[En-Nut-Discussion] IP Checksum calculation broken. Reenabled old algorithm for the meantime.

Harald Kipp harald.kipp at egnite.de
Wed Jul 4 09:09:57 CEST 2012

Hi Ulrich,

Great to have you in this thread.

On 04.07.2012 01:10, Ulrich Prinz wrote:
> Cortex architecture is able to do unaligned addressing. I guess it is 
> not as fast as 16 bit but it doesn't crash too.

The initial problem was, that IP checksum calculation failed on CM3. Ole re-enabled the legacy checksum algorithm _and_ set NUTMEM_ALIGNMENT back to 4, reverting r3196 in sys/types.h. Now we have a second issue.

1) Advanced checksum calculation is still broken and needs to be fixed, because the legacy version is too slow on 32-bit targets.
2) A decision needs to be made, whether the right alignment for CM3 is 1 or 4. Or may be 2?

What's your experience, advice on issue #2?



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