Note that the code you've got is already fairly efficient. Consider the following: 
my $n = 0x80061861;
for (1..10_000_000) {
    my $top14 = ( $n & 0xfffc0000 ) >> 18;
    my $nxt6  = ( $n & 0x0003f000 ) >> 12;
    my $mid6  = ( $n & 0x00000fc0 ) >>  6;
    my $bot6  = ( $n & 0x0000003f );

    # or replace the four lines above with:
    #my ($top14, $nxt6, $mid6, $bot6) = (1,1,1,1);
}

[download]
Running as-is on my system takes 3.1s; using just the last line (which represents a baseline of creating, setting and freeing those four lexical vars), takes 1.9s. So any savings you make are likely to be less than that.

Dave.

In reply to Re: Efficient bit-twiddling in Perl. by dave_the_m
in thread Efficient bit-twiddling in Perl. by BrowserUk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.