1 files changed, 28 insertions, 21 deletions

diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index 683087bd7b..e7579399f3 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -456,43 +456,50 @@ static bool intable(const struct interval *table, size_t n_items, int c)
   return false;
 }
 
-/*
- * For UTF-8 character "c" return 2 for a double-width character, 1 for others.
- * Returns 4 or 6 for an unprintable character.
- * Is only correct for characters >= 0x80.
- * When p_ambw is "double", return 2 for a character with East Asian Width
- * class 'A'(mbiguous).
- */
+/// For UTF-8 character "c" return 2 for a double-width character, 1 for others.
+/// Returns 4 or 6 for an unprintable character.
+/// Is only correct for characters >= 0x80.
+/// When p_ambw is "double", return 2 for a character with East Asian Width
+/// class 'A'(mbiguous).
+///
+/// @note Tables `doublewidth` and `ambiguous` are generated by
+///       gen_unicode_tables.lua, which must be manually invoked as needed.
 int utf_char2cells(int c)
 {
   if (c >= 0x100) {
 #ifdef USE_WCHAR_FUNCTIONS
-    /*
-     * Assume the library function wcwidth() works better than our own
-     * stuff.  It should return 1 for ambiguous width chars!
-     */
+    //
+    // Assume the library function wcwidth() works better than our own
+    // stuff.  It should return 1 for ambiguous width chars!
+    //
     int n = wcwidth(c);
 
-    if (n < 0)
-      return 6;                 /* unprintable, displays <xxxx> */
-    if (n > 1)
+    if (n < 0) {
+      return 6;                 // unprintable, displays <xxxx>
+    }
+    if (n > 1) {
       return n;
+    }
 #else
-    if (!utf_printable(c))
-      return 6;                 /* unprintable, displays <xxxx> */
-    if (intable(doublewidth, ARRAY_SIZE(doublewidth), c))
+    if (!utf_printable(c)) {
+      return 6;                 // unprintable, displays <xxxx>
+    }
+    if (intable(doublewidth, ARRAY_SIZE(doublewidth), c)) {
       return 2;
+    }
 #endif
     if (p_emoji && intable(emoji_width, ARRAY_SIZE(emoji_width), c)) {
       return 2;
     }
+  } else if (c >= 0x80 && !vim_isprintc(c)) {
+    // Characters below 0x100 are influenced by 'isprint' option.
+    return 4;                   // unprintable, displays <xx>
   }
-  /* Characters below 0x100 are influenced by 'isprint' option */
-  else if (c >= 0x80 && !vim_isprintc(c))
-    return 4;                   /* unprintable, displays <xx> */
 
-  if (c >= 0x80 && *p_ambw == 'd' && intable(ambiguous, ARRAY_SIZE(ambiguous), c))
+  if (c >= 0x80 && *p_ambw == 'd'
+      && intable(ambiguous, ARRAY_SIZE(ambiguous), c)) {
     return 2;
+  }
 
   return 1;
 }