RE: Checksum problem with lwip_chksum()

>Has anybody else seen this problem? 
Yes. I also had to modify lwip_chksum() to be byte oriented.

>Is it a particular problem of the H8
It's not H8 specific.  It is problem with all processors that require
16bit words to be aligned on an even boundary.   However, as you
mentioned the problem only show ups when a pbuf is referencing
"externally managed packet contents" AND that content is not aligned -
as your literal string example.

<sidebar>The H8 is particular annoying in that it does *not* throw a
hardware exception when attempting to read words from odd addresses.
You just get garbage for the odd byte and the CPU goes on its merry way.
Makes debugging alignment issues a joy .</sidebar>

-----Original Message-----
From:
lwip-users-bounces+jtaylor=shift-right.com@...
[mailto:lwip-users-bounces+jtaylor=shift-right.com@...]
On Behalf
Of Chris WIlliams
Sent: Thursday, September 02, 2004 6:33 AM
To: lwip-users@...
Subject: [lwip-users] Checksum problem with lwip_chksum()

I have had problems with checksums, and traced a problem in
lwip_chksum().

The problem is to do with alignment: