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Fix interrupts, implement halt mode and fix IME

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This commit is contained in:
Franco Colmenarez 2021-10-31 07:25:47 -05:00
parent 61db367f31
commit 5723c3b3b6
5 changed files with 112 additions and 66 deletions
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22
src/bus.rs
View File

@ -5,7 +5,7 @@ use crate::utils::{
join_bytes
};
use crate::rom::ROM;
use crate::ppu::{PPU, LCDStatus, LCDStatusModeFlag};
use crate::ppu::{PPU, LCDStatus, LCDStatusModeFlag, LCD_CONTROL_ADDRESS, LCD_Y_ADDRESS};
use crate::cpu::{Interrupt};
use crate::timer::{TIMER_DIVIDER_REGISTER_ADDRESS};
@ -50,7 +50,7 @@ pub struct Bus {
impl Bus {
pub fn new() -> Self {
let game_rom = match ROM::load_file("ignore/tetris.gb".to_string()) {
let game_rom = match ROM::load_file("ignore/mario-land.gb".to_string()) {
// let game_rom = match ROM::load_file("roms/cpu_instrs.gb".to_string()) {
// let game_rom = match ROM::load_file("roms/cpu_instrs_individual/01-special.gb".to_string()) {
// let game_rom = match ROM::load_file("roms/cpu_instrs_individual/02-interrupts.gb".to_string()) {
@ -74,14 +74,11 @@ impl Bus {
}
pub fn read(&self, address: u16) -> u8 {
if address == 0xFF00 {
return 0xFF;
}
if BANK_ZERO.in_range(address) || BANK_SWITCHABLE.in_range(address) {
return self.game_rom.read(address);
} else if VIDEO_RAM.in_range(address) {
if PPU::get_lcd_status(self, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD)) {
return 0xFF;
}
} else if IO_REGISTERS.in_range(address) {
return self.data[address as usize];
}
self.data[address as usize]
}
@ -106,10 +103,11 @@ impl Bus {
} else if ECHO_RAM.in_range(address) {
self.data[address as usize] = data;
self.data[(WORK_RAM_1.begin() + (address - ECHO_RAM.begin())) as usize] = data; // Copy to the working RAM
} else if VIDEO_RAM.in_range(address) {
self.data[address as usize] = data;
} else if address == TIMER_DIVIDER_REGISTER_ADDRESS {
self.data[address as usize] = 0x00;
} else if address == LCD_CONTROL_ADDRESS && get_bit(data, BitIndex::I7) {
self.data[address as usize] = data;
self.data[LCD_Y_ADDRESS as usize] = 0x00;
} else {
self.data[address as usize] = data;
}
@ -121,12 +119,12 @@ impl Bus {
self.write(address.wrapping_add(1), bytes[1]);
}
pub fn set_interrupt_master(&mut self, interrupt: Interrupt, val: bool) {
pub fn set_interrupt_enable(&mut self, interrupt: Interrupt, val: bool) {
let byte = self.read(INTERRUPT_ENABLE_ADDRESS);
self.write(INTERRUPT_ENABLE_ADDRESS, interrupt.set(byte, val));
}
pub fn set_interrupt(&mut self, interrupt: Interrupt, val: bool) {
pub fn set_interrupt_flag(&mut self, interrupt: Interrupt, val: bool) {
let byte = self.read(INTERRUPT_FLAG_ADDRESS);
self.write(INTERRUPT_FLAG_ADDRESS, interrupt.set(byte, val));
}

35
src/cpu.rs
View File

@ -841,6 +841,8 @@ pub struct CPU {
cycles: Cycles,
last_op_cycles: Cycles,
exec_calls_count: usize,
is_halted: bool,
ime: bool, // Interrupt Master Enable
}
impl CPU {
@ -850,6 +852,8 @@ impl CPU {
cycles: Cycles(0),
last_op_cycles: Cycles(0),
exec_calls_count: 0,
is_halted: false,
ime: true,
}
}
@ -905,8 +909,8 @@ impl CPU {
}
pub fn handle_interrupt(&mut self, bus: &mut Bus, interrupt: Interrupt) {
bus.set_interrupt_master(interrupt, false);
bus.set_interrupt(interrupt, false);
bus.set_interrupt_enable(interrupt, false);
bus.set_interrupt_flag(interrupt, false);
let vector = interrupt.get_vector();
self.exec(Opcode::CALL(OpcodeParameter::U16(vector)), bus);
self.increment_cycles(Cycles(5));
@ -914,6 +918,12 @@ impl CPU {
}
pub fn check_interrupts(&mut self, bus: &mut Bus) -> Option<Interrupt> {
if bus.read(INTERRUPT_ENABLE_ADDRESS) & bus.read(INTERRUPT_FLAG_ADDRESS) != 0 {
self.is_halted = false;
}
if !self.ime {
return None;
}
if bus.get_interrupt(Interrupt::VBlank) {
return Some(Interrupt::VBlank);
} else if bus.get_interrupt(Interrupt::LCDSTAT) {
@ -932,7 +942,7 @@ impl CPU {
let cycles_start = self.get_cycles();
if let Some(interrupt) = self.check_interrupts(bus) {
self.handle_interrupt(bus, interrupt);
} else {
} else if !self.is_halted {
let program_counter = self.registers.get(Register::PC);
let parameter_bytes = OpcodeParameterBytes::from_address(program_counter, bus);
let (opcode, cycles) = parameter_bytes.parse_opcode();
@ -941,6 +951,8 @@ impl CPU {
}
self.increment_cycles(cycles);
self.exec(opcode, bus);
} else if self.is_halted {
self.increment_cycles(Cycles(1));
}
let cycles_end = self.get_cycles();
self.set_last_op_cycles(cycles_start, cycles_end);
@ -1767,21 +1779,24 @@ impl CPU {
// Enable interrupts
Opcode::EI => {
self.registers.increment(Register::PC, 1);
bus.write(INTERRUPT_ENABLE_ADDRESS, 0xFF); // Disable all interrupts
self.ime = true;
// bus.write(INTERRUPT_MASTER_ENABLE_ADDRESS, 0xFF); // Enable all interrupts
},
// Disable interrupts
Opcode::DI => {
self.registers.increment(Register::PC, 1);
bus.write(INTERRUPT_ENABLE_ADDRESS, 0x00); // Disable all interrupts
self.ime = false;
// bus.write(INTERRUPT_MASTER_ENABLE_ADDRESS, 0x00); // Disable all interrupts
},
// Same as enabling interrupts and then executing RET
Opcode::RETI => {
self.exec(Opcode::EI, bus);
self.exec(Opcode::RET(OpcodeParameter::NoParam), bus);
},
// WIP
// Don't execute instructions until an interrupt is requested
Opcode::HALT => {
self.registers.increment(Register::PC, 1);
self.is_halted = true;
},
Opcode::STOP => {
self.registers.increment(Register::PC, 2);
@ -1919,16 +1934,16 @@ mod tests {
let mut bus = Bus::new();
let addr = 0xFF00;
cpu.registers.set(Register::A, 0xF1);
cpu.exec(Opcode::LD(OpcodeParameter::FF00plusU8_Register(4, Register::A)), &mut bus);
assert_eq!(bus.read(addr + 4), 0xF1);
cpu.exec(Opcode::LD(OpcodeParameter::FF00plusU8_Register(0x42, Register::A)), &mut bus);
assert_eq!(bus.read(addr + 0x42), 0xF1);
assert_eq!(cpu.registers.get(Register::PC), 0x102);
let mut cpu = CPU::new();
let mut bus = Bus::new();
let addr = 0xFF00;
cpu.registers.set(Register::A, 0x00);
bus.write(addr + 4, 0xF1);
cpu.exec(Opcode::LD(OpcodeParameter::Register_FF00plusU8(Register::A, 4)), &mut bus);
bus.write(addr + 0x42, 0xF1);
cpu.exec(Opcode::LD(OpcodeParameter::Register_FF00plusU8(Register::A, 0x42)), &mut bus);
assert_eq!(cpu.registers.get(Register::A), 0xF1);
assert_eq!(cpu.registers.get(Register::PC), 0x102);

4
src/emulator.rs
View File

@ -9,6 +9,7 @@ pub struct Emulator {
cpu: CPU,
ppu: PPU,
bus: Bus,
timer: Timer,
}
impl Emulator {
@ -17,6 +18,7 @@ impl Emulator {
cpu: CPU::new(),
ppu: PPU::new(),
bus: Bus::new(),
timer: Timer::new(),
}
}
@ -32,7 +34,7 @@ impl Emulator {
while self.cpu.get_cycles().0 <= cpu_cycles.0 {
self.cpu.run(&mut self.bus);
self.ppu.do_cycles(&mut self.bus, self.cpu.get_last_op_cycles());
Timer::do_cycles(&mut self.bus, self.cpu.get_last_op_cycles());
self.timer.do_cycles(&mut self.bus, self.cpu.get_last_op_cycles());
}
}

66
src/ppu.rs
View File

@ -19,7 +19,7 @@ enum Pixel {
struct ColorPalette(u8, u8, u8, u8);
pub enum LCDControl {
DisplayEnable,
LCDEnable,
WindowTileMapAddress,
WindowEnable,
BackgroundWindowTileAddress,
@ -51,20 +51,20 @@ pub const WIDTH: u32 = LCD_WIDTH;
pub const HEIGHT: u32 = LCD_HEIGHT;
pub const FRAME_BUFFER_LENGTH: u32 = WIDTH * HEIGHT;
const LCD_CONTROL_ADDRESS: u16 = 0xFF40;
const LCD_STATUS_ADDRESS: u16 = 0xFF41;
pub const LCD_CONTROL_ADDRESS: u16 = 0xFF40;
pub const LCD_STATUS_ADDRESS: u16 = 0xFF41;
const SCROLL_Y_ADDRESS: u16 = 0xFF42;
const SCROLL_X_ADDRESS: u16 = 0xFF43;
const LCD_Y_ADDRESS: u16 = 0xFF44;
const LCD_Y_COMPARE_ADDRESS: u16 = 0xFF45;
const DMA_ADDRESS: u16 = 0xFF46;
const BACKGROUND_PALETTE_ADDRESS: u16 = 0xFF47;
const OBJECT_PALETTE_0_ADDRESS: u16 = 0xFF48;
const OBJECT_PALETTE_1_ADDRESS: u16 = 0xFF49;
const WINDOW_X_ADDRESS: u16 = 0xFF4A;
const WINDOW_Y_ADDRESS: u16 = 0xFF4B;
const TILE_MAP_ADDRESS: u16 = 0x9800;
pub const SCROLL_Y_ADDRESS: u16 = 0xFF42;
pub const SCROLL_X_ADDRESS: u16 = 0xFF43;
pub const LCD_Y_ADDRESS: u16 = 0xFF44;
pub const LCD_Y_COMPARE_ADDRESS: u16 = 0xFF45;
pub const DMA_ADDRESS: u16 = 0xFF46;
pub const BACKGROUND_PALETTE_ADDRESS: u16 = 0xFF47;
pub const OBJECT_PALETTE_0_ADDRESS: u16 = 0xFF48;
pub const OBJECT_PALETTE_1_ADDRESS: u16 = 0xFF49;
pub const WINDOW_X_ADDRESS: u16 = 0xFF4A;
pub const WINDOW_Y_ADDRESS: u16 = 0xFF4B;
pub const TILE_MAP_ADDRESS: u16 = 0x9800;
pub struct PPU {
cycles: Cycles,
@ -96,30 +96,32 @@ impl PPU {
}
pub fn cycle(&mut self, bus: &mut Bus) {
// Mode 1 Vertical blank
if PPU::get_lcd_y(bus) >= 144 {
if PPU::get_lcd_y(bus) == 144 {
bus.set_interrupt(Interrupt::VBlank, true);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank), true);
}
} else {
self.increment_cycles(Cycles(1));
if !PPU::get_lcd_control(bus, LCDControl::LCDEnable) {
return;
}
if PPU::get_lcd_y(bus) < 144 {
if self.cycles.0 == 0 {
// Mode 2 OAM scan
PPU::request_interrupt(bus, Interrupt::LCDSTAT);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::SearchingOAM), true);
} else if self.cycles.0 == 80 + 1 {
// Mode 3 drawing pixel line. This could also last 289 cycles
bus.set_interrupt(Interrupt::LCDSTAT, true);
// PPU::request_interrupt(bus, Interrupt::LCDSTAT);
self.draw_line(bus);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD), true);
} else if self.cycles.0 == 80 + 172 + 1 {
// Mode 0 Horizontal blank. This could last 87 or 204 cycles depending on the mode 3
bus.set_interrupt(Interrupt::LCDSTAT, true);
PPU::request_interrupt(bus, Interrupt::LCDSTAT);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::HBlank), true);
}
} else if PPU::get_lcd_y(bus) == 144 && self.cycles.0 == 0 {
// Mode 1 Vertical blank
PPU::request_interrupt(bus, Interrupt::VBlank);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank), true);
}
self.increment_cycles(Cycles(1));
// Horizontal scan completed
if self.cycles.0 > 456 {
self.reset_cycles();
@ -129,7 +131,7 @@ impl PPU {
let lyc_compare = PPU::get_lcd_y(bus) == bus.read(LCD_Y_COMPARE_ADDRESS);
if lyc_compare {
PPU::set_lcd_status(bus, LCDStatus::LYCInterrupt, lyc_compare);
bus.set_interrupt(Interrupt::LCDSTAT, true);
PPU::request_interrupt(bus, Interrupt::LCDSTAT);
}
// Frame completed
@ -139,6 +141,14 @@ impl PPU {
}
}
fn request_interrupt(bus: &mut Bus, interrupt: Interrupt) {
if PPU::get_lcd_control(bus, LCDControl::LCDEnable) {
bus.set_interrupt_flag(interrupt, true);
} else {
println!("lcd off");
}
}
fn get_lcd_y(bus: &Bus) -> u8 {
bus.read(LCD_Y_ADDRESS)
}
@ -166,7 +176,7 @@ impl PPU {
pub fn get_lcd_control(bus: &Bus, control: LCDControl) -> bool {
let byte = bus.read(LCD_CONTROL_ADDRESS);
match control {
LCDControl::DisplayEnable => get_bit(byte, BitIndex::I7),
LCDControl::LCDEnable => get_bit(byte, BitIndex::I7),
LCDControl::WindowTileMapAddress => get_bit(byte, BitIndex::I6),
LCDControl::WindowEnable => get_bit(byte, BitIndex::I5),
LCDControl::BackgroundWindowTileAddress => get_bit(byte, BitIndex::I4),
@ -180,7 +190,7 @@ impl PPU {
fn set_lcd_control(bus: &mut Bus, control: LCDControl, val: bool) {
let mut byte = bus.read(LCD_CONTROL_ADDRESS);
byte = match control {
LCDControl::DisplayEnable => set_bit(byte, val, BitIndex::I7),
LCDControl::LCDEnable => set_bit(byte, val, BitIndex::I7),
LCDControl::WindowTileMapAddress => set_bit(byte, val, BitIndex::I6),
LCDControl::WindowEnable => set_bit(byte, val, BitIndex::I5),
LCDControl::BackgroundWindowTileAddress => set_bit(byte, val, BitIndex::I4),

51
src/timer.rs
View File

@ -10,45 +10,66 @@ pub const TIMER_COUNTER_ADDRESS: u16 = 0xFF05;
pub const TIMER_MODULO_ADDRESS: u16 = 0xFF06;
pub const TIMER_CONTROL_ADDRESS: u16 = 0xFF07;
pub struct Timer;
pub struct Timer {
cycles: Cycles,
}
impl Timer {
pub fn new() -> Self {
Self {
cycles: Cycles(0),
}
}
fn increment_cycles(&mut self, cycles: Cycles) {
self.cycles.0 += cycles.0;
}
fn reset_cycles(&mut self) {
self.cycles.0 = 0;
}
pub fn do_cycles(bus: &mut Bus, cycles: Cycles) {
pub fn do_cycles(&mut self, bus: &mut Bus, cycles: Cycles) {
let mut count = 0;
while count < cycles.to_t() {
Timer::cycle(bus);
self.cycle(bus);
count += 1;
}
}
fn cycle(bus: &mut Bus) {
fn cycle(&mut self, bus: &mut Bus) {
let div = bus.read(TIMER_DIVIDER_REGISTER_ADDRESS);
bus.write(TIMER_DIVIDER_REGISTER_ADDRESS, div.wrapping_add(1));
if Timer::is_timer_enabled(bus) {
let tima = bus.read(TIMER_COUNTER_ADDRESS);
let tima_increment = Timer::get_tima_increment(bus);
if tima.checked_add(tima_increment) == None {
bus.write(TIMER_COUNTER_ADDRESS, bus.read(TIMER_MODULO_ADDRESS));
bus.set_interrupt(Interrupt::Timer, true);
} else {
bus.write(TIMER_COUNTER_ADDRESS, tima.wrapping_add(tima_increment));
let tima_rate = Timer::get_tima_rate(bus);
if self.cycles.0 >= tima_rate {
if tima.checked_add(1) == None {
bus.write(TIMER_COUNTER_ADDRESS, bus.read(TIMER_MODULO_ADDRESS));
bus.set_interrupt_flag(Interrupt::Timer, true);
} else {
bus.write(TIMER_COUNTER_ADDRESS, tima.wrapping_add(1));
}
self.reset_cycles();
}
}
self.increment_cycles(Cycles(1));
}
fn is_timer_enabled(bus: &Bus) -> bool {
get_bit(bus.read(TIMER_CONTROL_ADDRESS), BitIndex::I2)
}
fn get_tima_increment(bus: &Bus) -> u8 {
fn get_tima_rate(bus: &Bus) -> usize {
let clock_select = bus.read(TIMER_CONTROL_ADDRESS) & 0b0000_0011;
match clock_select {
0b00 => (4096 as u16 / 1026 as u16 / 4 as u16).to_be_bytes()[1],
0b01 => (4096 as u16 / 16 as u16 / 4 as u16).to_be_bytes()[1],
0b10 => (4096 as u16 / 64 as u16 / 4 as u16).to_be_bytes()[1],
0b11 => (4096 as u16 / 256 as u16 / 4 as u16).to_be_bytes()[1],
0b00 => 16,
0b01 => 64,
0b10 => 256,
0b11 => 1024,
_ => 1,
}
}