+static SV *su_uid_get(pTHX_ I32 cxix) {
+#define su_uid_get(I) su_uid_get(aTHX_ (I))
+ su_uid *uid;
+ SV *uid_sv;
+ UV depth;
+
+ depth = su_uid_depth(cxix);
+ uid = su_uid_storage_fetch(depth);
+
+ if (!(uid->flags & SU_UID_ACTIVE)) {
+ su_ud_uid *ud;
+
+ uid->seq = su_uid_seq_next(depth);
+ uid->flags |= SU_UID_ACTIVE;
+
+ Newx(ud, 1, su_ud_uid);
+ SU_UD_TYPE(ud) = SU_UD_TYPE_UID;
+ ud->idx = depth;
+ su_init(ud, cxix, SU_SAVE_DESTRUCTOR_SIZE);
+ }
+
+ uid_sv = sv_newmortal();
+ sv_setpvf(uid_sv, "%"UVuf"-%"UVuf, depth, uid->seq);
+
+ return uid_sv;
+}
+
+#ifdef grok_number
+
+#define su_grok_number(S, L, VP) grok_number((S), (L), (VP))
+
+#else /* grok_number */
+
+#define IS_NUMBER_IN_UV 0x1
+
+static int su_grok_number(pTHX_ const char *s, STRLEN len, UV *valuep) {
+#define su_grok_number(S, L, VP) su_grok_number(aTHX_ (S), (L), (VP))
+ STRLEN i;
+ SV *tmpsv;
+
+ /* This crude check should be good enough for a fallback implementation.
+ * Better be too strict than too lax. */
+ for (i = 0; i < len; ++i) {
+ if (!isDIGIT(s[i]))
+ return 0;
+ }
+
+ tmpsv = sv_newmortal();
+ sv_setpvn(tmpsv, s, len);
+ *valuep = sv_2uv(tmpsv);
+
+ return IS_NUMBER_IN_UV;
+}
+
+#endif /* !grok_number */
+
+static int su_uid_validate(pTHX_ SV *uid) {
+#define su_uid_validate(U) su_uid_validate(aTHX_ (U))
+ const char *s;
+ STRLEN len, p = 0;
+ UV depth, seq;
+ int type;
+
+ s = SvPV_const(uid, len);
+
+ while (p < len && s[p] != '-')
+ ++p;
+ if (p >= len)
+ croak("UID contains only one part");
+
+ type = su_grok_number(s, p, &depth);
+ if (type != IS_NUMBER_IN_UV)
+ croak("First UID part is not an unsigned integer");
+
+ ++p; /* Skip '-'. As we used to have p < len, len - (p + 1) >= 0. */
+
+ type = su_grok_number(s + p, len - p, &seq);
+ if (type != IS_NUMBER_IN_UV)
+ croak("Second UID part is not an unsigned integer");
+
+ return su_uid_storage_check(depth, seq);
+}
+
+/* --- Context operations -------------------------------------------------- */
+
+/* Remove sequences of BLOCKs having DB for stash, followed by a SUB context
+ * for the debugger callback. */
+
+static I32 su_context_skip_db(pTHX_ I32 cxix) {
+#define su_context_skip_db(C) su_context_skip_db(aTHX_ (C))
+ I32 i;
+
+ if (!PL_DBsub)
+ return cxix;
+
+ for (i = cxix; i > 0; --i) {
+ PERL_CONTEXT *cx = cxstack + i;
+
+ switch (CxTYPE(cx)) {
+#if XSH_HAS_PERL(5, 17, 1)
+ case CXt_LOOP_PLAIN:
+#endif
+ case CXt_BLOCK:
+ if (cx->blk_oldcop && CopSTASH(cx->blk_oldcop) == GvSTASH(PL_DBgv))
+ continue;
+ break;
+ case CXt_SUB:
+ if (cx->blk_sub.cv == GvCV(PL_DBsub)) {
+ cxix = i - 1;
+ continue;
+ }
+ break;
+ default:
+ break;
+ }
+
+ break;
+ }
+
+ return cxix;
+}
+
+#if SU_HAS_NEW_CXT
+
+/* convert a physical context stack index into the logical equivalent:
+ * one that ignores all the context frames hidden by uplevel().
+ * Perl-level functions use logical args (e.g. UP takes an optional logical
+ * value and returns a logical value), while we use and store *real*
+ * values internally.
+ */
+
+static I32 su_context_real2logical(pTHX_ I32 cxix) {
+# define su_context_real2logical(C) su_context_real2logical(aTHX_ (C))
+ PERL_CONTEXT *cx;
+ I32 i, gaps = 0;
+
+ for (i = 0; i <= cxix; i++) {
+ cx = cxstack + i;
+ if (cx->cx_type == (CXt_NULL | CXp_SU_UPLEVEL_NULLED))
+ gaps++;
+ }
+
+ XSH_D(xsh_debug_log("su_context_real2logical: %d => %d\n", cxix, cxix - gaps));
+
+ return cxix - gaps;
+}
+
+/* convert a logical context stack index (one that ignores all the context
+ * frames hidden by uplevel) into the physical equivalent
+ */
+
+static I32 su_context_logical2real(pTHX_ I32 cxix) {
+# define su_context_logical2real(C) su_context_logical2real(aTHX_ (C))
+ PERL_CONTEXT *cx;
+ I32 i, seen = -1;
+
+ for (i = 0; i <= cxstack_ix; i++) {
+ PERL_CONTEXT *cx = cxstack + i;
+ if (cx->cx_type != (CXt_NULL | CXp_SU_UPLEVEL_NULLED))
+ seen++;
+ if (seen >= cxix)
+ break;
+ }
+
+ XSH_D(xsh_debug_log("su_context_logical2real: %d => %d\n", cxix, i));
+
+ if (i > cxstack_ix)
+ i = cxstack_ix;
+
+ return i;
+}