--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/harfbuzz/src/OT/Layout/GSUB/SingleSubstFormat1.hh	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,168 @@
+#ifndef OT_LAYOUT_GSUB_SINGLESUBSTFORMAT1_HH
+#define OT_LAYOUT_GSUB_SINGLESUBSTFORMAT1_HH
+
+#include "Common.hh"
+
+namespace OT {
+namespace Layout {
+namespace GSUB_impl {
+
+template <typename Types>
+struct SingleSubstFormat1_3
+{
+  protected:
+  HBUINT16      format;                 /* Format identifier--format = 1 */
+  typename Types::template OffsetTo<Coverage>
+                coverage;               /* Offset to Coverage table--from
+                                         * beginning of Substitution table */
+  typename Types::HBUINT
+                deltaGlyphID;           /* Add to original GlyphID to get
+                                         * substitute GlyphID, modulo 0x10000 */
+
+  public:
+  DEFINE_SIZE_STATIC (2 + 2 * Types::size);
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (coverage.sanitize (c, this) && deltaGlyphID.sanitize (c));
+  }
+
+  hb_codepoint_t get_mask () const
+  { return (1 << (8 * Types::size)) - 1; }
+
+  bool intersects (const hb_set_t *glyphs) const
+  { return (this+coverage).intersects (glyphs); }
+
+  bool may_have_non_1to1 () const
+  { return false; }
+
+  void closure (hb_closure_context_t *c) const
+  {
+    hb_codepoint_t d = deltaGlyphID;
+    hb_codepoint_t mask = get_mask ();
+
+    /* Help fuzzer avoid this function as much. */
+    unsigned pop = (this+coverage).get_population ();
+    if (pop >= mask)
+      return;
+
+    hb_set_t intersection;
+    (this+coverage).intersect_set (c->parent_active_glyphs (), intersection);
+
+    /* In degenerate fuzzer-found fonts, but not real fonts,
+     * this table can keep adding new glyphs in each round of closure.
+     * Refuse to close-over, if it maps glyph range to overlapping range. */
+    hb_codepoint_t min_before = intersection.get_min ();
+    hb_codepoint_t max_before = intersection.get_max ();
+    hb_codepoint_t min_after = (min_before + d) & mask;
+    hb_codepoint_t max_after = (max_before + d) & mask;
+    if (intersection.get_population () == max_before - min_before + 1 &&
+	((min_before <= min_after && min_after <= max_before) ||
+	 (min_before <= max_after && max_after <= max_before)))
+      return;
+
+    + hb_iter (intersection)
+    | hb_map ([d, mask] (hb_codepoint_t g) { return (g + d) & mask; })
+    | hb_sink (c->output)
+    ;
+  }
+
+  void closure_lookups (hb_closure_lookups_context_t *c) const {}
+
+  void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    if (unlikely (!(this+coverage).collect_coverage (c->input))) return;
+    hb_codepoint_t d = deltaGlyphID;
+    hb_codepoint_t mask = get_mask ();
+
+    + hb_iter (this+coverage)
+    | hb_map ([d, mask] (hb_codepoint_t g) { return (g + d) & mask; })
+    | hb_sink (c->output)
+    ;
+  }
+
+  const Coverage &get_coverage () const { return this+coverage; }
+
+  bool would_apply (hb_would_apply_context_t *c) const
+  { return c->len == 1 && (this+coverage).get_coverage (c->glyphs[0]) != NOT_COVERED; }
+
+  bool apply (hb_ot_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_codepoint_t glyph_id = c->buffer->cur().codepoint;
+    unsigned int index = (this+coverage).get_coverage (glyph_id);
+    if (likely (index == NOT_COVERED)) return_trace (false);
+
+    hb_codepoint_t d = deltaGlyphID;
+    hb_codepoint_t mask = get_mask ();
+
+    glyph_id = (glyph_id + d) & mask;
+
+    if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
+    {
+      c->buffer->sync_so_far ();
+      c->buffer->message (c->font,
+			  "replacing glyph at %d (single substitution)",
+			  c->buffer->idx);
+    }
+
+    c->replace_glyph (glyph_id);
+
+    if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
+    {
+      c->buffer->message (c->font,
+			  "replaced glyph at %d (single substitution)",
+			  c->buffer->idx - 1);
+    }
+
+    return_trace (true);
+  }
+
+  template<typename Iterator,
+           hb_requires (hb_is_sorted_source_of (Iterator, hb_codepoint_t))>
+  bool serialize (hb_serialize_context_t *c,
+                  Iterator glyphs,
+                  unsigned delta)
+  {
+    TRACE_SERIALIZE (this);
+    if (unlikely (!c->extend_min (this))) return_trace (false);
+    if (unlikely (!coverage.serialize_serialize (c, glyphs))) return_trace (false);
+    c->check_assign (deltaGlyphID, delta, HB_SERIALIZE_ERROR_INT_OVERFLOW);
+    return_trace (true);
+  }
+
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->glyphset_gsub ();
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    hb_codepoint_t d = deltaGlyphID;
+    hb_codepoint_t mask = get_mask ();
+
+    hb_set_t intersection;
+    (this+coverage).intersect_set (glyphset, intersection);
+
+    auto it =
+    + hb_iter (intersection)
+    | hb_map_retains_sorting ([d, mask] (hb_codepoint_t g) {
+                                return hb_codepoint_pair_t (g,
+                                                            (g + d) & mask); })
+    | hb_filter (glyphset, hb_second)
+    | hb_map_retains_sorting ([&] (hb_codepoint_pair_t p) -> hb_codepoint_pair_t
+                              { return hb_pair (glyph_map[p.first], glyph_map[p.second]); })
+    ;
+
+    bool ret = bool (it);
+    SingleSubst_serialize (c->serializer, it);
+    return_trace (ret);
+  }
+};
+
+}
+}
+}
+
+
+#endif /* OT_LAYOUT_GSUB_SINGLESUBSTFORMAT1_HH */