Adding mapper0 and new CPU instructions

CMakeLists.txt

@@ -3,4 +3,4 @@ project(nes)
 
 set(CMAKE_CXX_STANDARD 23)
 
-add_executable(nes main.cpp src/Rom.cpp src/Rom.h src/Nes.cpp src/Nes.h src/Cpu.cpp src/Cpu.h src/Bus.cpp src/Bus.h)
+add_executable(nes main.cpp src/Cartridge.cpp src/Cartridge.h src/Nes.cpp src/Nes.h src/Cpu.cpp src/Cpu.h src/Bus.cpp src/Bus.h src/Mapper/Mapper.cpp src/Mapper/Mapper.h src/Mapper/Mapper0.cpp src/Mapper/Mapper0.h)

main.cpp

@@ -6,21 +6,23 @@ int main() {
 
     nes::Nes device;
 
-    std::stringstream ss;
+//    std::stringstream ss;
-    ss << "A2 0A 8E 00 00 A2 03 8E 01 00 AC 00 00 A9 00 18 6D 01 00 88 D0 FA 8D 02 00 EA EA EA";
+//    ss << "A2 0A 8E 00 00 A2 03 8E 01 00 AC 00 00 A9 00 18 6D 01 00 88 D0 FA 8D 02 00 EA EA EA";
-    uint16_t nOffset = 0x8000;
+//    uint16_t nOffset = 0x8000;
-    while (!ss.eof())
+//    while (!ss.eof())
-    {
+//    {
-        std::string b;
+//        std::string b;
-        ss >> b;
+//        ss >> b;
-        device.write(nOffset++, (uint8_t)std::stoul(b, nullptr, 16));
+//        device.write(nOffset++, (uint8_t)std::stoul(b, nullptr, 16));
-    }
+//    }
+//
+//    // Set Reset Vector
+//    device.write(0xFFFC, 0x00);
+//    device.write(0xFFFD, 0x80);
+//
+//    device.reset();
 
-    // Set Reset Vector
+    device.runRom("/home/selim/Downloads/nestest.nes", 0xC000);
-    device.write(0xFFFC, 0x00);
-    device.write(0xFFFD, 0x80);
-
-    device.reset();
 
     return 0;
 }

src/Bus.cpp

@@ -3,22 +3,42 @@
 //
 
 #include "Bus.h"
+#include <iostream>
 
 namespace nes {
 
-    Bus::Bus(): _rom{nullptr} {
+    Bus::Bus(): _cartridge{nullptr} {
-        _ram = std::make_unique<uint8_t[]>(64*1024);
+        _ram = std::make_unique<uint8_t[]>(2*1024);
     }
 
     uint8_t Bus::read(uint16_t address) {
-        return _ram[address];
+        if(address < 0x2000) {
+            return _ram[address & 0x07FF];
+        }
+        else if(address >= 0x2000 && address < 0x4000) {
+            std::cout << "PPU read at address: " << address << std::endl;
+            return 0;
+        }
+        else if(address >= 0x8000) {
+            return _cartridge->readPrg(address);
+        }
+
+        return 0;
     }
 
     void Bus::write(uint16_t address, uint8_t value) {
-        _ram[address] = value;
+        if(address < 0x2000) {
+            _ram[address & 0x07FF] = value;
+        }
+        else if(address >= 0x2000 && address < 0x4000) {
+            std::cout << "PPU write at address: " << address << std::endl;
+        }
+        else if(address >= 0x8000) {
+            std::cout << "Cartridge write at address: " << address << std::endl;
+        }
     }
 
-    void Bus::connect(Rom *rom) {
+    void Bus::connect(Cartridge *cartridge) {
-        _rom = rom;
+        _cartridge = cartridge;
     }
 }

src/Bus.h

@@ -5,7 +5,7 @@
 #ifndef NES_BUS_H
 #define NES_BUS_H
 
-#include "Rom.h"
+#include "Cartridge.h"
 
 #include <cstdint>
 #include <memory>
@@ -17,11 +17,11 @@ namespace nes {
         Bus();
         uint8_t read(uint16_t address);
         void write(uint16_t address, uint8_t value);
-        void connect(Rom* rom);
+        void connect(Cartridge* cartridge);
 
     private:
         std::unique_ptr<uint8_t[]> _ram;
-        Rom* _rom;
+        Cartridge* _cartridge;
     };
 
 }

src/Cartridge.cpp

@@ -0,0 +1,43 @@
+//
+// Created by Selim Mustafaev on 09.08.2023.
+//
+
+#include "Cartridge.h"
+#include <fstream>
+#include <iostream>
+#include <memory>
+
+namespace nes {
+
+    Cartridge::Cartridge(const fs::path &path) {
+        auto romSize = fs::file_size(path);
+        _romData = std::make_unique<uint8_t[]>(romSize);
+
+        std::ifstream rom(path);
+        rom.read(reinterpret_cast<char*>(_romData.get()), static_cast<std::streamsize>(romSize));
+
+        // UB here
+        // Should be std::start_lifetime_as<RomHeader>(_romData);
+        // when it become available
+        _header = reinterpret_cast<RomHeader*>(_romData.get());
+
+        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);
+        _chrRom = std::span<uint8_t>(_romData.get() + sizeof(RomHeader) + prgSize, chrSize);
+
+        _mapper = std::make_unique<Mapper0>(_header->prgChunks, _header->chrChunks);
+    }
+
+    uint8_t Cartridge::readPrg(uint16_t address) {
+        uint32_t mappedAddress = _mapper->mapPrg(address);
+        return _prgRom[mappedAddress];
+    }
+
+    uint8_t Cartridge::readChr(uint16_t address) {
+        uint32_t mappedAddress = _mapper->mapChr(address);
+        return _chrRom[mappedAddress];
+    }
+
+}

src/Cartridge.h

@@ -2,8 +2,10 @@
 // Created by Selim Mustafaev on 09.08.2023.
 //
 
-#ifndef NES_ROM_H
+#ifndef NES_CARTRIDGE_H
-#define NES_ROM_H
+#define NES_CARTRIDGE_H
+
+#include "Mapper/Mapper0.h"
 
 #include <filesystem>
 #include <memory>
@@ -24,17 +26,22 @@ namespace nes {
         uint8_t reserved[10];
     };
 
-    class Rom {
+    class Cartridge {
     public:
-        explicit Rom(const fs::path& path);
+        explicit Cartridge(const fs::path& path);
+
+    public:
+        uint8_t readPrg(uint16_t address);
+        uint8_t readChr(uint16_t address);
 
     private:
-        std::unique_ptr<std::byte[]> _romData;
+        std::unique_ptr<uint8_t[]> _romData;
+        std::unique_ptr<Mapper> _mapper;
         RomHeader* _header;
-        std::span<std::byte> _prgRom;
+        std::span<uint8_t> _prgRom;
-        std::span<std::byte> _chrRom;
+        std::span<uint8_t> _chrRom;
     };
 
 }
 
-#endif //NES_ROM_H
+#endif //NES_CARTRIDGE_H

src/Cpu.cpp

@@ -9,16 +9,61 @@ namespace nes {
 
     Cpu::Cpu(Bus* bus): _ticks{}, _bus{bus}, A{}, X{}, Y{}, PC{}, SP{}, flags{} {
         _instructions = std::vector<Instruction>(256);
+        _instructions[0x00] = {"BRK", &Cpu::BRK, &Cpu::IMP, 7, false};
         _instructions[0xA2] = {"LDX", &Cpu::LDX, &Cpu::IMM, 2, false};
+        _instructions[0xAE] = {"LDX", &Cpu::LDX, &Cpu::ABS, 4, false};
+        _instructions[0x86] = {"STX", &Cpu::STX, &Cpu::ZP0, 3, false};
         _instructions[0x8E] = {"STX", &Cpu::STX, &Cpu::ABS, 4, false};
         _instructions[0xAC] = {"LDY", &Cpu::LDY, &Cpu::ABS, 4, false};
+        _instructions[0xA0] = {"LDY", &Cpu::LDY, &Cpu::IMM, 2, false};
         _instructions[0xA9] = {"LDA", &Cpu::LDA, &Cpu::IMM, 2, false};
+        _instructions[0xAD] = {"LDA", &Cpu::LDA, &Cpu::ABS, 4, false};
         _instructions[0x18] = {"CLC", &Cpu::CLC, &Cpu::IMP, 2, false};
         _instructions[0x6D] = {"ADC", &Cpu::ADC, &Cpu::ABS, 4, false};
+        _instructions[0x69] = {"ADC", &Cpu::ADC, &Cpu::IMM, 2, false};
         _instructions[0x88] = {"DEY", &Cpu::DEY, &Cpu::IMP, 2, false};
         _instructions[0xD0] = {"BNE", &Cpu::BNE, &Cpu::REL, 2, false};
         _instructions[0x8D] = {"STA", &Cpu::STA, &Cpu::ABS, 4, false};
         _instructions[0xEA] = {"NOP", &Cpu::NOP, &Cpu::IMP, 2, false};
+        _instructions[0x78] = {"SEI", &Cpu::SEI, &Cpu::IMP, 2, false};
+        _instructions[0xD8] = {"CLD", &Cpu::CLD, &Cpu::IMP, 2, false};
+        _instructions[0x9A] = {"TXS", &Cpu::TXS, &Cpu::IMP, 2, false};
+        _instructions[0x10] = {"BPL", &Cpu::BPL, &Cpu::REL, 2, false};
+        _instructions[0x4C] = {"JMP", &Cpu::JMP, &Cpu::ABS, 3, false};
+        _instructions[0x20] = {"JSR", &Cpu::JSR, &Cpu::ABS, 6, false};
+        _instructions[0x38] = {"SEC", &Cpu::SEC, &Cpu::IMP, 2, false};
+        _instructions[0xB0] = {"BCS", &Cpu::BCS, &Cpu::REL, 2, false};
+        _instructions[0x90] = {"BCC", &Cpu::BCC, &Cpu::REL, 2, false};
+        _instructions[0xF0] = {"BEQ", &Cpu::BEQ, &Cpu::REL, 2, false};
+        _instructions[0x85] = {"STA", &Cpu::STA, &Cpu::ZP0, 3, false};
+        _instructions[0x24] = {"BIT", &Cpu::BIT, &Cpu::ZP0, 3, false};
+        _instructions[0x70] = {"BVS", &Cpu::BVS, &Cpu::REL, 2, false};
+        _instructions[0x50] = {"BVC", &Cpu::BVC, &Cpu::REL, 2, false};
+        _instructions[0x60] = {"RTS", &Cpu::RTS, &Cpu::IMP, 6, false};
+        _instructions[0xF8] = {"SED", &Cpu::SED, &Cpu::IMP, 2, false};
+        _instructions[0x08] = {"PHP", &Cpu::PHP, &Cpu::IMP, 3, false};
+        _instructions[0x68] = {"PLA", &Cpu::PLA, &Cpu::IMP, 4, false};
+        _instructions[0x29] = {"AND", &Cpu::AND, &Cpu::IMM, 2, false};
+        _instructions[0xC9] = {"CMP", &Cpu::CMP, &Cpu::IMM, 2, false};
+        _instructions[0x30] = {"BMI", &Cpu::BMI, &Cpu::REL, 2, false};
+        _instructions[0x48] = {"PHA", &Cpu::PHA, &Cpu::IMP, 3, false};
+        _instructions[0x28] = {"PLP", &Cpu::PLP, &Cpu::IMP, 4, false};
+        _instructions[0x09] = {"ORA", &Cpu::ORA, &Cpu::IMM, 2, false};
+        _instructions[0xB8] = {"CLV", &Cpu::CLV, &Cpu::IMP, 2, false};
+        _instructions[0x49] = {"EOR", &Cpu::EOR, &Cpu::IMM, 2, false};
+        _instructions[0xC0] = {"CPY", &Cpu::CPY, &Cpu::IMM, 2, false};
+        _instructions[0xE0] = {"CPX", &Cpu::CPX, &Cpu::IMM, 2, false};
+        _instructions[0xE9] = {"SBC", &Cpu::SBC, &Cpu::IMM, 2, false};
+        _instructions[0x84] = {"STY", &Cpu::STY, &Cpu::ZP0, 3, false};
+        _instructions[0xC8] = {"INY", &Cpu::INY, &Cpu::IMP, 2, false};
+        _instructions[0xE8] = {"INX", &Cpu::INX, &Cpu::IMP, 2, false};
+        _instructions[0xCA] = {"DEX", &Cpu::DEX, &Cpu::IMP, 2, false};
+        _instructions[0xA8] = {"TAY", &Cpu::TAY, &Cpu::IMP, 2, false};
+        _instructions[0xAA] = {"TAX", &Cpu::TAX, &Cpu::IMP, 2, false};
+        _instructions[0x98] = {"TYA", &Cpu::TYA, &Cpu::IMP, 2, false};
+        _instructions[0x8A] = {"TXA", &Cpu::TXA, &Cpu::IMP, 2, false};
+        _instructions[0xBA] = {"TSX", &Cpu::TSX, &Cpu::IMP, 2, false};
+        _instructions[0x40] = {"RTI", &Cpu::RTI, &Cpu::IMP, 6, false};
     }
 
     void Cpu::reset() {
@@ -40,13 +85,14 @@ namespace nes {
             auto instruction = _instructions[opcode];
 
             if(instruction.getAddress == nullptr) {
+                std::cout << "Unknown instruction: " << (int)opcode << std::endl;
                 return;
             }
 
             auto args = (this->*instruction.getAddress)();
             (this->*instruction.process)(args);
 
-            std::cout << instruction.name << ", A: " << (int)A << ", X: " << (int)X << ", Y: " << (int)Y << std::endl;
+            std::cout << instruction.name << std::hex << ", PC: " << (int)PC << ", A: " << (int)A << ", X: " << (int)X << ", Y: " << (int)Y << std::endl;
 
             _ticks = instruction.cycles;
             if(instruction.variableCycles) {
@@ -69,6 +115,56 @@ namespace nes {
         return flags & flag;
     }
 
+    void Cpu::setStartAddress(uint16_t address) {
+        PC = address;
+    }
+
+    void Cpu::branch(Cpu::InstructionArgs args) {
+        _ticks++;
+
+        uint16_t address = PC + args.address;
+        uint16_t srcPage = PC & 0xFF00;
+        uint16_t dstPage = address & 0xFF00;
+
+        if(srcPage != dstPage) {
+            _ticks++;
+        }
+
+        PC = address;
+    }
+
+    // Addressing modes
+
+    Cpu::InstructionArgs Cpu::IMM() {
+        return {++PC,  0};
+    }
+
+    Cpu::InstructionArgs Cpu::ABS() {
+        uint8_t lo = _bus->read(PC++);
+        uint8_t hi = _bus->read(PC++);
+        uint16_t address = (hi << 8) | lo;
+        return {address, 0};
+    }
+
+    Cpu::InstructionArgs Cpu::IMP() {
+        return {0, 0};
+    }
+
+    Cpu::InstructionArgs Cpu::REL() {
+        uint16_t address = _bus->read(PC++);
+
+        if (address & 0x80) {
+            address |= 0xFF00;
+        }
+
+        return {address, 0};
+    }
+
+    Cpu::InstructionArgs Cpu::ZP0() {
+        uint16_t address = _bus->read(PC++);
+        return {address, 0};
+    }
+
     // CPU instructions
 
     void Cpu::LDA(Cpu::InstructionArgs args) {
@@ -126,55 +222,254 @@ namespace nes {
     }
 
     void Cpu::DEY(Cpu::InstructionArgs args) {
-        Y -= 1;
+        Y--;
         setFlag(Negative, Y & 0x80);
         setFlag(Zero, Y == 0);
     }
 
     void Cpu::BNE(Cpu::InstructionArgs args) {
         if(!getFlag(Zero)) {
-            _ticks++;
+            branch(args);
-
-            uint16_t address = PC + args.address;
-            uint16_t srcPage = PC & 0xFF00;
-            uint16_t dstPage = address & 0xFF00;
-
-            if(srcPage != dstPage) {
-                _ticks++;
-            }
-
-            PC = address;
         }
     }
 
     void Cpu::NOP(Cpu::InstructionArgs args) {
     }
 
-    // Addressing modes
+    void Cpu::SEI(Cpu::InstructionArgs args) {
-
+        setFlag(InterruptDisable, true);
-    Cpu::InstructionArgs Cpu::IMM() {
-        return {PC++,  0};
     }
 
-    Cpu::InstructionArgs Cpu::ABS() {
+    void Cpu::CLD(Cpu::InstructionArgs args) {
-        uint8_t lo = _bus->read(PC++);
+        setFlag(DecimalMode, false);
-        uint8_t hi = _bus->read(PC++);
-        uint16_t address = (hi << 8) | lo;
-        return {address, 0};
     }
 
-    Cpu::InstructionArgs Cpu::IMP() {
+    void Cpu::TXS(Cpu::InstructionArgs args) {
-        return {0, 0};
+        SP = X;
     }
 
-    Cpu::InstructionArgs Cpu::REL() {
+    void Cpu::BPL(Cpu::InstructionArgs args) {
-        uint16_t address = _bus->read(PC++);
+        if(!getFlag(Negative)) {
-
+            branch(args);
-        if (address & 0x80) {
-            address |= 0xFF00;
         }
+    }
 
-        return {address, 0};
+    void Cpu::JMP(Cpu::InstructionArgs args) {
+        PC = args.address;
+    }
+
+    void Cpu::JSR(Cpu::InstructionArgs args) {
+        std::cout << "+++ >>> Jumping from: " << PC << std::endl;
+        PC--;
+        _bus->write(STACK_BASE + SP--, PC >> 8);
+        _bus->write(STACK_BASE + SP--, PC & 0x00FF);
+        PC = args.address;
+    }
+
+    void Cpu::SEC(Cpu::InstructionArgs args) {
+        setFlag(Carry, true);
+    }
+
+    void Cpu::BCS(Cpu::InstructionArgs args) {
+        if(getFlag(Carry)) {
+            branch(args);
+        }
+    }
+
+    void Cpu::BCC(Cpu::InstructionArgs args) {
+        if(!getFlag(Carry)) {
+            branch(args);
+        }
+    }
+
+    void Cpu::BEQ(Cpu::InstructionArgs args) {
+        if(getFlag(Zero)) {
+            branch(args);
+        }
+    }
+
+    void Cpu::BIT(Cpu::InstructionArgs args) {
+        uint8_t value = _bus->read(args.address);
+        setFlag(Zero, (A & value) == 0);
+        setFlag(Negative, value & (1 << 7));
+        setFlag(Overflow, value & (1 << 6));
+    }
+
+    void Cpu::BVS(Cpu::InstructionArgs args) {
+        if(getFlag(Overflow)) {
+            branch(args);
+        }
+    }
+
+    void Cpu::BVC(Cpu::InstructionArgs args) {
+        if(!getFlag(Overflow)) {
+            branch(args);
+        }
+    }
+
+    void Cpu::RTS(Cpu::InstructionArgs args) {
+        uint16_t lo = _bus->read(STACK_BASE + ++SP);
+        uint16_t hi = _bus->read(STACK_BASE + ++SP);
+
+        PC = (hi << 8) | lo;
+        PC++;
+
+        std::cout << "+++ <<< return to: " << PC << std::endl;
+    }
+
+    void Cpu::SED(Cpu::InstructionArgs args) {
+        setFlag(DecimalMode, true);
+    }
+
+    void Cpu::PHP(Cpu::InstructionArgs args) {
+        _bus->write(STACK_BASE + SP--, flags | Break | Unused);
+        setFlag(Break, false);
+        setFlag(Unused, false);
+    }
+
+    void Cpu::PLA(Cpu::InstructionArgs args) {
+        A = _bus->read(STACK_BASE + ++SP);
+        setFlag(Zero, A == 0);
+        setFlag(Negative, A & 0x80);
+    }
+
+    void Cpu::AND(Cpu::InstructionArgs args) {
+        A &= _bus->read(args.address);;
+        setFlag(Zero, A == 0);
+        setFlag(Negative, A & 0x80);
+    }
+
+    void Cpu::CMP(Cpu::InstructionArgs args) {
+        uint16_t value = _bus->read(args.address);
+        uint16_t diff = A - value;
+        setFlag(Carry, A > value);
+        setFlag(Zero, (diff & 0x00FF) == 0);
+        setFlag(Negative, diff & 0x0080);
+    }
+
+    void Cpu::BMI(Cpu::InstructionArgs args) {
+        if(getFlag(Negative)) {
+            branch(args);
+        }
+    }
+
+    void Cpu::PHA(Cpu::InstructionArgs args) {
+        _bus->write(STACK_BASE + SP--, A);
+    }
+
+    void Cpu::PLP(Cpu::InstructionArgs args) {
+        flags = _bus->read(STACK_BASE + ++SP);
+        setFlag(Unused, true);
+    }
+
+    void Cpu::ORA(Cpu::InstructionArgs args) {
+        A |= _bus->read(args.address);
+        setFlag(Zero, A == 0);
+        setFlag(Negative, A & 0x80);
+    }
+
+    void Cpu::CLV(Cpu::InstructionArgs args) {
+        setFlag(Overflow, false);
+    }
+
+    void Cpu::EOR(Cpu::InstructionArgs args) {
+        A ^= _bus->read(args.address);
+        setFlag(Zero, A == 0);
+        setFlag(Negative, A & 0x80);
+    }
+
+    void Cpu::CPY(Cpu::InstructionArgs args) {
+        uint16_t value = _bus->read(args.address);
+        uint16_t diff = Y - value;
+        setFlag(Carry, Y > value);
+        setFlag(Zero, (diff & 0x00FF) == 0);
+        setFlag(Negative, diff & 0x0080);
+    }
+
+    void Cpu::CPX(Cpu::InstructionArgs args) {
+        uint16_t value = _bus->read(args.address);
+        uint16_t diff = X - value;
+        setFlag(Carry, X > value);
+        setFlag(Zero, (diff & 0x00FF) == 0);
+        setFlag(Negative, diff & 0x0080);
+    }
+
+    void Cpu::STY(Cpu::InstructionArgs args) {
+        _bus->write(args.address, Y);
+    }
+
+    void Cpu::INY(Cpu::InstructionArgs args) {
+        Y++;
+        setFlag(Zero, Y == 0);
+        setFlag(Negative, Y & 0x80);
+    }
+
+    void Cpu::INX(Cpu::InstructionArgs args) {
+        X++;
+        setFlag(Zero, X == 0);
+        setFlag(Negative, X & 0x80);
+    }
+
+    void Cpu::DEX(Cpu::InstructionArgs args) {
+        X--;
+        setFlag(Zero, X == 0);
+        setFlag(Negative, X & 0x80);
+    }
+
+    void Cpu::TAY(Cpu::InstructionArgs args) {
+        Y = A;
+        setFlag(Zero, Y == 0);
+        setFlag(Negative, Y & 0x80);
+    }
+
+    void Cpu::TAX(Cpu::InstructionArgs args) {
+        X = A;
+        setFlag(Zero, X == 0);
+        setFlag(Negative, X & 0x80);
+    }
+
+    void Cpu::TYA(Cpu::InstructionArgs args) {
+        A = Y;
+        setFlag(Zero, A == 0);
+        setFlag(Negative, A & 0x80);
+    }
+
+    void Cpu::TXA(Cpu::InstructionArgs args) {
+        A = X;
+        setFlag(Zero, A == 0);
+        setFlag(Negative, A & 0x80);
+    }
+
+    void Cpu::TSX(Cpu::InstructionArgs args) {
+        X = SP;
+        setFlag(Zero, X == 0);
+        setFlag(Negative, X & 0x80);
+    }
+
+    void Cpu::BRK(Cpu::InstructionArgs args) {
+        PC++;
+        setFlag(InterruptDisable, true);
+
+        _bus->write(STACK_BASE + SP--, PC >> 8);
+        _bus->write(STACK_BASE + SP--, PC & 0x00FF);
+
+        setFlag(Break, true);
+        _bus->write(STACK_BASE + SP--, flags);
+        setFlag(Break, false);
+
+        uint16_t lo = _bus->read(0xFFFE);
+        uint16_t hi = _bus->read(0xFFFF);
+        PC = (hi << 8) | lo;
+    }
+
+    void Cpu::RTI(Cpu::InstructionArgs args) {
+        flags = _bus->read(STACK_BASE + ++SP);
+        setFlag(Break, false);
+        setFlag(Unused, false);
+
+        uint16_t lo = _bus->read(STACK_BASE + ++SP);
+        uint16_t hi = _bus->read(STACK_BASE + ++SP);
+        PC = (hi << 8) | lo;
     }
 
 }

src/Cpu.h

@@ -37,12 +37,15 @@ namespace nes {
             bool variableCycles;
         };
 
+        static constexpr uint16_t STACK_BASE = 0x0100;
+
     public:
         explicit Cpu(Bus* bus);
         void reset();
         void tick();
         void setFlag(CpuFlags flag, bool value);
         bool getFlag(CpuFlags flag);
+        void setStartAddress(uint16_t address);
 
     private:
         size_t _ticks;
@@ -59,6 +62,16 @@ namespace nes {
         uint8_t SP;     // Stack Pointer
         uint8_t flags;
 
+    private:
+        void branch(InstructionArgs args);
+
+    private:
+        InstructionArgs IMM();
+        InstructionArgs ABS();
+        InstructionArgs IMP();
+        InstructionArgs REL();
+        InstructionArgs ZP0();
+
     private:
         void LDA(InstructionArgs args);
         void LDX(InstructionArgs args);
@@ -71,12 +84,44 @@ namespace nes {
         void DEY(InstructionArgs args);
         void BNE(InstructionArgs args);
         void NOP(InstructionArgs args);
-
+        void SEI(InstructionArgs args);
-    private:
+        void CLD(InstructionArgs args);
-        InstructionArgs IMM();
+        void TXS(InstructionArgs args);
-        InstructionArgs ABS();
+        void BPL(InstructionArgs args);
-        InstructionArgs IMP();
+        void JMP(InstructionArgs args);
-        InstructionArgs REL();
+        void JSR(InstructionArgs args);
+        void SEC(InstructionArgs args);
+        void BCS(InstructionArgs args);
+        void BCC(InstructionArgs args);
+        void BEQ(InstructionArgs args);
+        void BIT(InstructionArgs args);
+        void BVS(InstructionArgs args);
+        void BVC(InstructionArgs args);
+        void RTS(InstructionArgs args);
+        void SED(InstructionArgs args);
+        void PHP(InstructionArgs args);
+        void PLA(InstructionArgs args);
+        void AND(InstructionArgs args);
+        void CMP(InstructionArgs args);
+        void BMI(InstructionArgs args);
+        void PHA(InstructionArgs args);
+        void PLP(InstructionArgs args);
+        void ORA(InstructionArgs args);
+        void CLV(InstructionArgs args);
+        void EOR(InstructionArgs args);
+        void CPY(InstructionArgs args);
+        void CPX(InstructionArgs args);
+        void STY(InstructionArgs args);
+        void INY(InstructionArgs args);
+        void INX(InstructionArgs args);
+        void DEX(InstructionArgs args);
+        void TAY(InstructionArgs args);
+        void TAX(InstructionArgs args);
+        void TYA(InstructionArgs args);
+        void TXA(InstructionArgs args);
+        void TSX(InstructionArgs args);
+        void BRK(InstructionArgs args);
+        void RTI(InstructionArgs args);
     };
 
 }

src/Mapper/Mapper.cpp

@@ -0,0 +1,12 @@
+//
+// Created by selim on 8/19/23.
+//
+
+#include "Mapper.h"
+
+namespace nes {
+
+    Mapper::Mapper(uint8_t prgBanks, uint8_t chrBanks): _prgBanks(prgBanks), _chrBanks(chrBanks) {
+
+    }
+}

src/Mapper/Mapper.h

@@ -0,0 +1,28 @@
+//
+// Created by selim on 8/19/23.
+//
+
+#ifndef NES_MAPPER_H
+#define NES_MAPPER_H
+
+#include <cstdint>
+
+namespace nes {
+
+    class Mapper {
+    public:
+        Mapper(uint8_t prgBanks, uint8_t chrBanks);
+        virtual ~Mapper() = default;
+
+    public:
+        virtual uint32_t mapPrg(uint16_t address) = 0;
+        virtual uint32_t mapChr(uint16_t address) = 0;
+
+    protected:
+        uint8_t _prgBanks;
+        uint8_t _chrBanks;
+    };
+
+}
+
+#endif //NES_MAPPER_H

src/Mapper/Mapper0.cpp

@@ -0,0 +1,16 @@
+//
+// Created by selim on 8/19/23.
+//
+
+#include "Mapper0.h"
+
+namespace nes {
+
+    uint32_t Mapper0::mapPrg(uint16_t address) {
+        return address & (_prgBanks > 1 ? 0x7FFF : 0x3FFF);
+    }
+
+    uint32_t Mapper0::mapChr(uint16_t address) {
+        return address;
+    }
+}

src/Mapper/Mapper0.h

@@ -0,0 +1,24 @@
+//
+// Created by selim on 8/19/23.
+//
+
+#ifndef NES_MAPPER0_H
+#define NES_MAPPER0_H
+
+#include "Mapper.h"
+
+namespace nes {
+
+    class Mapper0: public Mapper {
+    public:
+        using Mapper::Mapper;
+        ~Mapper0() override = default;
+
+    public:
+        uint32_t mapPrg(uint16_t address) override;
+        uint32_t mapChr(uint16_t address) override;
+    };
+
+}
+
+#endif //NES_MAPPER0_H

src/Nes.cpp

@@ -3,9 +3,11 @@
 //
 
 #include "Nes.h"
-#include "Rom.h"
+#include "Cartridge.h"
 #include "Cpu.h"
 
+#include <iostream>
+
 namespace nes {
 
     Nes::Nes() {
@@ -13,10 +15,10 @@ namespace nes {
         _cpu = std::make_unique<Cpu>(_bus.get());
     }
 
-    void Nes::runRom(const fs::path &path) {
+    void Nes::runRom(const fs::path &path, std::optional<uint16_t> address) {
-        _rom = std::make_unique<Rom>(path);
+        _cartridge = std::make_unique<Cartridge>(path);
-        _bus->connect(_rom.get());
+        _bus->connect(_cartridge.get());
-        reset();
+        reset(address);
     }
 
     uint8_t Nes::read(uint16_t address) {
@@ -27,14 +29,20 @@ namespace nes {
         _bus->write(address, value);
     }
 
-    void Nes::reset() {
+    void Nes::reset(std::optional<uint16_t> address) {
         _cpu->reset();
 
-        size_t ticks = 5000;
+        if(address) {
-        while (ticks > 0) {
+            _cpu->setStartAddress(address.value());
-            _cpu->tick();
-            ticks--;
         }
+
+        size_t ticks = 0;
+        while (ticks <= 2000) {
+            _cpu->tick();
+            ticks++;
+        }
+
+        std::cout << "The end" << std::endl;
     }
 
 }

src/Nes.h

@@ -6,8 +6,9 @@
 #define NES_NES_H
 
 #include "Cpu.h"
-#include "Rom.h"
+#include "Cartridge.h"
 #include <filesystem>
+#include <optional>
 
 namespace nes {
 
@@ -16,8 +17,8 @@ namespace nes {
     class Nes {
     public:
         Nes();
-        void runRom(const fs::path& path);
+        void runRom(const fs::path& path, std::optional<uint16_t> address = std::nullopt);
-        void reset();
+        void reset(std::optional<uint16_t> address = std::nullopt);
 
     public: // For debug
         uint8_t read(uint16_t address);
@@ -26,7 +27,7 @@ namespace nes {
     private:
         std::unique_ptr<Bus> _bus;
         std::unique_ptr<Cpu> _cpu;
-        std::unique_ptr<Rom> _rom;
+        std::unique_ptr<Cartridge> _cartridge;
     };
 
 }

src/Rom.cpp

@@ -1,31 +0,0 @@
-//
-// Created by Selim Mustafaev on 09.08.2023.
-//
-
-#include "Rom.h"
-#include <fstream>
-#include <iostream>
-#include <memory>
-
-namespace nes {
-
-    Rom::Rom(const fs::path &path) {
-        auto romSize = fs::file_size(path);
-        _romData = std::make_unique<std::byte[]>(romSize);
-
-        std::ifstream rom(path);
-        rom.read(reinterpret_cast<char*>(_romData.get()), static_cast<std::streamsize>(romSize));
-
-        // UB here
-        // Should be std::start_lifetime_as<RomHeader>(_romData);
-        // when it become available
-        _header = reinterpret_cast<RomHeader*>(_romData.get());
-
-        const size_t prgSize = _header->prgChunks*PRG_CHUNK_SIZE;
-        const size_t chrSize = _header->chrChunks*CHR_CHUNK_SIZE;
-
-        _prgRom = std::span<std::byte>(_romData.get() + sizeof(RomHeader), prgSize);
-        _chrRom = std::span<std::byte>(_romData.get() + sizeof(RomHeader) + prgSize, chrSize);
-    }
-
-}