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Re: Re: Bug in crc32 routine?
- From: Gary Thomas <gthomas at ecoscentric dot com>
- To: Andrew Lunn <andrew dot lunn at ascom dot ch>
- Cc: Roland Caßebohm <roland dot cassebohm at visionsystems dot de>,eCos Discussion <ecos-discuss at sources dot redhat dot com>
- Date: 10 Oct 2002 09:17:12 -0600
- Subject: Re: [ECOS] Re: Bug in crc32 routine?
- References: <200210101454.g9AEsTE32032@hhlx01.visionsystems.de> <20021010150650.GL13852@biferten.ma.tech.ascom.ch>
On Thu, 2002-10-10 at 09:06, Andrew Lunn wrote:
> Hi Roland
>
> The crc32 routine came originally from RedBoot. Gary will correct me
> if im wrong, but i don't think it was supposed to be compatible with
> anything in particular. Gary just wanted a CRC for the flash
> contents. Thats they only place its used. I thought the crc functions
> are useful all general, so made a package out of them.
>
> If you want a CRC function that is compatible to something, use
> cyg_posix_crc32(). I have tested that and proved (on little endian at
> least) that it produces the same result as what the posix standard
> says.
>
> Changing this function would not be nice. New Redboot would compile
> about false checksums, when strictly they are not.
>
There's really no need to worry about keeping this the way it was.
I have no problem with code reuse or even "breaking" an existing
installation - the CRC's used by FIS are advisory only. So, if we
can fix it and/or let RedBoot use a common routine, all the better.
> What we could do is add a new crc32, which is compatible to zlib's
> crc. This would be easy and not cause any backward compatibility
> problems. Does the zlib CRC function have an official name, or
> reference a standard? We can use that for a basis for the function
> name.
>
Maybe we can come up with a way to only have one (or at least fewer)
CRC routine which is can be compatible with all of the existing uses.
Note that this might not be 100% possible - I seem to recall that the
"crc" calculations used by X-modem are broken [for everyone in the
world], but we would need to preserve that for compatibility.
> Andrew
>
> On Thu, Oct 10, 2002 at 04:54:28PM +0200, Roland Ca?ebohm wrote:
> > I think in the crc23 routine in the crc package is a bug.
> > If I use under linux the crc32 routine of the zlib I get not the same result
> > as the one of eCos.
> > I have seen, that in the Samsung KS32C5000 ethernet driver is a crc32 routin
> > too and it differs from the one off the crc package. After changing this
> > routine like the one off the ethernet driver, I get the same result right.
> > As an attachment I send the patch.
> >
> > Best regards
> >
> > Roland Caßebohm
>
>
>
> --
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eCosCentric, Ltd. |
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