de-utf8-ing a string

Hello,

I need an efficient way to do this:

my $buf;

sub append {
  my $x = shift;
  my $new;
  for (my $i = 0; $i < length($x); $i++) {
    $new .= chr(ord(substr($x, $i, 1)));
  }
  $buf .= $new;
}

In practice, $buf will not have its utf8 flag set, and $x may have it
set, but will not contain
any characters with ordinals over 255. I'm relying on chr() to return
a normal string in those
cases.

Any ideas?

Thanks,
ER