Re: [avr-libc-dev] [bug #37901] CRC-CCITT calculation incorrect

[Weddington, Eric]

> -----Original Message-----
> From: address@hidden
> [mailto:address@hidden On
> Behalf Of Erik Walthinsen
> Sent: Tuesday, December 11, 2012 9:03 AM
> To: address@hidden
> Subject: Re: [avr-libc-dev] [bug #37901] CRC-CCITT calculation incorrect
> 
> On 12/11/2012 07:50 AM, Weddington, Eric wrote:
> > We need to support the xmega users better. If they're getting easily
> confused, then we need to help.
> 
> It took me a while to discover that the Xmega "CCITT" wasn't the same as
> the avr-libc function, and yes, the difference between _xmodem and
> _ccitt isn't all that well described (esp if/since they're actually
> inverse of each other polynomial-wise).  Plenty of trouble finding the
> right Python code to insert into my passive bus sniffer too.  Not
> looking forward to figuring out CRC-32 re: the NVM, the CRC module, and
> python.  That *should* be easier since they claim it's 802.3 and afaik
> crc32 is quite a bit more standardized, but...
> 
> The key for me was finding this page:
> 
> <http://www.lammertbies.nl/comm/info/crc-calculation.html>

Sorry for the hassle, Erik. Thanks for telling your story and providing the 
link.

Please send ideas for improvement. We're always open-minded, but just sticklers 
for detail (as I'm sure you can tell).

Eric