+#define MgPV_const(mg,lp) ((((int)(lp = (mg)->mg_len)) == HEf_SVKEY) ? \
+ SvPV_const(MUTABLE_SV((mg)->mg_ptr),lp) : \
+ (const char*)(mg)->mg_ptr)
+#define MgPV_nolen_const(mg) (((((int)(mg)->mg_len)) == HEf_SVKEY) ? \
+ SvPV_nolen_const(MUTABLE_SV((mg)->mg_ptr)) : \
+ (const char*)(mg)->mg_ptr)