# Assume that rotate_up as defined in the original problem
# statement has been defined.

sub sordid
{
    local $len = pop(@stack);
    local $bum = $len;

    local ($x, $y, $limit);

    while ($bum > 1)
    {
        $limit = $bum;
        while (--$limit)
        {
            $x = pop(@stack);
            $y = pop(@stack);

            if ($x gt $y)
            {
                push(@stack, $x);
                push(@stack, $y);
            }
            else
            {
                push(@stack, $y);
                push(@stack, $x);
            }

            rotate_up($bum);
        }
        # At end of the $limit loop, top element is the max, and
        # top+1 to end is semi-sorted. One more rotate_up()
        # is needed before moving the floor up one notch.
        rotate_up($bum);
        $bum--;
    }

    push(@stack, $len);
}

@stack = qw(d b f a e c 6);  # <-- bottom .. top -->

print "(@stack)\n";
# Prints: (d b f a e c 6)
sordid();
print "(@stack)\n";
# Prints: (f e d c b a 6)