Implement stepping

src/emulator.rs

@@ -315,7 +315,7 @@ impl Emulator {
 
     fn stop_debugging(&mut self, sim_id: SimId) {
         if let Some(sim) = self.sims.get_mut(sim_id.to_index()) {
-            sim.clear_breakpoints();
+            sim.clear_debug_state();
         }
         self.debuggers.remove(&sim_id);
         if self.debuggers.is_empty() {
@@ -345,12 +345,21 @@ impl Emulator {
         }
     }
 
-    fn debug_continue(&mut self, sim_id: SimId) {
+    fn debug_continue(&mut self, sim_id: SimId) -> bool {
         let Some(debugger) = self.debuggers.get_mut(&sim_id) else {
             self.stop_debugging(sim_id);
-            return;
+            return false;
         };
         debugger.stop_reason = None;
+        true
+    }
+    fn debug_step(&mut self, sim_id: SimId) {
+        if self.debug_continue(sim_id) {
+            let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                return;
+            };
+            sim.step();
+        }
     }
 
     pub fn run(&mut self) {
@@ -412,6 +421,7 @@ impl Emulator {
                 };
                 if let Some(reason) = sim.stop_reason() {
                     let stop_reason = match reason {
+                        StopReason::Stepped => DebugStopReason::Trace,
                         StopReason::Breakpoint => DebugStopReason::Breakpoint,
                     };
                     self.debug_stop(sim_id, stop_reason);
@@ -509,6 +519,9 @@ impl Emulator {
             EmulatorCommand::DebugContinue(sim_id) => {
                 self.debug_continue(sim_id);
             }
+            EmulatorCommand::DebugStep(sim_id) => {
+                self.debug_step(sim_id);
+            }
             EmulatorCommand::ReadRegister(sim_id, register, done) => {
                 let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
                     return;
@@ -596,6 +609,7 @@ pub enum EmulatorCommand {
     StopDebugging(SimId),
     DebugInterrupt(SimId),
     DebugContinue(SimId),
+    DebugStep(SimId),
     ReadRegister(SimId, VBRegister, oneshot::Sender<u32>),
     ReadMemory(SimId, Range<u32>, Vec<u8>, oneshot::Sender<Vec<u8>>),
     AddBreakpoint(SimId, u32),
@@ -628,6 +642,8 @@ type DebugSender = tokio::sync::mpsc::UnboundedSender<DebugEvent>;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum DebugStopReason {
+    // We are stepping
+    Trace,
     // We hit a breakpoint
     Breakpoint,
     // The debugger told us to pause