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This commit is contained in:
Braiden Gent
2024-02-05 22:09:34 -08:00
parent 73a40230da
commit 2809dbfca8
7 changed files with 238 additions and 356 deletions
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12
src/defines.hpp
View File

@@ -9,7 +9,7 @@
// 6 n - - Add/Sub-Flag (BCD)
// 5 h - - Half Carry Flag (BCD)
// 4 cy C NC Carry Flag
// 3-0 - - - Not used (always zero)
// 3-0 - - - Not used
#define CARRY_FLAG 4 //'C'
#define HALFCARRY_FLAG 5 //'H'
#define SUBTRACT_FLAG 6 //'N'
@@ -21,7 +21,7 @@
#define SERIAL_INTERRUPT 3
#define JOYPAD_INTERRUPT 4
#define T_CLOCK_FREQ 4194304
#define T_CLOCK_FREQ 4194304 //2^22
#define DIVIDER_REGISTER_FREQ 16384
@@ -39,13 +39,13 @@
#define MODE2_DURATION 80
#define MODE3_MIN_DURATION 172
#define MODE0_3_DURATION 376 //mode3 is 172 to 289, mode0 87 to 204
#define MODE1_DURATION 4560
#define H_SYNC 9198
#define V_SYNC 59.73
#define HBlank_DURATION 204 //GPU_MODE 0
#define SCANLINE_OAM_FREQ 80 //GPU_MODE 2
#define SCANLINE_VRAM_FREQ 80 //GPU_MODE 3
#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
#endif

37
src/gameboy.cpp
View File

@@ -1,27 +1,22 @@
#include <iostream>
#include "gameboy.hpp"
bool AddressSpace::getBootromState()
{
bool AddressSpace::getBootromState() {
return bootromLoaded;
}
void AddressSpace::unmapBootrom()
{
void AddressSpace::unmapBootrom() {
bootromLoaded = false;
}
void AddressSpace::mapBootrom()
{
void AddressSpace::mapBootrom() {
bootromLoaded = true;
}
void AddressSpace::loadBootrom(std::string filename)
{
void AddressSpace::loadBootrom(std::string filename) {
std::ifstream file;
int size = std::filesystem::file_size(filename);
if(size != 256)
{
if (size != 256) {
std::cerr << "Bootrom was an unexpected size!\nQuitting!\n" << std::endl;
exit(1);
}
@@ -29,32 +24,27 @@ void AddressSpace::loadBootrom(std::string filename)
file.read(reinterpret_cast<char*>(bootrom), BOOTROM_SIZE);
}
void AddressSpace::loadGame(std::string filename)
{
void AddressSpace::loadGame(std::string filename) {
game.open(filename, std::ios::binary);
if(!game.is_open())
{
if (!game.is_open()) {
std::cerr << "Game was not found!\nQuitting!\n" << std::endl;
exit(1);
}
game.read(reinterpret_cast<char*>(memoryLayout.romBank1), ROM_BANK_SIZE * 2);
}
void GameBoy::addCycles(uint8_t ticks)
{
void GameBoy::addCycles(uint8_t ticks) {
cycles = (cycles + ticks) % T_CLOCK_FREQ;
lastOpTicks = ticks;
}
void GameBoy::start(std::string bootrom, std::string game)
{
void GameBoy::start(std::string bootrom, std::string game) {
addressSpace.loadBootrom(bootrom);
addressSpace.loadGame(game);
bool quit = false;
while(!quit)
{
while (!quit) {
// Event loop: Check and handle SDL events
// if(SDL_PollEvent(&event))
// {
@@ -68,16 +58,13 @@ void GameBoy::start(std::string bootrom, std::string game)
interruptHandler();
//timing();
ppuUpdate();
if(PC > 0xFF && addressSpace.getBootromState())
{
if (PC > 0xFF && addressSpace.getBootromState()) {
addressSpace.unmapBootrom();
}
int cyclesSince = cyclesSinceLastRefresh();
if(cyclesSince > FRAME_DURATION)
{
if (cyclesSince > FRAME_DURATION) {
lastRefresh = cycles;
SDL2present();
}
}
}

32
src/gameboy.hpp
View File

@@ -11,54 +11,47 @@
#include "defines.hpp"
//two bits per colour
enum Colour
{
enum Colour {
black = 0b11,
darkGray = 0b10,
lightGray = 0b01,
white = 0b00
};
enum PPUMode
{
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.
};
union RegisterPair
{
union RegisterPair {
Word reg; //register.reg == (hi << 8) + lo. (hi is more significant than lo)
struct
{
struct {
Byte lo;
Byte hi;
};
};
class AddressSpace
{
class AddressSpace {
private:
bool bootromLoaded = true;
Byte bootrom[BOOTROM_SIZE];
std::ifstream game;
public:
AddressSpace()
{
AddressSpace() {
// Initialize the memory to zero
memoryLayout = {};
std::memset(memoryLayout.memory, 0, sizeof(memoryLayout.memory));
}
// Nested union for the memory layout
union MemoryLayout
{
union MemoryLayout {
Byte memory[0x10000];
struct
{
struct {
Byte romBank1[ROM_BANK_SIZE]; // Mapped to 0x0000
Byte romBankSwitch[ROM_BANK_SIZE]; // Mapped to 0x4000
Byte vram[0x2000]; // Mapped to 0x8000
@@ -81,8 +74,7 @@ class AddressSpace
void loadGame(std::string filename);
//overload [] for echo ram and bootrom support
Byte operator[](uint32_t address) const
{
Byte operator[](uint32_t address) const {
if (address >= 0xE000 && address < 0xFE00)
return memoryLayout.echoRam[address - 0xE000];
if (address < 0x0100 && bootromLoaded)
@@ -90,8 +82,8 @@ class AddressSpace
else
return memoryLayout.memory[address];
}
Byte& operator[](uint32_t address)
{
Byte& operator[](uint32_t address) {
if (address >= 0xE000 && address < 0xFE00)
return memoryLayout.echoRam[address - 0xE000];
if (address < 0x0100 && bootromLoaded)

24
src/interupts.cpp
View File

@@ -1,18 +1,15 @@
#include "defines.hpp"
#include "gameboy.hpp"
bool GameBoy::testInterruptEnabled(Byte interrupt)
{
bool GameBoy::testInterruptEnabled(Byte interrupt) {
return (*IE) & (Byte)(1 << interrupt);
}
void GameBoy::resetInterrupt(Byte interrupt)
{
void GameBoy::resetInterrupt(Byte interrupt) {
*IF &= ~(1 << interrupt);
}
void GameBoy::interruptHandler()
{
void GameBoy::interruptHandler() {
if (!IME)
return;
@@ -28,8 +25,7 @@ void GameBoy::interruptHandler()
joypadHandle();
}
void GameBoy::VBlankHandle()
{
void GameBoy::VBlankHandle() {
printf("VBlank interrupt");
IME = 0;
push(PC);
@@ -37,8 +33,7 @@ void GameBoy::VBlankHandle()
resetInterrupt(VBLANK_INTERRUPT);
}
void GameBoy::LCDStatHandle()
{
void GameBoy::LCDStatHandle() {
printf("LCD stat interrupt");
IME = 0;
push(PC);
@@ -47,8 +42,7 @@ void GameBoy::LCDStatHandle()
resetInterrupt(LCD_STAT_INTERRUPT);
}
void GameBoy::timerHandle()
{
void GameBoy::timerHandle() {
printf("timer interrupt");
IME = 0;
push(PC);
@@ -57,8 +51,7 @@ void GameBoy::timerHandle()
resetInterrupt(TIMER_INTERRUPT);
}
void GameBoy::serialHandle()
{
void GameBoy::serialHandle() {
printf("serial interrupt");
IME = 0;
push(PC);
@@ -67,8 +60,7 @@ void GameBoy::serialHandle()
resetInterrupt(SERIAL_INTERRUPT);
}
void GameBoy::joypadHandle()
{
void GameBoy::joypadHandle() {
printf("joypad interrupt");
IME = 0;
push(PC);

3
src/main.cpp
View File

@@ -1,8 +1,7 @@
#include <string>
#include "gameboy.hpp"
int main(int argc, char** argv)
{
int main(int argc, char** argv) {
auto* gb = new GameBoy();
gb->SDL2setup();
gb->start("../bootrom.bin", "../roms/DrMario.gb");

240
src/opcode.cpp
View File

@@ -1,22 +1,18 @@
#include "gameboy.hpp"
void GameBoy::setFlag(Byte bit)
{
void GameBoy::setFlag(Byte bit) {
AF.lo |= (1 << bit);
}
void GameBoy::resetFlag(Byte bit)
{
void GameBoy::resetFlag(Byte bit) {
AF.lo &= ~(1 << bit);
}
bool GameBoy::getFlag(Byte bit) const
{
bool GameBoy::getFlag(Byte bit) const {
return (AF.lo >> bit) & 1;
}
Word GameBoy::getWordPC()
{
Word GameBoy::getWordPC() {
RegisterPair word;
//remember little endianness
@@ -26,13 +22,11 @@ Word GameBoy::getWordPC()
return word.reg;
}
Byte GameBoy::getBytePC()
{
Byte GameBoy::getBytePC() {
return addressSpace[PC + 1];
}
Word GameBoy::getWordSP()
{
Word GameBoy::getWordSP() {
RegisterPair word;
//remember little endianness
@@ -42,35 +36,29 @@ Word GameBoy::getWordSP()
return word.reg;
}
Byte GameBoy::getByteSP()
{
Byte GameBoy::getByteSP() {
return addressSpace[SP++];
}
void GameBoy::ret()
{
void GameBoy::ret() {
pop(PC);
}
template <typename T>
void GameBoy::ld(T &dest, T src)
{
void GameBoy::ld(T& dest, T src) {
dest = src;
}
template <typename T>
void GameBoy::ldW(T dest, T src)
{
if(sizeof(src) == sizeof(Word))
{
void GameBoy::ldW(T dest, T src) {
if (sizeof(src) == sizeof(Word)) {
addressSpace[dest] = (Byte)(src & 0xFF00) >> 8;
addressSpace[dest + 1] = (Byte)(src & 0xFF);
}
}
template <typename T>
void GameBoy::rla(T &reg)
{
void GameBoy::rla(T& reg) {
//printf("0x%.2x\n", REG);
//printf("%d\n", GET_FLAG(CARRY_FLAG));
bool carry;
@@ -99,10 +87,8 @@ void GameBoy::rla(T &reg)
}
template <typename T>
void GameBoy::add(T &reg, T value)
{
if(sizeof(reg) == sizeof(Byte))
{
void GameBoy::add(T& reg, T value) {
if (sizeof(reg) == sizeof(Byte)) {
//halfcarry test https://robdor.com/2016/08/10/gameboy-emulator-half-carry-flag/
if ((((value & 0xF) + (reg & 0xF)) & 0x10) == 0x10)
setFlag(HALFCARRY_FLAG);
@@ -115,8 +101,7 @@ void GameBoy::add(T &reg, T value)
resetFlag(CARRY_FLAG);
}
if(sizeof(reg) == sizeof(Word))
{
if (sizeof(reg) == sizeof(Word)) {
//halfcarry test https://robdor.com/2016/08/10/gameboy-emulator-half-carry-flag/
if ((((value & 0xFFF) + (reg & 0xFFF)) & 0x1000) == 0x1000)
setFlag(HALFCARRY_FLAG);
@@ -137,12 +122,10 @@ void GameBoy::add(T &reg, T value)
resetFlag(ZERO_FLAG);
resetFlag(SUBTRACT_FLAG);
}
template <typename T>
void GameBoy::orBitwise(T &dest, T src)
{
void GameBoy::orBitwise(T& dest, T src) {
dest |= src;
if (dest == 0)
@@ -154,8 +137,7 @@ void GameBoy::orBitwise(T &dest, T src)
}
template <typename T>
void GameBoy::andBitwise(T &dest, T src)
{
void GameBoy::andBitwise(T& dest, T src) {
dest &= src;
if (dest == 0)
@@ -167,8 +149,7 @@ void GameBoy::andBitwise(T &dest, T src)
}
template <typename T>
void GameBoy::xorBitwise(T &dest, T src)
{
void GameBoy::xorBitwise(T& dest, T src) {
dest ^= src;
if (dest == 0)
@@ -180,8 +161,7 @@ void GameBoy::xorBitwise(T &dest, T src)
}
template <typename T>
void GameBoy::bit(T testBit, T reg)
{
void GameBoy::bit(T testBit, T reg) {
Byte result = reg & (T)(1 << testBit);
if (result == 0)
@@ -194,8 +174,7 @@ void GameBoy::bit(T testBit, T reg)
}
template <typename T>
bool GameBoy::jrNZ(T offset)
{
bool GameBoy::jrNZ(T offset) {
bool jumped = false;
if (!getFlag(ZERO_FLAG)) //if not set
{
@@ -207,12 +186,10 @@ bool GameBoy::jrNZ(T offset)
}
template <typename T>
void GameBoy::inc(T &reg)
{
void GameBoy::inc(T& reg) {
reg++;
if(sizeof(reg) == sizeof(Byte))
{
if (sizeof(reg) == sizeof(Byte)) {
if (reg == 0)
setFlag(ZERO_FLAG);
else
@@ -225,13 +202,11 @@ void GameBoy::inc(T &reg)
setFlag(HALFCARRY_FLAG);
else
resetFlag(HALFCARRY_FLAG);
}
}
template <typename T>
void GameBoy::call(T address)
{
void GameBoy::call(T address) {
push(PC + 3);
PC = address;
}
@@ -239,13 +214,11 @@ void GameBoy::call(T address)
template <typename T>
void GameBoy::cp(T value) //compare
{
if(AF.hi < value)
{
if (AF.hi < value) {
setFlag(CARRY_FLAG);
resetFlag(ZERO_FLAG);
}
else if(AF.hi == value)
{
else if (AF.hi == value) {
setFlag(ZERO_FLAG);
resetFlag(CARRY_FLAG);
}
@@ -257,16 +230,13 @@ void GameBoy::cp(T value) //compare
setFlag(HALFCARRY_FLAG);
else
resetFlag(HALFCARRY_FLAG);
}
template <typename T>
void GameBoy::dec(T &reg)
{
void GameBoy::dec(T& reg) {
reg -= 1;
if(sizeof(reg) == sizeof(Byte))
{
if (sizeof(reg) == sizeof(Byte)) {
if (reg == 0)
setFlag(ZERO_FLAG);
else
@@ -279,14 +249,11 @@ void GameBoy::dec(T &reg)
setFlag(HALFCARRY_FLAG);
else
resetFlag(HALFCARRY_FLAG);
}
}
template <typename T>
bool GameBoy::jrZ(T offset)
{
bool GameBoy::jrZ(T offset) {
bool jumped = false;
if (getFlag(ZERO_FLAG)) //if not set
{
@@ -297,8 +264,7 @@ bool GameBoy::jrZ(T offset)
return jumped;
}
void GameBoy::swap(Byte &value)
{
void GameBoy::swap(Byte& value) {
// Extract the lower and upper nibbles of the register
Byte lowerNibble = value & 0x0F;
Byte upperNibble = (value >> 4) & 0x0F;
@@ -315,21 +281,15 @@ void GameBoy::swap(Byte &value)
resetFlag(CARRY_FLAG);
}
void GameBoy::halt()
{
}
void GameBoy::halt() {}
template <typename T>
void GameBoy::sub(T value)
{
if(AF.hi < value)
{
void GameBoy::sub(T value) {
if (AF.hi < value) {
setFlag(CARRY_FLAG);
resetFlag(ZERO_FLAG);
}
else if(AF.hi == value)
{
else if (AF.hi == value) {
setFlag(ZERO_FLAG);
resetFlag(CARRY_FLAG);
}
@@ -342,25 +302,17 @@ void GameBoy::sub(T value)
setFlag(HALFCARRY_FLAG);
else
resetFlag(HALFCARRY_FLAG);
}
template <typename T>
void GameBoy::jr(T offset)
{
void GameBoy::jr(T offset) {
PC += (int8_t)offset + 2; //PC moves 2 from original instruction
}
template <typename T>
void GameBoy::rl(T &reg)
{
//printf("0x%.2x\n", REG);
//printf("%d\n", GET_FLAG(CARRY_FLAG));
void GameBoy::rl(T& reg) {
bool carry;
//printf("\n0x%x\n", REG);
//printf("0x%x\n\n", REG & ((T)1 << 7));
if (reg & (1 << 7))
carry = true;
else
@@ -385,14 +337,12 @@ void GameBoy::rl(T &reg)
}
template <typename T>
void GameBoy::pop(T &reg)
{
void GameBoy::pop(T& reg) {
reg = getWordSP();
}
template <typename T>
void GameBoy::push(T reg)
{
void GameBoy::push(T reg) {
//little endian
RegisterPair temp;
temp.lo = reg & 0xFF;
@@ -404,27 +354,23 @@ void GameBoy::push(T reg)
}
template <typename T>
void GameBoy::jp(T address)
{
void GameBoy::jp(T address) {
PC = address;
}
template <typename T>
void GameBoy::rst(T address)
{
void GameBoy::rst(T address) {
push(PC);
PC = address;
}
void GameBoy::cpl()
{
void GameBoy::cpl() {
AF.hi = ~AF.hi;
setFlag(SUBTRACT_FLAG);
setFlag(HALFCARRY_FLAG);
}
void GameBoy::ccf()
{
void GameBoy::ccf() {
resetFlag(SUBTRACT_FLAG);
resetFlag(HALFCARRY_FLAG);
if (getFlag(CARRY_FLAG))
@@ -433,27 +379,21 @@ void GameBoy::ccf()
setFlag(CARRY_FLAG);
}
void GameBoy::stop()
{
}
void GameBoy::stop() {}
void GameBoy::opcodeHandler()
{
void GameBoy::opcodeHandler() {
bool jumped;
if(addressSpace[PC] != 0xCB)
{
if (addressSpace[PC] != 0xCB) {
//printf("PC:0x%.2x, Opcode:0x%.2x\n", PC, addressSpace[PC]);
if(PC == 0x100)
{
if (PC == 0x100) {
printf("LY:0x%.2x\n", (*LY));
// printf("PC:0x%.2x, Opcode:0x%.2x\n", PC, addressSpace[PC]);
// printf("IME:%b IF:0x%.2x IE:0x%.2x\n", IME, (*IF), (*IE));
}
//printf("IME:%b IF:0x%.2x IE:0x%.2x\n", IME, (*IF), (*IE));
switch(addressSpace[PC])
{
switch (addressSpace[PC]) {
case 0x00:
//NOP
PC += 1;
@@ -630,12 +570,10 @@ void GameBoy::opcodeHandler()
case 0x20:
jumped = jrNZ(getBytePC());
if(jumped)
{
if (jumped) {
addCycles(12);
}
else
{
else {
PC += 2;
addCycles(8);
}
@@ -674,12 +612,10 @@ void GameBoy::opcodeHandler()
case 0x28:
jumped = jrZ(getBytePC());
if(jumped)
{
if (jumped) {
addCycles(12);
}
else
{
else {
PC += 2;
addCycles(8);
}
@@ -1457,13 +1393,11 @@ void GameBoy::opcodeHandler()
break;
case 0xC0: //RET NZ
if(!getFlag(ZERO_FLAG))
{
if (!getFlag(ZERO_FLAG)) {
ret();
addCycles(20);
}
else
{
else {
addCycles(8);
PC += 1;
}
@@ -1476,13 +1410,11 @@ void GameBoy::opcodeHandler()
break;
case 0xC2:
if(!getFlag(ZERO_FLAG))
{
if (!getFlag(ZERO_FLAG)) {
jp(getWordPC());
addCycles(16);
}
else
{
else {
addCycles(12);
PC += 3;
}
@@ -1494,13 +1426,11 @@ void GameBoy::opcodeHandler()
break;
case 0xC4:
if(!getFlag(ZERO_FLAG))
{
if (!getFlag(ZERO_FLAG)) {
call(getWordPC());
addCycles(24);
}
else
{
else {
addCycles(12);
PC += 3;
}
@@ -1513,13 +1443,11 @@ void GameBoy::opcodeHandler()
break;
case 0xC8:
if(getFlag(ZERO_FLAG))
{
if (getFlag(ZERO_FLAG)) {
ret();
addCycles(20);
}
else
{
else {
addCycles(8);
PC += 1;
}
@@ -1531,26 +1459,22 @@ void GameBoy::opcodeHandler()
break;
case 0xCA:
if(getFlag(ZERO_FLAG))
{
if (getFlag(ZERO_FLAG)) {
jp(getWordPC());
addCycles(16);
}
else
{
else {
addCycles(12);
PC += 3;
}
break;
case 0xCC:
if(getFlag(ZERO_FLAG))
{
if (getFlag(ZERO_FLAG)) {
call(getWordPC());
addCycles(24);
}
else
{
else {
addCycles(12);
PC += 3;
}
@@ -1567,13 +1491,11 @@ void GameBoy::opcodeHandler()
break;
case 0xD0: //RET NC
if(!getFlag(CARRY_FLAG))
{
if (!getFlag(CARRY_FLAG)) {
ret();
addCycles(20);
}
else
{
else {
addCycles(8);
PC += 3;
}
@@ -1586,26 +1508,22 @@ void GameBoy::opcodeHandler()
break;
case 0xD2:
if(!getFlag(CARRY_FLAG))
{
if (!getFlag(CARRY_FLAG)) {
jp(getWordPC());
addCycles(24);
}
else
{
else {
addCycles(12);
PC += 3;
}
break;
case 0xD4:
if(!getFlag(CARRY_FLAG))
{
if (!getFlag(CARRY_FLAG)) {
call(getWordPC());
addCycles(24);
}
else
{
else {
addCycles(12);
PC += 3;
}
@@ -1618,13 +1536,11 @@ void GameBoy::opcodeHandler()
break;
case 0xD8:
if(getFlag(CARRY_FLAG))
{
if (getFlag(CARRY_FLAG)) {
ret();
addCycles(20);
}
else
{
else {
addCycles(8);
PC += 1;
}
@@ -1638,26 +1554,22 @@ void GameBoy::opcodeHandler()
break;
case 0xDA:
if(getFlag(CARRY_FLAG))
{
if (getFlag(CARRY_FLAG)) {
jp(getWordPC());
addCycles(16);
}
else
{
else {
addCycles(12);
PC += 3;
}
break;
case 0xDC:
if(getFlag(CARRY_FLAG))
{
if (getFlag(CARRY_FLAG)) {
call(getWordPC());
addCycles(24);
}
else
{
else {
addCycles(12);
PC += 3;
}
@@ -1773,7 +1685,6 @@ void GameBoy::opcodeHandler()
printf("Unimplemented opcode found: PC:0x%.2x, Opcode:0x%.2x\n", PC, addressSpace[PC]);
exit(1);
}
}
else //extension
{
@@ -1782,8 +1693,7 @@ void GameBoy::opcodeHandler()
addCycles(4);
//extension handler
switch(addressSpace[PC])
{
switch (addressSpace[PC]) {
case 0x11:
rl(BC.lo);
PC += 1;

8
src/ppu.cpp
View File

@@ -4,7 +4,7 @@
#include <cstdint>
void GameBoy::ppuUpdate() {
//test HBlank
//test for HBlank
checkPPUMode();
if (cyclesToStayInHblank != -1) {
@@ -53,7 +53,8 @@ void GameBoy::ppuUpdate() {
// bug on DMG models triggers a STAT interrupt anytime the STAT register is written
// Road Rage and Zerd no Denetsu rely on this
(*STAT) |= (1 << 2);
} else {
}
else {
(*STAT) &= ~(1 << 2);
}
@@ -96,7 +97,8 @@ void GameBoy::checkPPUMode() {
setPPUMode(PPUMode::mode3);
else
setPPUMode(PPUMode::mode0);
} else {
}
else {
// VBlank Period
setPPUMode(PPUMode::mode1);
}