xe::be basic arithmetic operators

src/xenia/base/byte_order.h

@@ -83,6 +83,14 @@ struct be {
   be(const T &src) : value(xe::byte_swap(src)) {}
   be(const be &other) { value = other.value; }
   operator T() const { return xe::byte_swap(value); }
+
+  be<T>& operator+=(int a) { *this = *this + a; return *this; }
+  be<T>& operator-=(int a) { *this = *this - a; return *this; }
+  be<T>& operator++() { *this += 1; return *this; } // ++a
+  be<T> operator++(int) { *this += 1; return (*this - 1); } // a++
+  be<T>& operator--() { *this -= 1; return *this; } // --a
+  be<T> operator--(int) { *this -= 1; return (*this + 1); } // a--
+
   T value;
 };