Implement a GDB stub and fix another huge issue in S-type immediate decoding

src/main.rs

@@ -4,33 +4,38 @@
 // This file is part of TRVE (https://gitea.taitep.se/taitep/trve)
 // See LICENSE file in the project root for full license text.
 
-use std::{env, sync::Arc, time::Duration};
+use std::{env, path::PathBuf, sync::Arc, time::Duration};
+
+use clap::Parser;
 
 use trve::{
     consts::{Addr, Byte, DWord, HWord, Word},
     core::Core,
     exceptions::MemoryExceptionType,
+    gdb,
     mem::{MemConfig, MemDeviceInterface, MmioRoot, Ram},
 };
 
-use anyhow::{Result, bail};
+use anyhow::Result;
 
 use crate::basic_uart::BasicUart;
 
 mod execload;
 
+#[derive(Parser)]
+struct Args {
+    executable: PathBuf,
+    #[arg(long)]
+    wait: bool,
+}
+
 fn main() -> Result<()> {
+    let args = Args::parse();
+
     let mut ram = Ram::try_new(16 * 1024 * 1024)?;
     let buf = ram.buf_mut();
 
-    let args: Vec<String> = env::args().collect();
-
-    if args.len() != 2 {
-        eprintln!("USAGE: trve <ram_image>");
-        bail!("Wrong number of arguments");
-    }
-
-    let entry_point = execload::load(&args[1], buf)?;
+    let entry_point = execload::load(args.executable, buf)?;
 
     let mut mmio_root = MmioRoot::default();
     mmio_root.insert(0, Arc::new(DbgOut));
@@ -44,9 +49,18 @@ fn main() -> Result<()> {
         mmio_root,
     };
 
-    let mut core = Core::new(mem_cfg);
+    let (cmd_sender, cmd_reciever) = std::sync::mpsc::channel();
+
+    gdb::run_stub(cmd_sender.clone());
+
+    let mut core = Core::new(mem_cfg, cmd_reciever);
     core.reset(entry_point);
-    core.run();
+
+    if args.wait {
+        core.run_waiting_for_cmd();
+    } else {
+        core.run();
+    }
 
     Ok(())
 }