feat: implement clap for cli and improve error messages

Cargo.lock

@@ -19,6 +19,15 @@ dependencies = [
  "xml-rs",
 ]
 
+[[package]]
+name = "ansi_term"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee49baf6cb617b853aa8d93bf420db2383fab46d314482ca2803b40d5fde979b"
+dependencies = [
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "anyhow"
 version = "1.0.39"
@@ -40,6 +49,17 @@ dependencies = [
  "libloading 0.6.7",
 ]
 
+[[package]]
+name = "atty"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9b39be18770d11421cdb1b9947a45dd3f37e93092cbf377614828a319d5fee8"
+dependencies = [
+ "hermit-abi",
+ "libc",
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "autocfg"
 version = "1.0.1"
@@ -128,6 +148,21 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "clap"
+version = "2.33.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37e58ac78573c40708d45522f0d80fa2f01cc4f9b4e2bf749807255454312002"
+dependencies = [
+ "ansi_term",
+ "atty",
+ "bitflags",
+ "strsim 0.8.0",
+ "textwrap",
+ "unicode-width",
+ "vec_map",
+]
+
 [[package]]
 name = "cocoa"
 version = "0.24.0"
@@ -278,7 +313,7 @@ dependencies = [
  "ident_case",
  "proc-macro2",
  "quote",
- "strsim",
+ "strsim 0.9.3",
  "syn",
 ]
 
@@ -478,6 +513,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "bitfield",
+ "clap",
  "pixels",
  "winit",
  "winit_input_helper",
@@ -629,6 +665,15 @@ dependencies = [
  "slab",
 ]
 
+[[package]]
+name = "hermit-abi"
+version = "0.1.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "322f4de77956e22ed0e5032c359a0f1273f1f7f0d79bfa3b8ffbc730d7fbcc5c"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "ident_case"
 version = "1.0.1"
@@ -1234,6 +1279,12 @@ dependencies = [
  "lock_api",
 ]
 
+[[package]]
+name = "strsim"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
+
 [[package]]
 name = "strsim"
 version = "0.9.3"
@@ -1251,6 +1302,15 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "textwrap"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d326610f408c7a4eb6f51c37c330e496b08506c9457c9d34287ecc38809fb060"
+dependencies = [
+ "unicode-width",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.24"
@@ -1327,12 +1387,24 @@ dependencies = [
  "wide",
 ]
 
+[[package]]
+name = "unicode-width"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9337591893a19b88d8d87f2cec1e73fad5cdfd10e5a6f349f498ad6ea2ffb1e3"
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"
 
+[[package]]
+name = "vec_map"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
+
 [[package]]
 name = "version_check"
 version = "0.9.3"

Cargo.toml

@@ -9,6 +9,7 @@ edition = "2018"
 [dependencies]
 anyhow = "^1.0"
 bitfield = "^0.13"
+clap = "^2.33"
 pixels = "^0.2"
 winit = "^0.24"
 winit_input_helper = "^0.9"

src/bus.rs

@@ -8,6 +8,7 @@ use super::serial::Serial;
 use super::sound::Sound;
 use super::timer::Timer;
 use super::work_ram::{VariableWorkRam, WorkRam};
+use anyhow::anyhow;
 use std::{convert::TryInto, fs::File, io::Read};
 
 const BOOT_ROM_SIZE: usize = 256;
@@ -46,21 +47,24 @@ impl Default for Bus {
 }
 
 impl Bus {
-    pub fn with_boot(path: &str) -> Self {
+    pub fn with_boot(path: &str) -> anyhow::Result<Self> {
-        let mut file = File::open(path).unwrap();
+        let mut file = File::open(path)?;
         let mut buf = Vec::with_capacity(BOOT_ROM_SIZE);
-        file.read_to_end(&mut buf).unwrap();
+        file.read_to_end(&mut buf)?;
 
-        let boot_rom: [u8; BOOT_ROM_SIZE] = buf.try_into().unwrap();
+        let boot_rom: [u8; BOOT_ROM_SIZE] = buf
+            .try_into()
+            .map_err(|_| anyhow!("{} was not {} bytes in size", path, BOOT_ROM_SIZE))?;
 
-        Self {
+        Ok(Self {
             boot: Some(boot_rom),
             ..Default::default()
-        }
+        })
     }
 
-    pub fn load_cartridge(&mut self, path: &str) {
+    pub fn load_cartridge(&mut self, path: &str) -> std::io::Result<()> {
-        self.cartridge = Some(Cartridge::new(path).unwrap());
+        self.cartridge = Some(Cartridge::new(path)?);
+        Ok(())
     }
 
     pub fn step(&mut self, cycles: Cycles) {

src/cpu.rs

@@ -33,11 +33,11 @@ impl Cpu {
         }
     }
 
-    pub fn boot_new(path: &str) -> Self {
+    pub fn boot_new(path: &str) -> anyhow::Result<Self> {
-        Self {
+        Ok(Self {
-            bus: Bus::with_boot(path),
+            bus: Bus::with_boot(path)?,
             ..Default::default()
-        }
+        })
     }
 
     pub fn ime(&self) -> bool {
@@ -52,8 +52,8 @@ impl Cpu {
         self.reg.pc += 1;
     }
 
-    pub fn load_cartridge(&mut self, path: &str) {
+    pub fn load_cartridge(&mut self, path: &str) -> std::io::Result<()> {
-        self.bus.load_cartridge(path);
+        Ok(self.bus.load_cartridge(path)?)
     }
 }
 

src/main.rs

@@ -1,8 +1,8 @@
 use anyhow::{anyhow, Result};
+use clap::{crate_authors, crate_description, crate_name, crate_version, App, Arg};
 use gb::LR35902_CLOCK_SPEED;
 use gb::{Cycles, LR35902};
 use pixels::{Pixels, SurfaceTexture};
-use std::env::args;
 use std::time::{Duration, Instant};
 use winit::dpi::LogicalSize;
 use winit::event::{Event, VirtualKeyCode};
@@ -19,20 +19,51 @@ const LR35902_CYCLE_TIME: f64 = 1.0f64 / LR35902_CLOCK_SPEED as f64;
 const CYCLES_IN_FRAME: Cycles = Cycles::new(70224);
 
 fn main() -> Result<()> {
+    let app = App::new(crate_name!())
+        .version(crate_version!())
+        .author(crate_authors!())
+        .about(crate_description!());
+
+    let m = app
+        .arg(
+            Arg::with_name("rom")
+                .value_name("ROM_FILE")
+                .takes_value(true)
+                .required(true)
+                .index(1)
+                .help("The ROM that the emulator will run"),
+        )
+        .arg(
+            Arg::with_name("boot")
+                .short("b")
+                .long("boot")
+                .value_name("FILE")
+                .takes_value(true)
+                .help("Path to Boot ROM"),
+        )
+        .get_matches();
+
+    let mut game_boy = match m.value_of("boot") {
+        Some(path) => LR35902::boot_new(path).expect("Failed to load boot ROM"),
+        None => LR35902::new(),
+    };
+
+    // This is a required value so if we program gets here,
+    // a string **will** have been provided to the rom argument
+    let rom_path = m
+        .value_of("rom")
+        .expect("ROM Path not provided despite it being a required argument");
+
+    game_boy
+        .load_cartridge(rom_path)
+        .expect("Failed to load ROM");
+
+    // Initialize GUI
     let event_loop = EventLoop::new();
     let mut input = WinitInputHelper::new();
     let window = create_window(&event_loop)?;
     let mut pixels = create_pixels(&window)?;
 
-    let mut game_boy = match args().nth(1) {
-        Some(boot_path) => LR35902::boot_new(&boot_path),
-        None => LR35902::new(),
-    };
-
-    // game_boy.load_cartridge("bin/instr_timing.gb");
-    game_boy.load_cartridge("bin/cpu_instrs.gb");
-    // game_boy.load_cartridge("bin/tetris.gb");
-
     let mut now = Instant::now();
     let mut cycles_in_frame = Cycles::default();
     event_loop.run(move |event, _, control_flow| {
@@ -83,7 +114,7 @@ fn main() -> Result<()> {
     });
 }
 
-pub fn create_window(event_loop: &EventLoop<()>) -> Result<Window> {
+fn create_window(event_loop: &EventLoop<()>) -> Result<Window> {
     let size = LogicalSize::new((GB_WIDTH as f64) * SCALE, (GB_HEIGHT as f64) * SCALE);
     Ok(WindowBuilder::new()
         .with_title("DMG-1 Emulator")
@@ -92,7 +123,7 @@ pub fn create_window(event_loop: &EventLoop<()>) -> Result<Window> {
         .build(&event_loop)?)
 }
 
-pub fn create_pixels(window: &Window) -> Result<Pixels<Window>> {
+fn create_pixels(window: &Window) -> Result<Pixels<Window>> {
     let window_size = window.inner_size();
     let surface_texture = SurfaceTexture::new(window_size.width, window_size.height, window);
     Ok(Pixels::new(GB_WIDTH, GB_HEIGHT, surface_texture)?)