+#endif /* VMG_UVAR */
+
+#if MGf_COPY
+STATIC int vmg_cb_call3(pTHX_ SV *cb, SV *sv, SV *data, SV *sv2, SV *sv3) {
+#define vmg_cb_call3(I, S, D, S2, S3) vmg_cb_call3(aTHX_ (I), (S), (D), (S2), (S3))
+ SV *svr;
+ int ret;
+
+ dSP;
+ int count;
+
+ ENTER;
+ SAVETMPS;
+
+ PUSHMARK(SP);
+ XPUSHs(sv_2mortal(newRV_inc(sv)));
+ XPUSHs(data ? data : &PL_sv_undef);
+ XPUSHs(sv2 ? sv2 : &PL_sv_undef);
+ if (sv3) { XPUSHs(sv3); }
+ PUTBACK;
+
+ count = call_sv(cb, G_SCALAR);
+
+ SPAGAIN;
+
+ if (count != 1) { croak("Callback needs to return 1 scalar\n"); }
+ svr = POPs;
+ ret = SvOK(svr) ? SvIV(svr) : 0;
+
+ PUTBACK;
+
+ FREETMPS;
+ LEAVE;
+
+ return ret;
+}
+#endif /* MGf_COPY */