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YayIguess
2026-03-13 18:07:43 -07:00
parent 712ee55e7b
commit 3bd1ef34d8
13 changed files with 4873 additions and 4932 deletions
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96
src/addressSpace.cpp
View File

@@ -2,66 +2,58 @@
#include <iostream>
#include <iterator>
bool AddressSpace::getBootromState() const {
return bootromLoaded;
bool AddressSpace::getBootromState() const { return bootromLoaded; }
void AddressSpace::unmapBootrom() { bootromLoaded = false; }
void AddressSpace::mapBootrom() { bootromLoaded = true; }
void AddressSpace::loadBootrom(const std::string &filename) {
std::ifstream file;
file.open(filename, std::ios::binary);
if (!file.is_open()) {
std::cerr << "Bootrom was not found!\nQuitting!\n" << std::endl;
exit(1);
}
const uintmax_t size = std::filesystem::file_size(filename);
if (size != 256) {
std::cerr << "Bootrom was an unexpected size!\nQuitting!\n" << std::endl;
exit(1);
}
file.read(reinterpret_cast<char *>(bootrom), BOOTROM_SIZE);
}
void AddressSpace::unmapBootrom() {
bootromLoaded = false;
}
void AddressSpace::loadGame(const std::string &filename) {
std::ifstream rom(filename, std::ios::binary);
rom.unsetf(std::ios::skipws);
void AddressSpace::mapBootrom() {
bootromLoaded = true;
}
if (!rom.is_open()) {
std::cerr << "Game was not found!\nQuitting!\n" << std::endl;
exit(1);
}
void AddressSpace::loadBootrom(const std::string& filename) {
std::ifstream file;
file.open(filename, std::ios::binary);
rom.seekg(0, std::ios::end);
const std::streampos rom_size = rom.tellg();
rom.seekg(0, std::ios::beg);
if (!file.is_open()) {
std::cerr << "Bootrom was not found!\nQuitting!\n" << std::endl;
exit(1);
}
game.reserve(rom_size);
game.insert(game.begin(), std::istream_iterator<Byte>(rom),
std::istream_iterator<Byte>());
const uintmax_t size = std::filesystem::file_size(filename);
if (size != 256) {
std::cerr << "Bootrom was an unexpected size!\nQuitting!\n" << std::endl;
exit(1);
}
file.read(reinterpret_cast<char*>(bootrom), BOOTROM_SIZE);
}
void AddressSpace::loadGame(const std::string& filename) {
std::ifstream rom(filename, std::ios::binary);
rom.unsetf(std::ios::skipws);
if (!rom.is_open()) {
std::cerr << "Game was not found!\nQuitting!\n" << std::endl;
exit(1);
}
rom.seekg(0, std::ios::end);
const std::streampos rom_size = rom.tellg();
rom.seekg(0, std::ios::beg);
game.reserve(rom_size);
game.insert(game.begin(),
std::istream_iterator<Byte>(rom),
std::istream_iterator<Byte>());
memoryLayout.romBank0 = game.data();
memoryLayout.romBankSwitch = game.data() + ROM_BANK_SIZE;
memoryLayout.romBank0 = game.data();
memoryLayout.romBankSwitch = game.data() + ROM_BANK_SIZE;
}
void AddressSpace::dmaTransfer() {
dmaTransferRequested = false;
const Word addr = memoryLayout.DMA << 8;
for (int i = 0; i < 0xA0; i++) {
const Byte data = (*this)[addr + i];;
(*this)[0xFE00 + i] = data;
}
dmaTransferRequested = false;
const Word addr = memoryLayout.DMA << 8;
for (int i = 0; i < 0xA0; i++) {
const Byte data = (*this)[addr + i];
;
(*this)[0xFE00 + i] = data;
}
}
void AddressSpace::setTesting(const bool state) {
testing = state;
}
void AddressSpace::setTesting(const bool state) { testing = state; }

723
src/addressSpace.hpp
View File

@@ -1,383 +1,384 @@
#ifndef ADDRESSSPACE_HPP
#define ADDRESSSPACE_HPP
#include <fstream>
#include <filesystem>
#include <cstdint>
#include <cstring>
#include <filesystem>
#include <fstream>
#include <string>
#include <vector>
#include "defines.hpp"
class AddressSpace {
bool bootromLoaded = true;
Byte bootrom[BOOTROM_SIZE] = {0};
std::vector<Byte> game;
bool testing;
Byte testRam[0xFFFF];
Byte* cartridgeRam = nullptr;
bool bootromLoaded = true;
Byte bootrom[BOOTROM_SIZE] = {0};
std::vector<Byte> game;
bool testing;
Byte testRam[0xFFFF];
Byte *cartridgeRam = nullptr;
public:
AddressSpace() {
// Initialize the memory to zero
memoryLayout = {};
}
AddressSpace() {
// Initialize the memory to zero
memoryLayout = {};
}
struct {
Byte* romBank0; //[ROM_BANK_SIZE] Mapped to 0x0000
Byte* romBankSwitch; //[ROM_BANK_SIZE] Mapped to 0x4000
Byte vram[0x2000]; //Mapped to 0x8000
Byte* externalRam; //[0x2000]; Mapped to 0xA000
Byte memoryBank1[0x1000]; //Mapped to 0xC000
Byte memoryBank2[0x1000]; //Mapped to 0xD000
Byte oam[0xA0]; //Mapped to 0xFE00
Byte notUsable[0x60]; //Mapped to 0xFEA0
//General purpose hardware registers
Byte JOYP = 0xCF;
Byte SB;
Byte SC = 0x7E;
Byte DIV;
//Timer registers
Byte TIMA;
Byte TMA;
Byte TAC = 0xF8;
//interrupt flag and enable
Byte IF = 0xE1;;
//Sound registers
Byte NR10;
Byte NR11;
Byte NR12;
Byte NR13;
Byte NR14;
Byte NR20; //not used
Byte NR21;
Byte NR22;
Byte NR23;
Byte NR24;
Byte NR30;
Byte NR31;
Byte NR32;
Byte NR33;
Byte NR34;
Byte NR40; //unused
Byte NR41;
Byte NR42;
Byte NR43;
Byte NR44;
Byte NR50;
Byte NR51;
Byte NR52;
Byte waveRam[0x10];
//PPU registers
Byte LCDC;
Byte STAT;
Byte SCY;
Byte SCX;
Byte LY;
Byte LYC;
Byte DMA;
Byte BGP;
Byte OBP0;
Byte OBP1;
Byte WY;
Byte WX;
Byte specialRam[0x7F]; //Mapped to 0xFF80
Byte IE; // Mapped to 0xFFFF
} memoryLayout{};
struct {
Byte *romBank0; //[ROM_BANK_SIZE] Mapped to 0x0000
Byte *romBankSwitch; //[ROM_BANK_SIZE] Mapped to 0x4000
Byte vram[0x2000]; // Mapped to 0x8000
Byte *externalRam; //[0x2000]; Mapped to 0xA000
Byte memoryBank1[0x1000]; // Mapped to 0xC000
Byte memoryBank2[0x1000]; // Mapped to 0xD000
Byte oam[0xA0]; // Mapped to 0xFE00
Byte notUsable[0x60]; // Mapped to 0xFEA0
// General purpose hardware registers
Byte JOYP = 0xCF;
Byte SB;
Byte SC = 0x7E;
Byte DIV;
// Timer registers
Byte TIMA;
Byte TMA;
Byte TAC = 0xF8;
// interrupt flag and enable
Byte IF = 0xE1;
;
// Sound registers
Byte NR10;
Byte NR11;
Byte NR12;
Byte NR13;
Byte NR14;
Byte NR20; // not used
Byte NR21;
Byte NR22;
Byte NR23;
Byte NR24;
Byte NR30;
Byte NR31;
Byte NR32;
Byte NR33;
Byte NR34;
Byte NR40; // unused
Byte NR41;
Byte NR42;
Byte NR43;
Byte NR44;
Byte NR50;
Byte NR51;
Byte NR52;
Byte waveRam[0x10];
// PPU registers
Byte LCDC;
Byte STAT;
Byte SCY;
Byte SCX;
Byte LY;
Byte LYC;
Byte DMA;
Byte BGP;
Byte OBP0;
Byte OBP1;
Byte WY;
Byte WX;
Byte specialRam[0x7F]; // Mapped to 0xFF80
Byte IE; // Mapped to 0xFFFF
} memoryLayout{};
void unmapBootrom();
void mapBootrom();
bool getBootromState() const;
void loadBootrom(const std::string& filename);
void loadGame(const std::string& filename);
void unmapBootrom();
void mapBootrom();
bool getBootromState() const;
void loadBootrom(const std::string &filename);
void loadGame(const std::string &filename);
void determineMBCInfo();
bool MBCWrite(Word address);
Byte* MBCRead(Word address);
//prevents seg faults when programs with no MBC try to write to ROM
Byte dummyVal = 0;
void MBCUpdate();
void loadRomBank();
void createRamBank();
void loadRamBank();
MBCType MBC = {};
uint32_t romSize = 0;
uint32_t romBanks = 0;
uint32_t externalRamSize = 0;
uint32_t externalRamBanks = 0;
void determineMBCInfo();
bool MBCWrite(Word address);
Byte *MBCRead(Word address);
// prevents seg faults when programs with no MBC try to write to ROM
Byte dummyVal = 0;
void MBCUpdate();
void loadRomBank();
void createRamBank();
void loadRamBank();
MBCType MBC = {};
uint32_t romSize = 0;
uint32_t romBanks = 0;
uint32_t externalRamSize = 0;
uint32_t externalRamBanks = 0;
bool dmaTransferRequested = false;
void dmaTransfer();
bool dmaTransferRequested = false;
void dmaTransfer();
//Selected ROM Bank = (Secondary Bank << 5) + ROM Bank
Byte selectedRomBank = 0;
Byte romBankRegister = 0x00;
//2 bit register acts as secondary rom bank register or ram bank number
Byte twoBitBankRegister = 0x0;
Byte selectedExternalRamBank = 0;
Byte romRamSelect = 0x00;
Byte ramEnable = 0x00;
//MBC3
Byte latchClockData = 0x00;
Byte ramBankRTCRegister = 0x00;
// Selected ROM Bank = (Secondary Bank << 5) + ROM Bank
Byte selectedRomBank = 0;
Byte romBankRegister = 0x00;
// 2 bit register acts as secondary rom bank register or ram bank number
Byte twoBitBankRegister = 0x0;
Byte selectedExternalRamBank = 0;
Byte romRamSelect = 0x00;
Byte ramEnable = 0x00;
// MBC3
Byte latchClockData = 0x00;
Byte ramBankRTCRegister = 0x00;
void setTesting(bool state);
void setTesting(bool state);
//read
Byte operator[](const Word address) const {
if (testing)
return testRam[address];
if (address < 0x0100 && bootromLoaded)
return bootrom[address];
if (address < 0x4000)
return memoryLayout.romBank0[address];
if (address < 0x8000)
return memoryLayout.romBankSwitch[address - 0x4000];
if (address < 0xA000)
return memoryLayout.vram[address - 0x8000];
if (address < 0xC000) {
if (externalRamSize == 0)
return 0xFF;
return memoryLayout.externalRam[address - 0xA000];
}
if (address < 0xD000)
return memoryLayout.memoryBank1[address - 0xC000];
if (address < 0xE000)
return memoryLayout.memoryBank2[address - 0xD000];
if (address < 0xFE00)
return memoryLayout.memoryBank1[address - 0xE000];
if (address < 0xFEA0)
return memoryLayout.oam[address - 0xFE00];
if (address < 0xFF00) {
if ((memoryLayout.STAT & 0x03) == 2 || (memoryLayout.STAT & 0x03) == 3)
return 0xFF;
return 0x00;
}
if (address < 0xFF80)
switch (address) {
case 0xFF00:
return memoryLayout.JOYP;
case 0xFF01:
return memoryLayout.SB;
case 0xFF02:
return memoryLayout.SC;
case 0xFF04:
return memoryLayout.DIV;
case 0xFF05:
return memoryLayout.TIMA;
case 0xFF06:
return memoryLayout.TMA;
case 0xFF07:
return memoryLayout.TAC | 0xF8;;
case 0xFF0F:
return memoryLayout.IF | 0xE0;
case 0xFF10:
return memoryLayout.NR10;
case 0xFF11:
return memoryLayout.NR11;
case 0xFF12:
return memoryLayout.NR12;
case 0xFF13:
return memoryLayout.NR13;
case 0xFF14:
return memoryLayout.NR14;
case 0xFF16:
return memoryLayout.NR21;
case 0xFF17:
return memoryLayout.NR22;
case 0xFF18:
return memoryLayout.NR23;
case 0xFF19:
return memoryLayout.NR24;
case 0xFF1A:
return memoryLayout.NR30;
case 0xFF1B:
return memoryLayout.NR31;
case 0xFF1C:
return memoryLayout.NR32;
case 0xFF1D:
return memoryLayout.NR33;
case 0xFF1E:
return memoryLayout.NR34;
case 0xFF20:
return memoryLayout.NR41;
case 0xFF21:
return memoryLayout.NR42;
case 0xFF22:
return memoryLayout.NR43;
case 0xFF23:
return memoryLayout.NR44;
case 0xFF24:
return memoryLayout.NR50;
case 0xFF25:
return memoryLayout.NR51;
case 0xFF26:
return memoryLayout.NR52;
// PPU registers
case 0xFF40:
return memoryLayout.LCDC;
case 0xFF41:
return memoryLayout.STAT;
case 0xFF42:
return memoryLayout.SCY;
case 0xFF43:
return memoryLayout.SCX;
case 0xFF44:
//for debugging only
//return 0x90;
return memoryLayout.LY;
case 0xFF45:
return memoryLayout.LYC;
case 0xFF46:
return memoryLayout.DMA;
case 0xFF47:
return memoryLayout.BGP;
case 0xFF48:
return memoryLayout.OBP0;
case 0xFF49:
return memoryLayout.OBP1;
case 0xFF4A:
return memoryLayout.WY;
case 0xFF4B:
return memoryLayout.WX;
default:
if (address >= 0xFF30 && address <= 0xFF3F) {
return memoryLayout.waveRam[address - 0xFF30];
}
return 0xFF;
}
if (address < 0xFFFF)
return memoryLayout.specialRam[address - 0xFF80];
//0xFFFF
return memoryLayout.IE;
}
// read
Byte operator[](const Word address) const {
if (testing)
return testRam[address];
if (address < 0x0100 && bootromLoaded)
return bootrom[address];
if (address < 0x4000)
return memoryLayout.romBank0[address];
if (address < 0x8000)
return memoryLayout.romBankSwitch[address - 0x4000];
if (address < 0xA000)
return memoryLayout.vram[address - 0x8000];
if (address < 0xC000) {
if (externalRamSize == 0)
return 0xFF;
return memoryLayout.externalRam[address - 0xA000];
}
if (address < 0xD000)
return memoryLayout.memoryBank1[address - 0xC000];
if (address < 0xE000)
return memoryLayout.memoryBank2[address - 0xD000];
if (address < 0xFE00)
return memoryLayout.memoryBank1[address - 0xE000];
if (address < 0xFEA0)
return memoryLayout.oam[address - 0xFE00];
if (address < 0xFF00) {
if ((memoryLayout.STAT & 0x03) == 2 || (memoryLayout.STAT & 0x03) == 3)
return 0xFF;
return 0x00;
}
if (address < 0xFF80)
switch (address) {
case 0xFF00:
return memoryLayout.JOYP;
case 0xFF01:
return memoryLayout.SB;
case 0xFF02:
return memoryLayout.SC;
case 0xFF04:
return memoryLayout.DIV;
case 0xFF05:
return memoryLayout.TIMA;
case 0xFF06:
return memoryLayout.TMA;
case 0xFF07:
return memoryLayout.TAC | 0xF8;
;
case 0xFF0F:
return memoryLayout.IF | 0xE0;
case 0xFF10:
return memoryLayout.NR10;
case 0xFF11:
return memoryLayout.NR11;
case 0xFF12:
return memoryLayout.NR12;
case 0xFF13:
return memoryLayout.NR13;
case 0xFF14:
return memoryLayout.NR14;
case 0xFF16:
return memoryLayout.NR21;
case 0xFF17:
return memoryLayout.NR22;
case 0xFF18:
return memoryLayout.NR23;
case 0xFF19:
return memoryLayout.NR24;
case 0xFF1A:
return memoryLayout.NR30;
case 0xFF1B:
return memoryLayout.NR31;
case 0xFF1C:
return memoryLayout.NR32;
case 0xFF1D:
return memoryLayout.NR33;
case 0xFF1E:
return memoryLayout.NR34;
case 0xFF20:
return memoryLayout.NR41;
case 0xFF21:
return memoryLayout.NR42;
case 0xFF22:
return memoryLayout.NR43;
case 0xFF23:
return memoryLayout.NR44;
case 0xFF24:
return memoryLayout.NR50;
case 0xFF25:
return memoryLayout.NR51;
case 0xFF26:
return memoryLayout.NR52;
// PPU registers
case 0xFF40:
return memoryLayout.LCDC;
case 0xFF41:
return memoryLayout.STAT;
case 0xFF42:
return memoryLayout.SCY;
case 0xFF43:
return memoryLayout.SCX;
case 0xFF44:
// for debugging only
// return 0x90;
return memoryLayout.LY;
case 0xFF45:
return memoryLayout.LYC;
case 0xFF46:
return memoryLayout.DMA;
case 0xFF47:
return memoryLayout.BGP;
case 0xFF48:
return memoryLayout.OBP0;
case 0xFF49:
return memoryLayout.OBP1;
case 0xFF4A:
return memoryLayout.WY;
case 0xFF4B:
return memoryLayout.WX;
default:
if (address >= 0xFF30 && address <= 0xFF3F) {
return memoryLayout.waveRam[address - 0xFF30];
}
return 0xFF;
}
if (address < 0xFFFF)
return memoryLayout.specialRam[address - 0xFF80];
// 0xFFFF
return memoryLayout.IE;
}
//write
Byte& operator[](const Word address) {
dummyVal = 0xFF;
if (testing)
return testRam[address];
if (address < 0x0100 && bootromLoaded)
return bootrom[address];
if (address < 0x8000)
return (*MBCRead(address));
if (address < 0xA000)
return memoryLayout.vram[address - 0x8000];
if (address < 0xC000) {
if (externalRamSize == 0)
return dummyVal;
return memoryLayout.externalRam[address - 0xA000];
}
if (address < 0xD000)
return memoryLayout.memoryBank1[address - 0xC000];
if (address < 0xE000)
return memoryLayout.memoryBank2[address - 0xD000];
if (address < 0xFE00)
return memoryLayout.memoryBank1[address - 0xE000];
if (address < 0xFEA0)
return memoryLayout.oam[address - 0xFE00];
if (address < 0xFF00)
return memoryLayout.notUsable[address - 0xFEA0];
if (address < 0xFF80)
switch (address) {
case 0xFF00:
return memoryLayout.JOYP;
case 0xFF01:
return memoryLayout.SB;
case 0xFF02:
return memoryLayout.SC;
case 0xFF04:
memoryLayout.DIV = 0;
return dummyVal;
// Timer registers
case 0xFF05:
return memoryLayout.TIMA;
case 0xFF06:
return memoryLayout.TMA;
case 0xFF07:
return memoryLayout.TAC;
case 0xFF0F:
return memoryLayout.IF;
case 0xFF10:
return memoryLayout.NR10;
case 0xFF11:
return memoryLayout.NR11;
case 0xFF12:
return memoryLayout.NR12;
case 0xFF13:
return memoryLayout.NR13;
case 0xFF14:
return memoryLayout.NR14;
case 0xFF16:
return memoryLayout.NR21;
case 0xFF17:
return memoryLayout.NR22;
case 0xFF18:
return memoryLayout.NR23;
case 0xFF19:
return memoryLayout.NR24;
case 0xFF1A:
return memoryLayout.NR30;
case 0xFF1B:
return memoryLayout.NR31;
case 0xFF1C:
return memoryLayout.NR32;
case 0xFF1D:
return memoryLayout.NR33;
case 0xFF1E:
return memoryLayout.NR34;
case 0xFF20:
return memoryLayout.NR41;
case 0xFF21:
return memoryLayout.NR42;
case 0xFF22:
return memoryLayout.NR43;
case 0xFF23:
return memoryLayout.NR44;
case 0xFF24:
return memoryLayout.NR50;
case 0xFF25:
return memoryLayout.NR51;
case 0xFF26:
return memoryLayout.NR52;
case 0xFF40:
return memoryLayout.LCDC;
case 0xFF41:
return memoryLayout.STAT;
case 0xFF42:
return memoryLayout.SCY;
case 0xFF43:
return memoryLayout.SCX;
case 0xFF44:
dummyVal = memoryLayout.LY;
return dummyVal;
case 0xFF45:
return memoryLayout.LYC;
case 0xFF46:
dmaTransferRequested = true;
return memoryLayout.DMA;
case 0xFF47:
return memoryLayout.BGP;
case 0xFF48:
return memoryLayout.OBP0;
case 0xFF49:
return memoryLayout.OBP1;
case 0xFF4A:
return memoryLayout.WY;
case 0xFF4B:
return memoryLayout.WX;
default:
if (address >= 0xFF30 && address <= 0xFF3F) {
return memoryLayout.waveRam[address - 0xFF30];
}
return dummyVal;
}
if (address < 0xFFFF)
return memoryLayout.specialRam[address - 0xFF80];
//0xFFFF
return memoryLayout.IE;
}
// write
Byte &operator[](const Word address) {
dummyVal = 0xFF;
if (testing)
return testRam[address];
if (address < 0x0100 && bootromLoaded)
return bootrom[address];
if (address < 0x8000)
return (*MBCRead(address));
if (address < 0xA000)
return memoryLayout.vram[address - 0x8000];
if (address < 0xC000) {
if (externalRamSize == 0)
return dummyVal;
return memoryLayout.externalRam[address - 0xA000];
}
if (address < 0xD000)
return memoryLayout.memoryBank1[address - 0xC000];
if (address < 0xE000)
return memoryLayout.memoryBank2[address - 0xD000];
if (address < 0xFE00)
return memoryLayout.memoryBank1[address - 0xE000];
if (address < 0xFEA0)
return memoryLayout.oam[address - 0xFE00];
if (address < 0xFF00)
return memoryLayout.notUsable[address - 0xFEA0];
if (address < 0xFF80)
switch (address) {
case 0xFF00:
return memoryLayout.JOYP;
case 0xFF01:
return memoryLayout.SB;
case 0xFF02:
return memoryLayout.SC;
case 0xFF04:
memoryLayout.DIV = 0;
return dummyVal;
// Timer registers
case 0xFF05:
return memoryLayout.TIMA;
case 0xFF06:
return memoryLayout.TMA;
case 0xFF07:
return memoryLayout.TAC;
case 0xFF0F:
return memoryLayout.IF;
case 0xFF10:
return memoryLayout.NR10;
case 0xFF11:
return memoryLayout.NR11;
case 0xFF12:
return memoryLayout.NR12;
case 0xFF13:
return memoryLayout.NR13;
case 0xFF14:
return memoryLayout.NR14;
case 0xFF16:
return memoryLayout.NR21;
case 0xFF17:
return memoryLayout.NR22;
case 0xFF18:
return memoryLayout.NR23;
case 0xFF19:
return memoryLayout.NR24;
case 0xFF1A:
return memoryLayout.NR30;
case 0xFF1B:
return memoryLayout.NR31;
case 0xFF1C:
return memoryLayout.NR32;
case 0xFF1D:
return memoryLayout.NR33;
case 0xFF1E:
return memoryLayout.NR34;
case 0xFF20:
return memoryLayout.NR41;
case 0xFF21:
return memoryLayout.NR42;
case 0xFF22:
return memoryLayout.NR43;
case 0xFF23:
return memoryLayout.NR44;
case 0xFF24:
return memoryLayout.NR50;
case 0xFF25:
return memoryLayout.NR51;
case 0xFF26:
return memoryLayout.NR52;
case 0xFF40:
return memoryLayout.LCDC;
case 0xFF41:
return memoryLayout.STAT;
case 0xFF42:
return memoryLayout.SCY;
case 0xFF43:
return memoryLayout.SCX;
case 0xFF44:
dummyVal = memoryLayout.LY;
return dummyVal;
case 0xFF45:
return memoryLayout.LYC;
case 0xFF46:
dmaTransferRequested = true;
return memoryLayout.DMA;
case 0xFF47:
return memoryLayout.BGP;
case 0xFF48:
return memoryLayout.OBP0;
case 0xFF49:
return memoryLayout.OBP1;
case 0xFF4A:
return memoryLayout.WY;
case 0xFF4B:
return memoryLayout.WX;
default:
if (address >= 0xFF30 && address <= 0xFF3F) {
return memoryLayout.waveRam[address - 0xFF30];
}
return dummyVal;
}
if (address < 0xFFFF)
return memoryLayout.specialRam[address - 0xFF80];
// 0xFFFF
return memoryLayout.IE;
}
};
#endif //ADDRESSSPACE_HPP
#endif // ADDRESSSPACE_HPP

106
src/defines.hpp
View File

@@ -10,10 +10,10 @@
// 5 h - - Half Carry Flag (BCD)
// 4 cy C NC Carry Flag
// 3-0 - - - Not used
#define CARRY_FLAG 4 //'C'
#define CARRY_FLAG 4 //'C'
#define HALFCARRY_FLAG 5 //'H'
#define SUBTRACT_FLAG 6 //'N'
#define ZERO_FLAG 7 //'Z'
#define SUBTRACT_FLAG 6 //'N'
#define ZERO_FLAG 7 //'Z'
#define VBLANK_INTERRUPT 0
#define LCD_STAT_INTERRUPT 1
@@ -21,9 +21,9 @@
#define SERIAL_INTERRUPT 3
#define JOYPAD_INTERRUPT 4
#define T_CLOCK_FREQ 4194304 //2^22
#define T_CLOCK_FREQ 4194304 // 2^22
#define DIVIDER_REGISTER_FREQ (4194304/16384)
#define DIVIDER_REGISTER_FREQ (4194304 / 16384)
#define BOOTROM_SIZE 0x100
@@ -31,7 +31,7 @@
#define RESOLUTION_Y 144
#define SCREEN_BPP 3
//lcdc
// lcdc
#define BG_WINDOW_ENABLE 0
#define OBJ_ENABLE 1
#define OBJ_SIZE 2
@@ -41,13 +41,12 @@
#define WINDOW_TILE_MAP_AREA 6
#define LCD_ENABLE 7
//oam
// oam
#define PRIORITY 7
#define Y_FLIP 6
#define X_FLIP 5
#define OBJ_PALETTE 4
#define ROM_BANK_SIZE 0x4000
#define RAM_BANK_SIZE 0x2000
@@ -59,10 +58,10 @@
#define H_SYNC 9198
#define V_SYNC 59.73
#define HBLANK_DURATION 204 //PPU_MODE 0
#define HBLANK_DURATION 204 // PPU_MODE 0
#define VBLANK_DURATION 4560
#define SCANLINE_OAM_FREQ 80 //PPU_MODE 2
#define SCANLINE_VRAM_FREQ 80 //PPU_MODE 3
#define SCANLINE_OAM_FREQ 80 // PPU_MODE 2
#define SCANLINE_VRAM_FREQ 80 // PPU_MODE 3
#define WHITE 0xFFFFFFFF;
#define LIGHT_GRAY 0xFFAAAAAA;
@@ -70,52 +69,57 @@
#define BLACK 0xFF000000
struct Input {
bool UP = false;
bool DOWN = false;
bool LEFT = false;
bool RIGHT = false;
bool B = false;
bool A = false;
bool START = false;
bool SELECT = false;
bool UP = false;
bool DOWN = false;
bool LEFT = false;
bool RIGHT = false;
bool B = false;
bool A = false;
bool START = false;
bool SELECT = false;
};
enum MBCType {
romOnly = 0x00,
MBC1 = 0x01,
MBC1Ram = 0x02,
MBC1RamBattery = 0x03,
MBC2 = 0x05,
MBC2Battery = 0x06,
RomRam = 0x08, //unused
RomRamBattery = 0x09, //unused
MMM01 = 0x0B, //multigame roms only
MMM01Ram = 0x0C,
MMM01RamBattery = 0x0D,
MBC3TimerBattery = 0x0F,
MBC3TimerRamBattery = 0x10,
MBC3 = 0x11,
MBC3Ram = 0x12, // MBC3 with 64 KiB of SRAM refers to MBC30, used only in Pocket Monsters: Crystal Version.
MBC3RamBattery = 0x13,
MBC5 = 0x19,
MBC5Ram = 0x1A,
MBC5RamBattery = 0x1B,
MBC5Rumble = 0x1C,
MBC5RumbleRam = 0x1D,
MBC5RumbleRamBattery = 0x1E,
MBC6 = 0x20,
MBC7SensorRumbleRamBattery = 0x22,
PocketCamera = 0xFC,
BandaiTama5 = 0xFD,
HuC3 = 0xFE,
HuC1RamBattery = 0xFF
romOnly = 0x00,
MBC1 = 0x01,
MBC1Ram = 0x02,
MBC1RamBattery = 0x03,
MBC2 = 0x05,
MBC2Battery = 0x06,
RomRam = 0x08, // unused
RomRamBattery = 0x09, // unused
MMM01 = 0x0B, // multigame roms only
MMM01Ram = 0x0C,
MMM01RamBattery = 0x0D,
MBC3TimerBattery = 0x0F,
MBC3TimerRamBattery = 0x10,
MBC3 = 0x11,
MBC3Ram = 0x12, // MBC3 with 64 KiB of SRAM refers to MBC30, used only in
// Pocket Monsters: Crystal Version.
MBC3RamBattery = 0x13,
MBC5 = 0x19,
MBC5Ram = 0x1A,
MBC5RamBattery = 0x1B,
MBC5Rumble = 0x1C,
MBC5RumbleRam = 0x1D,
MBC5RumbleRamBattery = 0x1E,
MBC6 = 0x20,
MBC7SensorRumbleRamBattery = 0x22,
PocketCamera = 0xFC,
BandaiTama5 = 0xFD,
HuC3 = 0xFE,
HuC1RamBattery = 0xFF
};
enum PPUMode {
mode0, // Horizontal Blank (Mode 0): No access to video RAM, occurs during horizontal blanking period.
mode1, // Vertical Blank (Mode 1): No access to video RAM, occurs during vertical blanking period.
mode2, // OAM Search (Mode 2): Access to OAM (Object Attribute Memory) only, sprite evaluation.
mode3 // Pixel Transfer (Mode 3): Access to both OAM and video RAM, actual pixel transfer to the screen.
mode0, // Horizontal Blank (Mode 0): No access to video RAM, occurs during
// horizontal blanking period.
mode1, // Vertical Blank (Mode 1): No access to video RAM, occurs during
// vertical blanking period.
mode2, // OAM Search (Mode 2): Access to OAM (Object Attribute Memory) only,
// sprite evaluation.
mode3 // Pixel Transfer (Mode 3): Access to both OAM and video RAM, actual
// pixel transfer to the screen.
};
#endif

3087
src/extendedOpcodeResolver.cpp
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File diff suppressed because it is too large Load Diff

358
src/gameboy.cpp
View File

@@ -1,202 +1,194 @@
#include <iostream>
#include "gameboy.hpp"
#include <iostream>
void GameBoy::addCycles(const uint8_t ticks) {
cycles += ticks;
if (ppuEnabled) {
ppuCycles += ticks;
}
lastOpTicks = ticks;
cycles += ticks;
if (ppuEnabled) {
ppuCycles += ticks;
}
lastOpTicks = ticks;
}
GameboyTestState GameBoy::runTest(GameboyTestState initial) {
addressSpace.setTesting(true);
addressSpace.setTesting(true);
PC = initial.PC;
SP = initial.SP;
AF.hi = initial.A;
AF.lo = initial.F;
BC.hi = initial.B;
BC.lo = initial.C;
DE.hi = initial.D;
DE.lo = initial.E;
HL.hi = initial.H;
HL.lo = initial.L;
addressSpace.memoryLayout.IE = 1;
PC = initial.PC;
SP = initial.SP;
AF.hi = initial.A;
AF.lo = initial.F;
BC.hi = initial.B;
BC.lo = initial.C;
DE.hi = initial.D;
DE.lo = initial.E;
HL.hi = initial.H;
HL.lo = initial.L;
addressSpace.memoryLayout.IE = 1;
for (const auto& [addr, val] : initial.RAM) {
addressSpace[addr] = val;
}
for (const auto &[addr, val] : initial.RAM) {
addressSpace[addr] = val;
}
opcodeResolver();
opcodeResolver();
std::vector<std::tuple<Word, Byte>> returnRAM;
for (const auto& [addr, val] : initial.RAM) {
returnRAM.emplace_back(addr, addressSpace[addr]);
}
return {
PC, SP,
AF.hi, AF.lo,
BC.hi, BC.lo,
DE.hi, DE.lo,
HL.hi, HL.lo,
returnRAM
};
std::vector<std::tuple<Word, Byte>> returnRAM;
for (const auto &[addr, val] : initial.RAM) {
returnRAM.emplace_back(addr, addressSpace[addr]);
}
return {PC, SP, AF.hi, AF.lo, BC.hi, BC.lo,
DE.hi, DE.lo, HL.hi, HL.lo, returnRAM};
}
void GameBoy::start(const std::string &bootrom, const std::string &game) {
addressSpace.loadBootrom(bootrom);
addressSpace.loadGame(game);
addressSpace.determineMBCInfo();
addressSpace.createRamBank();
void GameBoy::start(const std::string& bootrom, const std::string& game) {
addressSpace.loadBootrom(bootrom);
addressSpace.loadGame(game);
addressSpace.determineMBCInfo();
addressSpace.createRamBank();
bool quit = false;
bool setIME = false;
bool debug = false;
bool step = false;
bool quit = false;
bool setIME = false;
bool debug = false;
bool step = false;
while (!quit) {
// Event loop
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
quit = true;
break;
case SDL_KEYDOWN:
switch (event.key.keysym.sym) {
case SDLK_a:
joypadInput.LEFT = true;
break;
case SDLK_d:
joypadInput.RIGHT = true;
break;
case SDLK_w:
joypadInput.UP = true;
break;
case SDLK_s:
joypadInput.DOWN = true;
break;
case SDLK_k:
joypadInput.A = true;
break;
case SDLK_l:
joypadInput.B = true;
break;
case SDLK_o:
joypadInput.SELECT = true;
break;
case SDLK_p:
joypadInput.START = true;
break;
case SDLK_h:
debug = !debug;
break;
case SDLK_n:
step = true;
break;
default:
break;
}
break;
case SDL_KEYUP:
switch (event.key.keysym.sym) {
case SDLK_a:
joypadInput.LEFT = false;
break;
case SDLK_d:
joypadInput.RIGHT = false;
break;
case SDLK_w:
joypadInput.UP = false;
break;
case SDLK_s:
joypadInput.DOWN = false;
break;
case SDLK_k:
joypadInput.A = false;
break;
case SDLK_l:
joypadInput.B = false;
break;
case SDLK_o:
joypadInput.SELECT = false;
break;
case SDLK_p:
joypadInput.START = false;
break;
default:
break;
}
break;
default:
break;
}
}
while (!quit) {
// Event loop
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
quit = true;
break;
case SDL_KEYDOWN:
switch (event.key.keysym.sym) {
case SDLK_a:
joypadInput.LEFT = true;
break;
case SDLK_d:
joypadInput.RIGHT = true;
break;
case SDLK_w:
joypadInput.UP = true;
break;
case SDLK_s:
joypadInput.DOWN = true;
break;
case SDLK_k:
joypadInput.A = true;
break;
case SDLK_l:
joypadInput.B = true;
break;
case SDLK_o:
joypadInput.SELECT = true;
break;
case SDLK_p:
joypadInput.START = true;
break;
case SDLK_h:
debug = !debug;
break;
case SDLK_n:
step = true;
break;
default:
break;
}
break;
case SDL_KEYUP:
switch (event.key.keysym.sym) {
case SDLK_a:
joypadInput.LEFT = false;
break;
case SDLK_d:
joypadInput.RIGHT = false;
break;
case SDLK_w:
joypadInput.UP = false;
break;
case SDLK_s:
joypadInput.DOWN = false;
break;
case SDLK_k:
joypadInput.A = false;
break;
case SDLK_l:
joypadInput.B = false;
break;
case SDLK_o:
joypadInput.SELECT = false;
break;
case SDLK_p:
joypadInput.START = false;
break;
default:
break;
}
break;
default:
break;
}
}
while (!rendered) {
if (debug == true && step == false)
break;
step = false;
joypadHandler();
if (PC > 0xFF && addressSpace.getBootromState()) {
addressSpace.unmapBootrom();
}
ppuEnabled = addressSpace.memoryLayout.LCDC & 0x80;
prevTMA = addressSpace.memoryLayout.TMA;
while (!rendered) {
if (debug == true && step == false)
break;
step = false;
joypadHandler();
if (PC > 0xFF && addressSpace.getBootromState()) {
addressSpace.unmapBootrom();
}
ppuEnabled = addressSpace.memoryLayout.LCDC & 0x80;
prevTMA = addressSpace.memoryLayout.TMA;
if (debug) {
printf("A: %.2X F: %.2X B: %.2X C: %.2X D: %.2X E: %.2X H: %.2X L: "
"%.2X SP: %.4X PC: 00:%.4X (%.2X %.2X %.2X %.2X)\n",
AF.hi, AF.lo, BC.hi, BC.lo, DE.hi, DE.lo, HL.hi, HL.lo, SP, PC,
readOnlyAddressSpace[PC], readOnlyAddressSpace[PC + 1],
readOnlyAddressSpace[PC + 2], readOnlyAddressSpace[PC + 3]);
if (debug) {
printf(
"A: %.2X F: %.2X B: %.2X C: %.2X D: %.2X E: %.2X H: %.2X L: %.2X SP: %.4X PC: 00:%.4X (%.2X %.2X %.2X %.2X)\n",
AF.hi, AF.lo, BC.hi, BC.lo, DE.hi, DE.lo, HL.hi, HL.lo, SP, PC, readOnlyAddressSpace[PC],
readOnlyAddressSpace[PC + 1], readOnlyAddressSpace[PC + 2], readOnlyAddressSpace[PC + 3]);
// printf("Cycles: %lu, Opcode: 0x%.2x PPU cycles: %lu, PPMode: %d\n",
// cycles, readOnlyAddressSpace[PC],
// cyclesSinceLastScanline(), currentMode);
// printf("AF:0x%.4x, BC:0x%.4x\n", AF.reg, BC.reg);
// printf("DE:0x%.4x, HL:0x%.4x\n", DE.reg, HL.reg);
// printf("IME:%d IF:0x%.2x IE:0x%.2x\n", IME, (*IF), (*IE));
// printf("PC:0x%.4x, SP:0x%.4x\n", PC, SP);
// printf("LCDC:%.2x STAT:0x%.2x LY:%d LYC:%d\n", (*LCDC), (*STAT),
// (*LY), (*LYC)); printf("\n");
}
// printf("Cycles: %lu, Opcode: 0x%.2x PPU cycles: %lu, PPMode: %d\n", cycles, readOnlyAddressSpace[PC],
// cyclesSinceLastScanline(), currentMode);
// printf("AF:0x%.4x, BC:0x%.4x\n", AF.reg, BC.reg);
// printf("DE:0x%.4x, HL:0x%.4x\n", DE.reg, HL.reg);
// printf("IME:%d IF:0x%.2x IE:0x%.2x\n", IME, (*IF), (*IE));
// printf("PC:0x%.4x, SP:0x%.4x\n", PC, SP);
// printf("LCDC:%.2x STAT:0x%.2x LY:%d LYC:%d\n", (*LCDC), (*STAT), (*LY), (*LYC));
// printf("\n");
}
if (!halted) {
opcodeResolver();
addressSpace.MBCUpdate();
}
else {
addCycles(4);
}
timingHandler();
interruptHandler();
if (ppuEnabled) {
ppuUpdate();
}
else {
ppuCycles = 2;
lastScanline = 0;
lastRefresh = 0;
addressSpace.memoryLayout.LY = 0x00;
addressSpace.memoryLayout.STAT &= 0xfc;
}
if (setIME) {
IME = 1;
setIME = false;
}
if (IME_togge) {
setIME = true;
IME_togge = false;
}
if (addressSpace.dmaTransferRequested) {
cyclesUntilDMATransfer -= lastOpTicks;
if (cyclesUntilDMATransfer <= 0) {
cyclesUntilDMATransfer = 160;
addressSpace.dmaTransfer();
}
}
}
rendered = false;
}
if (!halted) {
opcodeResolver();
addressSpace.MBCUpdate();
} else {
addCycles(4);
}
timingHandler();
interruptHandler();
if (ppuEnabled) {
ppuUpdate();
} else {
ppuCycles = 2;
lastScanline = 0;
lastRefresh = 0;
addressSpace.memoryLayout.LY = 0x00;
addressSpace.memoryLayout.STAT &= 0xfc;
}
if (setIME) {
IME = 1;
setIME = false;
}
if (IME_togge) {
setIME = true;
IME_togge = false;
}
if (addressSpace.dmaTransferRequested) {
cyclesUntilDMATransfer -= lastOpTicks;
if (cyclesUntilDMATransfer <= 0) {
cyclesUntilDMATransfer = 160;
addressSpace.dmaTransfer();
}
}
}
rendered = false;
}
}

290
src/gameboy.hpp
View File

@@ -1,186 +1,172 @@
#ifndef GBPP_SRC_GAMEBOY_HPP_
#define GBPP_SRC_GAMEBOY_HPP_
#include <filesystem>
#include <cstdint>
#include <string>
#include <SDL.h>
#include "defines.hpp"
#include "addressSpace.hpp"
#include "defines.hpp"
#include "testing.hpp"
#include <SDL.h>
#include <cstdint>
#include <filesystem>
#include <string>
union RegisterPair {
Word reg; //register.reg == (hi << 8) + lo. (hi is more significant than lo)
Word reg; // register.reg == (hi << 8) + lo. (hi is more significant than lo)
struct {
Byte lo;
Byte hi;
};
struct {
Byte lo;
Byte hi;
};
};
class GameBoy {
//T-cycles not M-cycles (4 T-cycles = 1 M-cycle)
uint64_t cycles = 0;
//Start at 2 T-cycles https://github.com/Gekkio/mooneye-test-suite/blob/main/acceptance/ppu/lcdon_timing-GS.s
uint64_t ppuCycles = 2;
bool ppuEnabled = false;
uint16_t lastOpTicks = 0;
uint64_t lastRefresh = 0;
uint64_t lastScanline = 0;
uint64_t cyclesToStayInHblank = -1;
uint64_t lastDivUpdate = 0;
bool rendered = false;
// T-cycles not M-cycles (4 T-cycles = 1 M-cycle)
uint64_t cycles = 0;
// Start at 2 T-cycles
// https://github.com/Gekkio/mooneye-test-suite/blob/main/acceptance/ppu/lcdon_timing-GS.s
uint64_t ppuCycles = 2;
bool ppuEnabled = false;
uint16_t lastOpTicks = 0;
uint64_t lastRefresh = 0;
uint64_t lastScanline = 0;
uint64_t cyclesToStayInHblank = -1;
uint64_t lastDivUpdate = 0;
bool rendered = false;
uint8_t IME = 0; //enables interupts
// EI is actually "disable interrupts for one instruction, then enable them"
// This keeps track of that
bool IME_togge = false;
uint8_t IME = 0; // enables interupts
// EI is actually "disable interrupts for one instruction, then enable them"
// This keeps track of that
bool IME_togge = false;
//Accumulator and flags
RegisterPair AF = {0};
//General purpose CPU registers
RegisterPair BC = {0};
RegisterPair DE = {0};
RegisterPair HL = {0};
// Accumulator and flags
RegisterPair AF = {0};
// General purpose CPU registers
RegisterPair BC = {0};
RegisterPair DE = {0};
RegisterPair HL = {0};
Word SP = 0xFFFE; //stack pointer
Word PC = 0x0000; //program counter
Word SP = 0xFFFE; // stack pointer
Word PC = 0x0000; // program counter
AddressSpace addressSpace;
const AddressSpace& readOnlyAddressSpace = addressSpace;
AddressSpace addressSpace;
const AddressSpace &readOnlyAddressSpace = addressSpace;
PPUMode currentMode = PPUMode::mode0;
Byte windowLineCounter = 0;
int16_t cyclesUntilDMATransfer = 160;
PPUMode currentMode = PPUMode::mode0;
Byte windowLineCounter = 0;
int16_t cyclesUntilDMATransfer = 160;
Byte prevTMA = 0;
uint64_t lastTIMAUpdate = 0;
bool halted = false;
bool haltBug = true;
bool stopped = false;
Byte prevTMA = 0;
uint64_t lastTIMAUpdate = 0;
bool halted = false;
bool haltBug = true;
bool stopped = false;
//3 colour channels
uint32_t* framebuffer = new uint32_t[RESOLUTION_X * RESOLUTION_Y * SCREEN_BPP];
SDL_Window* screen = nullptr;
SDL_Renderer* renderer = nullptr;
SDL_Texture* texture = nullptr;
SDL_Event event = {0};
uint32_t frameStart = 0;
uint32_t frameTime = 0;
const int frameDelay = 1000 / V_SYNC;
// 3 colour channels
uint32_t *framebuffer =
new uint32_t[RESOLUTION_X * RESOLUTION_Y * SCREEN_BPP];
SDL_Window *screen = nullptr;
SDL_Renderer *renderer = nullptr;
SDL_Texture *texture = nullptr;
SDL_Event event = {0};
uint32_t frameStart = 0;
uint32_t frameTime = 0;
const int frameDelay = 1000 / V_SYNC;
Input joypadInput;
void joypadHandler();
Input joypadInput;
void joypadHandler();
void opcodeResolver();
void opcodeResolver();
bool statInteruptLine = false;
bool LCDCBitEnabled(Byte bit) const;
void incLY();
void ppuUpdate();
void drawLine();
static bool oamBitEnabled(Byte oamAttributeByte, Byte bit);
static unsigned int getColourFromPalette(Byte palette);
void SDL2present();
bool statInteruptLine = false;
bool LCDCBitEnabled(Byte bit) const;
void incLY();
void ppuUpdate();
void drawLine();
static bool oamBitEnabled(Byte oamAttributeByte, Byte bit);
static unsigned int getColourFromPalette(Byte palette);
void SDL2present();
void checkPPUMode();
void setPPUMode(PPUMode mode);
uint64_t cyclesSinceLastScanline() const;
uint64_t cyclesSinceLastRefresh() const;
void checkPPUMode();
void setPPUMode(PPUMode mode);
uint64_t cyclesSinceLastScanline() const;
uint64_t cyclesSinceLastRefresh() const;
void timingHandler();
void timingHandler();
void interruptHandler();
bool testInterruptEnabled(Byte interrupt) const;
void setInterrupt(Byte interrupt);
void resetInterrupt(Byte interrupt);
void interruptHandler();
bool testInterruptEnabled(Byte interrupt) const;
void setInterrupt(Byte interrupt);
void resetInterrupt(Byte interrupt);
void VBlankHandle();
void LCDStatHandle();
void timerHandle();
void serialHandle();
void joypadHandle();
void VBlankHandle();
void LCDStatHandle();
void timerHandle();
void serialHandle();
void joypadHandle();
void setFlag(Byte bit);
void resetFlag(Byte bit);
bool getFlag(Byte bit) const;
void setFlag(Byte bit);
void resetFlag(Byte bit);
bool getFlag(Byte bit) const;
Word getWordPC();
Byte getBytePC();
Word getWordSP();
Byte getByteSP();
Word getWordPC();
Byte getBytePC();
Word getWordSP();
Byte getByteSP();
void addCycles(Byte ticks);
void addCycles(Byte ticks);
//OPCODE FUNCTIONS
template <typename T>
void ld(T& dest, T src);
void ldW(Word destAddr, Word src);
template <typename T>
void orBitwise(T& dest, T src);
template <typename T>
void andBitwise(T& dest, T src);
template <typename T>
void xorBitwise(T& dest, T src);
void bit(Byte testBit, Byte reg);
void extendedOpcodeResolver();
static void set(uint8_t testBit, uint8_t& reg);
static void res(uint8_t testBit, uint8_t& reg);
template <typename T>
void jp(T address);
template <typename T>
bool jrNZ(T offset);
template <class T>
bool jrNC(T offset);
template <class T>
bool jrC(T offset);
template <typename T>
void inc(T& reg);
template <typename T>
void call(T address);
void halt();
void daa();
void stop();
void cp(Byte value);
template <typename T>
void dec(T& reg);
template <typename T>
bool jrZ(T offset);
void sub(Byte value);
void sbc(Byte value);
template <typename T>
void jr(T OFFSET);
void push(Word reg);
void rl(Byte& reg);
void sla(Byte& reg);
void sra(uint8_t& reg);
void srl(uint8_t& reg);
void rrc(Byte& reg);
void rrca();
void rra();
void rr(Byte& reg);
void rlc(Byte& reg);
void rlca();
void rla();
template <typename T>
void pop(T& reg);
template <typename T>
void rst(T address);
void ret();
template <typename T>
void add(T& reg, T value);
void adc(Byte value);
void cpl();
void scf();
void ccf();
void swap(Byte& value);
// OPCODE FUNCTIONS
template <typename T> void ld(T &dest, T src);
void ldW(Word destAddr, Word src);
template <typename T> void orBitwise(T &dest, T src);
template <typename T> void andBitwise(T &dest, T src);
template <typename T> void xorBitwise(T &dest, T src);
void bit(Byte testBit, Byte reg);
void extendedOpcodeResolver();
static void set(uint8_t testBit, uint8_t &reg);
static void res(uint8_t testBit, uint8_t &reg);
template <typename T> void jp(T address);
template <typename T> bool jrNZ(T offset);
template <class T> bool jrNC(T offset);
template <class T> bool jrC(T offset);
template <typename T> void inc(T &reg);
template <typename T> void call(T address);
void halt();
void daa();
void stop();
void cp(Byte value);
template <typename T> void dec(T &reg);
template <typename T> bool jrZ(T offset);
void sub(Byte value);
void sbc(Byte value);
template <typename T> void jr(T OFFSET);
void push(Word reg);
void rl(Byte &reg);
void sla(Byte &reg);
void sra(uint8_t &reg);
void srl(uint8_t &reg);
void rrc(Byte &reg);
void rrca();
void rra();
void rr(Byte &reg);
void rlc(Byte &reg);
void rlca();
void rla();
template <typename T> void pop(T &reg);
template <typename T> void rst(T address);
void ret();
template <typename T> void add(T &reg, T value);
void adc(Byte value);
void cpl();
void scf();
void ccf();
void swap(Byte &value);
public:
void start(const std::string& bootrom, const std::string& game);
void SDL2setup();
void SDL2destroy() const;
void start(const std::string &bootrom, const std::string &game);
void SDL2setup();
void SDL2destroy() const;
GameboyTestState runTest(GameboyTestState initial);
GameboyTestState runTest(GameboyTestState initial);
};
#endif //GBPP_SRC_GAMEBOY_HPP_
#endif // GBPP_SRC_GAMEBOY_HPP_

126
src/interupts.cpp
View File

@@ -2,88 +2,94 @@
#include "gameboy.hpp"
bool GameBoy::testInterruptEnabled(const Byte interrupt) const {
return readOnlyAddressSpace.memoryLayout.IE & static_cast<Byte>(1 << interrupt);
return readOnlyAddressSpace.memoryLayout.IE &
static_cast<Byte>(1 << interrupt);
}
void GameBoy::setInterrupt(const Byte interrupt) {
addressSpace.memoryLayout.IF |= 1 << interrupt;
addressSpace.memoryLayout.IF |= 0xE0;
addressSpace.memoryLayout.IF |= 1 << interrupt;
addressSpace.memoryLayout.IF |= 0xE0;
}
void GameBoy::resetInterrupt(const Byte interrupt) {
addressSpace.memoryLayout.IF &= ~(1 << interrupt);
addressSpace.memoryLayout.IF |= 0xE0;
addressSpace.memoryLayout.IF &= ~(1 << interrupt);
addressSpace.memoryLayout.IF |= 0xE0;
}
void GameBoy::interruptHandler() {
if (readOnlyAddressSpace.memoryLayout.IF & static_cast<Byte>(1 << VBLANK_INTERRUPT) && testInterruptEnabled(
VBLANK_INTERRUPT)) {
if (IME)
VBlankHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF & static_cast<Byte>(1 << LCD_STAT_INTERRUPT) && testInterruptEnabled(
LCD_STAT_INTERRUPT)) {
if (IME)
LCDStatHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF & static_cast<Byte>(1 << TIMER_INTERRUPT) && testInterruptEnabled(
TIMER_INTERRUPT)) {
if (IME)
timerHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF & static_cast<Byte>(1 << SERIAL_INTERRUPT) && testInterruptEnabled(
SERIAL_INTERRUPT)) {
if (IME)
serialHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF & static_cast<Byte>(1 << JOYPAD_INTERRUPT) && testInterruptEnabled(
JOYPAD_INTERRUPT)) {
if (IME)
joypadHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF &
static_cast<Byte>(1 << VBLANK_INTERRUPT) &&
testInterruptEnabled(VBLANK_INTERRUPT)) {
if (IME)
VBlankHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF &
static_cast<Byte>(1 << LCD_STAT_INTERRUPT) &&
testInterruptEnabled(LCD_STAT_INTERRUPT)) {
if (IME)
LCDStatHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF &
static_cast<Byte>(1 << TIMER_INTERRUPT) &&
testInterruptEnabled(TIMER_INTERRUPT)) {
if (IME)
timerHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF &
static_cast<Byte>(1 << SERIAL_INTERRUPT) &&
testInterruptEnabled(SERIAL_INTERRUPT)) {
if (IME)
serialHandle();
halted = false;
}
if (readOnlyAddressSpace.memoryLayout.IF &
static_cast<Byte>(1 << JOYPAD_INTERRUPT) &&
testInterruptEnabled(JOYPAD_INTERRUPT)) {
if (IME)
joypadHandle();
halted = false;
}
}
void GameBoy::VBlankHandle() {
IME = 0;
push(PC);
addCycles(20);
PC = 0x40;
resetInterrupt(VBLANK_INTERRUPT);
IME = 0;
push(PC);
addCycles(20);
PC = 0x40;
resetInterrupt(VBLANK_INTERRUPT);
}
void GameBoy::LCDStatHandle() {
IME = 0;
push(PC);
addCycles(20);
PC = 0x48;
resetInterrupt(LCD_STAT_INTERRUPT);
IME = 0;
push(PC);
addCycles(20);
PC = 0x48;
resetInterrupt(LCD_STAT_INTERRUPT);
}
void GameBoy::timerHandle() {
IME = 0;
push(PC);
addCycles(20);
PC = 0x50;
resetInterrupt(TIMER_INTERRUPT);
IME = 0;
push(PC);
addCycles(20);
PC = 0x50;
resetInterrupt(TIMER_INTERRUPT);
}
void GameBoy::serialHandle() {
IME = 0;
push(PC);
addCycles(20);
PC = 0x58;
resetInterrupt(SERIAL_INTERRUPT);
IME = 0;
push(PC);
addCycles(20);
PC = 0x58;
resetInterrupt(SERIAL_INTERRUPT);
}
void GameBoy::joypadHandle() {
IME = 0;
push(PC);
addCycles(20);
PC = 0x60;
resetInterrupt(JOYPAD_INTERRUPT);
IME = 0;
push(PC);
addCycles(20);
PC = 0x60;
resetInterrupt(JOYPAD_INTERRUPT);
}

72
src/joypad.cpp
View File

@@ -1,44 +1,44 @@
#include "gameboy.hpp"
#include "defines.hpp"
#include "gameboy.hpp"
void GameBoy::joypadHandler() {
const Byte joyP = addressSpace.memoryLayout.JOYP;
const bool buttons = (joyP & 0x20) == 0;
const bool dpad = (joyP & 0x10) == 0;
const Byte joyP = addressSpace.memoryLayout.JOYP;
const bool buttons = (joyP & 0x20) == 0;
const bool dpad = (joyP & 0x10) == 0;
addressSpace.memoryLayout.JOYP |= 0xCF;
addressSpace.memoryLayout.JOYP |= 0xCF;
if (buttons && !dpad) {
if (joypadInput.A)
addressSpace.memoryLayout.JOYP &= ~0x1;
if (joypadInput.B)
addressSpace.memoryLayout.JOYP &= ~0x2;
if (joypadInput.SELECT)
addressSpace.memoryLayout.JOYP &= ~0x4;
if (joypadInput.START)
addressSpace.memoryLayout.JOYP &= ~0x8;
}
if (!buttons && dpad) {
if (joypadInput.RIGHT)
addressSpace.memoryLayout.JOYP &= ~0x1;
if (joypadInput.LEFT)
addressSpace.memoryLayout.JOYP &= ~0x2;
if (joypadInput.UP)
addressSpace.memoryLayout.JOYP &= ~0x4;
if (joypadInput.DOWN)
addressSpace.memoryLayout.JOYP &= ~0x8;
}
if (buttons && !dpad) {
if (joypadInput.A)
addressSpace.memoryLayout.JOYP &= ~0x1;
if (joypadInput.B)
addressSpace.memoryLayout.JOYP &= ~0x2;
if (joypadInput.SELECT)
addressSpace.memoryLayout.JOYP &= ~0x4;
if (joypadInput.START)
addressSpace.memoryLayout.JOYP &= ~0x8;
}
if (!buttons && dpad) {
if (joypadInput.RIGHT)
addressSpace.memoryLayout.JOYP &= ~0x1;
if (joypadInput.LEFT)
addressSpace.memoryLayout.JOYP &= ~0x2;
if (joypadInput.UP)
addressSpace.memoryLayout.JOYP &= ~0x4;
if (joypadInput.DOWN)
addressSpace.memoryLayout.JOYP &= ~0x8;
}
if (buttons && dpad) {
addressSpace.memoryLayout.JOYP |= 0xCF;
if (buttons && dpad) {
addressSpace.memoryLayout.JOYP |= 0xCF;
if (joypadInput.RIGHT && joypadInput.A)
addressSpace.memoryLayout.JOYP &= ~0x1;
if (joypadInput.LEFT && joypadInput.B)
addressSpace.memoryLayout.JOYP &= ~0x2;
if (joypadInput.UP && joypadInput.SELECT)
addressSpace.memoryLayout.JOYP &= ~0x4;
if (joypadInput.DOWN && joypadInput.START)
addressSpace.memoryLayout.JOYP &= ~0x8;
}
if (joypadInput.RIGHT && joypadInput.A)
addressSpace.memoryLayout.JOYP &= ~0x1;
if (joypadInput.LEFT && joypadInput.B)
addressSpace.memoryLayout.JOYP &= ~0x2;
if (joypadInput.UP && joypadInput.SELECT)
addressSpace.memoryLayout.JOYP &= ~0x4;
if (joypadInput.DOWN && joypadInput.START)
addressSpace.memoryLayout.JOYP &= ~0x8;
}
}

147
src/main.cpp
View File

@@ -1,94 +1,91 @@
#include <string>
#include <filesystem>
#include <vector>
#include "3rdParty/json.hpp"
#include "gameboy.hpp"
#include <filesystem>
#include <string>
#include <vector>
namespace fs = std::filesystem;
using json = nlohmann::json;
void runJSONTests(GameBoy* gb);
void runJSONTests(GameBoy *gb);
int main(int argc, char** argv) {
if (argc != 3) {
std::cerr << "Usage: " << argv[0] << " <bios> <game>\n" << std::endl;
return 1;
}
int main(int argc, char **argv) {
if (argc != 3) {
std::cerr << "Usage: " << argv[0] << " <bios> <game>\n" << std::endl;
return 1;
}
auto* gb = new GameBoy();
gb->SDL2setup();
//runJSONTests(gb);
gb->start(argv[1], argv[2]);
gb->SDL2destroy();
delete gb;
auto *gb = new GameBoy();
gb->SDL2setup();
// runJSONTests(gb);
gb->start(argv[1], argv[2]);
gb->SDL2destroy();
delete gb;
return 0;
return 0;
}
void runJSONTests(GameBoy* gb) {
std::string path = "../tests/sm83/v1";
std::vector<std::string> testFiles;
int failed = 0;
for (const auto& entry : fs::directory_iterator(path))
testFiles.emplace_back(entry.path());
void runJSONTests(GameBoy *gb) {
std::string path = "../tests/sm83/v1";
std::vector<std::string> testFiles;
int failed = 0;
for (const auto &entry : fs::directory_iterator(path))
testFiles.emplace_back(entry.path());
for (const auto &testFile : testFiles) {
std::ifstream file(testFile);
std::cout << "Running test: " << testFile << std::endl;
const json tests = json::parse(file);
for (const auto& testFile : testFiles) {
std::ifstream file(testFile);
std::cout << "Running test: " << testFile << std::endl;
const json tests = json::parse(file);
for (auto &test : tests) {
// create state
std::vector<std::tuple<Word, Byte>> initialRAM;
for (int i = 0; i < test["initial"]["ram"].size(); i++)
initialRAM.emplace_back(test["initial"]["ram"][i][0],
test["initial"]["ram"][i][1]);
for (auto& test : tests) {
//create state
std::vector<std::tuple<Word, Byte>> initialRAM;
for (int i = 0; i < test["initial"]["ram"].size(); i++)
initialRAM.emplace_back(test["initial"]["ram"][i][0], test["initial"]["ram"][i][1]);
GameboyTestState initialState = {test["initial"]["pc"],
test["initial"]["sp"],
test["initial"]["a"],
test["initial"]["f"],
test["initial"]["b"],
test["initial"]["c"],
test["initial"]["d"],
test["initial"]["e"],
test["initial"]["h"],
test["initial"]["l"],
initialRAM};
GameboyTestState initialState = {
test["initial"]["pc"],
test["initial"]["sp"],
test["initial"]["a"],
test["initial"]["f"],
test["initial"]["b"],
test["initial"]["c"],
test["initial"]["d"],
test["initial"]["e"],
test["initial"]["h"],
test["initial"]["l"],
initialRAM
};
// run
GameboyTestState result = gb->runTest(initialState);
//run
GameboyTestState result = gb->runTest(initialState);
// compare new state to expected
std::vector<std::tuple<Word, Byte>> finalRAM;
for (int i = 0; i < test["final"]["ram"].size(); i++)
finalRAM.emplace_back(test["final"]["ram"][i][0],
test["final"]["ram"][i][1]);
//compare new state to expected
std::vector<std::tuple<Word, Byte>> finalRAM;
for (int i = 0; i < test["final"]["ram"].size(); i++)
finalRAM.emplace_back(test["final"]["ram"][i][0], test["final"]["ram"][i][1]);
GameboyTestState finalState = {test["final"]["pc"],
test["final"]["sp"],
test["final"]["a"],
test["final"]["f"],
test["final"]["b"],
test["final"]["c"],
test["final"]["d"],
test["final"]["e"],
test["final"]["h"],
test["final"]["l"],
finalRAM};
GameboyTestState finalState = {
test["final"]["pc"],
test["final"]["sp"],
test["final"]["a"],
test["final"]["f"],
test["final"]["b"],
test["final"]["c"],
test["final"]["d"],
test["final"]["e"],
test["final"]["h"],
test["final"]["l"],
finalRAM
};
if (finalState != result) {
std::cout << "Test " << testFile << " failed!" << std::endl;
failed += 1;
break;
}
}
}
if (!failed)
std::cout << "Success!" << std::endl;
else
std::cout << failed << "/" << testFiles.size() << " failed!" << std::endl;
if (finalState != result) {
std::cout << "Test " << testFile << " failed!" << std::endl;
failed += 1;
break;
}
}
}
if (!failed)
std::cout << "Success!" << std::endl;
else
std::cout << failed << "/" << testFiles.size() << " failed!" << std::endl;
}

4052
src/opcodeResolver.cpp
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File diff suppressed because it is too large Load Diff

616
src/ppu.cpp
View File

@@ -1,390 +1,408 @@
#include "gameboy.hpp"
#include "defines.hpp"
#include "gameboy.hpp"
#include <algorithm>
#include <cstdint>
#include <iostream>
#include <utility>
bool GameBoy::LCDCBitEnabled(const Byte bit) const {
return readOnlyAddressSpace.memoryLayout.LCDC & static_cast<Byte>(1 << bit);
return readOnlyAddressSpace.memoryLayout.LCDC & static_cast<Byte>(1 << bit);
}
bool GameBoy::oamBitEnabled(const Byte oamAttributeByte, const Byte bit) {
return oamAttributeByte & static_cast<Byte>(1 << bit);
return oamAttributeByte & static_cast<Byte>(1 << bit);
}
unsigned int GameBoy::getColourFromPalette(const Byte palette) {
switch (palette & 0x3) {
case 0:
return WHITE;
case 1:
return LIGHT_GRAY;
case 2:
return DARK_GRAY;
case 3:
return BLACK;
default:
std::unreachable();
}
switch (palette & 0x3) {
case 0:
return WHITE;
case 1:
return LIGHT_GRAY;
case 2:
return DARK_GRAY;
case 3:
return BLACK;
default:
std::unreachable();
}
}
void GameBoy::ppuUpdate() {
//test for HBlank
checkPPUMode();
// test for HBlank
checkPPUMode();
// TODO:
// bug on DMG models triggers a STAT interrupt anytime the STAT register is written
// Road Rage and Zerd no Denetsu rely on this
// TODO:
// bug on DMG models triggers a STAT interrupt anytime the STAT register is
// written Road Rage and Zerd no Denetsu rely on this
// Check for STAT interrupts and request if needed (e.g., when entering specific modes)
const bool hBlankInterruptEnabled = readOnlyAddressSpace.memoryLayout.STAT & (1 << 3);
const bool drawingInterruptEnabled = readOnlyAddressSpace.memoryLayout.STAT & (1 << 4);
const bool oamInterruptEnabled = readOnlyAddressSpace.memoryLayout.STAT & (1 << 5);
const bool previousInterruptLine = statInteruptLine;
// Check for STAT interrupts and request if needed (e.g., when entering
// specific modes)
const bool hBlankInterruptEnabled =
readOnlyAddressSpace.memoryLayout.STAT & (1 << 3);
const bool drawingInterruptEnabled =
readOnlyAddressSpace.memoryLayout.STAT & (1 << 4);
const bool oamInterruptEnabled =
readOnlyAddressSpace.memoryLayout.STAT & (1 << 5);
const bool previousInterruptLine = statInteruptLine;
if (currentMode == PPUMode::mode0 && hBlankInterruptEnabled ||
currentMode == PPUMode::mode3 && drawingInterruptEnabled ||
currentMode == PPUMode::mode2 && oamInterruptEnabled) {
statInteruptLine = true;
}
else {
statInteruptLine = false;
}
if (currentMode == PPUMode::mode0 && hBlankInterruptEnabled ||
currentMode == PPUMode::mode3 && drawingInterruptEnabled ||
currentMode == PPUMode::mode2 && oamInterruptEnabled) {
statInteruptLine = true;
} else {
statInteruptLine = false;
}
const bool lyLycInterruptEnabled = readOnlyAddressSpace.memoryLayout.STAT & (1 << 6);
const bool lyLycInterruptEnabled =
readOnlyAddressSpace.memoryLayout.STAT & (1 << 6);
if (readOnlyAddressSpace.memoryLayout.LY == readOnlyAddressSpace.memoryLayout.LYC) {
addressSpace.memoryLayout.STAT |= (1 << 2);
if (lyLycInterruptEnabled)
statInteruptLine = true;
}
else {
addressSpace.memoryLayout.STAT &= ~(1 << 2);
}
if (statInteruptLine && !previousInterruptLine)
addressSpace.memoryLayout.IF |= 1 << LCD_STAT_INTERRUPT;
if (readOnlyAddressSpace.memoryLayout.LY ==
readOnlyAddressSpace.memoryLayout.LYC) {
addressSpace.memoryLayout.STAT |= (1 << 2);
if (lyLycInterruptEnabled)
statInteruptLine = true;
} else {
addressSpace.memoryLayout.STAT &= ~(1 << 2);
}
if (statInteruptLine && !previousInterruptLine)
addressSpace.memoryLayout.IF |= 1 << LCD_STAT_INTERRUPT;
}
void GameBoy::checkPPUMode() {
// Check the PPU mode (HBlank, VBlank, OAM Search, or Pixel Transfer)
const uint64_t cyclesSinceScanline = cyclesSinceLastScanline();
// Check the PPU mode (HBlank, VBlank, OAM Search, or Pixel Transfer)
const uint64_t cyclesSinceScanline = cyclesSinceLastScanline();
switch (currentMode) {
//hblank AND vblank
case 0:
case 1:
if (cyclesSinceScanline > SCANLINE_DURATION) {
lastScanline = ppuCycles - (cyclesSinceScanline - SCANLINE_DURATION);
incLY();
}
break;
case 2:
if (cyclesSinceScanline > MODE2_DURATION) {
setPPUMode(PPUMode::mode3);
}
break;
case 3:
if (cyclesSinceScanline > MODE2_DURATION + MODE3_MIN_DURATION) {
drawLine();
setPPUMode(PPUMode::mode0);
}
break;
}
switch (currentMode) {
// hblank AND vblank
case 0:
case 1:
if (cyclesSinceScanline > SCANLINE_DURATION) {
lastScanline = ppuCycles - (cyclesSinceScanline - SCANLINE_DURATION);
incLY();
}
break;
case 2:
if (cyclesSinceScanline > MODE2_DURATION) {
setPPUMode(PPUMode::mode3);
}
break;
case 3:
if (cyclesSinceScanline > MODE2_DURATION + MODE3_MIN_DURATION) {
drawLine();
setPPUMode(PPUMode::mode0);
}
break;
}
}
void GameBoy::incLY() {
addressSpace.memoryLayout.LY += 1;
setPPUMode(PPUMode::mode2);
if (addressSpace.memoryLayout.LY > SCANLINES_PER_FRAME - 1) {
addressSpace.memoryLayout.LY = 0;
windowLineCounter = 0;
}
else if (addressSpace.memoryLayout.LY == 144) {
// VBlank Period
SDL2present();
setPPUMode(PPUMode::mode1);
addressSpace.memoryLayout.IF |= 0x1;
}
addressSpace.memoryLayout.LY += 1;
setPPUMode(PPUMode::mode2);
if (addressSpace.memoryLayout.LY > SCANLINES_PER_FRAME - 1) {
addressSpace.memoryLayout.LY = 0;
windowLineCounter = 0;
} else if (addressSpace.memoryLayout.LY == 144) {
// VBlank Period
SDL2present();
setPPUMode(PPUMode::mode1);
addressSpace.memoryLayout.IF |= 0x1;
}
}
uint64_t GameBoy::cyclesSinceLastScanline() const {
const uint64_t difference = ppuCycles - lastScanline;
return difference;
const uint64_t difference = ppuCycles - lastScanline;
return difference;
}
uint64_t GameBoy::cyclesSinceLastRefresh() const {
const uint64_t difference = ppuCycles - lastRefresh;
return difference;
const uint64_t difference = ppuCycles - lastRefresh;
return difference;
}
void GameBoy::setPPUMode(const PPUMode mode) {
switch (mode) {
case mode0:
addressSpace.memoryLayout.STAT &= ~0x03;
currentMode = mode0;
break;
case mode1:
addressSpace.memoryLayout.STAT &= ~0x03;
addressSpace.memoryLayout.STAT |= 0x01;
currentMode = mode1;
break;
case mode2:
addressSpace.memoryLayout.STAT &= ~0x03;
addressSpace.memoryLayout.STAT |= 0x02;
currentMode = mode2;
break;
case mode3:
addressSpace.memoryLayout.STAT &= ~0x03;
addressSpace.memoryLayout.STAT |= 0x03;
currentMode = mode3;
break;
}
//7th bit is unused but always set
addressSpace.memoryLayout.STAT |= 0x80;
switch (mode) {
case mode0:
addressSpace.memoryLayout.STAT &= ~0x03;
currentMode = mode0;
break;
case mode1:
addressSpace.memoryLayout.STAT &= ~0x03;
addressSpace.memoryLayout.STAT |= 0x01;
currentMode = mode1;
break;
case mode2:
addressSpace.memoryLayout.STAT &= ~0x03;
addressSpace.memoryLayout.STAT |= 0x02;
currentMode = mode2;
break;
case mode3:
addressSpace.memoryLayout.STAT &= ~0x03;
addressSpace.memoryLayout.STAT |= 0x03;
currentMode = mode3;
break;
}
// 7th bit is unused but always set
addressSpace.memoryLayout.STAT |= 0x80;
}
void GameBoy::drawLine() {
const uint8_t line = readOnlyAddressSpace.memoryLayout.LY;
const uint8_t line = readOnlyAddressSpace.memoryLayout.LY;
// Calculate the starting index of the current scanline in the framebuffer
const uint32_t lineStartIndex = line * RESOLUTION_X;
// Calculate the starting index of the current scanline in the framebuffer
const uint32_t lineStartIndex = line * RESOLUTION_X;
// Pointer to the current line's pixel data in the framebuffer
uint32_t* currentLinePixels = framebuffer + lineStartIndex;
std::fill_n(currentLinePixels, RESOLUTION_X, 0xFFFFFFFF);
// Pointer to the current line's pixel data in the framebuffer
uint32_t *currentLinePixels = framebuffer + lineStartIndex;
std::fill_n(currentLinePixels, RESOLUTION_X, 0xFFFFFFFF);
const uint16_t backgroundMapAddr =
LCDCBitEnabled(BG_TILE_MAP_AREA) ? 0x9C00 : 0x9800;
const uint16_t windowMapAddr =
LCDCBitEnabled(WINDOW_TILE_MAP_AREA) ? 0x9C00 : 0x9800;
const uint16_t tileDataTableAddr =
LCDCBitEnabled(BG_WINDOW_TILE_DATA_AREA) ? 0x8000 : 0x8800;
const bool signedIndex = !LCDCBitEnabled(BG_WINDOW_TILE_DATA_AREA);
const uint16_t backgroundMapAddr = LCDCBitEnabled(BG_TILE_MAP_AREA) ? 0x9C00 : 0x9800;
const uint16_t windowMapAddr = LCDCBitEnabled(WINDOW_TILE_MAP_AREA) ? 0x9C00 : 0x9800;
const uint16_t tileDataTableAddr = LCDCBitEnabled(BG_WINDOW_TILE_DATA_AREA) ? 0x8000 : 0x8800;
const bool signedIndex = !LCDCBitEnabled(BG_WINDOW_TILE_DATA_AREA);
// BG
if (LCDCBitEnabled(BG_WINDOW_ENABLE)) {
for (int pixel = 0; pixel < RESOLUTION_X; pixel++) {
const uint16_t xIndex =
(pixel + readOnlyAddressSpace.memoryLayout.SCX) % 256;
// 256 pixels in total BG width
const uint16_t yIndex =
(line + readOnlyAddressSpace.memoryLayout.SCY) % 256;
// 256 pixels in total BG height
//BG
if (LCDCBitEnabled(BG_WINDOW_ENABLE)) {
for (int pixel = 0; pixel < RESOLUTION_X; pixel++) {
const uint16_t xIndex = (pixel + readOnlyAddressSpace.memoryLayout.SCX) % 256;
// 256 pixels in total BG width
const uint16_t yIndex = (line + readOnlyAddressSpace.memoryLayout.SCY) % 256;
// 256 pixels in total BG height
const uint16_t tileUpper = (yIndex / 8) << 5;
const uint16_t tileLower = xIndex / 8 & 0x1F;
const uint16_t tileIndex = tileUpper + tileLower;
const uint16_t tileUpper = (yIndex / 8) << 5;
const uint16_t tileLower = xIndex / 8 & 0x1F;
const uint16_t tileIndex = tileUpper + tileLower;
const uint16_t tileAddr = backgroundMapAddr + tileIndex;
const int16_t tileID =
signedIndex ? static_cast<int16_t>(readOnlyAddressSpace[tileAddr])
: readOnlyAddressSpace[tileAddr];
const uint16_t tileAddr = backgroundMapAddr + tileIndex;
const int16_t tileID = signedIndex
? static_cast<int16_t>(readOnlyAddressSpace[tileAddr])
: readOnlyAddressSpace[tileAddr];
uint16_t tileDataAddr;
if (signedIndex)
tileDataAddr = tileDataTableAddr +
(((tileID + 128) % 256) << 4); // For signed, wrap around
else
tileDataAddr = tileDataTableAddr + (tileID * 16);
uint16_t tileDataAddr;
if (signedIndex)
tileDataAddr = tileDataTableAddr + (((tileID + 128) % 256) << 4); // For signed, wrap around
else
tileDataAddr = tileDataTableAddr + (tileID * 16);
const uint8_t lineOffset = yIndex % 8;
const uint8_t tileRowData1 =
readOnlyAddressSpace[tileDataAddr + (lineOffset * 2)];
const uint8_t tileRowData2 =
readOnlyAddressSpace[tileDataAddr + (lineOffset * 2) + 1];
// get pixel data (2 bits)
const uint8_t colourBit = 7 - (xIndex % 8);
const uint8_t colourNum = ((tileRowData2 >> colourBit) & 0x1) << 1 |
((tileRowData1 >> colourBit) & 0x1);
const uint8_t lineOffset = yIndex % 8;
const uint8_t tileRowData1 = readOnlyAddressSpace[tileDataAddr + (lineOffset * 2)];
const uint8_t tileRowData2 = readOnlyAddressSpace[tileDataAddr + (lineOffset * 2) + 1];
// Apply the BGP register for palette mapping
const uint8_t palette =
(readOnlyAddressSpace.memoryLayout.BGP >> (colourNum * 2)) & 0x3;
//get pixel data (2 bits)
const uint8_t colourBit = 7 - (xIndex % 8);
const uint8_t colourNum = ((tileRowData2 >> colourBit) & 0x1) << 1 | ((tileRowData1 >> colourBit) & 0x1);
currentLinePixels[pixel] = getColourFromPalette(palette);
}
// Apply the BGP register for palette mapping
const uint8_t palette = (readOnlyAddressSpace.memoryLayout.BGP >> (colourNum * 2)) & 0x3;
// For the window to be displayed on a scanline, the following conditions
// must be met: WY condition was triggered: i.e. at some point in this frame
// the value of WY was equal to LY (checked at the start of Mode 2 only) WX
// condition was triggered: i.e. the current X coordinate being rendered + 7
// was equal to WX Window enable bit in LCDC is set
// Window
const uint8_t windowY = readOnlyAddressSpace.memoryLayout.WY;
const int16_t windowX =
static_cast<int16_t>(readOnlyAddressSpace.memoryLayout.WX - 7);
if (LCDCBitEnabled(WINDOW_ENABLE) && windowX >= 0 &&
windowX < RESOLUTION_X && line >= windowY) {
for (int pixel = windowX; pixel < RESOLUTION_X; pixel++) {
const uint16_t yIndex = windowLineCounter;
const uint16_t windowTileUpper = (yIndex / 8) << 5;
currentLinePixels[pixel] = getColourFromPalette(palette);
}
const uint16_t xIndex = pixel - windowX;
const uint16_t windowTileLower = (xIndex / 8) & 0x1F;
// For the window to be displayed on a scanline, the following conditions must be met:
// WY condition was triggered: i.e. at some point in this frame the value of WY was equal to LY (checked at the start of Mode 2 only)
// WX condition was triggered: i.e. the current X coordinate being rendered + 7 was equal to WX
// Window enable bit in LCDC is set
//Window
const uint8_t windowY = readOnlyAddressSpace.memoryLayout.WY;
const int16_t windowX = static_cast<int16_t>(readOnlyAddressSpace.memoryLayout.WX - 7);
if (LCDCBitEnabled(WINDOW_ENABLE) && windowX >= 0 && windowX < RESOLUTION_X && line >= windowY) {
for (int pixel = windowX; pixel < RESOLUTION_X; pixel++) {
const uint16_t yIndex = windowLineCounter;
const uint16_t windowTileUpper = (yIndex / 8) << 5;
const uint16_t tileIndex = windowTileUpper + windowTileLower;
const uint16_t tileAddr = windowMapAddr + tileIndex;
const uint16_t xIndex = pixel - windowX;
const uint16_t windowTileLower = (xIndex / 8) & 0x1F;
const int16_t tileID =
signedIndex ? static_cast<int16_t>(readOnlyAddressSpace[tileAddr])
: readOnlyAddressSpace[tileAddr];
const uint16_t tileIndex = windowTileUpper + windowTileLower;
const uint16_t tileAddr = windowMapAddr + tileIndex;
uint16_t tileDataAddr;
if (signedIndex)
tileDataAddr = tileDataTableAddr + (((tileID + 128) % 256) *
16); // For signed, wrap around
else
tileDataAddr = tileDataTableAddr + (tileID * 16);
const int16_t tileID = signedIndex
? static_cast<int16_t>(readOnlyAddressSpace[tileAddr])
: readOnlyAddressSpace[tileAddr];
const uint8_t lineOffset = yIndex % 8;
const uint8_t tileRowData1 =
readOnlyAddressSpace[tileDataAddr + (lineOffset * 2)];
const uint8_t tileRowData2 =
readOnlyAddressSpace[tileDataAddr + (lineOffset * 2) + 1];
uint16_t tileDataAddr;
if (signedIndex)
tileDataAddr = tileDataTableAddr + (((tileID + 128) % 256) * 16); // For signed, wrap around
else
tileDataAddr = tileDataTableAddr + (tileID * 16);
// get pixel data (2 bits)
const uint8_t colourBit = 7 - (xIndex % 8);
const uint8_t colourNum = ((tileRowData2 >> colourBit) & 0x1) << 1 |
((tileRowData1 >> colourBit) & 0x1);
// Apply the BGP register for palette mapping
const uint8_t palette =
(readOnlyAddressSpace.memoryLayout.BGP >> (colourNum * 2)) & 0x3;
const uint8_t lineOffset = yIndex % 8;
const uint8_t tileRowData1 = readOnlyAddressSpace[tileDataAddr + (lineOffset * 2)];
const uint8_t tileRowData2 = readOnlyAddressSpace[tileDataAddr + (lineOffset * 2) + 1];
currentLinePixels[pixel] = getColourFromPalette(palette);
}
windowLineCounter += 1;
}
}
// oam/sprites
if (LCDCBitEnabled(OBJ_ENABLE)) {
uint32_t oamPixels[RESOLUTION_X];
std::fill_n(oamPixels, RESOLUTION_X, 0);
//get pixel data (2 bits)
const uint8_t colourBit = 7 - (xIndex % 8);
const uint8_t colourNum = ((tileRowData2 >> colourBit) & 0x1) << 1 | ((tileRowData1 >> colourBit) &
0x1);
constexpr Word oamAddrStart = 0xFE00;
const int spriteHeight = LCDCBitEnabled(OBJ_SIZE) ? 16 : 8;
// Apply the BGP register for palette mapping
const uint8_t palette = (readOnlyAddressSpace.memoryLayout.BGP >> (colourNum * 2)) & 0x3;
int objects[10] = {0};
int found = 0;
currentLinePixels[pixel] = getColourFromPalette(palette);
}
windowLineCounter += 1;
}
}
// oam/sprites
if (LCDCBitEnabled(OBJ_ENABLE)) {
uint32_t oamPixels[RESOLUTION_X];
std::fill_n(oamPixels, RESOLUTION_X, 0);
// oam hold 40 objects
// find first 10
for (int i = 0; i < 40 && found < 10; i++) {
const int offset = i * 4;
const int yPos = readOnlyAddressSpace[oamAddrStart + offset] - 16;
constexpr
Word oamAddrStart = 0xFE00;
const int spriteHeight = LCDCBitEnabled(OBJ_SIZE) ? 16 : 8;
if (line >= yPos && line <= yPos + spriteHeight - 1) {
objects[found] = oamAddrStart + offset;
found += 1;
}
}
int objects[10] = {0};
int found = 0;
// sort by xPos (lower has higher priority when rendering) and then earlier
// objects
for (int i = 0; i < found; i++) {
for (int j = 0; j < found - i - 1; j++) {
const int xPos1 = readOnlyAddressSpace[objects[j] + 1];
const int xPos2 = readOnlyAddressSpace[objects[j + 1] + 1];
//oam hold 40 objects
//find first 10
for (int i = 0; i < 40 && found < 10; i++) {
const int offset = i * 4;
const int yPos = readOnlyAddressSpace[oamAddrStart + offset] - 16;
if (xPos1 > xPos2) {
const int tmp = objects[j];
objects[j] = objects[j + 1];
objects[j + 1] = tmp;
}
}
}
if (line >= yPos && line <= yPos + spriteHeight - 1) {
objects[found] = oamAddrStart + offset;
found += 1;
}
}
for (int objectIndex = found - 1; objectIndex >= 0; objectIndex--) {
const int yPos = readOnlyAddressSpace[objects[objectIndex]] - 16;
const int xPos = readOnlyAddressSpace[objects[objectIndex] + 1] - 8;
const int tileIndex = readOnlyAddressSpace[objects[objectIndex] + 2];
const Byte attributes = readOnlyAddressSpace[objects[objectIndex] + 3];
//sort by xPos (lower has higher priority when rendering) and then earlier objects
for (int i = 0; i < found; i++) {
for (int j = 0; j < found - i - 1; j++) {
const int xPos1 = readOnlyAddressSpace[objects[j] + 1];
const int xPos2 = readOnlyAddressSpace[objects[j + 1] + 1];
const bool priority = oamBitEnabled(attributes, PRIORITY);
const bool yFlip = oamBitEnabled(attributes, Y_FLIP);
const bool xFlip = oamBitEnabled(attributes, X_FLIP);
// get obp0 or obj1
const Byte objPalette = oamBitEnabled(attributes, OBJ_PALETTE)
? addressSpace.memoryLayout.OBP1
: addressSpace.memoryLayout.OBP0;
if (xPos1 > xPos2) {
const int tmp = objects[j];
objects[j] = objects[j + 1];
objects[j + 1] = tmp;
}
}
}
for (int pixel = xPos; pixel < RESOLUTION_X && pixel < xPos + 8;
pixel++) {
constexpr Word objectTileAddr = 0x8000;
if (pixel < 0)
continue;
const uint32_t colour = currentLinePixels[pixel];
const Byte BGP = readOnlyAddressSpace.memoryLayout.BGP;
if (priority && (colour == getColourFromPalette((BGP >> 2) & 0x3) ||
colour == getColourFromPalette((BGP >> 4) & 0x3) ||
colour == getColourFromPalette((BGP >> 6) & 0x3))) {
oamPixels[pixel] = colour;
continue;
}
for (int objectIndex = found - 1; objectIndex >= 0; objectIndex--) {
const int yPos = readOnlyAddressSpace[objects[objectIndex]] - 16;
const int xPos = readOnlyAddressSpace[objects[objectIndex] + 1] - 8;
const int tileIndex = readOnlyAddressSpace[objects[objectIndex] + 2];
const Byte attributes = readOnlyAddressSpace[objects[objectIndex] + 3];
Byte objectX = pixel - xPos;
Byte objectY = line - yPos;
if (xFlip)
objectX = 7 - objectX;
if (yFlip)
objectY = (spriteHeight - 1) - objectY;
const bool priority = oamBitEnabled(attributes, PRIORITY);
const bool yFlip = oamBitEnabled(attributes, Y_FLIP);
const bool xFlip = oamBitEnabled(attributes, X_FLIP);
//get obp0 or obj1
const Byte objPalette = oamBitEnabled(attributes, OBJ_PALETTE)
? addressSpace.memoryLayout.OBP1
: addressSpace.memoryLayout.OBP0;
const Word objTileDataAddr =
spriteHeight == 8 ? objectTileAddr + (tileIndex * 16)
: objectTileAddr + ((tileIndex & 0xFE) * 16);
for (int pixel = xPos; pixel < RESOLUTION_X && pixel < xPos + 8; pixel++) {
constexpr
Word objectTileAddr = 0x8000;
if (pixel < 0)
continue;
const Byte tileRow = objectY * 2;
const Byte tileRowData1 =
readOnlyAddressSpace[objTileDataAddr + tileRow];
const Byte tileRowData2 =
readOnlyAddressSpace[objTileDataAddr + tileRow + 1];
const uint32_t colour = currentLinePixels[pixel];
const Byte BGP = readOnlyAddressSpace.memoryLayout.BGP;
if (priority && (colour == getColourFromPalette((BGP >> 2) & 0x3) ||
colour == getColourFromPalette((BGP >> 4) & 0x3) ||
colour == getColourFromPalette((BGP >> 6) & 0x3)
)) {
oamPixels[pixel] = colour;
continue;
}
const int bit = 7 - objectX;
const int colorIndex =
((tileRowData2 >> bit) & 1) << 1 | ((tileRowData1 >> bit) & 1);
Byte objectX = pixel - xPos;
Byte objectY = line - yPos;
if (xFlip)
objectX = 7 - objectX;
if (yFlip)
objectY = (spriteHeight - 1) - objectY;
// 0 is always transparent
if (colorIndex != 0) {
const uint8_t paletteColor = (objPalette >> (colorIndex * 2)) & 0x3;
const uint32_t finalColor = getColourFromPalette(paletteColor);
oamPixels[pixel] = finalColor;
} else if (oamPixels[pixel] == 0) {
oamPixels[pixel] = currentLinePixels[pixel];
}
}
}
const Word objTileDataAddr = spriteHeight == 8
? objectTileAddr + (tileIndex * 16)
: objectTileAddr + ((tileIndex & 0xFE) * 16);
const Byte tileRow = objectY * 2;
const Byte tileRowData1 = readOnlyAddressSpace[objTileDataAddr + tileRow];
const Byte tileRowData2 = readOnlyAddressSpace[objTileDataAddr + tileRow + 1];
const int bit = 7 - objectX;
const int colorIndex = ((tileRowData2 >> bit) & 1) << 1 | ((tileRowData1 >> bit) & 1);
// 0 is always transparent
if (colorIndex != 0) {
const uint8_t paletteColor = (objPalette >> (colorIndex * 2)) & 0x3;
const uint32_t finalColor = getColourFromPalette(paletteColor);
oamPixels[pixel] = finalColor;
}
else if (oamPixels[pixel] == 0) {
oamPixels[pixel] = currentLinePixels[pixel];
}
}
}
//help ensure correct interaction with "BG OVER OBJ" flag
for (int i = 0; i < RESOLUTION_X; i++) {
if (oamPixels[i] != currentLinePixels[i] && oamPixels[i] != 0)
currentLinePixels[i] = oamPixels[i];
}
}
// help ensure correct interaction with "BG OVER OBJ" flag
for (int i = 0; i < RESOLUTION_X; i++) {
if (oamPixels[i] != currentLinePixels[i] && oamPixels[i] != 0)
currentLinePixels[i] = oamPixels[i];
}
}
}
void GameBoy::SDL2setup() {
SDL_Init(SDL_INIT_EVERYTHING);
screen = SDL_CreateWindow("GameBoy++",
SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
RESOLUTION_X, RESOLUTION_Y,
0);
SDL_Init(SDL_INIT_EVERYTHING);
screen =
SDL_CreateWindow("GameBoy++", SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED, RESOLUTION_X, RESOLUTION_Y, 0);
// Create an SDL renderer to draw on the window
renderer = SDL_CreateRenderer(screen, -1, SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_ACCELERATED);
// Create an SDL renderer to draw on the window
renderer = SDL_CreateRenderer(
screen, -1, SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_ACCELERATED);
// Create an SDL texture to hold the framebuffer data
texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888,
SDL_TEXTUREACCESS_STREAMING, RESOLUTION_X, RESOLUTION_Y);
// Create an SDL texture to hold the framebuffer data
texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888,
SDL_TEXTUREACCESS_STREAMING, RESOLUTION_X,
RESOLUTION_Y);
}
void GameBoy::SDL2destroy() const {
SDL_DestroyTexture(texture);
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(screen);
SDL_Quit();
SDL_DestroyTexture(texture);
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(screen);
SDL_Quit();
}
void GameBoy::SDL2present() {
SDL_UpdateTexture(texture, nullptr, framebuffer, RESOLUTION_X * sizeof(uint32_t));
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, texture, nullptr, nullptr);
SDL_UpdateTexture(texture, nullptr, framebuffer,
RESOLUTION_X * sizeof(uint32_t));
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, texture, nullptr, nullptr);
frameTime = SDL_GetTicks() - frameStart;
frameTime = SDL_GetTicks() - frameStart;
if (frameDelay > frameTime) {
SDL_Delay(frameDelay - frameTime);
}
if (frameDelay > frameTime) {
SDL_Delay(frameDelay - frameTime);
}
SDL_RenderPresent(renderer);
frameStart = SDL_GetTicks();
rendered = true;
SDL_RenderPresent(renderer);
frameStart = SDL_GetTicks();
rendered = true;
}

56
src/testing.hpp
View File

@@ -1,43 +1,39 @@
#ifndef TESTING_HPP
#define TESTING_HPP
#include "defines.hpp"
#include <cstdint>
#include <vector>
#include <tuple>
#include <iostream>
#include <stdexcept>
#include <string>
#include "defines.hpp"
#include <tuple>
#include <vector>
struct GameboyTestState {
Word PC;
Word SP;
Byte A;
Byte F;
Byte B;
Byte C;
Byte D;
Byte E;
Byte H;
Byte L;
//Byte IME;
//Byte IE;
std::vector<std::tuple<Word, Byte>> RAM;
Word PC;
Word SP;
Byte A;
Byte F;
Byte B;
Byte C;
Byte D;
Byte E;
Byte H;
Byte L;
// Byte IME;
// Byte IE;
std::vector<std::tuple<Word, Byte>> RAM;
};
inline bool operator==(const GameboyTestState& lhs, const GameboyTestState& rhs) {
for (int i = 0; i < lhs.RAM.size(); i++) {
if (std::get<1>(lhs.RAM[i]) != std::get<1>(rhs.RAM[i]))
return false;
}
return (lhs.A == rhs.A &&
lhs.F == rhs.F &&
lhs.B == rhs.B &&
lhs.C == rhs.C &&
lhs.D == rhs.D &&
lhs.E == rhs.E &&
lhs.H == rhs.H &&
lhs.L == rhs.L);
inline bool operator==(const GameboyTestState &lhs,
const GameboyTestState &rhs) {
for (int i = 0; i < lhs.RAM.size(); i++) {
if (std::get<1>(lhs.RAM[i]) != std::get<1>(rhs.RAM[i]))
return false;
}
return (lhs.A == rhs.A && lhs.F == rhs.F && lhs.B == rhs.B &&
lhs.C == rhs.C && lhs.D == rhs.D && lhs.E == rhs.E &&
lhs.H == rhs.H && lhs.L == rhs.L);
}
#endif //TESTING_HPP
#endif // TESTING_HPP

76
src/timing.cpp
View File

@@ -1,43 +1,45 @@
#include "gameboy.hpp"
//handles most of the behavoir as described here: https://gbdev.io/pandocs/Timer_and_Divider_Registers.html#ff04--div-divider-register
// handles most of the behavoir as described here:
// https://gbdev.io/pandocs/Timer_and_Divider_Registers.html#ff04--div-divider-register
void GameBoy::timingHandler() {
//can't do this as we use cycles for PPU timing but this is what should happen
//addressSpace.memoryLayout.DIV = ((cycles / 4) >> 6) & 0xFF;
// can't do this as we use cycles for PPU timing but this is what should
// happen addressSpace.memoryLayout.DIV = ((cycles / 4) >> 6) & 0xFF;
if (cycles - lastDivUpdate >= DIVIDER_REGISTER_FREQ) {
const uint8_t increments = (cycles - lastDivUpdate) / DIVIDER_REGISTER_FREQ;
addressSpace.memoryLayout.DIV += increments;
lastDivUpdate += increments * DIVIDER_REGISTER_FREQ;
}
if (cycles - lastDivUpdate >= DIVIDER_REGISTER_FREQ) {
const uint8_t increments = (cycles - lastDivUpdate) / DIVIDER_REGISTER_FREQ;
addressSpace.memoryLayout.DIV += increments;
lastDivUpdate += increments * DIVIDER_REGISTER_FREQ;
}
//if enabled
uint64_t TIMAFrequency = 0;
if (addressSpace.memoryLayout.TAC & 0x04) {
switch (addressSpace.memoryLayout.TAC & 0x03) {
case 0:
TIMAFrequency = 1024;
break;
case 1:
TIMAFrequency = 16;
break;
case 2:
TIMAFrequency = 64;
break;
case 3:
TIMAFrequency = 256;
break;
}
//if TIMA overflowed and prevTMA != current TMA, use prevTMA (ie use prevTMA regardless)
const int increments = (cycles - lastTIMAUpdate) / TIMAFrequency;
if (cycles - lastTIMAUpdate >= TIMAFrequency) {
if (static_cast<int>(addressSpace.memoryLayout.TIMA) + increments > 255) {
addressSpace.memoryLayout.TIMA = prevTMA + ((addressSpace.memoryLayout.TIMA + increments) % 256);
setInterrupt(TIMER_INTERRUPT);
}
else
addressSpace.memoryLayout.TIMA += increments;
lastTIMAUpdate += increments * TIMAFrequency;
}
}
// if enabled
uint64_t TIMAFrequency = 0;
if (addressSpace.memoryLayout.TAC & 0x04) {
switch (addressSpace.memoryLayout.TAC & 0x03) {
case 0:
TIMAFrequency = 1024;
break;
case 1:
TIMAFrequency = 16;
break;
case 2:
TIMAFrequency = 64;
break;
case 3:
TIMAFrequency = 256;
break;
}
// if TIMA overflowed and prevTMA != current TMA, use prevTMA (ie use
// prevTMA regardless)
const int increments = (cycles - lastTIMAUpdate) / TIMAFrequency;
if (cycles - lastTIMAUpdate >= TIMAFrequency) {
if (static_cast<int>(addressSpace.memoryLayout.TIMA) + increments > 255) {
addressSpace.memoryLayout.TIMA =
prevTMA + ((addressSpace.memoryLayout.TIMA + increments) % 256);
setInterrupt(TIMER_INTERRUPT);
} else
addressSpace.memoryLayout.TIMA += increments;
lastTIMAUpdate += increments * TIMAFrequency;
}
}
}