use vars '@r';

sub supffl (\@) {
    local *r = pop;
    my $sz = @r;
    my $i = -1;
    while ($sz) {
        $a = ++$i + rand $sz--;
        @r[$i, $a] = @r[$a, $i];
    }
}

=pod

$ supshfl.pl
Benchmark:running FAQ_FY, shuffl, supffl, each for at least 2 CPU sec
   FAQ_FY: 2 wc secs(2.19 usr + 0.00 sys = 2.19 CPU) @ 19.63/s (n=43)
   shuffl: 2 wc secs(2.13 usr + 0.00 sys = 2.13 CPU) @ 21.60/s (n=46)
   supffl: 2 wc secs(2.16 usr + 0.00 sys = 2.16 CPU) @ 23.15/s (n=50)

         Rate FAQ_FY shuffl supffl
FAQ_FY 19.6/s     --    -9%   -15%
shuffl 21.6/s    10%     --    -7%
supffl 23.1/s    18%     7%     --

permutation |  FAQ_FY |  shuffl |  supffl 
-------------------------------------------
-------------------------------------------
Std. Dev.   |   6.404 |   6.397 |   5.746 

=cut