feat: use signed integers for integer storages

Author: henryiii

include/bh_python/storage.hpp

@@ -22,8 +22,8 @@
 namespace storage {
 
 // Names match Python names
-using int64         = bh::dense_storage<uint64_t>;
-using atomic_int64  = bh::dense_storage<bh::accumulators::count<uint64_t, true>>;
+using int64         = bh::dense_storage<int64_t>;
+using atomic_int64  = bh::dense_storage<bh::accumulators::count<int64_t, true>>;
 using double_       = bh::dense_storage<double>;
 using unlimited     = bh::unlimited_storage<>;
 using weight        = bh::dense_storage<accumulators::weighted_sum<double>>;
@@ -80,7 +80,7 @@ template <class Archive>
 void save(Archive& ar, const storage::atomic_int64& s, unsigned /* version */) {
     // We cannot view the memory as a numpy array, because the internal layout of
     // std::atomic is undefined. So no reinterpret_casts are allowed.
-    py::array_t<std::uint64_t> a(static_cast<py::ssize_t>(s.size()));
+    py::array_t<std::int64_t> a(static_cast<py::ssize_t>(s.size()));
 
     auto in_ptr  = s.begin();
     auto out_ptr = a.mutable_data();
@@ -191,15 +191,15 @@ struct type_caster<storage::atomic_int64::value_type> {
         auto ptr = PyNumber_Long(src.ptr());
         if(!ptr)
             return false;
-        value = PyLong_AsUnsignedLongLong(ptr);
+        value = PyLong_AsLongLong(ptr);
         Py_DECREF(ptr);
         return !PyErr_Occurred();
     }
 
     static handle cast(storage::atomic_int64::value_type src,
                        return_value_policy /* policy */,
                        handle /* parent */) {
-        return PyLong_FromUnsignedLongLong(src.value());
+        return PyLong_FromLongLong(src.value());
     }
 };
 } // namespace detail