--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/harfbuzz/src/hb-ot-shaper-arabic-fallback.hh	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,376 @@
+/*
+ * Copyright © 2012  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_OT_SHAPER_ARABIC_FALLBACK_HH
+#define HB_OT_SHAPER_ARABIC_FALLBACK_HH
+
+#include "hb.hh"
+
+#include "hb-ot-shape.hh"
+#include "hb-ot-layout-gsub-table.hh"
+
+
+/* Features ordered the same as the entries in shaping_table rows,
+ * followed by rlig.  Don't change.
+ *
+ * We currently support one subtable per lookup, and one lookup
+ * per feature.  But we allow duplicate features, so we use that!
+ */
+static const hb_tag_t arabic_fallback_features[] =
+{
+  HB_TAG('i','n','i','t'),
+  HB_TAG('m','e','d','i'),
+  HB_TAG('f','i','n','a'),
+  HB_TAG('i','s','o','l'),
+  HB_TAG('r','l','i','g'),
+  HB_TAG('r','l','i','g'),
+  HB_TAG('r','l','i','g'),
+};
+
+static OT::SubstLookup *
+arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED,
+					  hb_font_t *font,
+					  unsigned int feature_index)
+{
+  OT::HBGlyphID16 glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
+  OT::HBGlyphID16 substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
+  unsigned int num_glyphs = 0;
+
+  /* Populate arrays */
+  for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++)
+  {
+    hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index];
+    hb_codepoint_t u_glyph, s_glyph;
+
+    if (!s ||
+	!hb_font_get_glyph (font, u, 0, &u_glyph) ||
+	!hb_font_get_glyph (font, s, 0, &s_glyph) ||
+	u_glyph == s_glyph ||
+	u_glyph > 0xFFFFu || s_glyph > 0xFFFFu)
+      continue;
+
+    glyphs[num_glyphs] = u_glyph;
+    substitutes[num_glyphs] = s_glyph;
+
+    num_glyphs++;
+  }
+
+  if (!num_glyphs)
+    return nullptr;
+
+  /* Bubble-sort or something equally good!
+   * May not be good-enough for presidential candidate interviews, but good-enough for us... */
+  hb_stable_sort (&glyphs[0], num_glyphs,
+		  (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID16::cmp,
+		  &substitutes[0]);
+
+
+  /* Each glyph takes four bytes max, and there's some overhead. */
+  char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
+  hb_serialize_context_t c (buf, sizeof (buf));
+  OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
+  bool ret = lookup->serialize_single (&c,
+				       OT::LookupFlag::IgnoreMarks,
+				       hb_sorted_array (glyphs, num_glyphs),
+				       hb_array (substitutes, num_glyphs));
+  c.end_serialize ();
+
+  return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr;
+}
+
+template <typename T>
+static OT::SubstLookup *
+arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
+					    hb_font_t *font,
+					    const T &ligature_table,
+					    unsigned lookup_flags)
+{
+  OT::HBGlyphID16 first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
+  unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
+  unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
+  unsigned int num_first_glyphs = 0;
+
+  /* We know that all our ligatures have the same number of components. */
+  OT::HBGlyphID16 ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
+  unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
+  OT::HBGlyphID16 component_list[ARRAY_LENGTH_CONST (ligature_list) *
+				 ARRAY_LENGTH_CONST (ligature_table[0].ligatures[0].components)];
+  unsigned int num_ligatures = 0;
+  unsigned int num_components = 0;
+
+  /* Populate arrays */
+
+  /* Sort out the first-glyphs */
+  for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
+  {
+    hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
+    hb_codepoint_t first_glyph;
+    if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
+      continue;
+    first_glyphs[num_first_glyphs] = first_glyph;
+    ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
+    first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
+    num_first_glyphs++;
+  }
+  hb_stable_sort (&first_glyphs[0], num_first_glyphs,
+		  (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID16::cmp,
+		  &first_glyphs_indirection[0]);
+
+  /* Now that the first-glyphs are sorted, walk again, populate ligatures. */
+  for (unsigned int i = 0; i < num_first_glyphs; i++)
+  {
+    unsigned int first_glyph_idx = first_glyphs_indirection[i];
+
+    for (unsigned int ligature_idx = 0; ligature_idx < ARRAY_LENGTH (ligature_table[0].ligatures); ligature_idx++)
+    {
+      hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[ligature_idx].ligature;
+      hb_codepoint_t ligature_glyph;
+      if (!hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))
+	continue;
+
+      const auto &components = ligature_table[first_glyph_idx].ligatures[ligature_idx].components;
+      unsigned component_count = ARRAY_LENGTH_CONST (components);
+
+      for (unsigned i = 0; i < component_count; i++)
+      {
+	hb_codepoint_t component_u   = ligature_table[first_glyph_idx].ligatures[ligature_idx].components[i];
+	hb_codepoint_t component_glyph;
+	if (!component_u ||
+	    !hb_font_get_glyph (font, component_u,   0, &component_glyph))
+	  continue;
+
+	component_list[num_components++] = component_glyph;
+      }
+
+      component_count_list[num_ligatures] = 1 + component_count;
+      ligature_list[num_ligatures] = ligature_glyph;
+
+      ligature_per_first_glyph_count_list[i]++;
+
+      num_ligatures++;
+    }
+  }
+
+  if (!num_ligatures)
+    return nullptr;
+
+
+  /* 16 bytes per ligature ought to be enough... */
+  char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
+  hb_serialize_context_t c (buf, sizeof (buf));
+  OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
+  bool ret = lookup->serialize_ligature (&c,
+					 lookup_flags,
+					 hb_sorted_array (first_glyphs, num_first_glyphs),
+					 hb_array (ligature_per_first_glyph_count_list, num_first_glyphs),
+					 hb_array (ligature_list, num_ligatures),
+					 hb_array (component_count_list, num_ligatures),
+					 hb_array (component_list, num_components));
+  c.end_serialize ();
+
+  return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr;
+}
+
+static OT::SubstLookup *
+arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
+				   hb_font_t *font,
+				   unsigned int feature_index)
+{
+  if (feature_index < 4)
+    return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
+  else
+  {
+    switch (feature_index) {
+      case 4: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_3_table, OT::LookupFlag::IgnoreMarks);
+      case 5: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_table, OT::LookupFlag::IgnoreMarks);
+      case 6: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_mark_table, 0);
+    }
+  }
+  assert (false);
+  return nullptr;
+}
+
+#define ARABIC_FALLBACK_MAX_LOOKUPS ARRAY_LENGTH_CONST (arabic_fallback_features)
+
+struct arabic_fallback_plan_t
+{
+  unsigned int num_lookups;
+  bool free_lookups;
+
+  hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];
+  OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];
+  OT::hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
+};
+
+#if defined(_WIN32) && !defined(HB_NO_WIN1256)
+#define HB_WITH_WIN1256
+#endif
+
+#ifdef HB_WITH_WIN1256
+#include "hb-ot-shaper-arabic-win1256.hh"
+#endif
+
+struct ManifestLookup
+{
+  public:
+  OT::Tag tag;
+  OT::Offset16To<OT::SubstLookup> lookupOffset;
+  public:
+  DEFINE_SIZE_STATIC (6);
+};
+typedef OT::Array16Of<ManifestLookup> Manifest;
+
+static bool
+arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan HB_UNUSED,
+				   const hb_ot_shape_plan_t *plan HB_UNUSED,
+				   hb_font_t *font HB_UNUSED)
+{
+#ifdef HB_WITH_WIN1256
+  /* Does this font look like it's Windows-1256-encoded? */
+  hb_codepoint_t g;
+  if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ &&
+	hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ &&
+	hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ &&
+	hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ &&
+	hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */))
+    return false;
+
+  const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest);
+  static_assert (sizeof (arabic_win1256_gsub_lookups.manifestData) <=
+		 ARABIC_FALLBACK_MAX_LOOKUPS * sizeof (ManifestLookup), "");
+
+  unsigned j = 0;
+  unsigned int count = manifest.len;
+  for (unsigned int i = 0; i < count; i++)
+  {
+    fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag);
+    if (fallback_plan->mask_array[j])
+    {
+      fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset));
+      if (fallback_plan->lookup_array[j])
+      {
+	fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
+	j++;
+      }
+    }
+  }
+
+  fallback_plan->num_lookups = j;
+  fallback_plan->free_lookups = false;
+
+  return j > 0;
+#else
+  return false;
+#endif
+}
+
+static bool
+arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan,
+				   const hb_ot_shape_plan_t *plan,
+				   hb_font_t *font)
+{
+  static_assert ((ARRAY_LENGTH_CONST (arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS), "");
+  unsigned int j = 0;
+  for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)
+  {
+    fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]);
+    if (fallback_plan->mask_array[j])
+    {
+      fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i);
+      if (fallback_plan->lookup_array[j])
+      {
+	fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
+	j++;
+      }
+    }
+  }
+
+  fallback_plan->num_lookups = j;
+  fallback_plan->free_lookups = true;
+
+  return j > 0;
+}
+
+static arabic_fallback_plan_t *
+arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
+			     hb_font_t *font)
+{
+  arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_calloc (1, sizeof (arabic_fallback_plan_t));
+  if (unlikely (!fallback_plan))
+    return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t));
+
+  fallback_plan->num_lookups = 0;
+  fallback_plan->free_lookups = false;
+
+  /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms,
+   * in case the font has cmap entries for the presentation-forms characters. */
+  if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font))
+    return fallback_plan;
+
+  /* See if this looks like a Windows-1256-encoded font.  If it does, use a
+   * hand-coded GSUB table. */
+  if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font))
+    return fallback_plan;
+
+  assert (fallback_plan->num_lookups == 0);
+  hb_free (fallback_plan);
+  return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t));
+}
+
+static void
+arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
+{
+  if (!fallback_plan || fallback_plan->num_lookups == 0)
+    return;
+
+  for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
+    if (fallback_plan->lookup_array[i])
+    {
+      fallback_plan->accel_array[i].fini ();
+      if (fallback_plan->free_lookups)
+	hb_free (fallback_plan->lookup_array[i]);
+    }
+
+  hb_free (fallback_plan);
+}
+
+static void
+arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
+			    hb_font_t *font,
+			    hb_buffer_t *buffer)
+{
+  OT::hb_ot_apply_context_t c (0, font, buffer);
+  for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
+    if (fallback_plan->lookup_array[i]) {
+      c.set_lookup_mask (fallback_plan->mask_array[i]);
+      hb_ot_layout_substitute_lookup (&c,
+				      *fallback_plan->lookup_array[i],
+				      fallback_plan->accel_array[i]);
+    }
+}
+
+
+#endif /* HB_OT_SHAPER_ARABIC_FALLBACK_HH */