[lwip-users] Re: [lwip] Using lwIP with CS8900A on Atmel 89C51

[Adam Dunkels]

Hi Andrea!

On Sunday 03 February 2002 14:04, you wrote:
> Some month ago I tried with the 0.4.1 version of lwIP: using extensively
> XDATA optimization for Keil compiler, I reach about 30kB for the code
> (about 42kB without optimization). RAM usage obviously depends from
> lwipopts.h.
>
> Last month I ported 0.5.0, without any optimization for code size: 52kB,
> with a very simple web server.
> Monday I will tell more about TCP code size.

Ouch! 52kb is quite a lot too much in a 64kb address space. Would it be 
possible for you to post the code size of each module separately? That could 
give some insight into what modules that are the worst offenders. Usually, 
TCP is 50% of the code size.

I'm not familiar with the XDATA optimization, could you give a short 
description of that? If it is a keyword that is placed next to variable 
declarations, it is possible to include it in the lwIP source code and let 
the arch files for all other compilers just have a null #definition of XDATA.

> I guess lwIP is growing too much for 8051 architecture.
> Likely it is still usable (I mean it leaves more code space for the
> application) with other more recent and efficient 8 bit micros, as Atmel
> AVR.

I tested running a quick'n'dirty compilation with avr-gcc 3.0 and it compiled 
lwIP to around 28k (which still is quite a lot). lwIP wasn't really designed 
for 8 bitters. For instance, so there is a lot of 32-bit arithmetic that 
isn't suited well for 8-bit CPUs.

> To Adam: is it possible to promote an old release as 0.4.1 or 0.4.2
> (lighter that the latest) to a "stable" and "bug free" release, so we
> people of damned 8051 can port it and optimize to the max?
> The problem with Keil is that if you begin to optimize the code, you can't
> switch easely to the next release.

I guess that it is possible, but quite frankly I wouldn't really have the 
time and interest to do so. Anyone else might of course pick this up, though.

/adam
-- 
Adam Dunkels <address@hidden>
http://www.sics.se/~adam
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