experimenting with more mappers, nametable adjustment, four screen mirroring
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README.md
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README.md
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@ -1,6 +1,6 @@
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# nestur
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# nestur
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This is an NES emulator and a work in progress. There are still some minor bugs and the audio is kind of scratchy. I've mostly tested on Donkey Kong, Super Mario Bros., and Zelda so far. There are plenty of full-featured emulators out there; this is primarily an educational project but I do want it to run well. SDL2 is the only dependency, it's NTSC timing, and contains no `unsafe` code.
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Nestur is an NES emulator and a work in progress. There are still some minor bugs and the audio is kind of scratchy. I've mostly tested on Donkey Kong, Super Mario Bros., and Zelda so far. There are plenty of full-featured emulators out there; this is primarily an educational project but I do want it to run well. SDL2 is the only dependency, it's NTSC timing, and contains no `unsafe` code.
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<img src="pics/smb.png" width=350> <img src="pics/zelda_dungeon.png" width=350>
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<img src="pics/smb.png" width=350> <img src="pics/zelda_dungeon.png" width=350>
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@ -20,13 +20,25 @@ ___________________
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```
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```
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The code aims to follow the explanations from the [NES dev wiki](https://wiki.nesdev.com/w/index.php/NES_reference_guide) where possible, especially in the PPU, and the comments quote from it often. Thanks to everyone who contributes to that wiki/forum, and to Michael Fogleman's [NES](https://github.com/fogleman/nes) and Scott Ferguson's [Fergulator](https://github.com/scottferg/Fergulator) for getting me unstuck at several points.
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The code aims to follow the explanations from the [NES dev wiki](https://wiki.nesdev.com/w/index.php/NES_reference_guide) where possible, especially in the PPU, and the comments quote from it often. Thanks to everyone who contributes to that wiki/forum, and to Michael Fogleman's [NES](https://github.com/fogleman/nes) and Scott Ferguson's [Fergulator](https://github.com/scottferg/Fergulator) for getting me unstuck at several points.
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## Compilation and Use
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1. Install Rust: https://www.rust-lang.org/tools/install
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2. Configure SDL2 for your platform:
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- Windows: `SDL2.dll` is already in the repo so you don't have to do anything.
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- macOS: Install [Homebrew](https://brew.sh/) and run `brew install sdl2`
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- Linux: `sudo apt-get install libsdl2-dev` (or whatever your package manager is)
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3. `cd nestur/ && cargo build --release`
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4. The `nestur` executable or `nestur.exe` will be in `nestur/target/release`.
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5. Run with `$ ./nestur path/to/rom_filename.nes` or `> nestur.exe path\to\rom_filename.nes`.
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6. If the game uses battery-backed RAM (if it can save data when turned off), a save file like `rom_filename.sav` will be created in the same folder as the ROM when the program is exited. When Nestur is run again, it will look for a file matching the ROM name, with a `.sav` extension instead of `.nes`.
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## To do:
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## To do:
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- More mappers (only mappers 0 (NROM) and 1 (MMC1) implemented so far)
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- More mappers (only mappers 0 (NROM) and 1 (MMC1) implemented so far)
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- DMC audio channel, high- and low-pass filters
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- DMC audio channel, high- and low-pass filters
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- Save/load functionality and battery-backed RAM solution
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- Save state/load functionality
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- Player 2 controller?
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- Player 2 controller?
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@ -0,0 +1,48 @@
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use super::{Cartridge, Mapper, Mirror};
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pub struct Cnrom {
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cart: Cartridge,
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chr_bank_select: usize,
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}
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impl Cnrom {
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pub fn new(cart: Cartridge) -> Self {
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Cnrom{
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cart: cart,
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chr_bank_select: 0,
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}
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}
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}
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impl Mapper for Cnrom {
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fn read(&mut self, address: usize) -> u8 {
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let cl = self.cart.chr_rom.len();
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let pl = self.cart.prg_rom.len();
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let addr = address % 0x4000;
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match address {
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0x0000..=0x1FFF => self.cart.chr_rom[self.chr_bank_select][address],
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0x8000..=0xBFFF => self.cart.prg_rom[0][addr],
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0xC000..=0xFFFF => self.cart.prg_rom[pl-1][addr],
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_ => panic!("bad address read from CNROM mapper: 0x{:X}", address),
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}
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}
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fn write(&mut self, address: usize, value: u8) {
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match address {
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0x8000..=0xFFFF => self.chr_bank_select = (value & 0b11) as usize,
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_ => println!("bad address written to CNROM mapper: 0x{:X}", address),
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}
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}
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fn get_mirroring(&mut self) -> Mirror {
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self.cart.mirroring
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// if self.cart.four_screen_vram {
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// Mirror::FourScreen
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// } else {
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// self.cart.mirroring
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// }
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}
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fn load_battery_backed_ram(&mut self) {}
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fn save_battery_backed_ram(&self) {}
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}
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use super::{Cartridge, Mapper, Mirror};
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pub struct Mmc3 {
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cart: Cartridge,
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reg0: u8,
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reg1: u8,
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reg2: u8,
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reg3: u8,
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reg4: u8,
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reg5: u8,
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reg6: u8,
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reg7: u8,
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irq_counter: u8,
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irq_latch: u8,
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}
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impl Mmc3 {
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pub fn new(cart: Cartridge) -> Self {
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Mmc3{
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cart: cart,
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reg0: 0,
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reg1: 0,
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reg2: 0,
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reg3: 0,
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reg4: 0,
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reg5: 0,
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reg6: 0,
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reg7: 0,
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}
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}
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}
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impl Mmc3 {
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}
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impl Mapper for Mmc3 {
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fn read(&mut self, address: usize) -> u8 {
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match address {
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0x0000..=0x07FF => ,
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0x0800..=0x0FFF => ,
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0x1000..=0x13FF => ,
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0x1400..=0x17FF => ,
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0x1800..=0x1BFF => ,
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0x1C00..=0x1FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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}
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}
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fn write(&mut self, address: usize, value: u8) {
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match address % 2 == 0 {
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true => { // even
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match address {
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0x8000..=0x9FFF => self.bank_select(address),
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0xA000..=0xBFFF => self.mirroring = if value & 1 == 0 {Mirror::Vertical} else {Mirror::Horizontal},
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0xC000..=0xDFFF => ,
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0x1400..=0x17FF => ,
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0x1800..=0x1BFF => ,
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0x1C00..=0x1FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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}
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},
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false => { // odd
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match address {
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0x8000..=0x9FFF => self.bank_data(value),
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0xA000..=0xBFFF => self.prg_ram_protect(value),
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0xC000..=0xDFFF => ,
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0x1400..=0x17FF => ,
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0x1800..=0x1BFF => ,
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0x1C00..=0x1FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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0x6000..=0x7FFF => ,
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}
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},
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}
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fn get_mirroring(&mut self) -> Mirror {}
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fn load_battery_backed_ram(&mut self) {}
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fn save_battery_backed_ram(&self) {}
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}
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mod nrom;
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mod nrom;
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mod mmc1;
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mod mmc1;
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mod uxrom;
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mod cnrom;
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// mod mmc3;
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use nrom::Nrom;
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use nrom::Nrom;
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use mmc1::Mmc1;
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use mmc1::Mmc1;
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use uxrom::Uxrom;
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use cnrom::Cnrom;
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// use mmc3::Mmc3;
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use std::cell::RefCell;
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use std::cell::RefCell;
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use std::rc::Rc;
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use std::rc::Rc;
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HighBank,
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HighBank,
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Horizontal,
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Horizontal,
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Vertical,
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Vertical,
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FourScreen,
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}
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}
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pub fn get_mapper() -> Rc<RefCell<dyn Mapper>> {
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pub fn get_mapper() -> Rc<RefCell<dyn Mapper>> {
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match num {
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match num {
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0 => Rc::new(RefCell::new(Nrom::new(cart))),
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0 => Rc::new(RefCell::new(Nrom::new(cart))),
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1 => Rc::new(RefCell::new(Mmc1::new(cart))),
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1 => Rc::new(RefCell::new(Mmc1::new(cart))),
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2 => Rc::new(RefCell::new(Uxrom::new(cart))),
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3 => Rc::new(RefCell::new(Cnrom::new(cart))),
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// 4 => Rc::new(RefCell::new(Mmc3::new(cart))),
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_ => panic!("unimplemented mapper: {}", num),
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_ => panic!("unimplemented mapper: {}", num),
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}
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}
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}
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}
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pub mirroring: Mirror, // 0 horizontal, 1 vertical
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pub mirroring: Mirror, // 0 horizontal, 1 vertical
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battery_backed_ram: bool, // 1: Cartridge contains battery-backed PRG RAM ($6000-7FFF) or other persistent memory
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battery_backed_ram: bool, // 1: Cartridge contains battery-backed PRG RAM ($6000-7FFF) or other persistent memory
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trainer_present: bool, // 1: 512-byte trainer at $7000-$71FF (stored before PRG data)
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trainer_present: bool, // 1: 512-byte trainer at $7000-$71FF (stored before PRG data)
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_four_screen_vram: u8, // 1: Ignore mirroring control or above mirroring bit; instead provide four-screen VRAM
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four_screen_vram: bool, // 1: Ignore mirroring control or above mirroring bit; instead provide four-screen VRAM
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// TODO: other iNES header flags
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// TODO: other iNES header flags
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pub prg_rom: Vec<Vec<u8>>, // 16 KiB chunks for CPU
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pub prg_rom: Vec<Vec<u8>>, // 16 KiB chunks for CPU
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mirroring: if data[6] & (1 << 0) == 0 {Mirror::Horizontal} else {Mirror::Vertical},
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mirroring: if data[6] & (1 << 0) == 0 {Mirror::Horizontal} else {Mirror::Vertical},
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battery_backed_ram: data[6] & (1 << 1) != 0,
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battery_backed_ram: data[6] & (1 << 1) != 0,
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trainer_present: data[6] & (1 << 2) != 0,
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trainer_present: data[6] & (1 << 2) != 0,
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_four_screen_vram: (data[6] & (1 << 3) != 0) as u8,
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four_screen_vram: data[6] & (1 << 3) != 0,
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prg_rom: Vec::new(),
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prg_rom: Vec::new(),
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chr_rom: Vec::new(),
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chr_rom: Vec::new(),
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all_data: data,
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all_data: data,
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0xC000..=0xFFFF => {
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0xC000..=0xFFFF => {
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self.cart.prg_rom[pl-1][addr]
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self.cart.prg_rom[pl-1][addr]
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},
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},
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_ => panic!("bad address sent to NROM mapper: 0x{:X}", address),
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_ => {println!("bad address read from NROM mapper: 0x{:X}", address); 0},
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}
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}
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}
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}
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self.cart.chr_rom[cl-1][address] = value;
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self.cart.chr_rom[cl-1][address] = value;
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}
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}
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},
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},
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0x8000..=0xBFFF => {
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0x8000..=0xBFFF => self.cart.prg_rom[0][addr] = value,
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self.cart.prg_rom[0][addr] = value;
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0xC000..=0xFFFF => self.cart.prg_rom[pl-1][addr] = value,
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},
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_ => println!("bad address written to NROM mapper: 0x{:X}", address),
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0xC000..=0xFFFF => {
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self.cart.prg_rom[pl-1][addr] = value;
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},
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_ => panic!("bad address sent to NROM mapper: 0x{:X}", address),
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}
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}
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}
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}
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use super::{Cartridge, Mapper, Mirror};
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pub struct Uxrom {
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cart: Cartridge,
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chr_ram: Vec<u8>,
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bank_select: usize,
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}
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impl Uxrom {
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pub fn new(cart: Cartridge) -> Self {
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Uxrom{
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cart: cart,
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chr_ram: vec![0; 0x2000],
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bank_select: 0,
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}
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}
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}
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impl Mapper for Uxrom {
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fn read(&mut self, address: usize) -> u8 {
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match address {
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0x0000..=0x1FFF => {
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if self.cart.chr_rom_size > 0 {
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self.cart.chr_rom[0][address]
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} else {
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self.chr_ram[address]
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}
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},
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0x8000..=0xBFFF => self.cart.prg_rom[self.bank_select][address % 0x4000],
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0xC000..=0xFFFF => self.cart.prg_rom[self.cart.prg_rom.len()-1][address % 0x4000],
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_ => {println!("bad address read from UxROM mapper: 0x{:X}", address); 0},
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}
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}
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fn write(&mut self, address: usize, value: u8) {
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match address {
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0x0000..=0x1FFF => {
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if self.cart.chr_rom_size == 0 {
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self.chr_ram[address] = value;
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}
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},
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0x8000..=0xFFFF => self.bank_select = value as usize,
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_ => println!("bad address written to UxROM mapper: 0x{:X}", address),
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}
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}
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fn get_mirroring(&mut self) -> Mirror {
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self.cart.mirroring
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}
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fn load_battery_backed_ram(&mut self) {}
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fn save_battery_backed_ram(&self) {}
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}
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@ -55,19 +55,28 @@ impl super::Ppu {
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let base = address % 0x1000;
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let base = address % 0x1000;
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let offset = base % 0x0400;
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let offset = base % 0x0400;
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match self.mapper.borrow_mut().get_mirroring() {
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match self.mapper.borrow_mut().get_mirroring() {
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Mirror::LowBank => self.nametable_low_bank[offset],
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Mirror::LowBank => self.nametable_A[offset],
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Mirror::HighBank => self.nametable_high_bank[offset],
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Mirror::HighBank => self.nametable_B[offset],
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Mirror::Horizontal => {
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Mirror::Horizontal => {
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match base {
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match base {
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0x0000..=0x07FF => self.nametable_low_bank[offset],
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0x0000..=0x07FF => self.nametable_A[offset],
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0x0800..=0x0FFF => self.nametable_high_bank[offset],
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0x0800..=0x0FFF => self.nametable_B[offset],
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_ => panic!("panicked reading nametable base: {}", base),
|
_ => panic!("panicked reading nametable base: {}", base),
|
||||||
}
|
}
|
||||||
},
|
},
|
||||||
Mirror::Vertical => {
|
Mirror::Vertical => {
|
||||||
match base {
|
match base {
|
||||||
0x0000..=0x03FF | 0x0800..=0x0BFF => self.nametable_low_bank[offset],
|
0x0000..=0x03FF | 0x0800..=0x0BFF => self.nametable_A[offset],
|
||||||
0x0400..=0x07FF | 0x0C00..=0x0FFF => self.nametable_high_bank[offset],
|
0x0400..=0x07FF | 0x0C00..=0x0FFF => self.nametable_B[offset],
|
||||||
|
_ => panic!("panicked reading nametable base: {}", base),
|
||||||
|
}
|
||||||
|
},
|
||||||
|
Mirror::FourScreen => {
|
||||||
|
match base {
|
||||||
|
0x0000..=0x03FF => self.nametable_A[offset],
|
||||||
|
0x0400..=0x07FF => self.nametable_B[offset],
|
||||||
|
0x0800..=0x0BFF => self.nametable_C[offset],
|
||||||
|
0x0C00..=0x0FFF => self.nametable_D[offset],
|
||||||
_ => panic!("panicked reading nametable base: {}", base),
|
_ => panic!("panicked reading nametable base: {}", base),
|
||||||
}
|
}
|
||||||
},
|
},
|
||||||
|
@ -78,23 +87,28 @@ impl super::Ppu {
|
||||||
let base = address % 0x1000;
|
let base = address % 0x1000;
|
||||||
let offset = base % 0x0400;
|
let offset = base % 0x0400;
|
||||||
match self.mapper.borrow_mut().get_mirroring() {
|
match self.mapper.borrow_mut().get_mirroring() {
|
||||||
Mirror::LowBank => {
|
Mirror::LowBank => self.nametable_A[offset] = value,
|
||||||
self.nametable_low_bank[offset] = value;
|
Mirror::HighBank => self.nametable_B[offset] = value,
|
||||||
},
|
|
||||||
Mirror::HighBank => {
|
|
||||||
self.nametable_high_bank[offset] = value;
|
|
||||||
},
|
|
||||||
Mirror::Horizontal => {
|
Mirror::Horizontal => {
|
||||||
match base {
|
match base {
|
||||||
0x0000..=0x07FF => self.nametable_low_bank[offset] = value,
|
0x0000..=0x07FF => self.nametable_A[offset] = value,
|
||||||
0x0800..=0x0FFF => self.nametable_high_bank[offset] = value,
|
0x0800..=0x0FFF => self.nametable_B[offset] = value,
|
||||||
_ => panic!("panicked writing nametable base: {}", base),
|
_ => panic!("panicked writing nametable base: {}", base),
|
||||||
}
|
}
|
||||||
},
|
},
|
||||||
Mirror::Vertical => {
|
Mirror::Vertical => {
|
||||||
match base {
|
match base {
|
||||||
0x0000..=0x03FF | 0x0800..=0x0BFF => self.nametable_low_bank[offset] = value,
|
0x0000..=0x03FF | 0x0800..=0x0BFF => self.nametable_A[offset] = value,
|
||||||
0x0400..=0x07FF | 0x0C00..=0x0FFF => self.nametable_high_bank[offset] = value,
|
0x0400..=0x07FF | 0x0C00..=0x0FFF => self.nametable_B[offset] = value,
|
||||||
|
_ => panic!("panicked writing nametable base: {}", base),
|
||||||
|
}
|
||||||
|
},
|
||||||
|
Mirror::FourScreen => {
|
||||||
|
match base {
|
||||||
|
0x0000..=0x03FF => self.nametable_A[offset] = value,
|
||||||
|
0x0400..=0x07FF => self.nametable_B[offset] = value,
|
||||||
|
0x0800..=0x0BFF => self.nametable_C[offset] = value,
|
||||||
|
0x0C00..=0x0FFF => self.nametable_D[offset] = value,
|
||||||
_ => panic!("panicked writing nametable base: {}", base),
|
_ => panic!("panicked writing nametable base: {}", base),
|
||||||
}
|
}
|
||||||
},
|
},
|
||||||
|
|
|
@ -26,8 +26,10 @@ pub struct Ppu {
|
||||||
// Pictures on http://wiki.nesdev.com/w/index.php/Mirroring refer to them as A and B.
|
// Pictures on http://wiki.nesdev.com/w/index.php/Mirroring refer to them as A and B.
|
||||||
// http://wiki.nesdev.com/w/index.php/MMC1 calls them higher and lower.
|
// http://wiki.nesdev.com/w/index.php/MMC1 calls them higher and lower.
|
||||||
// They can be mirrored at certain memory ranges.
|
// They can be mirrored at certain memory ranges.
|
||||||
nametable_low_bank: Vec<u8>,
|
nametable_A: Vec<u8>,
|
||||||
nametable_high_bank: Vec<u8>,
|
nametable_B: Vec<u8>,
|
||||||
|
nametable_C: Vec<u8>,
|
||||||
|
nametable_D: Vec<u8>,
|
||||||
|
|
||||||
// The palette shared by both background and sprites.
|
// The palette shared by both background and sprites.
|
||||||
// Consists of 32 bytes, each of which represents an index into the global PALETTE_TABLE.
|
// Consists of 32 bytes, each of which represents an index into the global PALETTE_TABLE.
|
||||||
|
@ -99,8 +101,10 @@ impl Ppu {
|
||||||
x: 0,
|
x: 0,
|
||||||
w: 0,
|
w: 0,
|
||||||
mapper: mapper,
|
mapper: mapper,
|
||||||
nametable_low_bank: vec![0u8; 0x0400],
|
nametable_A: vec![0u8; 0x0400],
|
||||||
nametable_high_bank: vec![0u8; 0x0400],
|
nametable_B: vec![0u8; 0x0400],
|
||||||
|
nametable_C: vec![0u8; 0x0400],
|
||||||
|
nametable_D: vec![0u8; 0x0400],
|
||||||
palette_ram: vec![0u8; 0x0020],
|
palette_ram: vec![0u8; 0x0020],
|
||||||
background_pattern_sr_low: 0,
|
background_pattern_sr_low: 0,
|
||||||
background_pattern_sr_high: 0,
|
background_pattern_sr_high: 0,
|
||||||
|
|
Loading…
Reference in New Issue