Re: [usb] crc algorithm

[Madhusudhan Rao <madhu_sudhana_rao@yahoo.com>]

HiTambunan,
   G(x) = x^16+x^15+x^2+1 for  1000000000000101B.
   G(x) = x^5+x^2+1 for  00101B.
X^5 in the above expression will give u information as
you are using 5 bit crc. otherwise we will not have
any idea that how much crc polynomial length.
I hope the above explanation is clear to u.
If u still not clear i will send u an example code for
crc aslo.

Best regards
Madhu

--- kebloo@mitra.net.id wrote:
> Hello,
> 
> Sorry for this beginner question, but I wish some
> one could
> answer my curiosity...
> 
> USB 1.1 specification defines generator polynomial
> of 5-bit crc 
> as G(x) = x^5+x^2+1 and binary pattern that
> represent it as
> 00101B and 16-bit crc as G(x) = x^16+x^15+x^2+1 and
> binary pattern that represent it as
> 1000000000000101B.
> My question is why the binary pattern stated like
> that and
> not 100101B for 5-bit crc and 11000000000000101B ?
> Thanks....
> 
> 
> 
> Best Regard,
> 
> 
> RE Tambunan
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=====
MadhusudhanaRao.M

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