+CowREFCNT(SV* sv)
+ CODE:
+#ifdef SV_COW_REFCNT_MAX
+ if (SvIsCOW(sv)) XSRETURN_IV(0 < SvLEN(sv) ? CowREFCNT(sv) : 0);
+#endif
+ XSRETURN_UNDEF;
+ OUTPUT:
+ RETVAL
+
+SV*
+kdf_aes_transform_half(const char* key, const char* seed, unsigned int rounds)