Adding some logic for MMC1 mapper

CMakeLists.txt

@@ -28,7 +28,9 @@ add_executable(nes
         examples/sdl/SdlKeyboardController.cpp
         examples/sdl/SdlKeyboardController.h src/Dma.cpp src/Dma.h
         src/Oam.cpp
-        src/Oam.h)
+        src/Oam.h
+        src/Mapper/Mapper1.cpp
+        src/Mapper/Mapper1.h)
 
 find_package(SDL2 CONFIG REQUIRED)
 find_package(fmt REQUIRED)

examples/sdl/main.cpp

@@ -11,7 +11,7 @@ int main() {
 
     nes::System device;
     nes::SdlWindow window(nes::Ppu::SCREEN_WIDTH, nes::Ppu::SCREEN_HEIGHT);
-    window.setSize(nes::Ppu::SCREEN_WIDTH * 4, nes::Ppu::SCREEN_HEIGHT * 4);
+    window.setSize(nes::Ppu::SCREEN_WIDTH, nes::Ppu::SCREEN_HEIGHT);
 
     SDL_Event e;
     bool frameRendered = false;
@@ -22,7 +22,7 @@ int main() {
     });
     device.connect(std::make_shared<SdlKeyboardController>());
     //device.insertCartridge("/home/selim/Downloads/dk.nes");
-    device.insertCartridge("/Users/selim/Documents/ff.nes");
+    device.insertCartridge("/Users/selim/Documents/smb.nes");
     //device.insertCartridge("C:\\Users\\selim\\Documents\\nestest.nes");
 
     auto frameStart = std::chrono::steady_clock::now();

src/Cartridge.cpp

@@ -3,9 +3,12 @@
 //
 
 #include "Cartridge.h"
+#include "Mapper/Mapper0.h"
+#include "Mapper/Mapper1.h"
 #include <fstream>
 #include <iostream>
 #include <memory>
+#include <cstddef>
 
 namespace nes {
 
@@ -21,13 +24,28 @@ namespace nes {
         // when it become available
         _header = reinterpret_cast<RomHeader*>(_romData.get());
 
+        if (memcmp(_header->magic, ROM_MAGIC, sizeof(ROM_MAGIC)) != 0) {
+            throw std::runtime_error("Wrong ROM magic");
+        }
+
         const size_t prgSize = _header->prgChunks*PRG_CHUNK_SIZE;
         const size_t chrSize = _header->chrChunks*CHR_CHUNK_SIZE;
 
-        _prgRom = std::span<uint8_t>(_romData.get() + sizeof(RomHeader), prgSize);
+        _prgRom = std::span(_romData.get() + sizeof(RomHeader), prgSize);
-        _chrRom = std::span<uint8_t>(_romData.get() + sizeof(RomHeader) + prgSize, chrSize);
+        _chrRom = std::span(_romData.get() + sizeof(RomHeader) + prgSize, chrSize);
 
-        _mapper = std::make_unique<Mapper0>(_header->prgChunks, _header->chrChunks);
+        switch (_header->flags.mapper) {
+            case 0:
+                _mapper = std::make_unique<Mapper0>(_header->prgChunks, _header->chrChunks);
+            case 1:
+                _mapper = std::make_unique<Mapper1>(_header->prgChunks, _header->chrChunks);
+            default:
+                _mapper = std::make_unique<Mapper0>(_header->prgChunks, _header->chrChunks);
+        }
+
+        if (const auto ramSize = _mapper->ramSize(); ramSize > 0) {
+            _ram = std::make_unique<uint8_t[]>(ramSize);
+        }
     }
 
     uint8_t Cartridge::readPrg(uint16_t address) {
@@ -40,6 +58,11 @@ namespace nes {
         return _chrRom[mappedAddress];
     }
 
+    uint8_t Cartridge::readRam(uint16_t address) {
+        uint32_t mappedAddress = _mapper->mapRam(address);
+        return _ram[mappedAddress];
+    }
+
     Cartridge::Mirroring Cartridge::mirroring() const {
         return _header->flags.mirroring;
     }

src/Cartridge.h

@@ -5,7 +5,7 @@
 #ifndef NES_CARTRIDGE_H
 #define NES_CARTRIDGE_H
 
-#include "Mapper/Mapper0.h"
+#include "Mapper/Mapper.h"
 
 #include <filesystem>
 #include <memory>
@@ -15,13 +15,13 @@ namespace nes {
 
     namespace fs = std::filesystem;
 
-    constexpr uint32_t ROM_MAGIC = 0x4E45531A;
+    constexpr uint8_t ROM_MAGIC[4] = { 'N', 'E', 'S', 0x1a };
     constexpr size_t PRG_CHUNK_SIZE = 16*1024;
     constexpr size_t CHR_CHUNK_SIZE = 8*1024;
 
     class Cartridge {
     public:
-        enum Mirroring {
+        enum Mirroring: uint8_t {
             Horizontal = 0,
             Vertical = 1
         };
@@ -35,7 +35,7 @@ namespace nes {
         };
 
         struct RomHeader {
-            uint32_t magic;
+            uint8_t magic[4];
             uint8_t prgChunks;
             uint8_t chrChunks;
             Flags flags;
@@ -48,6 +48,7 @@ namespace nes {
     public:
         uint8_t readPrg(uint16_t address);
         uint8_t readChr(uint16_t address);
+        uint8_t readRam(uint16_t address);
         Mirroring mirroring() const;
 
     private:
@@ -56,6 +57,7 @@ namespace nes {
         RomHeader* _header;
         std::span<uint8_t> _prgRom;
         std::span<uint8_t> _chrRom;
+        std::unique_ptr<uint8_t[]> _ram;
     };
 
 }

src/Mapper/Mapper.h

@@ -6,6 +6,7 @@
 #define NES_MAPPER_H
 
 #include <cstdint>
+#include <cstddef>
 
 namespace nes {
 
@@ -17,6 +18,8 @@ namespace nes {
     public:
         virtual uint32_t mapPrg(uint16_t address) = 0;
         virtual uint32_t mapChr(uint16_t address) = 0;
+        virtual uint32_t mapRam(uint16_t address) = 0;
+        virtual size_t ramSize() = 0;
 
     protected:
         uint8_t _prgBanks;

src/Mapper/Mapper0.cpp

@@ -13,4 +13,12 @@ namespace nes {
     uint32_t Mapper0::mapChr(uint16_t address) {
         return address;
     }
-}
+
+    uint32_t Mapper0::mapRam(uint16_t address) {
+        return address;
+    }
+
+    size_t Mapper0::ramSize() {
+        return 0;
+    }
+}

src/Mapper/Mapper0.h

@@ -17,6 +17,8 @@ namespace nes {
     public:
         uint32_t mapPrg(uint16_t address) override;
         uint32_t mapChr(uint16_t address) override;
+        uint32_t mapRam(uint16_t address) override;
+        size_t ramSize() override;
     };
 
 }

src/Mapper/Mapper1.cpp

@@ -0,0 +1,31 @@
+//
+// Created by Selim Mustafaev on 27.06.2025.
+//
+
+#include "Mapper1.h"
+
+namespace nes {
+
+    uint32_t Mapper1::mapPrg(uint16_t address) {
+
+        if(_controlReg.prgBankMode == FixFirst16 || _controlReg.prgBankMode == FixLast16) {
+
+        } else {
+
+        }
+
+        return address;
+    }
+
+    uint32_t Mapper1::mapChr(uint16_t address) {
+        return address;
+    }
+
+    uint32_t Mapper1::mapRam(uint16_t address) {
+        return address & 0x1FFF;
+    }
+
+    size_t Mapper1::ramSize() {
+        return 32*1024;
+    }
+}

src/Mapper/Mapper1.h

@@ -0,0 +1,53 @@
+//
+// Created by Selim Mustafaev on 27.06.2025.
+//
+
+#ifndef MAPPER1_H
+#define MAPPER1_H
+
+#include "Mapper.h"
+
+namespace nes {
+
+    class Mapper1 final : public Mapper {
+    public:
+        enum PrgBankMode: uint8_t {
+            FixFirst32 = 0,
+            FixLast32 = 1,
+            FixFirst16 = 2,
+            FixLast16 = 3,
+        };
+
+        enum ChrBankMode: uint8_t {
+            Single8 = 0,
+            Double4 = 1
+        };
+
+        union ControlRegister {
+            struct {
+                uint8_t reserved: 2;
+                PrgBankMode prgBankMode: 2;
+                ChrBankMode chrBankMode: 1;
+            };
+            uint8_t value;
+        };
+
+    public:
+        using Mapper::Mapper;
+        ~Mapper1() override = default;
+
+    public:
+        uint32_t mapPrg(uint16_t address) override;
+        uint32_t mapChr(uint16_t address) override;
+        uint32_t mapRam(uint16_t address) override;
+        size_t ramSize() override;
+
+    private:
+        ControlRegister _controlReg = {};
+        uint8_t _shiftReg = 0;
+        uint8_t _writes = 0;
+    };
+
+}
+
+#endif //MAPPER1_H

src/System.cpp

@@ -92,6 +92,9 @@ namespace nes {
         else if(address >= 0x2000 && address < 0x4000) {
             return _ppu->read(address & 0x0007);
         }
+        else if (address >= 0x6000 && address < 0x8000) {
+            return _cartridge->readRam(address);
+        }
         else if(address >= 0x8000) {
             return _cartridge->readPrg(address);
         }