RE: [lwip-users] Question on structure packing

[Mountifield, Tony]

Hi John,

I am doing exactly the same exercise for the STi5516 evaluation system, and 
found exactly the same problem. I have it working now, although still some 
tidying to do, but had to rewrite the struture elements as arrays of bytes 
instead of u16 and u32, and use macros to access them.

Since you're at ST, you probably know more about the issues than I do. I found 
that if I did a longword access with a pointer that was not a multiple of four, 
it fetched an aligned longword anyway. e.g.: if the pointer value was NNN0, 
NNN1, NNN2 or NNN3, it would fetch the longword consisting of those bytes, 
NNN0/1/2/3. So you can't even play clever games with pointers, and have instead 
to fetch a byte at a time and stick them together.

Cheers,
Tony

> -----Original Message-----
> From: John BODDIE [mailto:address@hidden
> Sent: 20 April 2004 16:30
> To: address@hidden
> Subject: [lwip-users] Question on structure packing
> 
> 
> Hi,
> 
> I am currently porting lwIP 0.7.1 to run under OS20 on a 
> 32-bit STMicro ST20. Unfortunately the ST20 compiler does not 
> support structure packing leading to all sorts of data 
> corruption problems.
> 
> Does anyone know of anyway around the issue of structure packing?
> 
> Regards,
> 
> John
> 
> 
> 
> _______________________________________________
> lwip-users mailing list
> address@hidden
> http://mail.gnu.org/mailman/listinfo/lwip-users
> 


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