+#define __PACKAGE__ "Variable::Magic"
+
+#define PERL_VERSION_GE(R, V, S) (PERL_REVISION > (R) || (PERL_REVISION == (R) && (PERL_VERSION > (V) || (PERL_VERSION == (V) && (PERL_SUBVERSION >= (S))))))
+
+#define PERL_VERSION_LE(R, V, S) (PERL_REVISION < (R) || (PERL_REVISION == (R) && (PERL_VERSION < (V) || (PERL_VERSION == (V) && (PERL_SUBVERSION <= (S))))))
+
+#ifndef VMG_PERL_PATCHLEVEL
+# ifdef PERL_PATCHNUM
+# define VMG_PERL_PATCHLEVEL PERL_PATCHNUM
+# else
+# define VMG_PERL_PATCHLEVEL 0
+# endif
+#endif
+
+#define VMG_HAS_PERL_OR(P, R, V, S) ((VMG_PERL_PATCHLEVEL >= (P)) || (!VMG_PERL_PATCHLEVEL && PERL_VERSION_GE((R), (V), (S))))
+
+#define VMG_HAS_PERL_AND(P, R, V, S) (PERL_VERSION_GE((R), (V), (S)) && (!VMG_PERL_PATCHLEVEL || (VMG_PERL_PATCHLEVEL >= (P))))
+
+/* --- Threads and multiplicity -------------------------------------------- */
+
+#ifndef NOOP
+# define NOOP
+#endif
+
+#ifndef dNOOP
+# define dNOOP
+#endif
+
+#ifndef VMG_MULTIPLICITY
+# if defined(MULTIPLICITY) || defined(PERL_IMPLICIT_CONTEXT)
+# define VMG_MULTIPLICITY 1
+# else
+# define VMG_MULTIPLICITY 0
+# endif
+#endif
+#if VMG_MULTIPLICITY && !defined(tTHX)
+# define tTHX PerlInterpreter*
+#endif
+
+#if VMG_MULTIPLICITY && defined(dMY_CXT) && defined(MY_CXT) && defined(START_MY_CXT) && defined(MY_CXT_INIT) && (defined(MY_CXT_CLONE) || defined(dMY_CXT_SV))
+# define VMG_THREADSAFE 1
+# ifndef MY_CXT_CLONE
+# define MY_CXT_CLONE \
+ dMY_CXT_SV; \
+ my_cxt_t *my_cxtp = (my_cxt_t*)SvPVX(newSV(sizeof(my_cxt_t)-1)); \
+ Copy(INT2PTR(my_cxt_t*, SvUV(my_cxt_sv)), my_cxtp, 1, my_cxt_t); \
+ sv_setuv(my_cxt_sv, PTR2UV(my_cxtp))
+# endif
+#else
+# define VMG_THREADSAFE 0
+# undef dMY_CXT
+# define dMY_CXT dNOOP
+# undef MY_CXT
+# define MY_CXT vmg_globaldata
+# undef START_MY_CXT
+# define START_MY_CXT STATIC my_cxt_t MY_CXT;
+# undef MY_CXT_INIT
+# define MY_CXT_INIT NOOP
+# undef MY_CXT_CLONE
+# define MY_CXT_CLONE NOOP
+#endif
+
+#if VMG_THREADSAFE
+
+STATIC SV *vmg_clone(pTHX_ SV *sv, tTHX owner) {
+#define vmg_clone(P, O) vmg_clone(aTHX_ (P), (O))
+ CLONE_PARAMS param;
+ param.stashes = NULL; /* don't need it unless sv is a PVHV */
+ param.flags = 0;
+ param.proto_perl = owner;
+ return sv_dup(sv, ¶m);
+}
+
+#endif /* VMG_THREADSAFE */
+
+/* --- Compatibility ------------------------------------------------------- */
+
+#ifndef Newx
+# define Newx(v, n, c) New(0, v, n, c)
+#endif
+
+#ifndef SvMAGIC_set
+# define SvMAGIC_set(sv, val) (SvMAGIC(sv) = (val))
+#endif
+
+#ifndef mPUSHi
+# define mPUSHi(I) PUSHs(sv_2mortal(newSViv(I)))
+#endif
+
+#ifndef PERL_MAGIC_ext
+# define PERL_MAGIC_ext '~'
+#endif
+
+#ifndef MGf_COPY
+# define MGf_COPY 0
+#endif
+
+#ifndef MGf_DUP
+# define MGf_DUP 0
+#endif
+
+#ifndef MGf_LOCAL
+# define MGf_LOCAL 0
+#endif
+
+/* uvar magic and Hash::Util::FieldHash were commited with p28419 */
+#if VMG_HAS_PERL_AND(28419, 5, 9, 4)
+# define VMG_UVAR 1
+#else
+# define VMG_UVAR 0
+#endif
+
+#if !defined(VMG_COMPAT_ARRAY_PUSH_NOLEN) && VMG_HAS_PERL_OR(25854, 5, 9, 3)
+# define VMG_COMPAT_ARRAY_PUSH_NOLEN 1
+#else
+# define VMG_COMPAT_ARRAY_PUSH_NOLEN 0
+#endif
+
+/* since 5.9.5 - see #43357 */
+#if VMG_HAS_PERL_OR(31473, 5, 9, 5)
+# define VMG_COMPAT_ARRAY_UNDEF_CLEAR 1
+#else
+# define VMG_COMPAT_ARRAY_UNDEF_CLEAR 0
+#endif
+
+#if VMG_HAS_PERL_OR(32969, 5, 11, 0)
+# define VMG_COMPAT_SCALAR_LENGTH_NOLEN 1
+#else
+# define VMG_COMPAT_SCALAR_LENGTH_NOLEN 0
+#endif
+
+#if VMG_UVAR
+
+/* Bug-free mg_magical - see http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-01/msg00036.html - but specialized to our needs. */
+STATIC void vmg_sv_magicuvar(pTHX_ SV *sv, const char *uf, I32 len) {
+#define vmg_sv_magicuvar(S, U, L) vmg_sv_magicuvar(aTHX_ (S), (U), (L))
+ const MAGIC* mg;
+ sv_magic(sv, NULL, PERL_MAGIC_uvar, uf, len);
+ /* uvar magic has set and get magic, hence this has set SVs_GMG and SVs_SMG. */
+ PERL_UNUSED_CONTEXT;
+ if ((mg = SvMAGIC(sv))) {
+ SvRMAGICAL_off(sv);
+ do {
+ const MGVTBL* const vtbl = mg->mg_virtual;
+ if (vtbl) {
+ if (vtbl->svt_clear) {
+ SvRMAGICAL_on(sv);
+ break;
+ }
+ }
+ } while ((mg = mg->mg_moremagic));
+ }
+}
+
+#endif /* VMG_UVAR */
+
+/* --- Context-safe global data -------------------------------------------- */
+
+#define MY_CXT_KEY __PACKAGE__ "::_guts" XS_VERSION
+
+typedef HV * my_cxt_t;