sub xxx {
    my $string = shift;
    my @cache = unpack q(x*X3 .@0/(NX3)), $string."\0\0\0";
    my @indices = sort {$cache[$a] <=> $cache[$b] ||
        substr($string, $a) cmp substr($string, $b) } 0 .. $#cache;
    $_++ for @indices;
    return @indices;
}