Re: Efficient bit-twiddling in Perl.

[salva]

Not a big improvement, but you can eliminate the AND operation when calculating $top14.

If you have to do that millions of times, you can try building a table for the combined three 6bit quantities:

my @table;
$table[$_] = [..., ..., ...] for 0..0x0003ffff;
...
for my $n (...) {
  my $top = $n >> 18;
  my ($nxt, $mid, $bot) = @{$table[$n & 0x0003ffff]};
  ...
}

[BrowserUk]

you can try building a table for the combined three 6bit quantities:

The lookup table gains about 20%. Less than I expected, but worth having. Thank you.