CRC clarifications

Hi,

I find that the polynomial for CRC-8-ATM is 1 + x + x^2 + x^8
and the corresponding representations as 0x07 or 0xE0
in the below link :-
http://en.wikipedia.org/wiki/Cyclic_redundancy_check

But, What does that 0x07 or 0xE0 refer to ?
Is there different algorithms for both 0x07 and 0xE0 ?

When and Where should we need to use 0x07 ?
When and Where should we need to use 0xE0 ?

Which is efficient ?

I find an online calculator for verifying the 0x07 -
http://www.usstmba.cn/chenjq/www2/so...culation0b.htm

But, unable to find one online calculator for 0xE0 .
Can anyone provide me with an online calculator for verifying
0xE0 ? Any ideas ?

Thx in advans,
Karthik Balaguru

On Mon, 4 May 2009 03:56:22 -0700 (PDT), karthikbalaguru
<(E-Mail Removed)> wrote:

> I find that the polynomial for CRC-8-ATM is 1 + x + x^2 + x^8
> and the corresponding representations as 0x07 or 0xE0
> in the below link :-
> http://en.wikipedia.org/wiki/Cyclic_redundancy_check
>
> But, What does that 0x07 or 0xE0 refer to ?
> Is there different algorithms for both 0x07 and 0xE0 ?

I think these refer to the Rocksoft method of modelling CRC's. The
paper about that is here:

<http://www.ross.net/crc/crcpaper.html>

IIRC 0xE0 would be the reflected version of 0x07. The paper discusses
how to get from one to the other.


--
-| Bob Hauck (Brother Nail Gun of The Short Path)
-| http://www.haucks.org/

On May 4, 4:54 pm, Bob Hauck <postmas...@avalanche.org> wrote:
> On Mon, 4 May 2009 03:56:22 -0700 (PDT), karthikbalaguru
>
> <karthikbalagur...@gmail.com> wrote:
> > I find that the polynomial for CRC-8-ATM is 1 + x + x^2 + x^8
> > and the corresponding representations as 0x07 or 0xE0
> > in the below link :-
> >http://en.wikipedia.org/wiki/Cyclic_redundancy_check
>
> > But, What does that 0x07 or 0xE0 refer to ?
> > Is there different algorithms for both 0x07 and 0xE0 ?
>
> I think these refer to the Rocksoft method of modelling CRC's. The
> paper about that is here:
>
> <http://www.ross.net/crc/crcpaper.html>
>
> IIRC 0xE0 would be the reflected version of 0x07. The paper discusses
> how to get from one to the other.
>

http://www.ross.net/crc/download/crc_v3.txt -> Very good document.
This info was very helpful.

Thx,
Karthik Balaguru