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Refactoring. Extracting all read/write routing into separate Bus class

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This commit is contained in:
Selim Mustafaev 2025-07-02 11:55:38 +03:00
parent e6e8c71794
commit c0ac8bfb58
11 changed files with 263 additions and 145 deletions
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4
CMakeLists.txt
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@ -30,7 +30,9 @@ add_executable(nes
src/Oam.cpp src/Oam.cpp
src/Oam.h src/Oam.h
src/Mapper/Mapper1.cpp src/Mapper/Mapper1.cpp
src/Mapper/Mapper1.h) src/Mapper/Mapper1.h
src/Bus.cpp
src/Bus.h)
find_package(SDL2 CONFIG REQUIRED) find_package(SDL2 CONFIG REQUIRED)
find_package(fmt REQUIRED) find_package(fmt REQUIRED)

97
src/Bus.cpp Normal file
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@ -0,0 +1,97 @@
//
// Created by Selim Mustafaev on 01.07.2025.
//
#include "Bus.h"
#include <iostream>
namespace nes {
Bus::Bus(uint8_t *ram,
Cpu *cpu,
Ppu *ppu,
Cartridge *cartridge,
Controller *controller1,
Controller *controller2,
Dma *dma): _ram(ram),
_cpu(cpu),
_ppu(ppu),
_cartridge(cartridge),
_controller1(controller1),
_controller2(controller2),
_dma(dma) {
_cpu->connectToBus(this);
_ppu->connectToBus(this);
_dma->connectToBus(this);
}
void Bus::connectCartridge(Cartridge *cartridge) {
_cartridge = cartridge;
}
void Bus::connectController1(Controller *controller1) {
_controller1 = controller1;
}
void Bus::connectController2(Controller *controller2) {
_controller2 = controller2;
}
Cartridge::Mirroring Bus::cartridgeMirroring() const {
return _cartridge->mirroring();
}
uint8_t Bus::readChr(uint16_t address) const {
return _cartridge->readChr(address);
}
uint8_t Bus::read(uint16_t address) const {
if(address < 0x2000) {
return _ram[address & 0x07FF];
}
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);
}
else if(address == 0x4016) {
return _controller1->read();
}
else if(address == 0x4017) {
if (_controller2) {
return _controller2->read();
}
}
return 0;
}
void Bus::write(uint16_t address, uint8_t value) {
if(address < 0x2000) {
_ram[address & 0x07FF] = value;
}
else if(address >= 0x2000 && address < 0x4000) {
_ppu->write(address & 0x0007, value);
}
else if(address >= 0x8000) {
std::cout << "Cartridge (PRG) write at address: " << address << std::endl;
}
else if(address == 0x4014) {
_dma->start(value);
}
else if(address == 0x4016) {
_controller1->poll();
}
else if(address == 0x4017) {
if (_controller2) {
_controller2->poll();
}
}
}
}

49
src/Bus.h Normal file
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@ -0,0 +1,49 @@
//
// Created by Selim Mustafaev on 01.07.2025.
//
#ifndef BUS_H
#define BUS_H
#include "Cpu.h"
#include "Ppu.h"
#include "Cartridge.h"
#include "Controller.h"
#include "Dma.h"
#include <cstdint>
namespace nes {
class Bus {
public:
Bus(uint8_t *ram,
Cpu *cpu,
Ppu *ppu,
Cartridge *cartridge,
Controller *controller1,
Controller *controller2,
Dma *dma);
void connectCartridge(Cartridge *cartridge);
void connectController1(Controller *controller1);
void connectController2(Controller *controller2);
[[nodiscard]] Cartridge::Mirroring cartridgeMirroring() const;
uint8_t readChr(uint16_t address) const;
uint8_t read(uint16_t address) const;
void write(uint16_t address, uint8_t value);
private:
uint8_t* _ram;
Cpu* _cpu;
Ppu* _ppu;
Cartridge* _cartridge;
Controller* _controller1;
Controller* _controller2;
Dma* _dma;
};
}
#endif //BUS_H

155
src/Cpu.cpp
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@ -3,7 +3,7 @@
// //
#include "Cpu.h" #include "Cpu.h"
#include "System.h" #include "Bus.h"
#include <iostream> #include <iostream>
#ifdef NES_LOGGING #ifdef NES_LOGGING
@ -12,8 +12,7 @@
namespace nes { namespace nes {
Cpu::Cpu(System* system): _ticks{}, A{}, X{}, Y{}, PC{}, SP{}, flags{} { Cpu::Cpu(): _ticks{}, A{}, X{}, Y{}, PC{}, SP{}, flags{} {
_system = system;
_instructions = std::vector<Instruction>(256); _instructions = std::vector<Instruction>(256);
_instructions[0x00] = {"BRK", &Cpu::BRK, &Cpu::IMPL, 7, false}; _instructions[0x00] = {"BRK", &Cpu::BRK, &Cpu::IMPL, 7, false};
_instructions[0x01] = {"ORA", &Cpu::ORA, &Cpu::IZX, 6, false}; _instructions[0x01] = {"ORA", &Cpu::ORA, &Cpu::IZX, 6, false};
@ -174,8 +173,8 @@ namespace nes {
SP = 0xFD; SP = 0xFD;
flags = 0; flags = 0;
uint16_t lo = _system->read(0xFFFC); uint16_t lo = _bus->read(0xFFFC);
uint16_t hi = _system->read(0xFFFD); uint16_t hi = _bus->read(0xFFFD);
PC = (hi << 8) | lo; PC = (hi << 8) | lo;
@ -186,7 +185,7 @@ namespace nes {
bool executed = false; bool executed = false;
if(_ticks == 0) { if(_ticks == 0) {
uint8_t opcode = _system->read(PC++); uint8_t opcode = _bus->read(PC++);
auto instruction = _instructions[opcode]; auto instruction = _instructions[opcode];
_currentOpcode = opcode; _currentOpcode = opcode;
@ -211,21 +210,25 @@ namespace nes {
} }
void Cpu::nmi() { void Cpu::nmi() {
_system->write(STACK_BASE + SP--, PC >> 8); _bus->write(STACK_BASE + SP--, PC >> 8);
_system->write(STACK_BASE + SP--, PC & 0x00FF); _bus->write(STACK_BASE + SP--, PC & 0x00FF);
setFlag(Break, false); setFlag(Break, false);
setFlag(Unused, true); setFlag(Unused, true);
setFlag(InterruptDisable, true); setFlag(InterruptDisable, true);
_system->write(STACK_BASE + SP--, flags); _bus->write(STACK_BASE + SP--, flags);
uint8_t lo = _system->read(0xFFFA); uint8_t lo = _bus->read(0xFFFA);
uint8_t hi = _system->read(0xFFFB); uint8_t hi = _bus->read(0xFFFB);
PC = (hi << 8) | lo; PC = (hi << 8) | lo;
_ticks = 8; _ticks = 8;
} }
void Cpu::connectToBus(Bus *bus) {
_bus = bus;
}
#ifdef NES_LOGGING #ifdef NES_LOGGING
std::string Cpu::state() const { std::string Cpu::state() const {
return fmt::format("{} ({:02X}), PC: {:X}, SP: {:X}, A: {:02X}, X: {:02X}, Y: {:02X}, [N:{}, V:{}, B{}, D{}, I{}, Z:{}, C:{}], H: {:08X}", return fmt::format("{} ({:02X}), PC: {:X}, SP: {:X}, A: {:02X}, X: {:02X}, Y: {:02X}, [N:{}, V:{}, B{}, D{}, I{}, Z:{}, C:{}], H: {:08X}",
@ -239,7 +242,7 @@ namespace nes {
(int)getFlag(InterruptDisable), (int)getFlag(InterruptDisable),
(int)getFlag(Zero), (int)getFlag(Zero),
(int)getFlag(Carry), (int)getFlag(Carry),
_system->zpHash()); _bus->zpHash());
} }
#endif #endif
@ -280,8 +283,8 @@ namespace nes {
} }
Cpu::InstructionArgs Cpu::ABSL() { Cpu::InstructionArgs Cpu::ABSL() {
uint8_t lo = _system->read(PC++); uint8_t lo = _bus->read(PC++);
uint8_t hi = _system->read(PC++); uint8_t hi = _bus->read(PC++);
uint16_t address = (hi << 8) | lo; uint16_t address = (hi << 8) | lo;
return {address, 0}; return {address, 0};
} }
@ -291,7 +294,7 @@ namespace nes {
} }
Cpu::InstructionArgs Cpu::REL() { Cpu::InstructionArgs Cpu::REL() {
uint16_t address = _system->read(PC++); uint16_t address = _bus->read(PC++);
if (address & 0x80) { if (address & 0x80) {
address |= 0xFF00; address |= 0xFF00;
@ -301,22 +304,22 @@ namespace nes {
} }
Cpu::InstructionArgs Cpu::ZP0() { Cpu::InstructionArgs Cpu::ZP0() {
uint16_t address = _system->read(PC++); uint16_t address = _bus->read(PC++);
return {address, 0}; return {address, 0};
} }
Cpu::InstructionArgs Cpu::IZX() { Cpu::InstructionArgs Cpu::IZX() {
uint8_t ptrAddress = _system->read(PC++) + X; uint8_t ptrAddress = _bus->read(PC++) + X;
uint8_t lo = _system->read(ptrAddress); uint8_t lo = _bus->read(ptrAddress);
uint8_t hi = _system->read(++ptrAddress); uint8_t hi = _bus->read(++ptrAddress);
uint16_t address = (hi << 8) | lo; uint16_t address = (hi << 8) | lo;
return {address, 0}; return {address, 0};
} }
Cpu::InstructionArgs Cpu::IZY() { Cpu::InstructionArgs Cpu::IZY() {
uint8_t ptrAddress = _system->read(PC++); uint8_t ptrAddress = _bus->read(PC++);
uint8_t lo = _system->read(ptrAddress); uint8_t lo = _bus->read(ptrAddress);
uint8_t hi = _system->read(++ptrAddress); uint8_t hi = _bus->read(++ptrAddress);
uint16_t address = (hi << 8) | lo; uint16_t address = (hi << 8) | lo;
address += Y; address += Y;
@ -329,17 +332,17 @@ namespace nes {
} }
Cpu::InstructionArgs Cpu::IND() { Cpu::InstructionArgs Cpu::IND() {
uint8_t ptrLo = _system->read(PC++); uint8_t ptrLo = _bus->read(PC++);
uint8_t ptrHi = _system->read(PC++); uint8_t ptrHi = _bus->read(PC++);
uint16_t ptrAddress = (ptrHi << 8) | ptrLo; uint16_t ptrAddress = (ptrHi << 8) | ptrLo;
uint8_t lo = _system->read(ptrAddress); uint8_t lo = _bus->read(ptrAddress);
uint8_t hi = 0; uint8_t hi = 0;
if(ptrLo == 0xFF) { if(ptrLo == 0xFF) {
hi = _system->read(ptrAddress & 0xFF00); hi = _bus->read(ptrAddress & 0xFF00);
} else { } else {
hi = _system->read(++ptrAddress); hi = _bus->read(++ptrAddress);
} }
uint16_t address = (hi << 8) | lo; uint16_t address = (hi << 8) | lo;
@ -347,8 +350,8 @@ namespace nes {
} }
Cpu::InstructionArgs Cpu::ABX() { Cpu::InstructionArgs Cpu::ABX() {
uint8_t lo = _system->read(PC++); uint8_t lo = _bus->read(PC++);
uint8_t hi = _system->read(PC++); uint8_t hi = _bus->read(PC++);
uint16_t address = (hi << 8) | lo; uint16_t address = (hi << 8) | lo;
address += X; address += X;
@ -361,8 +364,8 @@ namespace nes {
} }
Cpu::InstructionArgs Cpu::ABY() { Cpu::InstructionArgs Cpu::ABY() {
uint8_t lo = _system->read(PC++); uint8_t lo = _bus->read(PC++);
uint8_t hi = _system->read(PC++); uint8_t hi = _bus->read(PC++);
uint16_t address = (hi << 8) | lo; uint16_t address = (hi << 8) | lo;
address += Y; address += Y;
@ -375,41 +378,41 @@ namespace nes {
} }
Cpu::InstructionArgs Cpu::ZPX() { Cpu::InstructionArgs Cpu::ZPX() {
uint8_t address = _system->read(PC++) + X; uint8_t address = _bus->read(PC++) + X;
return {address, 0}; return {address, 0};
} }
Cpu::InstructionArgs Cpu::ZPY() { Cpu::InstructionArgs Cpu::ZPY() {
uint8_t address = _system->read(PC++) + Y; uint8_t address = _bus->read(PC++) + Y;
return {address, 0}; return {address, 0};
} }
// CPU instructions // CPU instructions
void Cpu::LDA(Cpu::InstructionArgs args) { void Cpu::LDA(Cpu::InstructionArgs args) {
A = _system->read(args.address); A = _bus->read(args.address);
setFlag(Negative, A & 0x80); setFlag(Negative, A & 0x80);
setFlag(Zero, A == 0); setFlag(Zero, A == 0);
} }
void Cpu::LDX(InstructionArgs args) { void Cpu::LDX(InstructionArgs args) {
X = _system->read(args.address); X = _bus->read(args.address);
setFlag(Negative, X & 0x80); setFlag(Negative, X & 0x80);
setFlag(Zero, X == 0); setFlag(Zero, X == 0);
} }
void Cpu::LDY(Cpu::InstructionArgs args) { void Cpu::LDY(Cpu::InstructionArgs args) {
Y = _system->read(args.address); Y = _bus->read(args.address);
setFlag(Negative, Y & 0x80); setFlag(Negative, Y & 0x80);
setFlag(Zero, Y == 0); setFlag(Zero, Y == 0);
} }
void Cpu::STA(Cpu::InstructionArgs args) { void Cpu::STA(Cpu::InstructionArgs args) {
_system->write(args.address, A); _bus->write(args.address, A);
} }
void Cpu::STX(InstructionArgs args) { void Cpu::STX(InstructionArgs args) {
_system->write(args.address, X); _bus->write(args.address, X);
} }
void Cpu::CLC(Cpu::InstructionArgs args) { void Cpu::CLC(Cpu::InstructionArgs args) {
@ -417,7 +420,7 @@ namespace nes {
} }
void Cpu::ADC(Cpu::InstructionArgs args) { void Cpu::ADC(Cpu::InstructionArgs args) {
uint16_t value = _system->read(args.address); uint16_t value = _bus->read(args.address);
uint16_t result = A + value + getFlag(Carry); uint16_t result = A + value + getFlag(Carry);
setFlag(Carry, result > 255); setFlag(Carry, result > 255);
@ -429,7 +432,7 @@ namespace nes {
} }
void Cpu::SBC(Cpu::InstructionArgs args) { void Cpu::SBC(Cpu::InstructionArgs args) {
uint16_t value = _system->read(args.address) ^ 0xFF; uint16_t value = _bus->read(args.address) ^ 0xFF;
uint16_t result = A + value + getFlag(Carry); uint16_t result = A + value + getFlag(Carry);
setFlag(Carry, result > 255); setFlag(Carry, result > 255);
@ -479,8 +482,8 @@ namespace nes {
void Cpu::JSR(Cpu::InstructionArgs args) { void Cpu::JSR(Cpu::InstructionArgs args) {
PC--; PC--;
_system->write(STACK_BASE + SP--, PC >> 8); _bus->write(STACK_BASE + SP--, PC >> 8);
_system->write(STACK_BASE + SP--, PC & 0x00FF); _bus->write(STACK_BASE + SP--, PC & 0x00FF);
PC = args.address; PC = args.address;
} }
@ -507,7 +510,7 @@ namespace nes {
} }
void Cpu::BIT(Cpu::InstructionArgs args) { void Cpu::BIT(Cpu::InstructionArgs args) {
uint8_t value = _system->read(args.address); uint8_t value = _bus->read(args.address);
setFlag(Zero, (A & value) == 0); setFlag(Zero, (A & value) == 0);
setFlag(Negative, value & (1 << 7)); setFlag(Negative, value & (1 << 7));
setFlag(Overflow, value & (1 << 6)); setFlag(Overflow, value & (1 << 6));
@ -526,8 +529,8 @@ namespace nes {
} }
void Cpu::RTS(Cpu::InstructionArgs args) { void Cpu::RTS(Cpu::InstructionArgs args) {
uint16_t lo = _system->read(STACK_BASE + ++SP); uint16_t lo = _bus->read(STACK_BASE + ++SP);
uint16_t hi = _system->read(STACK_BASE + ++SP); uint16_t hi = _bus->read(STACK_BASE + ++SP);
PC = (hi << 8) | lo; PC = (hi << 8) | lo;
PC++; PC++;
@ -538,25 +541,25 @@ namespace nes {
} }
void Cpu::PHP(Cpu::InstructionArgs args) { void Cpu::PHP(Cpu::InstructionArgs args) {
_system->write(STACK_BASE + SP--, flags | Break | Unused); _bus->write(STACK_BASE + SP--, flags | Break | Unused);
setFlag(Break, false); setFlag(Break, false);
setFlag(Unused, false); setFlag(Unused, false);
} }
void Cpu::PLA(Cpu::InstructionArgs args) { void Cpu::PLA(Cpu::InstructionArgs args) {
A = _system->read(STACK_BASE + ++SP); A = _bus->read(STACK_BASE + ++SP);
setFlag(Zero, A == 0); setFlag(Zero, A == 0);
setFlag(Negative, A & 0x80); setFlag(Negative, A & 0x80);
} }
void Cpu::AND(Cpu::InstructionArgs args) { void Cpu::AND(Cpu::InstructionArgs args) {
A &= _system->read(args.address);; A &= _bus->read(args.address);;
setFlag(Zero, A == 0); setFlag(Zero, A == 0);
setFlag(Negative, A & 0x80); setFlag(Negative, A & 0x80);
} }
void Cpu::CMP(Cpu::InstructionArgs args) { void Cpu::CMP(Cpu::InstructionArgs args) {
uint16_t value = _system->read(args.address); uint16_t value = _bus->read(args.address);
uint16_t diff = A - value; uint16_t diff = A - value;
setFlag(Carry, A >= value); setFlag(Carry, A >= value);
setFlag(Zero, (diff & 0x00FF) == 0); setFlag(Zero, (diff & 0x00FF) == 0);
@ -570,16 +573,16 @@ namespace nes {
} }
void Cpu::PHA(Cpu::InstructionArgs args) { void Cpu::PHA(Cpu::InstructionArgs args) {
_system->write(STACK_BASE + SP--, A); _bus->write(STACK_BASE + SP--, A);
} }
void Cpu::PLP(Cpu::InstructionArgs args) { void Cpu::PLP(Cpu::InstructionArgs args) {
flags = _system->read(STACK_BASE + ++SP); flags = _bus->read(STACK_BASE + ++SP);
setFlag(Unused, true); setFlag(Unused, true);
} }
void Cpu::ORA(Cpu::InstructionArgs args) { void Cpu::ORA(Cpu::InstructionArgs args) {
A |= _system->read(args.address); A |= _bus->read(args.address);
setFlag(Zero, A == 0); setFlag(Zero, A == 0);
setFlag(Negative, A & 0x80); setFlag(Negative, A & 0x80);
} }
@ -589,13 +592,13 @@ namespace nes {
} }
void Cpu::EOR(Cpu::InstructionArgs args) { void Cpu::EOR(Cpu::InstructionArgs args) {
A ^= _system->read(args.address); A ^= _bus->read(args.address);
setFlag(Zero, A == 0); setFlag(Zero, A == 0);
setFlag(Negative, A & 0x80); setFlag(Negative, A & 0x80);
} }
void Cpu::CPY(Cpu::InstructionArgs args) { void Cpu::CPY(Cpu::InstructionArgs args) {
uint16_t value = _system->read(args.address); uint16_t value = _bus->read(args.address);
uint16_t diff = Y - value; uint16_t diff = Y - value;
setFlag(Carry, Y >= value); setFlag(Carry, Y >= value);
setFlag(Zero, (diff & 0x00FF) == 0); setFlag(Zero, (diff & 0x00FF) == 0);
@ -603,7 +606,7 @@ namespace nes {
} }
void Cpu::CPX(Cpu::InstructionArgs args) { void Cpu::CPX(Cpu::InstructionArgs args) {
uint16_t value = _system->read(args.address); uint16_t value = _bus->read(args.address);
uint16_t diff = X - value; uint16_t diff = X - value;
setFlag(Carry, X >= value); setFlag(Carry, X >= value);
setFlag(Zero, (diff & 0x00FF) == 0); setFlag(Zero, (diff & 0x00FF) == 0);
@ -611,7 +614,7 @@ namespace nes {
} }
void Cpu::STY(Cpu::InstructionArgs args) { void Cpu::STY(Cpu::InstructionArgs args) {
_system->write(args.address, Y); _bus->write(args.address, Y);
} }
void Cpu::INY(Cpu::InstructionArgs args) { void Cpu::INY(Cpu::InstructionArgs args) {
@ -666,25 +669,25 @@ namespace nes {
PC++; PC++;
setFlag(InterruptDisable, true); setFlag(InterruptDisable, true);
_system->write(STACK_BASE + SP--, PC >> 8); _bus->write(STACK_BASE + SP--, PC >> 8);
_system->write(STACK_BASE + SP--, PC & 0x00FF); _bus->write(STACK_BASE + SP--, PC & 0x00FF);
setFlag(Break, true); setFlag(Break, true);
_system->write(STACK_BASE + SP--, flags); _bus->write(STACK_BASE + SP--, flags);
setFlag(Break, false); setFlag(Break, false);
uint16_t lo = _system->read(0xFFFE); uint16_t lo = _bus->read(0xFFFE);
uint16_t hi = _system->read(0xFFFF); uint16_t hi = _bus->read(0xFFFF);
PC = (hi << 8) | lo; PC = (hi << 8) | lo;
} }
void Cpu::RTI(Cpu::InstructionArgs args) { void Cpu::RTI(Cpu::InstructionArgs args) {
flags = _system->read(STACK_BASE + ++SP); flags = _bus->read(STACK_BASE + ++SP);
setFlag(Break, false); setFlag(Break, false);
setFlag(Unused, false); setFlag(Unused, false);
uint16_t lo = _system->read(STACK_BASE + ++SP); uint16_t lo = _bus->read(STACK_BASE + ++SP);
uint16_t hi = _system->read(STACK_BASE + ++SP); uint16_t hi = _bus->read(STACK_BASE + ++SP);
PC = (hi << 8) | lo; PC = (hi << 8) | lo;
} }
@ -696,12 +699,12 @@ namespace nes {
} }
void Cpu::LSR(Cpu::InstructionArgs args) { void Cpu::LSR(Cpu::InstructionArgs args) {
uint8_t value = _system->read(args.address); uint8_t value = _bus->read(args.address);
setFlag(Carry, value & 0x01); setFlag(Carry, value & 0x01);
value = value >> 1; value = value >> 1;
setFlag(Zero, value == 0); setFlag(Zero, value == 0);
setFlag(Negative, value & 0x80); setFlag(Negative, value & 0x80);
_system->write(args.address, value); _bus->write(args.address, value);
} }
void Cpu::ASL_ACC(Cpu::InstructionArgs args) { void Cpu::ASL_ACC(Cpu::InstructionArgs args) {
@ -712,12 +715,12 @@ namespace nes {
} }
void Cpu::ASL(Cpu::InstructionArgs args) { void Cpu::ASL(Cpu::InstructionArgs args) {
uint8_t value = _system->read(args.address); uint8_t value = _bus->read(args.address);
setFlag(Carry, value & 0x80); setFlag(Carry, value & 0x80);
value = value << 1; value = value << 1;
setFlag(Zero, value == 0); setFlag(Zero, value == 0);
setFlag(Negative, value & 0x80); setFlag(Negative, value & 0x80);
_system->write(args.address, value); _bus->write(args.address, value);
} }
void Cpu::ROR_ACC(Cpu::InstructionArgs args) { void Cpu::ROR_ACC(Cpu::InstructionArgs args) {
@ -729,13 +732,13 @@ namespace nes {
} }
void Cpu::ROR(Cpu::InstructionArgs args) { void Cpu::ROR(Cpu::InstructionArgs args) {
uint8_t value = _system->read(args.address); uint8_t value = _bus->read(args.address);
uint8_t carryOriginal = getFlag(Carry); uint8_t carryOriginal = getFlag(Carry);
setFlag(Carry, value & 0x01); setFlag(Carry, value & 0x01);
value = (value >> 1) | (carryOriginal << 7); value = (value >> 1) | (carryOriginal << 7);
setFlag(Zero, value == 0); setFlag(Zero, value == 0);
setFlag(Negative, value & 0x80); setFlag(Negative, value & 0x80);
_system->write(args.address, value); _bus->write(args.address, value);
} }
void Cpu::ROL_ACC(Cpu::InstructionArgs args) { void Cpu::ROL_ACC(Cpu::InstructionArgs args) {
@ -747,25 +750,25 @@ namespace nes {
} }
void Cpu::ROL(Cpu::InstructionArgs args) { void Cpu::ROL(Cpu::InstructionArgs args) {
uint8_t value = _system->read(args.address); uint8_t value = _bus->read(args.address);
uint8_t carryOriginal = getFlag(Carry); uint8_t carryOriginal = getFlag(Carry);
setFlag(Carry, value & 0x80); setFlag(Carry, value & 0x80);
value = (value << 1) | carryOriginal; value = (value << 1) | carryOriginal;
setFlag(Zero, value == 0); setFlag(Zero, value == 0);
setFlag(Negative, value & 0x80); setFlag(Negative, value & 0x80);
_system->write(args.address, value); _bus->write(args.address, value);
} }
void Cpu::INC(Cpu::InstructionArgs args) { void Cpu::INC(Cpu::InstructionArgs args) {
uint8_t value = _system->read(args.address); uint8_t value = _bus->read(args.address);
_system->write(args.address, ++value); _bus->write(args.address, ++value);
setFlag(Zero, value == 0); setFlag(Zero, value == 0);
setFlag(Negative, value & 0x80); setFlag(Negative, value & 0x80);
} }
void Cpu::DEC(Cpu::InstructionArgs args) { void Cpu::DEC(Cpu::InstructionArgs args) {
uint8_t value = _system->read(args.address); uint8_t value = _bus->read(args.address);
_system->write(args.address, --value); _bus->write(args.address, --value);
setFlag(Zero, value == 0); setFlag(Zero, value == 0);
setFlag(Negative, value & 0x80); setFlag(Negative, value & 0x80);
} }

7
src/Cpu.h
View File

@ -11,7 +11,7 @@
namespace nes { namespace nes {
class System; class Bus;
enum CpuFlags: uint8_t { enum CpuFlags: uint8_t {
Carry = (1 << 0), Carry = (1 << 0),
@ -42,13 +42,14 @@ namespace nes {
static constexpr uint16_t STACK_BASE = 0x0100; static constexpr uint16_t STACK_BASE = 0x0100;
public: public:
explicit Cpu(System* system); explicit Cpu();
void reset(); void reset();
bool tick(); bool tick();
void setFlag(CpuFlags flag, bool value); void setFlag(CpuFlags flag, bool value);
bool getFlag(CpuFlags flag) const; bool getFlag(CpuFlags flag) const;
void setStartAddress(uint16_t address); void setStartAddress(uint16_t address);
void nmi(); void nmi();
void connectToBus(Bus* bus);
#ifdef NES_LOGGING #ifdef NES_LOGGING
std::string state() const; std::string state() const;
@ -56,7 +57,7 @@ namespace nes {
private: private:
size_t _ticks; size_t _ticks;
System* _system; Bus* _bus;
std::vector<Instruction> _instructions; std::vector<Instruction> _instructions;
private: private:

9
src/Dma.cpp
View File

@ -4,11 +4,11 @@
#include "Dma.h" #include "Dma.h"
#include "Ppu.h" #include "Ppu.h"
#include "System.h" #include "Bus.h"
namespace nes { namespace nes {
Dma::Dma(System *system, Ppu *ppu): _system{system}, _ppu{ppu} { Dma::Dma(Ppu *ppu): _ppu{ppu} {
} }
@ -23,7 +23,7 @@ namespace nes {
} }
} else { } else {
if(cycles % 2 == 0) { if(cycles % 2 == 0) {
_data = _system->read((_page << 8) | _address); _data = _bus->read((_page << 8) | _address);
} else { } else {
_ppu->writeOam(_address, _data); _ppu->writeOam(_address, _data);
_address++; _address++;
@ -41,4 +41,7 @@ namespace nes {
_active = true; _active = true;
} }
void Dma::connectToBus(Bus *bus) {
_bus = bus;
}
} }

7
src/Dma.h
View File

@ -9,18 +9,19 @@
namespace nes { namespace nes {
class System; class Bus;
class Ppu; class Ppu;
class Dma { class Dma {
public: public:
Dma(System* system, Ppu* ppu); Dma(Ppu* ppu);
[[nodiscard]] bool active() const; [[nodiscard]] bool active() const;
void tick(uint64_t cycles); void tick(uint64_t cycles);
void start(uint8_t page); void start(uint8_t page);
void connectToBus(Bus *bus);
private: private:
System* _system; Bus* _bus;
Ppu* _ppu; Ppu* _ppu;
private: private:

10
src/Ppu.cpp
View File

@ -237,8 +237,8 @@ namespace nes {
_frameBuffer[index] = pixel; _frameBuffer[index] = pixel;
} }
void Ppu::connect(Cartridge* cartridge) { void Ppu::connectToBus(Bus* bus) {
_cartridge = cartridge; _bus = bus;
} }
void Ppu::reset() { void Ppu::reset() {
@ -261,11 +261,11 @@ namespace nes {
address &= 0x3FFF; address &= 0x3FFF;
if(address < 0x2000) { if(address < 0x2000) {
return _cartridge->readChr(address); return _bus->readChr(address);
} }
else if(address >= 0x2000 && address < 0x3F00) { else if(address >= 0x2000 && address < 0x3F00) {
address &= 0x0FFF; address &= 0x0FFF;
if(_cartridge->mirroring() == Cartridge::Mirroring::Vertical) { if(_bus->cartridgeMirroring() == Cartridge::Mirroring::Vertical) {
if (address >= 0x0000 && address <= 0x03FF) if (address >= 0x0000 && address <= 0x03FF)
return _nameTable[address & 0x03FF]; return _nameTable[address & 0x03FF];
if (address >= 0x0400 && address <= 0x07FF) if (address >= 0x0400 && address <= 0x07FF)
@ -305,7 +305,7 @@ namespace nes {
} }
else if(address >= 0x2000 && address < 0x3F00) { else if(address >= 0x2000 && address < 0x3F00) {
address &= 0x0FFF; address &= 0x0FFF;
if(_cartridge->mirroring() == Cartridge::Mirroring::Vertical) { if(_bus->cartridgeMirroring() == Cartridge::Mirroring::Vertical) {
if (address >= 0x0000 && address <= 0x03FF) if (address >= 0x0000 && address <= 0x03FF)
_nameTable[address & 0x03FF] = value; _nameTable[address & 0x03FF] = value;
if (address >= 0x0400 && address <= 0x07FF) if (address >= 0x0400 && address <= 0x07FF)

6
src/Ppu.h
View File

@ -5,7 +5,7 @@
#ifndef NES_PPU_H #ifndef NES_PPU_H
#define NES_PPU_H #define NES_PPU_H
#include "Cartridge.h" #include "Bus.h"
#include "Shifter.h" #include "Shifter.h"
#include "Oam.h" #include "Oam.h"
@ -105,7 +105,7 @@ namespace nes {
void write(uint16_t address, uint8_t value); void write(uint16_t address, uint8_t value);
uint8_t read(uint16_t address); uint8_t read(uint16_t address);
void setPixel(uint16_t row, uint16_t column, Pixel pixel); void setPixel(uint16_t row, uint16_t column, Pixel pixel);
void connect(Cartridge* cartridge); void connectToBus(Bus* bus);
void reset(); void reset();
void writeOam(uint8_t address, uint8_t data); void writeOam(uint8_t address, uint8_t data);
uint8_t internalRead(uint16_t address); uint8_t internalRead(uint16_t address);
@ -152,7 +152,7 @@ namespace nes {
private: private:
std::unique_ptr<Pixel[]> _frameBuffer; std::unique_ptr<Pixel[]> _frameBuffer;
Cartridge* _cartridge; Bus* _bus;
}; };
} }

60
src/System.cpp
View File

@ -20,20 +20,28 @@ namespace nes {
#endif #endif
{ {
_ram = std::make_unique<uint8_t[]>(2*1024); _ram = std::make_unique<uint8_t[]>(2*1024);
_cpu = std::make_unique<Cpu>(this); _cpu = std::make_unique<Cpu>();
_ppu = std::make_unique<Ppu>(); _ppu = std::make_unique<Ppu>();
_dma = std::make_unique<Dma>(this, _ppu.get()); _dma = std::make_unique<Dma>(_ppu.get());
_controller1 = std::make_shared<Controller>(); _controller1 = std::make_shared<Controller>();
_bus = std::make_unique<Bus>(_ram.get(),
_cpu.get(),
_ppu.get(),
_cartridge.get(),
_controller1.get(),
nullptr,
_dma.get());
} }
void System::insertCartridge(const fs::path &path, std::optional<uint16_t> address) { void System::insertCartridge(const fs::path &path, std::optional<uint16_t> address) {
_cartridge = std::make_unique<Cartridge>(path); _cartridge = std::make_unique<Cartridge>(path);
_ppu->connect(_cartridge.get()); _bus->connectCartridge(_cartridge.get());
reset(address); reset(address);
} }
void System::connect(std::shared_ptr<Controller> controller) { void System::connect(std::shared_ptr<Controller> controller) {
_controller1 = std::move(controller); _controller1 = std::move(controller);
_bus->connectController1(_controller1.get());
} }
void System::reset(std::optional<uint16_t> address) { void System::reset(std::optional<uint16_t> address) {
@ -49,7 +57,6 @@ namespace nes {
} }
void System::tick() { void System::tick() {
bool needInterrupt = _ppu->tick(); bool needInterrupt = _ppu->tick();
#ifdef NES_LOGGING #ifdef NES_LOGGING
_logger.addLine(_cycles, _ppu->state()); _logger.addLine(_cycles, _ppu->state());
@ -85,51 +92,6 @@ namespace nes {
_cycles++; _cycles++;
} }
uint8_t System::read(uint16_t address) {
if(address < 0x2000) {
return _ram[address & 0x07FF];
}
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);
}
else if(address == 0x4016) {
return _controller1->read();
}
else if(address == 0x4017) {
// Controller 2
return 0;
}
return 0;
}
void System::write(uint16_t address, uint8_t value) {
if(address < 0x2000) {
_ram[address & 0x07FF] = value;
}
else if(address >= 0x2000 && address < 0x4000) {
_ppu->write(address & 0x0007, value);
}
else if(address >= 0x8000) {
std::cout << "Cartridge write at address: " << address << std::endl;
}
else if(address == 0x4014) {
_dma->start(value);
}
else if(address == 0x4016) {
_controller1->poll();
}
else if(address == 0x4017) {
// Controller 2
}
}
// For debug // For debug
// Calc "hash" - just sum of the bytes of RAM // Calc "hash" - just sum of the bytes of RAM
// Can be useful for detecting changes in memory // Can be useful for detecting changes in memory

4
src/System.h
View File

@ -10,6 +10,7 @@
#include "Ppu.h" #include "Ppu.h"
#include "Cartridge.h" #include "Cartridge.h"
#include "Dma.h" #include "Dma.h"
#include "Bus.h"
#include <filesystem> #include <filesystem>
#include <optional> #include <optional>
@ -30,8 +31,6 @@ namespace nes {
void setNewFrameCallback(std::function<void(const Pixel*)> onNewFrame); void setNewFrameCallback(std::function<void(const Pixel*)> onNewFrame);
void tick(); void tick();
uint8_t read(uint16_t address);
void write(uint16_t address, uint8_t value);
[[nodiscard]] uint32_t zpHash() const; [[nodiscard]] uint32_t zpHash() const;
private: private:
@ -42,6 +41,7 @@ namespace nes {
std::unique_ptr<Cartridge> _cartridge; std::unique_ptr<Cartridge> _cartridge;
std::shared_ptr<Controller> _controller1; std::shared_ptr<Controller> _controller1;
std::unique_ptr<Dma> _dma; std::unique_ptr<Dma> _dma;
std::unique_ptr<Bus> _bus;
#ifdef NES_LOGGING #ifdef NES_LOGGING
Logger _logger; Logger _logger;