Initial commit: xenia-rs workspace for Xbox 360 RE

Rust reimplementation of the xenia Xbox 360 emulator targeting reverse-
engineering and preservation, initially scoped to Project Sylpheed.

Includes:
- XEX2 loader (LZX decompression, AES decryption, PE parsing)
- XISO / XGD2 disc image VFS
- PPC interpreter with 200+ opcodes and VMX128 decoding
- Static analyzer: functions, cross-references, labels, asm + SQLite output
- HLE kernel covering the xboxkrnl/xam subset used by Sylpheed init
- Debugger with in-memory and SQLite-backed execution tracing
- `xenia-rs` CLI with extract/dis/exec commands that produce cumulative,
  superset SQLite databases and opt-in instruction/import/branch traces

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/xenia-debugger/src/breakpoint.rs

@@ -0,0 +1,7 @@
+/// A code breakpoint at a specific guest address.
+#[derive(Debug, Clone)]
+pub struct Breakpoint {
+    pub addr: u32,
+    pub enabled: bool,
+    pub condition: Option<String>,
+}

crates/xenia-debugger/src/lib.rs

@@ -0,0 +1,125 @@
+pub mod breakpoint;
+pub mod trace;
+
+use std::collections::HashMap;
+use xenia_cpu::context::PpcContext;
+use xenia_memory::MemoryAccess;
+
+pub use breakpoint::Breakpoint;
+pub use trace::TraceEntry;
+
+/// The debugger. Hooks into every instruction step for observation.
+pub struct Debugger {
+    pub breakpoints: HashMap<u32, Breakpoint>,
+    pub trace_log: Vec<TraceEntry>,
+    pub trace_enabled: bool,
+    pub max_trace_entries: usize,
+    pub paused: bool,
+    pub step_mode: StepMode,
+    break_pending: bool,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum StepMode {
+    /// Run freely until breakpoint or pause
+    Run,
+    /// Execute one instruction then pause
+    StepInto,
+    /// Run but break after current function returns (when LR changes)
+    StepOver { return_addr: u32 },
+}
+
+impl Debugger {
+    pub fn new() -> Self {
+        Self {
+            breakpoints: HashMap::new(),
+            trace_log: Vec::new(),
+            trace_enabled: true,
+            max_trace_entries: 100_000,
+            paused: true, // Start paused for debugging
+            step_mode: StepMode::StepInto,
+            break_pending: false,
+        }
+    }
+
+    /// Called before each instruction executes.
+    pub fn pre_step(&mut self, ctx: &PpcContext, _mem: &dyn MemoryAccess) {
+        // Check breakpoints
+        if let Some(bp) = self.breakpoints.get(&ctx.pc) {
+            if bp.enabled {
+                self.break_pending = true;
+                tracing::info!("Breakpoint hit at {:#010x}", ctx.pc);
+            }
+        }
+    }
+
+    /// Called after each instruction executes.
+    pub fn post_step(&mut self, ctx: &PpcContext, _mem: &dyn MemoryAccess) {
+        // Log to trace
+        if self.trace_enabled {
+            if self.trace_log.len() >= self.max_trace_entries {
+                self.trace_log.remove(0);
+            }
+            self.trace_log.push(TraceEntry {
+                pc: ctx.pc,
+                cycle: ctx.cycle_count,
+                gpr_snapshot: [ctx.gpr[0], ctx.gpr[1], ctx.gpr[3], ctx.gpr[4]],
+                lr: ctx.lr,
+            });
+        }
+
+        // Handle step mode
+        match self.step_mode {
+            StepMode::StepInto => {
+                self.break_pending = true;
+            }
+            StepMode::StepOver { return_addr } => {
+                if ctx.pc == return_addr {
+                    self.break_pending = true;
+                }
+            }
+            StepMode::Run => {}
+        }
+    }
+
+    /// Should we break execution?
+    pub fn should_break(&self) -> bool {
+        self.break_pending || self.paused
+    }
+
+    /// Add a breakpoint at the given address.
+    pub fn add_breakpoint(&mut self, addr: u32) {
+        self.breakpoints.insert(addr, Breakpoint { addr, enabled: true, condition: None });
+    }
+
+    /// Remove a breakpoint.
+    pub fn remove_breakpoint(&mut self, addr: u32) {
+        self.breakpoints.remove(&addr);
+    }
+
+    /// Continue execution.
+    pub fn continue_execution(&mut self) {
+        self.paused = false;
+        self.break_pending = false;
+        self.step_mode = StepMode::Run;
+    }
+
+    /// Step one instruction.
+    pub fn step_into(&mut self) {
+        self.paused = false;
+        self.break_pending = false;
+        self.step_mode = StepMode::StepInto;
+    }
+
+    /// Clear break state after handling.
+    pub fn acknowledge_break(&mut self) {
+        self.break_pending = false;
+        self.paused = true;
+    }
+}
+
+impl Default for Debugger {
+    fn default() -> Self {
+        Self::new()
+    }
+}

crates/xenia-debugger/src/trace.rs

@@ -0,0 +1,9 @@
+/// A single entry in the instruction trace log.
+#[derive(Debug, Clone)]
+pub struct TraceEntry {
+    pub pc: u32,
+    pub cycle: u64,
+    /// Snapshot of key GPRs: [r0, r1(sp), r3(arg0/retval), r4(arg1)]
+    pub gpr_snapshot: [u64; 4],
+    pub lr: u64,
+}