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

@@ -24,6 +24,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         .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"))

src/emulator.rs

@@ -311,7 +311,7 @@ impl Emulator {
         }
         let debug = DebugInfo {
             sender,
-            stop_reason: Some(DebugStopReason::Trapped),
+            stop_reason: Some(DebugStopReason::Paused),
         };
         self.debuggers.insert(sim_id, debug);
         self.state
@@ -334,7 +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) {
@@ -686,7 +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

@@ -170,6 +170,7 @@ extern "C" {
     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.
@@ -214,13 +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.
@@ -241,13 +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.

src/gdbserver.rs

@@ -521,7 +521,11 @@ fn parse_memory_range(req: &mut Request<'_>) -> Option<(u32, usize)> {
 
 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;";
     }
@@ -542,7 +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;",
         };
     }