[lwip-users] Re: [lwip] lwIP in a non-OS environment

[Adam Dunkels]

Hi Alex!

On Wednesday 13 February 2002 10.05, you wrote:
> Also it seems very complicated to write an appropriate sys_arch-adaption to
> a non-OS environment. Is it possible to share some information about the
> architecture layer for C16x w/ Keil?

A sys_arch for an OS-less environment is really simple - just look at the 
sys_arch in src/arch/6502/sys_arch.c. That is actually a full sys_arch 
implementation for an OS-less environment.

> I talked to somebody who works with lwIP. They use lwIP with an OS because
> for them it seemed lwIP without OS would be "nothing more than a crutch". I
> don't know if that's true. Is it working good for you?

The main problem with running lwIP without a multithreaded OS is that the 
application programs will have to use the raw API, which might be slightly 
akward for some applications. (It might also be good in some circumstances 
since it provides multi-connection support for free.)

> | > - How can I give lwIP CPU cycles that it can process enqueued packets?
> |
> | Basically, each time a packet is received by the network interface, you
> | call a lwIP function that processes the packet (or, this is done using
> | the network interface vector routine, if you use that). It will then
> | callback to your application so that it can process the packet.
>
> And how about sending packets? Do I need to deal with packet retransmissons
> and lost ACKs for instance? Thats very important to me, because I already
> coded with another stack that supports some kind of "non-blocking"-ness
> too, but there you have to handle _everything_ covering a correct TCP
> transmission (e.g. retransmisson).

That is all taken care of by the TCP functions that are called periodically 
(tcp_slow_tmr() and tcp_fast_tmr()). The application does not have to deal 
with TCP-stuff - that is all done by lwIP.

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