+#define mutArrCardMask ((1 << MUT_ARR_PTRS_CARD_BITS) - 1)
+#define mutArrPtrCardDown(i) ((i) >> MUT_ARR_PTRS_CARD_BITS)
+#define mutArrPtrCardUp(i) (((i) + mutArrCardMask) >> MUT_ARR_PTRS_CARD_BITS)
+#define mutArrPtrsCardWords(n) ROUNDUP_BYTES_TO_WDS(mutArrPtrCardUp(n))
+
+#if defined(PROFILING) || (!defined(THREADED_RTS) && defined(DEBUG))
+#define OVERWRITING_CLOSURE(c) foreign "C" overwritingClosure(c "ptr")
+#else
+#define OVERWRITING_CLOSURE(c) /* nothing */
+#endif
+