Beefy Boxes and Bandwidth Generously Provided by pair Networks
"be consistent"

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??

I can't see how 0x8404 is the 'reverse' of 0x1021 by any stretch of my imagination,(*)

but a simple brute force conversion yields:

#! perl -slw use strict; sub crc16 { use constant POLY => 0x8408; my $crc = 0; for my $c ( unpack 'C*', $_[0] ) { $crc ^= $c; for my $b ( 0 .. 7 ) { my $carry = $crc & 1; $crc >>= 1; if( $carry ) { $crc ^= POLY; } } } return $crc; } my $data = "\x64\x01"; printf "crc: %04x\n", crc16( $data ); __END__ C:\test> crc: 13bc

Which works for the (inadequate, single) sample data.

(* 0x1021 -> 0001_0000_0010_0001 bitwise reversed -> 1000_0100_0000_1000 -> 0x8408 )

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

RIP Neil Armstrong

In reply to Re: CRC 16 by BrowserUk
in thread CRC 16 by igor1212

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, 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, 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.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others examining the Monastery: (4)
    As of 2015-12-01 06:57 GMT
    Find Nodes?
      Voting Booth?

      What would be the most significant thing to happen if a rope (or wire) tied the Earth and the Moon together?

      Results (795 votes), past polls