[mort] Refactor offset-to-index mapping

diff --git a/src/hb-aat-layout-morx-table.hh b/src/hb-aat-layout-morx-table.hh
index 45dbc28..396457c 100644 (file)
--- a/src/hb-aat-layout-morx-table.hh
+++ b/src/hb-aat-layout-morx-table.hh
@@ -457,6 +457,14 @@ struct LigatureSubtable
        ligature (table+table->ligature),
        match_length (0) {}
 
+    template <typename T>
+    static inline unsigned int offsetToIndex (unsigned int offset,
+                                             const void *base,
+                                             const T *array)
+    {
+      return (offset - ((const char *) array - (const char *) base)) / sizeof (T);
+    }
+
     inline bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED,
                               const Entry<EntryData> *entry)
     {
@@ -497,9 +505,9 @@ struct LigatureSubtable
          return false; // TODO Work on previous instead?
 
        unsigned int cursor = match_length;
-       const HBUINT32 *actionData = Types::extended ?
-                                    &ligAction[action_idx] :
-                                    &StructAtOffset<HBUINT32> (table, action_idx);
+       if (!Types::extended)
+         action_idx = offsetToIndex (action_idx, table, ligAction.arrayZ);
+       const HBUINT32 *actionData = &ligAction[action_idx];
         do
        {
          if (unlikely (!cursor))
@@ -522,11 +530,8 @@ struct LigatureSubtable
          int32_t offset = (int32_t) uoffset;
          unsigned int component_idx = buffer->cur().codepoint + offset;
          if (!Types::extended)
-           component_idx *= 2;
-
-         const HBUINT16 &componentData = Types::extended ?
-                                         component[component_idx] :
-                                         StructAtOffset<HBUINT16> (table, component_idx);
+           component_idx = offsetToIndex (component_idx * 2, table, component.arrayZ);
+         const HBUINT16 &componentData = component[component_idx];
          if (unlikely (!componentData.sanitize (&c->sanitizer))) return false;
          ligature_idx += componentData;
 
@@ -535,9 +540,9 @@ struct LigatureSubtable
                     bool (action & LigActionLast));
          if (action & (LigActionStore | LigActionLast))
          {
-           const GlyphID &ligatureData = Types::extended ?
-                                         ligature[ligature_idx] :
-                                         StructAtOffset<GlyphID> (table, ligature_idx);
+           if (!Types::extended)
+             ligature_idx = offsetToIndex (ligature_idx, table, ligature.arrayZ);
+           const GlyphID &ligatureData = ligature[ligature_idx];
            if (unlikely (!ligatureData.sanitize (&c->sanitizer))) return false;
            hb_codepoint_t lig = ligatureData;