Fix status returned on interrupt

README.md

@@ -5,7 +5,7 @@ A Virtual Boy emulator built around the shrooms-vb core. Written in Rust, using
 ## Setup
 
 Install the following dependencies:
- - `cargo`
+ - `cargo` (via [rustup](https://rustup.rs/), the version from your package manager is too old)
 
 Run
 ```sh

build.Dockerfile

@@ -23,13 +23,15 @@ ENV PATH="/osxcross/bin:$PATH" \
     CXX_x86_64-apple-darwin="o64-clang++" \
     CC_aarch64-apple-darwin="oa64-clang" \
     CXX_aarch64-apple-darwin="o6a4-clang++" \
+    SHROOMS_CFLAGS_x86_64-unknown-linux-gnu="-flto" \
+    CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS="-Clinker-plugin-lto -Clinker=clang -Clink-arg=-fuse-ld=lld" \
+    SHROOMS_CFLAGS_x86_64-pc-windows-msvc="-flto" \
+    CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_RUSTFLAGS="-Lnative=/xwin/crt/lib/x86_64 -Lnative=/xwin/sdk/lib/um/x86_64 -Lnative=/xwin/sdk/lib/ucrt/x86_64 -Clinker-plugin-lto -Clink-arg=-fuse-ld=lld" \
     CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_LINKER="lld-link-19" \
     CARGO_TARGET_X86_64_APPLE_DARWIN_LINKER="o64-clang" \
     CARGO_TARGET_X86_64_APPLE_DARWIN_AR="llvm-ar-19" \
     CARGO_TARGET_AARCH64_APPLE_DARWIN_LINKER="oa64-clang" \
     CARGO_TARGET_AARCH64_APPLE_DARWIN_AR="llvm-ar-19" \
     CROSS_COMPILE="setting-this-to-silence-a-warning-" \
-    SHROOMS_CFLAGS="-flto" \
     RC_PATH="llvm-rc-19" \
-    RUSTFLAGS="-Lnative=/xwin/crt/lib/x86_64 -Lnative=/xwin/sdk/lib/um/x86_64 -Lnative=/xwin/sdk/lib/ucrt/x86_64" \
     MACOSX_DEPLOYMENT_TARGET="14.5"

build.rs

@@ -23,6 +23,10 @@ fn main() -> Result<(), Box<dyn Error>> {
         .define("VB_LITTLE_ENDIAN", None)
         .define("VB_SIGNED_PROPAGATE", None)
         .define("VB_DIV_GENERIC", None)
+        .define("VB_DIRECT_EXECUTE", "on_execute")
+        .define("VB_DIRECT_FRAME", "on_frame")
+        .define("VB_DIRECT_READ", "on_read")
+        .define("VB_DIRECT_WRITE", "on_write")
         .file(Path::new("shrooms-vb-core/core/vb.c"))
         .compile("vb");
 

src/emulator.rs

@@ -305,9 +305,13 @@ impl Emulator {
     }
 
     fn start_debugging(&mut self, sim_id: SimId, sender: DebugSender) {
+        if self.sim_state[sim_id.to_index()].load(Ordering::Acquire) != SimState::Ready {
+            // Can't debug unless a game is connected
+            return;
+        }
         let debug = DebugInfo {
             sender,
-            stop_reason: Some(DebugStopReason::Trapped),
+            stop_reason: Some(DebugStopReason::Paused),
         };
         self.debuggers.insert(sim_id, debug);
         self.state
@@ -330,7 +334,7 @@ impl Emulator {
     }
 
     fn debug_interrupt(&mut self, sim_id: SimId) {
-        self.debug_stop(sim_id, DebugStopReason::Trapped);
+        self.debug_stop(sim_id, DebugStopReason::Paused);
     }
 
     fn debug_stop(&mut self, sim_id: SimId, reason: DebugStopReason) {
@@ -533,6 +537,12 @@ impl Emulator {
                 let value = sim.read_register(register);
                 let _ = done.send(value);
             }
+            EmulatorCommand::WriteRegister(sim_id, register, value) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.write_register(register, value);
+            }
             EmulatorCommand::ReadMemory(sim_id, start, length, mut buffer, done) => {
                 let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
                     return;
@@ -540,6 +550,13 @@ impl Emulator {
                 sim.read_memory(start, length, &mut buffer);
                 let _ = done.send(buffer);
             }
+            EmulatorCommand::WriteMemory(sim_id, start, buffer, done) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.write_memory(start, &buffer);
+                let _ = done.send(buffer);
+            }
             EmulatorCommand::AddBreakpoint(sim_id, address) => {
                 let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
                     return;
@@ -627,7 +644,9 @@ pub enum EmulatorCommand {
     DebugContinue(SimId),
     DebugStep(SimId),
     ReadRegister(SimId, VBRegister, oneshot::Sender<u32>),
+    WriteRegister(SimId, VBRegister, u32),
     ReadMemory(SimId, u32, usize, Vec<u8>, oneshot::Sender<Vec<u8>>),
+    WriteMemory(SimId, u32, Vec<u8>, oneshot::Sender<Vec<u8>>),
     AddBreakpoint(SimId, u32),
     RemoveBreakpoint(SimId, u32),
     AddWatchpoint(SimId, u32, usize, VBWatchpointType),
@@ -667,7 +686,7 @@ pub enum DebugStopReason {
     // We hit a watchpoint
     Watchpoint(VBWatchpointType, u32),
     // The debugger told us to pause
-    Trapped,
+    Paused,
 }
 
 struct DebugInfo {

src/emulator/address_set.rs

@@ -1,11 +1,11 @@
 use std::{
-    collections::{BTreeMap, HashSet},
+    collections::{BTreeMap, BTreeSet},
     ops::Bound,
 };
 
 #[derive(Debug, Default)]
 pub struct AddressSet {
-    ranges: HashSet<(u32, usize)>,
+    ranges: BTreeSet<(u32, usize)>,
     bounds: BTreeMap<u32, usize>,
 }
 
@@ -109,6 +109,22 @@ impl AddressSet {
             .next_back()
             .is_some_and(|(_, &val)| val > 0)
     }
+
+    pub fn start_of_range_containing(&self, address: u32) -> Option<u32> {
+        if !self.contains(address) {
+            return None;
+        }
+        self.ranges
+            .range(..=(address, usize::MAX))
+            .rev()
+            .find_map(|&(start, length)| {
+                let contains = start <= address
+                    && (start as usize)
+                        .checked_add(length)
+                        .is_none_or(|end| end > address as usize);
+                contains.then_some(start)
+            })
+    }
 }
 
 #[cfg(test)]
@@ -120,6 +136,7 @@ mod tests {
         let set = AddressSet::new();
         assert!(set.is_empty());
         assert!(!set.contains(0x13374200));
+        assert_eq!(set.start_of_range_containing(0x13374200), None);
     }
 
     #[test]
@@ -127,6 +144,7 @@ mod tests {
         let mut set = AddressSet::new();
         set.add(0x00000000, 0x100000000);
         assert!(set.contains(0x13374200));
+        assert_eq!(set.start_of_range_containing(0x13374200), Some(0x00000000));
     }
 
     #[test]
@@ -228,4 +246,25 @@ mod tests {
             assert!(!set.contains(address));
         }
     }
+
+    #[test]
+    fn should_find_start_of_range() {
+        let mut set = AddressSet::new();
+        set.add(0x13374200, 4);
+        assert_eq!(set.start_of_range_containing(0x133741ff), None);
+        for address in 0x13374200..0x13374204 {
+            assert_eq!(set.start_of_range_containing(address), Some(0x13374200));
+        }
+        assert_eq!(set.start_of_range_containing(0x13374204), None);
+    }
+
+    #[test]
+    fn should_ignore_ranges_not_containing_address() {
+        let mut set = AddressSet::new();
+        set.add(0x10000000, 1024);
+        set.add(0x30000000, 1024);
+
+        assert!(!set.contains(0x20000000));
+        assert_eq!(set.start_of_range_containing(0x20000000), None);
+    }
 }

src/emulator/shrooms_vb_core.rs

@@ -145,6 +145,10 @@ extern "C" {
     fn vb_set_option(sim: *mut VB, key: VBOption, value: c_int);
     #[link_name = "vbSetPeer"]
     fn vb_set_peer(sim: *mut VB, peer: *mut VB);
+    #[link_name = "vbSetProgramCounter"]
+    fn vb_set_program_counter(sim: *mut VB, value: u32) -> u32;
+    #[link_name = "vbSetProgramRegister"]
+    fn vb_set_program_register(sim: *mut VB, index: c_uint, value: i32) -> i32;
     #[link_name = "vbSetReadCallback"]
     fn vb_set_read_callback(sim: *mut VB, callback: Option<OnRead>) -> Option<OnRead>;
     #[link_name = "vbSetSamples"]
@@ -154,14 +158,19 @@ extern "C" {
         typ_: VBDataType,
         capacity: c_uint,
     ) -> c_int;
+    #[link_name = "vbSetSystemRegister"]
+    fn vb_set_system_register(sim: *mut VB, index: c_uint, value: u32) -> u32;
     #[link_name = "vbSetUserData"]
     fn vb_set_user_data(sim: *mut VB, tag: *mut c_void);
     #[link_name = "vbSetWriteCallback"]
     fn vb_set_write_callback(sim: *mut VB, callback: Option<OnWrite>) -> Option<OnWrite>;
     #[link_name = "vbSizeOf"]
     fn vb_size_of() -> usize;
+    #[link_name = "vbWrite"]
+    fn vb_write(sim: *mut VB, address: u32, _type: VBDataType, value: i32) -> i32;
 }
 
+#[no_mangle]
 extern "C" fn on_frame(sim: *mut VB) -> c_int {
     // SAFETY: the *mut VB owns its userdata.
     // There is no way for the userdata to be null or otherwise invalid.
@@ -170,6 +179,7 @@ extern "C" fn on_frame(sim: *mut VB) -> c_int {
     1
 }
 
+#[no_mangle]
 extern "C" fn on_execute(sim: *mut VB, address: u32, _code: *const u16, _length: c_int) -> c_int {
     // SAFETY: the *mut VB owns its userdata.
     // There is no way for the userdata to be null or otherwise invalid.
@@ -193,6 +203,7 @@ extern "C" fn on_execute(sim: *mut VB, address: u32, _code: *const u16, _length:
     }
 }
 
+#[no_mangle]
 extern "C" fn on_read(
     sim: *mut VB,
     address: u32,
@@ -204,13 +215,13 @@ extern "C" fn on_read(
     // There is no way for the userdata to be null or otherwise invalid.
     let data: &mut VBState = unsafe { &mut *vb_get_user_data(sim).cast() };
 
-    if data.read_watchpoints.contains(address) {
+    if let Some(start) = data.read_watchpoints.start_of_range_containing(address) {
         let watch = if data.write_watchpoints.contains(address) {
             VBWatchpointType::Access
         } else {
             VBWatchpointType::Read
         };
-        data.stop_reason = Some(StopReason::Watchpoint(watch, address));
+        data.stop_reason = Some(StopReason::Watchpoint(watch, start));
     }
 
     // Don't stop here, the debugger expects us to break after the memory access.
@@ -218,6 +229,7 @@ extern "C" fn on_read(
     0
 }
 
+#[no_mangle]
 extern "C" fn on_write(
     sim: *mut VB,
     address: u32,
@@ -230,13 +242,13 @@ extern "C" fn on_write(
     // There is no way for the userdata to be null or otherwise invalid.
     let data: &mut VBState = unsafe { &mut *vb_get_user_data(sim).cast() };
 
-    if data.write_watchpoints.contains(address) {
+    if let Some(start) = data.write_watchpoints.start_of_range_containing(address) {
         let watch = if data.read_watchpoints.contains(address) {
             VBWatchpointType::Access
         } else {
             VBWatchpointType::Write
         };
-        data.stop_reason = Some(StopReason::Watchpoint(watch, address));
+        data.stop_reason = Some(StopReason::Watchpoint(watch, start));
     }
 
     // Don't stop here, the debugger expects us to break after the memory access.
@@ -447,6 +459,20 @@ impl Sim {
         }
     }
 
+    pub fn write_register(&mut self, register: VBRegister, value: u32) {
+        match register {
+            VBRegister::Program(index) => unsafe {
+                vb_set_program_register(self.sim, index, value as i32);
+            },
+            VBRegister::System(index) => unsafe {
+                vb_set_system_register(self.sim, index, value);
+            },
+            VBRegister::PC => unsafe {
+                vb_set_program_counter(self.sim, value);
+            },
+        }
+    }
+
     pub fn read_memory(&mut self, start: u32, length: usize, into: &mut Vec<u8>) {
         let mut address = start;
         for _ in 0..length {
@@ -456,6 +482,14 @@ impl Sim {
         }
     }
 
+    pub fn write_memory(&mut self, start: u32, buffer: &[u8]) {
+        let mut address = start;
+        for byte in buffer {
+            unsafe { vb_write(self.sim, address, VBDataType::U8, *byte as i32) };
+            address = address.wrapping_add(1);
+        }
+    }
+
     pub fn add_breakpoint(&mut self, address: u32) {
         let data = self.get_state();
         if let Err(index) = data.breakpoints.binary_search(&address) {

src/gdbserver.rs

@@ -9,7 +9,7 @@ use std::{
 use tokio::{
     io::{AsyncWriteExt as _, BufReader},
     net::{TcpListener, TcpStream},
-    select,
+    pin, select,
     sync::{mpsc, oneshot},
 };
 use tracing::{debug, enabled, error, info, Level};
@@ -57,8 +57,9 @@ impl GdbServer {
                 .unwrap()
                 .block_on(async move {
                     select! {
-                        _ = run_server(sim_id, client, port, &status) => {}
+                        _ = run_server(sim_id, client.clone(), port, &status) => {}
                         _ = rx => {
+                            client.send_command(EmulatorCommand::StopDebugging(sim_id));
                             *status.lock().unwrap() = GdbServerStatus::Stopped;
                         }
                     }
@@ -73,19 +74,46 @@ impl GdbServer {
     }
 }
 
+impl Drop for GdbServer {
+    fn drop(&mut self) {
+        self.stop();
+    }
+}
+
 async fn run_server(
     sim_id: SimId,
     client: EmulatorClient,
     port: u16,
     status: &Mutex<GdbServerStatus>,
 ) {
+    let (debug_sink, mut debug_source) = mpsc::unbounded_channel();
+    client.send_command(EmulatorCommand::StartDebugging(sim_id, debug_sink));
+
     info!("Connecting to debugger on port {port}...");
-    let Some(stream) = try_connect(port, status).await else {
-        return;
+    let connect_future = try_connect(port, status);
+    pin!(connect_future);
+
+    let stream = loop {
+        select! {
+            stream = &mut connect_future => {
+                if let Some(stream) = stream {
+                    break stream;
+                } else {
+                    return;
+                }
+            }
+            event = debug_source.recv() => {
+                if event.is_none() {
+                    // The sim has stopped (or was never started)
+                    *status.lock().unwrap() = GdbServerStatus::Stopped;
+                    return;
+                }
+            }
+        }
     };
     info!("Connected!");
     let mut connection = GdbConnection::new(sim_id, client);
-    match connection.run(stream).await {
+    match connection.run(stream, debug_source).await {
         Ok(()) => {
             info!("Finished debugging.");
             *status.lock().unwrap() = GdbServerStatus::Stopped;
@@ -154,12 +182,13 @@ impl GdbConnection {
             memory_buf: None,
         }
     }
-    async fn run(&mut self, stream: TcpStream) -> Result<()> {
-        let (debug_sink, mut debug_source) = mpsc::unbounded_channel();
+    async fn run(
+        &mut self,
+        stream: TcpStream,
+        mut debug_source: mpsc::UnboundedReceiver<DebugEvent>,
+    ) -> Result<()> {
         let (rx, mut tx) = stream.into_split();
         let mut request_source = RequestSource::new(BufReader::new(rx));
-        self.client
-            .send_command(EmulatorCommand::StartDebugging(self.sim_id, debug_sink));
         loop {
             let response = select! {
                 maybe_event = debug_source.recv() => {
@@ -289,24 +318,37 @@ impl GdbConnection {
             } else {
                 self.response()
             }
+        } else if req.match_str("P") {
+            let mut write_register = || {
+                let register_index = req.match_hex::<usize>()?;
+                let register = REGISTERS.get(register_index)?.to_vb_register();
+                if !req.match_str("=") {
+                    return None;
+                }
+                let value = {
+                    let mut buffer = [0; 4];
+                    if !req.match_hex_bytes(&mut buffer) {
+                        return None;
+                    }
+                    u32::from_le_bytes(buffer)
+                };
+                self.client.send_command(EmulatorCommand::WriteRegister(
+                    self.sim_id,
+                    register,
+                    value,
+                ));
+                Some(())
+            };
+            if let Some(()) = write_register() {
+                self.response().write_str("OK")
+            } else {
+                self.response()
+            }
         } else if let Some(op) = req.match_some_str(["m", "x"]) {
             let mut read_memory = || {
-                let start = req.match_hex::<u64>()?;
-                if !req.match_str(",") {
-                    return None;
-                };
-                let length = req.match_hex::<usize>()?;
-
+                let (start, length) = parse_memory_range(&mut req)?;
                 let mut buf = self.memory_buf.take().unwrap_or_default();
                 buf.clear();
-
-                // The v810 has a 32-bit address space.
-                // Addresses wrap within that space, but we don't need to implement that for 64-bit addresses.
-                // Just refuse to return any info for addresses above 0xffffffff.
-                let Ok(start) = u32::try_from(start) else {
-                    return Some(buf);
-                };
-                let length = length.min((u32::MAX - start) as usize + 1);
                 if length == 0 {
                     return Some(buf);
                 }
@@ -340,6 +382,38 @@ impl GdbConnection {
             } else {
                 self.response()
             }
+        } else if let Some(op) = req.match_some_str(["M", "X"]) {
+            let mut write_memory = || {
+                let (start, length) = parse_memory_range(&mut req)?;
+                if length == 0 {
+                    return Some(());
+                }
+                if !req.match_str(":") {
+                    return None;
+                }
+                let mut buf = self.memory_buf.take().unwrap_or_default();
+                buf.resize(length, 0);
+                let successful_read = if op == "M" {
+                    req.match_hex_bytes(&mut buf)
+                } else {
+                    req.match_bytes(&mut buf)
+                };
+                if !successful_read {
+                    self.memory_buf = Some(buf);
+                    return None;
+                }
+                let (tx, rx) = ::oneshot::channel();
+                self.client
+                    .send_command(EmulatorCommand::WriteMemory(self.sim_id, start, buf, tx));
+                let buf = rx.recv().ok()?;
+                self.memory_buf = Some(buf);
+                Some(())
+            };
+            if write_memory().is_some() {
+                self.response().write_str("OK")
+            } else {
+                self.response()
+            }
         } else if req.match_str("Z") {
             let mut parse_request = || {
                 let type_ = req.match_hex::<u8>()?;
@@ -428,9 +502,30 @@ impl Drop for GdbConnection {
     }
 }
 
+// parse a memory range into a start and a length.
+fn parse_memory_range(req: &mut Request<'_>) -> Option<(u32, usize)> {
+    let start = req.match_hex::<u64>()?;
+    if !req.match_str(",") {
+        return None;
+    };
+    let length = req.match_hex::<usize>()?;
+    let Ok(start) = u32::try_from(start) else {
+        // The v810 has a 32-bit address space.
+        // Addresses wrap within that space, but we don't need to implement that for 64-bit addresses.
+        // Just refuse to return any info for addresses above 0xffffffff.
+        return Some((0, 0));
+    };
+    let length = length.min((u32::MAX - start) as usize + 1);
+    Some((start, length))
+}
+
 fn debug_stop_reason_string(reason: Option<DebugStopReason>) -> String {
     let mut result = String::new();
-    result += if reason.is_some() { "T05;" } else { "T00;" };
+    result += if reason.is_some_and(|r| r != DebugStopReason::Paused) {
+        "T05;"
+    } else {
+        "T00;"
+    };
     if let Some(DebugStopReason::Breakpoint) = reason {
         result += "swbreak;";
     }
@@ -451,7 +546,7 @@ fn debug_stop_reason_string(reason: Option<DebugStopReason>) -> String {
             DebugStopReason::Trace => "trace;",
             DebugStopReason::Breakpoint => "breakpoint;",
             DebugStopReason::Watchpoint(_, _) => "watchpoint;",
-            DebugStopReason::Trapped => "trap;",
+            DebugStopReason::Paused => "trap;",
         };
     }
 

src/gdbserver/request.rs

@@ -60,6 +60,29 @@ impl Request<'_> {
             }
         }
     }
+
+    pub fn match_hex_bytes(&mut self, buffer: &mut [u8]) -> bool {
+        if self.buffer.len() < buffer.len() * 2 {
+            return false;
+        }
+        for (i, item) in buffer.iter_mut().enumerate() {
+            match u8::from_radix_16(&self.buffer[(i * 2)..(i * 2) + 2]) {
+                (byte, 2) => *item = byte,
+                _ => return false,
+            };
+        }
+        self.buffer = self.buffer.split_at(buffer.len()).1;
+        true
+    }
+
+    pub fn match_bytes(&mut self, buffer: &mut [u8]) -> bool {
+        if self.buffer.len() < buffer.len() {
+            return false;
+        }
+        buffer.copy_from_slice(&self.buffer[0..buffer.len()]);
+        self.buffer = self.buffer.split_at(buffer.len()).1;
+        true
+    }
 }
 
 pub struct RequestSource<R> {

src/main.rs

@@ -3,7 +3,7 @@
 
 use std::{path::PathBuf, process, time::SystemTime};
 
-use anyhow::Result;
+use anyhow::{bail, Result};
 use app::Application;
 use clap::Parser;
 use emulator::EmulatorBuilder;
@@ -95,10 +95,13 @@ fn main() -> Result<()> {
     let args = Args::parse();
 
     let (mut builder, client) = EmulatorBuilder::new();
-    if let Some(path) = args.rom {
-        builder = builder.with_rom(&path);
+    if let Some(path) = &args.rom {
+        builder = builder.with_rom(path);
     }
     if args.debug_port.is_some() {
+        if args.rom.is_none() {
+            bail!("to start debugging, please select a game.");
+        }
         builder = builder.start_paused(true);
     }
 

src/window/gdb.rs

@@ -3,7 +3,7 @@ use winit::event_loop::EventLoopProxy;
 
 use crate::{
     app::UserEvent,
-    emulator::{EmulatorClient, SimId},
+    emulator::{EmulatorClient, SimId, SimState},
     gdbserver::{GdbServer, GdbServerStatus},
 };
 
@@ -11,6 +11,7 @@ use super::AppWindow;
 
 pub struct GdbServerWindow {
     sim_id: SimId,
+    client: EmulatorClient,
     port_str: String,
     connected: bool,
     quit_on_disconnect: bool,
@@ -22,6 +23,7 @@ impl GdbServerWindow {
     pub fn new(sim_id: SimId, client: EmulatorClient, proxy: EventLoopProxy<UserEvent>) -> Self {
         Self {
             sim_id,
+            client: client.clone(),
             port_str: (8080 + sim_id.to_index()).to_string(),
             connected: false,
             quit_on_disconnect: false,
@@ -78,7 +80,9 @@ impl AppWindow for GdbServerWindow {
                     self.connected = false;
                 }
                 let start_button = Button::new("Start");
-                if ui.add_enabled(port_num.is_some(), start_button).clicked() {
+                let can_start =
+                    port_num.is_some() && self.client.sim_state(self.sim_id) == SimState::Ready;
+                if ui.add_enabled(can_start, start_button).clicked() {
                     let port = port_num.unwrap();
                     self.server.start(port);
                     self.connected = true;