Day: November 3, 2005

Optimizing g_utf8_offset_to_pointer

Hey Federico,

I’m most likely missing something extremely important here but simply doing,

gchar *
g_utf8_offset_to_pointer (const gchar *str,
                          glong        offset)
{
  const gchar *s = str;
  while (offset--)
    if (*s < 191) s++;
    else s = g_utf8_next_char (s);

  return (gchar *)s;
}

Makes it a little bit faster (on my system). Oh and that way can the utf8_skip_data bitmap also be 191 bytes smaller, of course (adjust the macro to subtract 191 from (*s)). The idea here is that arithmetic operations are less expensive (on my CPU/architecture/system) than looking up memory. Just compile test.c using gcc -S test.c with and without -DOPT and check the differences in the resulting test.s file.