Made g_utf8_to_ucs4_fast() even faster

https://bugzilla.gnome.org/show_bug.cgi?id=619435

diff --git a/glib/gutf8.c b/glib/gutf8.c
index ed245dc..46f71b1 100644 (file)
--- a/glib/gutf8.c
+++ b/glib/gutf8.c
@@ -851,7 +851,6 @@ g_utf8_to_ucs4_fast (const gchar *str,
                     glong        len,              
                     glong       *items_written)    
 {
-  gint j, charlen;
   gunichar *result;
   gint n_chars, i;
   const gchar *p;
@@ -882,49 +881,37 @@ g_utf8_to_ucs4_fast (const gchar *str,
   p = str;
   for (i=0; i < n_chars; i++)
     {
-      gunichar wc = ((unsigned char *)p)[0];
+      gunichar wc = (guchar)*p++;
 
       if (wc < 0x80)
        {
          result[i] = wc;
-         p++;
        }
       else
        { 
-         if (wc < 0xe0)
-           {
-             charlen = 2;
-             wc &= 0x1f;
-           }
-         else if (wc < 0xf0)
-           {
-             charlen = 3;
-             wc &= 0x0f;
-           }
-         else if (wc < 0xf8)
-           {
-             charlen = 4;
-             wc &= 0x07;
-           }
-         else if (wc < 0xfc)
-           {
-             charlen = 5;
-             wc &= 0x03;
-           }
-         else
+         gunichar mask = 0x40;
+
+         if (G_UNLIKELY ((wc & mask) == 0))
            {
-             charlen = 6;
-             wc &= 0x01;
+             /* It's an out-of-sequence 10xxxxxxx byte.
+              * Rather than making an ugly hash of this and the next byte
+              * and overrunning the buffer, it's more useful to treat it
+              * with a replacement character */
+             result[i] = 0xfffd;
+             continue;
            }
 
-         for (j = 1; j < charlen; j++)
+         do
            {
              wc <<= 6;
-             wc |= ((unsigned char *)p)[j] & 0x3f;
+             wc |= (guchar)(*p++) & 0x3f;
+             mask <<= 5;
            }
+         while((wc & mask) != 0);
+
+         wc &= mask - 1;
 
          result[i] = wc;
-         p += charlen;
        }
     }
   result[i] = 0;