diff options
| -rw-r--r-- | .gitignore | 1 | ||||
| -rw-r--r-- | Cargo.lock | 7 | ||||
| -rw-r--r-- | Cargo.toml | 6 | ||||
| -rw-r--r-- | Readme.md | 1 | ||||
| -rw-r--r-- | rust-toolchain.toml | 2 | ||||
| -rw-r--r-- | shell.nix | 11 | ||||
| -rw-r--r-- | src/chip8.rs | 144 | ||||
| -rw-r--r-- | src/main.rs | 21 |
8 files changed, 193 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..ea8c4bf --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +/target diff --git a/Cargo.lock b/Cargo.lock new file mode 100644 index 0000000..0e6cf8f --- /dev/null +++ b/Cargo.lock @@ -0,0 +1,7 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +version = 4 + +[[package]] +name = "chip8" +version = "0.1.0" diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..73f1c6d --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,6 @@ +[package] +name = "chip8" +version = "0.1.0" +edition = "2024" + +[dependencies] diff --git a/Readme.md b/Readme.md new file mode 100644 index 0000000..d4e7470 --- /dev/null +++ b/Readme.md @@ -0,0 +1 @@ +Following along on https://multigesture.net/articles/how-to-write-an-emulator-chip-8-interpreter/
diff --git a/rust-toolchain.toml b/rust-toolchain.toml new file mode 100644 index 0000000..c5794a6 --- /dev/null +++ b/rust-toolchain.toml @@ -0,0 +1,2 @@ +[toolchain] +channel = "1.85" diff --git a/shell.nix b/shell.nix new file mode 100644 index 0000000..7df07fd --- /dev/null +++ b/shell.nix @@ -0,0 +1,11 @@ +let + moz_overlay = import (builtins.fetchTarball https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz); + nixpkgs = import <nixpkgs> { overlays = [ moz_overlay ]; }; +in + with nixpkgs; + stdenv.mkDerivation { + name = "moz_overlay_shell"; + buildInputs = [ + (nixpkgs.rustChannelOf { rustToolchain = ./rust-toolchain.toml; }).rust + ]; + } diff --git a/src/chip8.rs b/src/chip8.rs new file mode 100644 index 0000000..50b5c12 --- /dev/null +++ b/src/chip8.rs @@ -0,0 +1,144 @@ +use std::io::Read;
+use std::io::Write;
+
+const WIDTH: u16 = 64;
+const HEIGHT: u16 = 32;
+const PIXELS: usize = (WIDTH * HEIGHT) as usize;
+
+fn unknown_opcode(opcode: u16) {
+ eprintln!("Unknwown opcode {:#06x}", opcode);
+ std::process::exit(1);
+}
+
+pub struct Chip8 {
+ v: [u8; 4096],
+ i: u16,
+ pc: u16,
+ stack: [u16; 16],
+ sp: u16,
+ memory: [u8; 4096],
+ screen: [u8; PIXELS],
+ delay_timer: u8,
+ sound_timer: u8,
+ key: [u8; 16],
+ draw: bool,
+}
+
+impl Chip8 {
+ pub fn new() -> Self {
+ return Self {
+ v: [0; 4096],
+ i: 0,
+ pc: 0x200,
+ stack: [0; 16],
+ sp: 0,
+ memory: [0; 4096],
+ screen: [0; PIXELS],
+ delay_timer: 0,
+ sound_timer: 0,
+ key: [0; 16],
+ draw: false,
+ };
+ }
+
+ pub fn load_rom<R: Read>(&mut self, mut reader: R) -> std::io::Result<()> {
+ reader.read(&mut self.memory[0x200..])?;
+ Ok(())
+ }
+
+ pub fn cycle(&mut self) {
+ let pc = self.pc as usize;
+ let opcode = (self.memory[pc] as u16) << 8 | self.memory[pc + 1] as u16;
+ match opcode & 0xF000 {
+ 0x0000 => match opcode & 0x000F {
+ 0x0000 => {
+ eprintln!("CLS");
+ self.screen = [0; PIXELS];
+ self.draw = true;
+ self.pc += 2;
+ }
+ 0x000E => {
+ eprintln!("RET");
+ self.pc += 2;
+ }
+ _ => unknown_opcode(opcode),
+ },
+ 0x6000 => {
+ let x = (opcode & 0x0F00) >> 8;
+ let value = opcode & 0x00FF;
+ eprintln!("LD V{}, {}", x, value);
+ self.v[x as usize] = value as u8;
+ self.pc += 2;
+ }
+ 0xA000 => {
+ self.i = opcode & 0x0FFF;
+ self.pc += 2;
+ eprintln!("LD I, {}", self.i);
+ }
+ 0xD000 => {
+ let x = (opcode & 0x0F00) >> 8;
+ let y = (opcode & 0x00F0) >> 4;
+ let nibble = opcode & 0x000F;
+ eprintln!("DRW V{}, V{}, {}", x, y, nibble);
+ self.v[0xF] = 0;
+ for yy in 0..nibble {
+ let pixel = self.memory[(self.i + yy) as usize];
+ for xx in 0..8 {
+ if (pixel & (0x80 >> xx)) != 0 {
+ let si = x + xx + ((y + yy) * WIDTH);
+ if self.screen[si as usize] == 1 {
+ self.v[0xF] = 1;
+ }
+ self.screen[si as usize] ^= 1;
+ }
+ }
+ }
+ self.draw = true;
+ self.pc += 2;
+ }
+ _ => unknown_opcode(opcode),
+ };
+
+ if self.delay_timer > 0 {
+ self.delay_timer -= 1;
+ }
+
+ if self.sound_timer > 0 {
+ if self.sound_timer == 1 {
+ eprintln!("BEEP");
+ }
+ self.sound_timer -= 1;
+ }
+ }
+
+ pub fn display(&mut self) -> std::io::Result<()> {
+ if self.draw {
+ self.draw = false;
+ self.draw()
+ } else {
+ Ok(())
+ }
+ }
+
+ fn draw(&self) -> std::io::Result<()> {
+ let lines: String = std::iter::once("\x1B[2J\n")
+ .chain((0..HEIGHT).flat_map(|y| {
+ (0..WIDTH)
+ .map(move |x| {
+ let si = x + y * WIDTH;
+ if self.screen[si as usize] == 0 {
+ "░"
+ } else {
+ "█"
+ }
+ })
+ .chain(std::iter::once("\n"))
+ }))
+ .collect();
+
+ let stdout = std::io::stdout();
+ let mut handle = stdout.lock();
+ handle.write_all(lines.as_bytes())?;
+ handle.flush()
+ }
+}
diff --git a/src/main.rs b/src/main.rs new file mode 100644 index 0000000..82374b0 --- /dev/null +++ b/src/main.rs @@ -0,0 +1,21 @@ +use std::{fs::File, io::BufReader}; + +mod chip8; + +fn main() -> std::io::Result<()> { + if let Some(arg) = std::env::args().skip(1).next() { + let mut chip8 = chip8::Chip8::new(); + { + let file = File::open(arg)?; + let buf_reader = BufReader::new(file); + chip8.load_rom(buf_reader)?; + } + loop { + chip8.cycle(); + chip8.display()?; + } + } else { + println!("usage: chip8 rompath") + } + Ok(()) +} |