Gdb fixes

Former-commit-id: f8507472a94386902962d1ffead7dd6f85624d82
Former-commit-id: 15446ef199288e887b7bc02fec08f9798c4c6ea2

arm7tdmi/src/lib.rs

@@ -95,6 +95,7 @@ impl fmt::Display for CpuState {
 }
 
 #[derive(Debug, Primitive, Copy, Clone, PartialEq, Eq)]
+#[repr(u8)]
 pub enum CpuMode {
     User = 0b10000,
     Fiq = 0b10001,

core/src/gba.rs

@@ -2,7 +2,6 @@
 use std::cell::Cell;
 use std::rc::Rc;
 
-use arm7tdmi::gdbstub::stub::SingleThreadStopReason;
 use bincode;
 use serde::{Deserialize, Serialize};
 
@@ -251,20 +250,10 @@ impl GameBoyAdvance {
 
     /// Recv & handle messages from the debugger, and return if we are stopped or not
     pub fn debugger_run(&mut self) {
-        let mut should_interrupt_frame = false;
         let debugger = self.debugger.take().expect("debugger should be None here");
-        self.debugger = debugger.handle_incoming_requests(self, &mut should_interrupt_frame);
+        self.debugger = debugger.handle_incoming_requests(self);
-
-        if let Some(debugger) = &mut self.debugger {
-            if should_interrupt_frame {
-                debugger.notify_stop_reason(SingleThreadStopReason::DoneStep);
-            } else {
         self.frame_interruptible();
     }
-        } else {
-            error!("debugger was disconnected!");
-        }
-    }
 
     #[inline]
     fn dma_step(&mut self) {
@@ -272,10 +261,15 @@ impl GameBoyAdvance {
     }
 
     #[inline]
-    pub(crate) fn cpu_step(&mut self) {
+    fn cpu_interrupt(&mut self) {
-        if self.io_devs.intc.irq_pending() {
         self.cpu.irq();
-            self.io_devs.haltcnt = HaltState::Running;
+        self.io_devs.haltcnt = HaltState::Running; // Clear out from low power mode
+    }
+
+    #[inline]
+    fn cpu_step(&mut self) {
+        if self.io_devs.intc.irq_pending() {
+            self.cpu_interrupt();
         }
         self.cpu.step();
     }
@@ -285,7 +279,29 @@ impl GameBoyAdvance {
         match (self.io_devs.dmac.is_active(), self.io_devs.haltcnt) {
             (true, _) => Some(BusMaster::Dma),
             (false, HaltState::Running) => Some(BusMaster::Cpu),
-            (false, _) => None,
+            (false, HaltState::Halt) => None,
+        }
+    }
+
+    #[inline]
+    pub(crate) fn single_step(&mut self) {
+        // 3 Options:
+        // 1. DMA is active - thus CPU is blocked
+        // 2. DMA inactive and halt state is RUN - CPU can run
+        // 3. DMA inactive and halt state is HALT - CPU is blocked
+        match self.get_bus_master() {
+            Some(BusMaster::Dma) => self.dma_step(),
+            Some(BusMaster::Cpu) => self.cpu_step(),
+            None => {
+                // Halt mode - system is in a low-power mode, only (IE and IF) can release CPU from this state.
+                if self.io_devs.intc.irq_pending() {
+                    self.cpu_interrupt();
+                } else {
+                    // Fast-forward to next pending HW event so we don't waste time idle-looping when we know the only way
+                    // To get out of Halt mode is through an interrupt.
+                    self.scheduler.fast_forward_to_next();
+                }
+            }
         }
     }
 
@@ -293,60 +309,45 @@ impl GameBoyAdvance {
     /// @return number of cycle actually ran
     #[inline]
     pub(super) fn run<const CHECK_BREAKPOINTS: bool>(&mut self, cycles_to_run: usize) -> usize {
-        let run_start_time = self.scheduler.timestamp();
+        let start_time = self.scheduler.timestamp();
+        let end_time = start_time + cycles_to_run;
 
         // Register an event to mark the end of this run
         self.scheduler
-            .schedule_at(EventType::RunLimitReached, run_start_time + cycles_to_run);
+            .schedule_at(EventType::RunLimitReached, end_time);
 
-        let mut running = true;
+        'running: loop {
-        while running {
+            // The tricky part is to avoid unnecessary calls for Scheduler::handle_events,
-            // The tricky part is to avoid unnecessary calls for Scheduler::process_pending,
             // performance-wise it would be best to run as many cycles as fast as possible while we know there are no pending events.
-            // Fast forward emulation until an event occurs
+            // Safety: Since we pushed a RunLimitReached event, we know this check has a hard limit
-            'run_unitl_next_event: while self.scheduler.timestamp()
+            while self.scheduler.timestamp()
-                <= self.scheduler.timestamp_of_next_event()
+                <= unsafe { self.scheduler.timestamp_of_next_event_unchecked() }
             {
-                // 3 Options:
+                self.single_step();
-                // 1. DMA is active - thus CPU is blocked
-                // 2. DMA inactive and halt state is RUN - CPU can run
-                // 3. DMA inactive and halt state is HALT - CPU is blocked
-                match self.get_bus_master() {
-                    Some(BusMaster::Dma) => self.dma_step(),
-                    Some(BusMaster::Cpu) => {
-                        self.cpu_step();
                 if CHECK_BREAKPOINTS {
                     if let Some(bp) = self.cpu.check_breakpoint() {
                         debug!("Arm7tdmi breakpoint hit 0x{:08x}", bp);
                         self.scheduler.cancel_pending(EventType::RunLimitReached);
-                                running = false;
+                        let _ = self.handle_events();
-
                         if let Some(debugger) = &mut self.debugger {
                             debugger.notify_breakpoint(bp);
                         }
-
+                        break 'running;
-                                break 'run_unitl_next_event;
-                            }
-                        }
-                    }
-                    None => {
-                        if self.io_devs.intc.irq_pending() {
-                            self.io_devs.haltcnt = HaltState::Running;
-                        } else {
-                            self.scheduler.fast_forward_to_next();
-                            self.handle_events(&mut running)
-                        }
                     }
                 }
             }
 
-            self.handle_events(&mut running);
+            if self.handle_events() {
+                break 'running;
+            }
         }
 
-        self.scheduler.timestamp() - run_start_time
+        self.scheduler.timestamp() - start_time
     }
 
-    fn handle_events(&mut self, run_limit_flag: &mut bool) {
+    /// Handle all pending scheduler events and return if run limit was reached.
+    #[inline]
+    pub(super) fn handle_events(&mut self) -> bool {
         let io = &mut (*self.io_devs);
         while let Some((event, event_time)) = self.scheduler.pop_pending_event() {
             // Since we only examine the scheduler queue every so often, most events will be handled late by a few cycles.
@@ -354,8 +355,8 @@ impl GameBoyAdvance {
             // every cpu cycle, where in 99% of cases it will always be empty.
             let new_event = match event {
                 EventType::RunLimitReached => {
-                    *run_limit_flag = false;
+                    // If we have pending events, we handle by the next frame.
-                    None
+                    return true;
                 }
                 EventType::DmaActivateChannel(channel_id) => {
                     io.dmac.activate_channel(channel_id);
@@ -375,6 +376,7 @@ impl GameBoyAdvance {
                 self.scheduler.schedule_at(new_event, event_time + when)
             }
         }
+        false
     }
 
     pub fn skip_bios(&mut self) {
@@ -414,26 +416,6 @@ impl GameBoyAdvance {
         None
     }
 
-    #[cfg(feature = "debugger")]
-    /// 'step' function that checks for breakpoints
-    /// TODO avoid code duplication
-    pub fn step_debugger(&mut self) -> Option<u32> {
-        // clear any pending DMAs
-        self.dma_step();
-
-        // Run the CPU
-        self.cpu_step();
-
-        let breakpoint = self.check_breakpoint();
-
-        let mut _running = true;
-        while let Some((event, cycles_late)) = self.scheduler.pop_pending_event() {
-            self.handle_event(event, cycles_late, &mut _running);
-        }
-
-        breakpoint
-    }
-
     pub fn get_frame_buffer(&self) -> &[u32] {
         self.sysbus.io.gpu.get_frame_buffer()
     }

core/src/gdb_support.rs

@@ -9,13 +9,14 @@ use arm7tdmi::gdbstub::target::TargetError;
 use arm7tdmi::gdbstub::target::{ext::base::singlethread::SingleThreadBase, Target};
 use arm7tdmi::gdbstub_arch::arm::reg::ArmCoreRegs;
 use arm7tdmi::memory::Addr;
-use crossbeam::channel::{Receiver, Sender};
+use crossbeam::channel::Receiver;
 
 // mod target;
 mod event_loop;
 pub(crate) mod gdb_thread;
 mod memory_map;
 mod target;
+use target::DebuggerTarget;
 
 use crate::GameBoyAdvance;
 
@@ -34,153 +35,119 @@ pub(crate) enum DebuggerRequest {
     Disconnected(DisconnectReason),
 }
 
-pub struct DebuggerTarget {
-    tx: Sender<DebuggerRequest>,
-    request_complete_signal: Arc<(Mutex<bool>, Condvar)>,
-    stop_signal: Arc<(Mutex<SingleThreadStopReason<u32>>, Condvar)>,
-    memory_map: String,
-}
-
-impl DebuggerTarget {
-    #[inline]
-    pub fn wait_for_operation(&mut self) {
-        let (lock, cvar) = &*self.request_complete_signal;
-        let mut finished = lock.lock().unwrap();
-        while !*finished {
-            finished = cvar.wait(finished).unwrap();
-        }
-        *finished = false;
-    }
-}
-
 pub(crate) struct DebuggerRequestHandler {
     rx: Receiver<DebuggerRequest>,
     request_complete_signal: Arc<(Mutex<bool>, Condvar)>,
-    stop_signal: Arc<(Mutex<SingleThreadStopReason<u32>>, Condvar)>,
+    stop_signal: Arc<(Mutex<Option<SingleThreadStopReason<u32>>>, Condvar)>,
     thread: JoinHandle<()>,
     stopped: bool,
 }
 
-enum DebuggerStatus {
+impl DebuggerRequestHandler {
-    RequestComplete,
+    pub fn handle_incoming_requests(
-    ResumeRequested,
+        mut self,
-    StopRequested,
+        gba: &mut GameBoyAdvance,
-    Disconnected(DisconnectReason),
+    ) -> Option<DebuggerRequestHandler> {
+        if self.thread.is_finished() {
+            warn!("gdb server thread unexpectdly died");
+            return self.terminate();
+        }
+        loop {
+            // Handle as much as messages as possible
+            while let Ok(mut req) = self.rx.try_recv() {
+                match self.handle_request(gba, &mut req) {
+                    Ok(Some(disconnect_reason)) => {
+                        debug!("Debugger disconnected due to {:?}", disconnect_reason);
+                        debug!("closing gdbserver thread");
+                        return self.terminate();
+                    }
+                    Ok(None) => {}
+                    Err(_) => {
+                        error!("An error occured while handling debug request {:?}", req);
+                        return self.terminate();
+                    }
+                }
+            }
+            // If target is in stopped state, stay here.
+            if !self.stopped {
+                break;
+            }
+        }
+        Some(self)
     }
 
-impl DebuggerRequestHandler {
     fn handle_request(
         &mut self,
         gba: &mut GameBoyAdvance,
         req: &mut DebuggerRequest,
-    ) -> Result<DebuggerStatus, TargetError<<DebuggerTarget as Target>::Error>> {
+    ) -> Result<Option<DisconnectReason>, TargetError<<DebuggerTarget as Target>::Error>> {
         use DebuggerRequest::*;
         match req {
             ReadRegs(regs) => {
                 let mut regs = regs.lock().unwrap();
                 gba.cpu.read_registers(&mut regs)?;
-                debug!("Debugger requested to read regs: {:?}", regs);
+                trace!("Debugger requested to read regs: {:?}", regs);
-                Ok(DebuggerStatus::RequestComplete)
+                self.complete_request(None)
             }
             WriteRegs(regs) => {
-                debug!("Debugger requested to write regs: {:?}", regs);
+                trace!("Debugger requested to write regs: {:?}", regs);
                 gba.cpu.write_registers(regs)?;
-                Ok(DebuggerStatus::RequestComplete)
+                self.complete_request(None)
             }
             ReadAddrs(addr, data) => {
                 let mut data = data.lock().unwrap();
-                debug!(
+                trace!(
                     "Debugger requested to read {} bytes from 0x{:08x}",
                     data.len(),
                     addr
                 );
                 gba.cpu.read_addrs(*addr, &mut data)?;
-                Ok(DebuggerStatus::RequestComplete)
+                self.complete_request(None)
             }
             WriteAddrs(addr, data) => {
-                debug!(
+                trace!(
                     "Debugger requested to write {} bytes at 0x{:08x}",
                     data.len(),
                     addr
                 );
                 gba.cpu.write_addrs(*addr, &data)?;
-                Ok(DebuggerStatus::RequestComplete)
+                self.complete_request(None)
             }
             Interrupt => {
-                debug!("Debugger requested stopped");
+                debug!("Ctrl-C from debugger");
-                self.notify_stop_reason(SingleThreadStopReason::Signal(Signal::SIGINT));
+                self.stopped = true;
-                Ok(DebuggerStatus::StopRequested)
+                self.complete_request(Some(SingleThreadStopReason::Signal(Signal::SIGINT)))
             }
             Resume => {
-                debug!("Debugger requested resume");
+                debug!("Resume");
                 self.stopped = false;
-                Ok(DebuggerStatus::ResumeRequested)
+                self.complete_request(None)
             }
             SingleStep => {
                 debug!("Debugger requested single step");
-                gba.cpu_step();
+                self.stopped = true;
-                let stop_reason = SingleThreadStopReason::DoneStep;
+                gba.single_step();
-                self.notify_stop_reason(stop_reason);
+                let _ = gba.handle_events();
-                Ok(DebuggerStatus::StopRequested)
+                self.complete_request(Some(SingleThreadStopReason::DoneStep))
             }
             AddSwBreakpoint(addr) => {
                 gba.cpu.add_breakpoint(*addr);
-                Ok(DebuggerStatus::RequestComplete)
+                self.complete_request(None)
             }
             DelSwBreakpoint(addr) => {
                 gba.cpu.del_breakpoint(*addr);
-                Ok(DebuggerStatus::RequestComplete)
+                self.complete_request(None)
             }
-            Disconnected(reason) => Ok(DebuggerStatus::Disconnected(*reason)),
+            Disconnected(reason) => Ok(Some(*reason)),
         }
     }
 
-    fn terminate(mut self, should_interrupt_frame: &mut bool) -> Option<DebuggerRequestHandler> {
+    fn terminate(mut self) -> Option<DebuggerRequestHandler> {
         self.notify_stop_reason(SingleThreadStopReason::Exited(1));
         self.thread.join().unwrap();
-        self.stopped = true;
-        *should_interrupt_frame = true;
         None
     }
 
-    pub fn handle_incoming_requests(
-        mut self,
-        gba: &mut GameBoyAdvance,
-        should_interrupt_frame: &mut bool,
-    ) -> Option<DebuggerRequestHandler> {
-        if self.thread.is_finished() {
-            warn!("gdb server thread unexpectdly died");
-            return self.terminate(should_interrupt_frame);
-        }
-        while let Ok(mut req) = self.rx.try_recv() {
-            match self.handle_request(gba, &mut req) {
-                Ok(DebuggerStatus::RequestComplete) => {
-                    self.notify_request_complete();
-                }
-                Ok(DebuggerStatus::StopRequested) => {
-                    self.stopped = true;
-                    self.notify_request_complete();
-                }
-                Ok(DebuggerStatus::ResumeRequested) => {
-                    self.stopped = false;
-                    self.notify_request_complete();
-                }
-                Ok(DebuggerStatus::Disconnected(reason)) => {
-                    debug!("Debugger disconnected due to {:?}", reason);
-                    debug!("closing gdbserver thread");
-                    return self.terminate(should_interrupt_frame);
-                }
-
-                Err(_) => {
-                    error!("An error occured while handling debug request {:?}", req);
-                    return self.terminate(should_interrupt_frame);
-                }
-            }
-        }
-        *should_interrupt_frame = self.stopped;
-        Some(self)
-    }
-
     fn notify_request_complete(&mut self) {
         let (lock, cvar) = &*self.request_complete_signal;
         let mut finished = lock.lock().unwrap();
@@ -188,15 +155,27 @@ impl DebuggerRequestHandler {
         cvar.notify_one();
     }
 
+    fn complete_request(
+        &mut self,
+        stop_reason: Option<SingleThreadStopReason<u32>>,
+    ) -> Result<Option<DisconnectReason>, TargetError<<DebuggerTarget as Target>::Error>> {
+        self.notify_request_complete();
+        if let Some(stop_reason) = stop_reason {
+            self.notify_stop_reason(stop_reason);
+        }
+        Ok(None)
+    }
+
     pub fn notify_stop_reason(&mut self, reason: SingleThreadStopReason<u32>) {
-        self.stopped = true;
+        debug!("Notifying debugger on stop reason: {:?}", reason);
         let (lock, cvar) = &*self.stop_signal;
         let mut stop_reason = lock.lock().unwrap();
-        *stop_reason = reason;
+        *stop_reason = Some(reason);
         cvar.notify_one();
     }
 
     pub fn notify_breakpoint(&mut self, _bp: Addr) {
+        self.stopped = true;
         self.notify_stop_reason(SingleThreadStopReason::SwBreak(()));
     }
 }

core/src/gdb_support/event_loop.rs

@@ -6,9 +6,9 @@ use arm7tdmi::gdb::gdbstub::{
     target::Target,
 };
 
-use super::{DebuggerRequest, DebuggerTarget};
+use super::{target::DebuggerTarget, DebuggerRequest};
 
-pub struct DebuggerEventLoop {}
+pub(crate) struct DebuggerEventLoop {}
 
 impl run_blocking::BlockingEventLoop for DebuggerEventLoop {
     type Target = DebuggerTarget;
@@ -35,17 +35,12 @@ impl run_blocking::BlockingEventLoop for DebuggerEventLoop {
                 return Ok(run_blocking::Event::IncomingData(byte));
             } else {
                 // try and wait for the stop reason
-                let (lock, cvar) = &*target.stop_signal;
+                if let Some(stop_reason) =
-                let stop_reason = lock.lock().unwrap();
+                    target.wait_for_stop_reason_timeout(Duration::from_millis(10))
-                let (stop_reason, timeout_result) = cvar
+                {
-                    .wait_timeout(stop_reason, Duration::from_millis(10))
-                    .unwrap();
-                if timeout_result.timed_out() {
-                    // timed-out, try again later
-                    continue;
-                }
                     info!("Target stopped due to {:?}!", stop_reason);
-                return Ok(run_blocking::Event::TargetStopped(*stop_reason));
+                    return Ok(run_blocking::Event::TargetStopped(stop_reason));
+                }
             }
         }
     }
@@ -54,12 +49,8 @@ impl run_blocking::BlockingEventLoop for DebuggerEventLoop {
         target: &mut DebuggerTarget,
     ) -> Result<Option<SingleThreadStopReason<u32>>, <DebuggerTarget as Target>::Error> {
         info!("on_interrupt: sending stop message");
-        target.tx.send(DebuggerRequest::Interrupt).unwrap();
+        target.debugger_request(DebuggerRequest::Interrupt);
-        target.wait_for_operation();
         info!("Waiting for target to stop <blocking>");
-        let (lock, cvar) = &*target.stop_signal;
+        Ok(Some(target.wait_for_stop_reason_blocking()))
-        let stop_signal = lock.lock().unwrap();
-        let stop_signal = cvar.wait(stop_signal).unwrap();
-        Ok(Some(*stop_signal))
     }
 }

core/src/gdb_support/gdb_thread.rs

@@ -11,9 +11,8 @@ use arm7tdmi::{
 
 use crate::{GBAError, GameBoyAdvance};
 
-use super::{
+use super::target::DebuggerTarget;
-    event_loop::DebuggerEventLoop, DebuggerRequest, DebuggerRequestHandler, DebuggerTarget,
+use super::{event_loop::DebuggerEventLoop, DebuggerRequestHandler};
-};
 
 /// Starts a gdbserver thread
 pub(crate) fn start_gdb_server_thread(
@@ -22,10 +21,7 @@ pub(crate) fn start_gdb_server_thread(
 ) -> Result<DebuggerRequestHandler, GBAError> {
     let (tx, rx) = crossbeam::channel::unbounded();
     let request_complete_signal = Arc::new((Mutex::new(false), Condvar::new()));
-    let stop_signal = Arc::new((
+    let stop_signal = Arc::new((Mutex::new(None), Condvar::new()));
-        Mutex::new(SingleThreadStopReason::Signal(Signal::SIGINT)),
-        Condvar::new(),
-    ));
     let stop_signal_2 = stop_signal.clone();
     let request_complete_signal_2 = request_complete_signal.clone();
     let memory_map = gba.sysbus.generate_memory_map_xml().unwrap();
@@ -35,21 +31,14 @@ pub(crate) fn start_gdb_server_thread(
         debug!("starting GDB Server thread");
         let conn: Box<dyn ConnectionExt<Error = std::io::Error>> = Box::new(conn);
 
-        let mut target = DebuggerTarget {
+        let mut target =
-            tx,
+            DebuggerTarget::new(tx, request_complete_signal_2, stop_signal_2, memory_map);
-            request_complete_signal: request_complete_signal_2,
-            stop_signal: stop_signal_2,
-            memory_map,
-        };
         let gdbserver = GdbStub::new(conn);
         let disconnect_reason = gdbserver
             .run_blocking::<DebuggerEventLoop>(&mut target)
             .map_err(|e| e.to_string())
             .unwrap();
-        target
+        target.disconnect(disconnect_reason);
-            .tx
-            .send(DebuggerRequest::Disconnected(disconnect_reason))
-            .unwrap();
     });
 
     let mut debugger = DebuggerRequestHandler {

core/src/gdb_support/target.rs

@@ -1,8 +1,11 @@
-use std::sync::{Arc, Mutex};
+use std::sync::{Arc, Condvar, Mutex};
+use std::time::Duration;
 
 /// Implementing the Target trait for gdbstub
 use arm7tdmi::gdb::{copy_range_to_buf, gdbstub, gdbstub_arch};
+use crossbeam::channel::Sender;
 use gdbstub::common::Signal;
+use gdbstub::stub::{DisconnectReason, SingleThreadStopReason};
 use gdbstub::target::ext::base::singlethread::{
     SingleThreadBase, SingleThreadResume, SingleThreadSingleStep,
 };
@@ -12,7 +15,78 @@ use gdbstub::target::ext::breakpoints::BreakpointsOps;
 use gdbstub::target::{self, Target, TargetError, TargetResult};
 use gdbstub_arch::arm::reg::ArmCoreRegs;
 
-use super::{DebuggerRequest, DebuggerTarget};
+use super::DebuggerRequest;
+
+pub(crate) struct DebuggerTarget {
+    tx: Sender<DebuggerRequest>,
+    request_complete_signal: Arc<(Mutex<bool>, Condvar)>,
+    pub(crate) stop_signal: Arc<(Mutex<Option<SingleThreadStopReason<u32>>>, Condvar)>,
+    pub(crate) memory_map: String,
+}
+
+impl DebuggerTarget {
+    pub fn new(
+        tx: Sender<DebuggerRequest>,
+        request_complete_signal: Arc<(Mutex<bool>, Condvar)>,
+        stop_signal: Arc<(Mutex<Option<SingleThreadStopReason<u32>>>, Condvar)>,
+        memory_map: String,
+    ) -> DebuggerTarget {
+        DebuggerTarget {
+            tx,
+            request_complete_signal,
+            stop_signal,
+            memory_map,
+        }
+    }
+
+    pub fn debugger_request(&mut self, req: DebuggerRequest) {
+        let (lock, cvar) = &*self.request_complete_signal;
+        let mut finished = lock.lock().unwrap();
+        *finished = false;
+
+        // now send the request
+        self.tx.send(req).unwrap();
+
+        // wait for the notification
+        while !*finished {
+            finished = cvar.wait(finished).unwrap();
+        }
+        *finished = false;
+    }
+
+    pub fn wait_for_stop_reason_timeout(
+        &mut self,
+        timeout: Duration,
+    ) -> Option<SingleThreadStopReason<u32>> {
+        let (lock, cvar) = &*self.stop_signal;
+        let mut stop_reason = lock.lock().unwrap();
+        if let Some(stop_reason) = stop_reason.take() {
+            return Some(stop_reason);
+        }
+        let (mut stop_reason, timeout_result) = cvar.wait_timeout(stop_reason, timeout).unwrap();
+        if timeout_result.timed_out() {
+            None
+        } else {
+            Some(stop_reason.take().expect("None is not expected here"))
+        }
+    }
+
+    pub fn wait_for_stop_reason_blocking(&mut self) -> SingleThreadStopReason<u32> {
+        let (lock, cvar) = &*self.stop_signal;
+        let mut stop_reason = lock.lock().unwrap();
+        if let Some(stop_reason) = stop_reason.take() {
+            return stop_reason;
+        }
+        let mut stop_reason = cvar.wait(stop_reason).unwrap();
+        stop_reason.take().expect("None is not expected here")
+    }
+
+    pub fn disconnect(&mut self, disconnect_reason: DisconnectReason) {
+        self.tx
+            .send(DebuggerRequest::Disconnected(disconnect_reason))
+            .unwrap();
+    }
+}
 
 impl Target for DebuggerTarget {
     type Error = ();
@@ -37,28 +111,19 @@ impl Target for DebuggerTarget {
 impl SingleThreadBase for DebuggerTarget {
     fn read_registers(&mut self, regs: &mut ArmCoreRegs) -> TargetResult<(), Self> {
         let regs_copy = Arc::new(Mutex::new(ArmCoreRegs::default()));
-        self.tx
+        self.debugger_request(DebuggerRequest::ReadRegs(regs_copy.clone()));
-            .send(DebuggerRequest::ReadRegs(regs_copy.clone()))
-            .unwrap();
-        self.wait_for_operation();
         regs_copy.lock().unwrap().clone_into(regs);
         Ok(())
     }
 
     fn write_registers(&mut self, regs: &ArmCoreRegs) -> TargetResult<(), Self> {
-        self.tx
+        self.debugger_request(DebuggerRequest::WriteRegs(regs.clone()));
-            .send(DebuggerRequest::WriteRegs(regs.clone()))
-            .unwrap();
-        self.wait_for_operation();
         Ok(())
     }
 
     fn read_addrs(&mut self, start_addr: u32, data: &mut [u8]) -> TargetResult<(), Self> {
         let buffer = Arc::new(Mutex::new(vec![0; data.len()].into_boxed_slice()));
-        self.tx
+        self.debugger_request(DebuggerRequest::ReadAddrs(start_addr, buffer.clone()));
-            .send(DebuggerRequest::ReadAddrs(start_addr, buffer.clone()))
-            .unwrap();
-        self.wait_for_operation();
         data.copy_from_slice(&buffer.lock().unwrap());
         Ok(())
     }
@@ -78,8 +143,7 @@ impl SingleThreadBase for DebuggerTarget {
 
 impl SingleThreadResume for DebuggerTarget {
     fn resume(&mut self, _signal: Option<Signal>) -> Result<(), Self::Error> {
-        self.tx.send(DebuggerRequest::Resume).unwrap();
+        self.debugger_request(DebuggerRequest::Resume);
-        self.wait_for_operation();
         Ok(())
     }
 
@@ -94,8 +158,7 @@ impl SingleThreadResume for DebuggerTarget {
 
 impl SingleThreadSingleStep for DebuggerTarget {
     fn step(&mut self, _signal: Option<Signal>) -> Result<(), Self::Error> {
-        self.tx.send(DebuggerRequest::SingleStep).unwrap();
+        self.debugger_request(DebuggerRequest::SingleStep);
-        self.wait_for_operation();
         Ok(())
     }
 }
@@ -132,10 +195,7 @@ impl target::ext::breakpoints::SwBreakpoint for DebuggerTarget {
         addr: u32,
         _kind: gdbstub_arch::arm::ArmBreakpointKind,
     ) -> TargetResult<bool, Self> {
-        self.tx
+        self.debugger_request(DebuggerRequest::AddSwBreakpoint(addr));
-            .send(DebuggerRequest::AddSwBreakpoint(addr))
-            .unwrap();
-        self.wait_for_operation();
         Ok(true)
     }
 
@@ -144,10 +204,7 @@ impl target::ext::breakpoints::SwBreakpoint for DebuggerTarget {
         addr: u32,
         _kind: gdbstub_arch::arm::ArmBreakpointKind,
     ) -> TargetResult<bool, Self> {
-        self.tx
+        self.debugger_request(DebuggerRequest::DelSwBreakpoint(addr));
-            .send(DebuggerRequest::DelSwBreakpoint(addr))
-            .unwrap();
-        self.wait_for_operation();
         Ok(true)
     }
 }

core/src/iodev.rs

@@ -22,7 +22,7 @@ use self::consts::*;
 pub enum HaltState {
     Running,
     Halt, // In Halt mode, the CPU is paused as long as (IE AND IF)=0,
-    Stop, // In Stop mode, most of the hardware including sound and video are paused
+          // Stop, // In Stop mode, most of the hardware including sound and video are paused TODO: handle
 }
 
 #[derive(Clone, Serialize, Deserialize)]
@@ -288,7 +288,7 @@ impl BusIO for IoDevices {
             REG_POSTFLG => io.post_boot_flag = value != 0,
             REG_HALTCNT => {
                 if value & 0x80 != 0 {
-                    io.haltcnt = HaltState::Stop;
+                    // io.haltcnt = HaltState::Stop;
                     panic!("Can't handle HaltCtrl == Stop yet");
                 } else {
                     io.haltcnt = HaltState::Halt;

core/src/sched.rs

@@ -194,9 +194,12 @@ impl Scheduler {
     }
 
     #[inline]
-    /// The event queue is assumed to be not empty
+    /// Safety - Onyl safe to call when we know the event queue is not empty
-    pub fn timestamp_of_next_event(&self) -> usize {
+    pub unsafe fn timestamp_of_next_event_unchecked(&self) -> usize {
-        self.events.peek().unwrap_or_else(|| unreachable!()).time
+        self.events
+            .peek()
+            .unwrap_or_else(|| std::hint::unreachable_unchecked())
+            .time
     }
 
     #[inline]

platform/rustboyadvance-sdl2/src/main.rs

@@ -107,7 +107,6 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     //     normal_panic(panic_info);
     // }));
 
-
     if opts.skip_bios {
         println!("Skipping bios animation..");
         gba.skip_bios();