Add commandline argument parser

It is often useful to be able to directly specify a serial port and its
settings from the commandline rather than having to select it in the GUI
each time.

Add a CLI parser based on `gumdrop` to parse commandline arguments.  The
selected serial port is then immediately opened on startup.

Author: Rahix

Cargo.lock

@@ -26,6 +26,7 @@ tempfile = { version = "3.15", optional = true }
 reqwest = { version = "0.12", default-features = false, features = ["blocking", "json", "rustls-tls", "http2"], optional = true }
 semver = { version = "1.0.24", optional = true }
 crossbeam-channel = "0.5.14"
+gumdrop = "0.8.1"
 
 [target.'cfg(not(target_os = "ios"))'.dependencies]
 eframe = { version = "0.32", features = ["persistence", "wayland", "x11"] }

Cargo.toml

@@ -13,12 +13,13 @@ use crossbeam_channel::{select, Receiver, Sender};
 use eframe::egui::{vec2, ViewportBuilder};
 use eframe::{egui, icon_data};
 use egui_plot::PlotPoint;
+pub use gumdrop::Options;
 use preferences::AppInfo;
 use std::cmp::max;
 use std::path::PathBuf;
 use std::sync::{Arc, RwLock};
+use std::thread;
 use std::time::Duration;
-use std::{env, thread};
 
 mod color_picker;
 mod custom_highlighter;
@@ -262,13 +263,100 @@ fn main_thread(
     }
 }
 
+fn parse_databits(s: &str) -> Result<serialport::DataBits, String> {
+    let d: u8 = s
+        .parse()
+        .map_err(|_e| format!("databits not a number: {s}"))?;
+    Ok(serialport::DataBits::try_from(d).map_err(|_e| format!("invalid databits: {s}"))?)
+}
+
+fn parse_flow(s: &str) -> Result<serialport::FlowControl, String> {
+    match s {
+        "none" => Ok(serialport::FlowControl::None),
+        "soft" => Ok(serialport::FlowControl::Software),
+        "hard" => Ok(serialport::FlowControl::Hardware),
+        _ => Err(format!("invalid flow-control: {s}")),
+    }
+}
+
+fn parse_stopbits(s: &str) -> Result<serialport::StopBits, String> {
+    let d: u8 = s
+        .parse()
+        .map_err(|_e| format!("stopbits not a number: {s}"))?;
+    Ok(serialport::StopBits::try_from(d).map_err(|_e| format!("invalid stopbits: {s}"))?)
+}
+
+fn parse_parity(s: &str) -> Result<serialport::Parity, String> {
+    match s {
+        "none" => Ok(serialport::Parity::None),
+        "odd" => Ok(serialport::Parity::Odd),
+        "even" => Ok(serialport::Parity::Even),
+        _ => Err(format!("invalid parity setting: {s}")),
+    }
+}
+
+#[derive(Debug, Options)]
+struct CliOptions {
+    /// Serial port device to open on startup
+    #[options(free)]
+    device: Option<String>,
+
+    /// Baudrate (default=9600)
+    #[options(short = "b")]
+    baudrate: Option<u32>,
+
+    /// Data bits (5, 6, 7, default=8)
+    #[options(short = "d", parse(try_from_str = "parse_databits"))]
+    databits: Option<serialport::DataBits>,
+
+    /// Flow conrol (hard, soft, default=none)
+    #[options(short = "f", parse(try_from_str = "parse_flow"))]
+    flow: Option<serialport::FlowControl>,
+
+    /// Stop bits (default=1, 2)
+    #[options(short = "s", parse(try_from_str = "parse_stopbits"))]
+    stopbits: Option<serialport::StopBits>,
+
+    /// Parity (odd, even, default=none)
+    #[options(short = "p", parse(try_from_str = "parse_parity"))]
+    parity: Option<serialport::Parity>,
+
+    /// Load data from a file instead of a serial port
+    #[options(short = "F")]
+    file: Option<std::path::PathBuf>,
+
+    help: bool,
+}
+
 fn main() {
     egui_logger::builder().init().unwrap();
 
+    let args = CliOptions::parse_args_default_or_exit();
+
     let gui_settings = load_gui_settings();
     let saved_serial_device_configs = load_serial_settings();
 
-    let device_lock = Arc::new(RwLock::new(Device::default()));
+    let mut device = Device::default();
+    if let Some(name) = args.device {
+        device.name = name;
+    }
+    if let Some(baudrate) = args.baudrate {
+        device.baud_rate = baudrate;
+    }
+    if let Some(databits) = args.databits {
+        device.data_bits = databits;
+    }
+    if let Some(flow) = args.flow {
+        device.flow_control = flow;
+    }
+    if let Some(stopbits) = args.stopbits {
+        device.stop_bits = stopbits;
+    }
+    if let Some(parity) = args.parity {
+        device.parity = parity;
+    }
+
+    let device_lock = Arc::new(RwLock::new(device));
     let devices_lock = Arc::new(RwLock::new(vec![gui_settings.device.clone()]));
     let data_lock = Arc::new(RwLock::new(GuiOutputDataContainer::default()));
     let connected_lock = Arc::new(RwLock::new(false));
@@ -319,11 +407,8 @@ fn main() {
         );
     });
 
-    let args: Vec<String> = env::args().collect();
-    if args.len() > 1 {
-        load_tx
-            .send(PathBuf::from(&args[1]))
-            .expect("failed to send file");
+    if let Some(file) = args.file {
+        load_tx.send(file).expect("failed to send file");
     }
 
     let options = eframe::NativeOptions {