;
 }
 
-bool InsertROM(std::unique_ptr<CartCommon>&& cart)
+bool NDSCartSlot::InsertROM(std::unique_ptr<CartCommon>&& cart) noexcept
 {
     if (!cart) {
         Log(LogLevel::Error, "Failed to insert invalid cart; existing cart (if any) was not ejected.\n");
@@ -1793,36 +1766,26 @@ bool InsertROM(std::unique_ptr<CartCommon>&& cart)
     return true;
 }
 
-bool LoadROM(const u8* romdata, u32 romlen)
+bool NDSCartSlot::LoadROM(const u8* romdata, u32 romlen) noexcept
 {
     std::unique_ptr<CartCommon> cart = ParseROM(romdata, romlen);
 
     return InsertROM(std::move(cart));
 }
 
-void LoadSave(const u8* savedata, u32 savelen)
+void NDSCartSlot::LoadSave(const u8* savedata, u32 savelen) noexcept
 {
     if (Cart)
         Cart->LoadSave(savedata, savelen);
 }
 
-void SetupDirectBoot(const std::string& romname)
+void NDSCartSlot::SetupDirectBoot(const std::string& romname) noexcept
 {
     if (Cart)
         Cart->SetupDirectBoot(romname);
 }
 
-u8* GetSaveMemory()
-{
-    return Cart ? Cart->GetSaveMemory() : nullptr;
-}
-
-u32 GetSaveMemoryLength()
-{
-    return Cart ? Cart->GetSaveMemoryLength() : 0;
-}
-
-void EjectCart()
+void NDSCartSlot::EjectCart() noexcept
 {
     if (!Cart) return;
 
@@ -1837,7 +1800,7 @@ void EjectCart()
     // CHECKME: does an eject imply anything for the ROM/SPI transfer registers?
 }
 
-void ResetCart()
+void NDSCartSlot::ResetCart() noexcept
 {
     // CHECKME: what if there is a transfer in progress?
 
@@ -1848,24 +1811,24 @@ void ResetCart()
     SPIDataPos = 0;
     SPIHold = false;
 
-    memset(ROMCommand, 0, 8);
+    memset(ROMCommand.data(), 0, sizeof(ROMCommand));
     ROMData = 0;
 
     Key2_X = 0;
     Key2_Y = 0;
 
-    memset(TransferData, 0, 0x4000);
+    memset(TransferData.data(), 0, sizeof(TransferData));
     TransferPos = 0;
     TransferLen = 0;
     TransferDir = 0;
-    memset(TransferCmd, 0, 8);
+    memset(TransferCmd.data(), 0, sizeof(TransferCmd));
     TransferCmd[0] = 0xFF;
 
     if (Cart) Cart->Reset();
 }
 
 
-void ROMEndTransfer(u32 param)
+void NDSCartSlot::ROMEndTransfer(u32 param) noexcept
 {
     ROMCnt &= ~(1<<31);
 
@@ -1873,10 +1836,10 @@ void ROMEndTransfer(u32 param)
         NDS::SetIRQ((NDS::ExMemCnt[0]>>11)&0x1, NDS::IRQ_CartXferDone);
 
     if (Cart)
-        Cart->ROMCommandFinish(TransferCmd, TransferData, TransferLen);
+        Cart->ROMCommandFinish(TransferCmd.data(), TransferData.data(), TransferLen);
 }
 
-void ROMPrepareData(u32 param)
+void NDSCartSlot::ROMPrepareData(u32 param) noexcept
 {
     if (TransferDir == 0)
     {
@@ -1896,7 +1859,7 @@ void ROMPrepareData(u32 param)
         NDS::CheckDMAs(0, 0x05);
 }
 
-void WriteROMCnt(u32 val)
+void NDSCartSlot::WriteROMCnt(u32 val) noexcept
 {
     u32 xferstart = (val & ~ROMCnt) & (1<<31);
     ROMCnt = (val & 0xFF7F7FFF) | (ROMCnt & 0x20800000);
@@ -1941,7 +1904,7 @@ void WriteROMCnt(u32 val)
     *(u32*)&TransferCmd[0] = *(u32*)&ROMCommand[0];
     *(u32*)&TransferCmd[4] = *(u32*)&ROMCommand[4];
 
-    memset(TransferData, 0xFF, TransferLen);
+    memset(TransferData.data(), 0xFF, TransferLen);
 
     /*printf("ROM COMMAND %04X %08X %02X%02X%02X%02X%02X%02X%02X%02X SIZE %04X\n",
            SPICnt, ROMCnt,
@@ -1954,7 +1917,7 @@ void WriteROMCnt(u32 val)
     TransferDir = 0;
 
     if (Cart)
-        TransferDir = Cart->ROMCommandStart(TransferCmd, TransferData, TransferLen);
+        TransferDir = Cart->ROMCommandStart(*this, TransferCmd.data(), TransferData.data(), TransferLen);
 
     if ((datasize > 0) && (((ROMCnt >> 30) & 0x1) != TransferDir))
         Log(LogLevel::Debug, "NDSCART: !! BAD TRANSFER DIRECTION FOR CMD %02X, DIR=%d, ROMCNT=%08X\n", ROMCommand[0], TransferDir, ROMCnt);
@@ -1985,7 +1948,7 @@ void WriteROMCnt(u32 val)
         NDS::ScheduleEvent(NDS::Event_ROMTransfer, false, xfercycle*(cmddelay+4), ROMTransfer_PrepareData, 0);
 }
 
-void AdvanceROMTransfer()
+void NDSCartSlot::AdvanceROMTransfer() noexcept
 {
     ROMCnt &= ~(1<<23);
 
@@ -2005,7 +1968,7 @@ void AdvanceROMTransfer()
         ROMEndTransfer(0);
 }
 
-u32 ReadROMData()
+u32 NDSCartSlot::ReadROMData() noexcept
 {
     if (ROMCnt & (1<<30)) return 0;
 
@@ -2017,7 +1980,7 @@ u32 ReadROMData()
     return ROMData;
 }
 
-void WriteROMData(u32 val)
+void NDSCartSlot::WriteROMData(u32 val) noexcept
 {
     if (!(ROMCnt & (1<<30))) return;
 
@@ -2038,7 +2001,7 @@ void WriteROMData(u32 val)
 }
 
 
-void WriteSPICnt(u16 val)
+void NDSCartSlot::WriteSPICnt(u16 val) noexcept
 {
     if ((SPICnt & 0x2040) == 0x2040 && (val & 0x2000) == 0x0000)
     {
@@ -2055,12 +2018,12 @@ void WriteSPICnt(u16 val)
         Log(LogLevel::Debug, "!! CHANGING AUXSPICNT DURING TRANSFER: %04X\n", val);
 }
 
-void SPITransferDone(u32 param)
+void NDSCartSlot::SPITransferDone(u32 param) noexcept
 {
     SPICnt &= ~(1<<7);
 }
 
-u8 ReadSPIData()
+u8 NDSCartSlot::ReadSPIData() const noexcept
 {
     if (!(SPICnt & (1<<15))) return 0;
     if (!(SPICnt & (1<<13))) return 0;
@@ -2069,7 +2032,7 @@ u8 ReadSPIData()
     return SPIData;
 }
 
-void WriteSPIData(u8 val)
+void NDSCartSlot::WriteSPIData(u8 val) noexcept
 {
     if (!(SPICnt & (1<<15))) return;
     if (!(SPICnt & (1<<13))) return;
diff --git a/src/NDSCart.h b/src/NDSCart.h
index 059fd24..1b17251 100644
--- a/src/NDSCart.h
+++ b/src/NDSCart.h
@@ -41,6 +41,8 @@ enum CartType
     Homebrew = 0x201,
 };
 
+class NDSCartSlot;
+
 // CartCommon -- base code shared by all cart types
 class CartCommon
 {
@@ -59,7 +61,7 @@ public:
     virtual void SetupSave(u32 type);
     virtual void LoadSave(const u8* savedata, u32 savelen);
 
-    virtual int ROMCommandStart(u8* cmd, u8* data, u32 len);
+    virtual int ROMCommandStart(NDSCart::NDSCartSlot& cartslot, u8* cmd, u8* data, u32 len);
     virtual void ROMCommandFinish(u8* cmd, u8* data, u32 len);
 
     virtual u8 SPIWrite(u8 val, u32 pos, bool last);
@@ -112,7 +114,7 @@ public:
     virtual void SetupSave(u32 type) override;
     virtual void LoadSave(const u8* savedata, u32 savelen) override;
 
-    virtual int ROMCommandStart(u8* cmd, u8* data, u32 len) override;
+    virtual int ROMCommandStart(NDSCart::NDSCartSlot& cartslot, u8* cmd, u8* data, u32 len) override;
 
     virtual u8 SPIWrite(u8 val, u32 pos, bool last) override;
 
@@ -151,7 +153,7 @@ public:
 
     void LoadSave(const u8* savedata, u32 savelen) override;
 
-    int ROMCommandStart(u8* cmd, u8* data, u32 len) override;
+    int ROMCommandStart(NDSCart::NDSCartSlot& cartslot, u8* cmd, u8* data, u32 len) override;
     void ROMCommandFinish(u8* cmd, u8* data, u32 len) override;
 
     u8 SPIWrite(u8 val, u32 pos, bool last) override;
@@ -216,7 +218,7 @@ public:
 
     void DoSavestate(Savestate* file) override;
 
-    int ROMCommandStart(u8* cmd, u8* data, u32 len) override;
+    int ROMCommandStart(NDSCart::NDSCartSlot& cartslot, u8* cmd, u8* data, u32 len) override;
     void ROMCommandFinish(u8* cmd, u8* data, u32 len) override;
 
 private:
@@ -228,21 +230,110 @@ private:
     bool ReadOnly;
 };
 
-extern u16 SPICnt;
-extern u32 ROMCnt;
-
-extern u8 ROMCommand[8];
-
-/// The currently loaded NDS cart.
-extern std::unique_ptr<CartCommon> Cart;
-
-bool Init();
-void DeInit();
-void Reset();
-
-void DoSavestate(Savestate* file);
-
-void DecryptSecureArea(u8* out);
+class NDSCartSlot
+{
+public:
+    NDSCartSlot() noexcept;
+    ~NDSCartSlot() noexcept;
+    void Reset() noexcept;
+    void ResetCart() noexcept;
+    void DoSavestate(Savestate* file) noexcept;
+    void DecryptSecureArea(u8* out) noexcept;
+
+    /// Loads a Nintendo DS cart object into the cart slot.
+    /// The cart slot takes ownership of the cart object and its underlying resources
+    /// and re-encrypts the ROM's secure area if necessary.
+    /// If a cartridge is already inserted, it is first ejected
+    /// and its state is discarded.
+    /// If the provided cart is not valid,
+    /// then the currently-loaded ROM will not be ejected.
+    ///
+    /// @param cart Movable reference to the cart.
+    /// @returns \c true if the cart was successfully loaded,
+    /// \c false otherwise.
+    /// @post If the cart was successfully loaded,
+    /// then \c cart will be \c nullptr
+    /// and \c Cart will contain the object that \c cart previously pointed to.
+    /// Otherwise, \c cart and \c Cart will be both be unchanged.
+    bool InsertROM(std::unique_ptr<CartCommon>&& cart) noexcept;
+
+    /// Parses a ROM image and loads it into the emulator.
+    /// This function is equivalent to calling ::ParseROM() and ::InsertROM() in sequence.
+    /// @param romdata Pointer to the ROM image.
+    /// The cart emulator maintains its own copy of this data,
+    /// so the caller is free to discard this data after calling this function.
+    /// @param romlen The length of the ROM image, in bytes.
+    /// @returns \c true if the ROM image was successfully loaded,
+    /// \c false if not.
+    bool LoadROM(const u8* romdata, u32 romlen) noexcept;
+    void LoadSave(const u8* savedata, u32 savelen) noexcept;
+    void SetupDirectBoot(const std::string& romname) noexcept;
+
+    /// This function is intended to allow frontends to save and load SRAM
+    /// without using melonDS APIs.
+    /// Modifying the emulated SRAM for any other reason is strongly discouraged.
+    /// The returned pointer may be invalidated if the emulator is reset,
+    /// or when a new game is loaded.
+    /// Consequently, don't store the returned pointer for any longer than necessary.
+    /// @returns Pointer to this cart's SRAM if a cart is loaded and supports SRAM, otherwise \c nullptr.
+    [[nodiscard]] const u8* GetSaveMemory() const noexcept { return Cart ? Cart->GetSaveMemory() : nullptr; }
+    [[nodiscard]] u8* GetSaveMemory() noexcept { return Cart ? Cart->GetSaveMemory() : nullptr; }
+
+    /// @returns The length of the buffer returned by ::GetSaveMemory()
+    /// if a cart is loaded and supports SRAM, otherwise zero.
+    [[nodiscard]] u32 GetSaveMemoryLength() const noexcept { return Cart ? Cart->GetSaveMemoryLength() : 0; }
+    void EjectCart() noexcept;
+    u32 ReadROMData() noexcept;
+    void WriteROMData(u32 val) noexcept;
+    void WriteSPICnt(u16 val) noexcept;
+    void WriteROMCnt(u32 val) noexcept;
+    [[nodiscard]] u8 ReadSPIData() const noexcept;
+    void WriteSPIData(u8 val) noexcept;
+
+    [[nodiscard]] CartCommon* GetCart() noexcept { return Cart.get(); }
+    [[nodiscard]] const CartCommon* GetCart() const noexcept { return Cart.get(); }
+
+    [[nodiscard]] u8 GetROMCommand(u8 index) const noexcept { return ROMCommand[index]; }
+    void SetROMCommand(u8 index, u8 val) noexcept { ROMCommand[index] = val; }
+
+    [[nodiscard]] u32 GetROMCnt() const noexcept { return ROMCnt; }
+    [[nodiscard]] u16 GetSPICnt() const noexcept { return SPICnt; }
+    void SetSPICnt(u16 val) noexcept { SPICnt = val; }
+private:
+    friend class CartCommon;
+    u16 SPICnt {};
+    u32 ROMCnt {};
+    std::array<u8, 8> ROMCommand {};
+    u8 SPIData;
+    u32 SPIDataPos;
+    bool SPIHold;
+
+    u32 ROMData;
+
+    std::array<u8, 0x4000> TransferData;
+    u32 TransferPos;
+    u32 TransferLen;
+    u32 TransferDir;
+    std::array<u8, 8> TransferCmd;
+
+    std::unique_ptr<CartCommon> Cart;
+
+    std::array<u32, 0x412> Key1_KeyBuf;
+
+    u64 Key2_X;
+    u64 Key2_Y;
+
+    void Key1_Encrypt(u32* data) noexcept;
+    void Key1_Decrypt(u32* data) noexcept;
+    void Key1_ApplyKeycode(u32* keycode, u32 mod) noexcept;
+    void Key1_LoadKeyBuf(bool dsi, bool externalBios, u8 *bios, u32 biosLength) noexcept;
+    void Key1_InitKeycode(bool dsi, u32 idcode, u32 level, u32 mod, u8 *bios, u32 biosLength) noexcept;
+    void Key2_Encrypt(u8* data, u32 len) noexcept;
+    void ROMEndTransfer(u32 param) noexcept;
+    void ROMPrepareData(u32 param) noexcept;
+    void AdvanceROMTransfer() noexcept;
+    void SPITransferDone(u32 param) noexcept;
+};
 
 /// Parses the given ROM data and constructs a \c NDSCart::CartCommon subclass
 /// that can be inserted into the emulator or used to extract information about the cart beforehand.
@@ -253,65 +344,6 @@ void DecryptSecureArea(u8* out);
 /// @returns A \c NDSCart::CartCommon object representing the parsed ROM,
 /// or \c nullptr if the ROM data couldn't be parsed.
 std::unique_ptr<CartCommon> ParseROM(const u8* romdata, u32 romlen);
-
-/// Loads a Nintendo DS cart object into the emulator.
-/// The emulator takes ownership of the cart object and its underlying resources
-/// and re-encrypts the ROM's secure area if necessary.
-/// If a cartridge is already inserted, it is first ejected
-/// and its state is discarded.
-/// If the provided cart is not valid,
-/// then the currently-loaded ROM will not be ejected.
-///
-/// @param cart Movable reference to the cart.
-/// @returns \c true if the cart was successfully loaded,
-/// \c false otherwise.
-/// @post If the cart was successfully loaded,
-/// then \c cart will be \c nullptr
-/// and \c Cart will contain the object that \c cart previously pointed to.
-/// Otherwise, \c cart and \c Cart will be both be unchanged.
-bool InsertROM(std::unique_ptr<CartCommon>&& cart);
-
-/// Parses a ROM image and loads it into the emulator.
-/// This function is equivalent to calling ::ParseROM() and ::InsertROM() in sequence.
-/// @param romdata Pointer to the ROM image.
-/// The cart emulator maintains its own copy of this data,
-/// so the caller is free to discard this data after calling this function.
-/// @param romlen The length of the ROM image, in bytes.
-/// @returns \c true if the ROM image was successfully loaded,
-/// \c false if not.
-bool LoadROM(const u8* romdata, u32 romlen);
-void LoadSave(const u8* savedata, u32 savelen);
-void SetupDirectBoot(const std::string& romname);
-
-/// This function is intended to allow frontends to save and load SRAM
-/// without using melonDS APIs.
-/// Modifying the emulated SRAM for any other reason is strongly discouraged.
-/// The returned pointer may be invalidated if the emulator is reset,
-/// or when a new game is loaded.
-/// Consequently, don't store the returned pointer for any longer than necessary.
-/// @returns Pointer to this cart's SRAM if a cart is loaded and supports SRAM, otherwise \c nullptr.
-u8* GetSaveMemory();
-
-/// @returns The length of the buffer returned by ::GetSaveMemory()
-/// if a cart is loaded and supports SRAM, otherwise zero.
-u32 GetSaveMemoryLength();
-
-void EjectCart();
-
-void ResetCart();
-
-void WriteROMCnt(u32 val);
-u32 ReadROMData();
-void WriteROMData(u32 val);
-
-void WriteSPICnt(u16 val);
-u8 ReadSPIData();
-void WriteSPIData(u8 val);
-
-void ROMPrepareData(u32 param);
-void ROMEndTransfer(u32 param);
-void SPITransferDone(u32 param);
-
 }
 
 #endif
diff --git a/src/frontend/qt_sdl/ROMInfoDialog.cpp b/src/frontend/qt_sdl/ROMInfoDialog.cpp
index 2c1acee..b381803 100644
--- a/src/frontend/qt_sdl/ROMInfoDialog.cpp
+++ b/src/frontend/qt_sdl/ROMInfoDialog.cpp
@@ -43,8 +43,8 @@ ROMInfoDialog::ROMInfoDialog(QWidget* parent) : QDialog(parent), ui(new Ui::ROMI
     ui->setupUi(this);

     setAttribute(Qt::WA_DeleteOnClose);

 

-    const NDSBanner* banner = NDSCart::Cart->Banner();

-    const NDSHeader& header = NDSCart::Cart->GetHeader();

+    const NDSBanner* banner = NDS::NDSCartSlot->GetCart()->Banner();

+    const NDSHeader& header = NDS::NDSCartSlot->GetCart()->GetHeader();

     u32 iconData[32 * 32];

     ROMManager::ROMIcon(banner->Icon, banner->Palette, iconData);

     iconImage = QImage(reinterpret_cast<unsigned char*>(iconData), 32, 32, QImage::Format_ARGB32).copy();