finalize downhill iterator

common/route/awooter.cc

@@ -57,6 +57,8 @@ using DownhillIter = decltype(Context(ArchArgs()).getPipsDownhill(WireId()).begi
 struct DownhillIterWrapper {
     DownhillIter current;
     DownhillIter end;
+
+    DownhillIterWrapper(DownhillIter begin, DownhillIter end) : current(begin), end(end) {}
 };
 
 extern "C" {
@@ -232,6 +234,15 @@ extern "C" {
         return size;
     }
 
+    DownhillIterWrapper *npnr_context_get_pips_downhill(Context *ctx, uint64_t wire_id) {
+        auto wire = unwrap_wire(wire_id);
+        auto range = ctx->getPipsDownhill(wire);
+        return new DownhillIterWrapper(range.begin(), range.end());
+    }
+    void npnr_delete_downhill_iter(DownhillIterWrapper *iter) {
+        delete iter;
+    }
+
     PortRef* npnr_netinfo_driver(NetInfo *const net) {
         if (net == nullptr) {
             return nullptr;
@@ -267,7 +278,7 @@ extern "C" {
     }
 
     uint64_t npnr_deref_downhill_iter(DownhillIterWrapper *iter) {
-        wrap(*iter->current);
+        return wrap(*iter->current);
     }
 
     bool npnr_is_downhill_iter_done(DownhillIterWrapper *iter) {

common/route/awooter/rust/src/npnr.rs

@@ -217,6 +217,14 @@ impl Context {
         unsafe { std::slice::from_raw_parts(pips, len as usize) }
     }
 
+    pub fn get_downhill_pips(&self, wire: WireId) -> DownhillPipsIter {
+        let iter = unsafe { npnr_context_get_pips_downhill(self, wire) };
+        DownhillPipsIter {
+            iter,
+            phantom_data: Default::default(),
+        }
+    }
+
     pub fn pip_location(&self, pip: PipId) -> Loc {
         unsafe { npnr_context_get_pip_location(self, pip) }
     }
@@ -307,6 +315,8 @@ extern "C" {
         names: *mut *mut libc::c_int,
         nets: *mut *mut *mut NetInfo,
     ) -> u32;
+    fn npnr_context_get_pips_downhill(ctx: *const Context, wire: WireId) -> *mut RawDownhillIter;
+    fn npnr_delete_downhill_iter(iter: *mut RawDownhillIter);
 
     fn npnr_netinfo_driver(net: *mut NetInfo) -> *mut PortRef;
     fn npnr_netinfo_users_leak(net: *mut NetInfo, users: *mut *mut *mut PortRef) -> u32;
@@ -405,11 +415,12 @@ struct RawDownhillIter {
     content: [u8; 0],
 }
 
-struct DownhillPipsIter {
+pub struct DownhillPipsIter<'a> {
     iter: *mut RawDownhillIter,
+    phantom_data: std::marker::PhantomData<&'a PipId>,
 }
 
-impl Iterator for DownhillPipsIter {
+impl<'a> Iterator for DownhillPipsIter<'a> {
     type Item = PipId;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -423,6 +434,12 @@ impl Iterator for DownhillPipsIter {
     }
 }
 
+impl<'a> Drop for DownhillPipsIter<'a> {
+    fn drop(&mut self) {
+        unsafe { npnr_delete_downhill_iter(self.iter) };
+    }
+}
+
 macro_rules! log_info {
     ($($t:tt)*) => {
         let s = std::ffi::CString::new(format!($($t)*)).unwrap();