Re: Crc32

[Michael Zimmermann <sigmaepsilon92@gmail.com>]

well as u already said, the spec says it uses 'a standard  CCITT32 CRC
algorithm with a seed polynomial value of 0x04c11db7'

this is the implementation which confirms it:
https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/RuntimeDxe/Crc32.c

after testing it it indeed produces CCITT32 results like this online
generator:
http://g6auc.me.uk/CRC32/index.html

Thanks
Michael

On Tue, Aug 30, 2016 at 2:54 AM, valerij zaporogeci <vlrzprgts@gmail.com>
wrote:

> Hi, all.
> Yet another dumb question from me.
> UEFI specification has Crc32 calculation service and uses Crc32 in
> several places. but it only humbly mentions in the note somewhere in
> the description of System Table about what exact one it wants. Namely
> it states that the polynomial seed is 04c11db7. And that's all.
> My question is - does really the specification means the 33-bit polynomial
> 104c11db7? And is the algorithm just a plain remainder calculation
> without any additional pre/post processing of it? So that for example
> Crc32 of the 4-byte sequence b16b00b5 would be
> 8c1f0a7c?
> Thank you.
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