RE: [lwip-users] Example port for a beginner

[Goldschmidt Simon]

> You are right ,i was talking about full api layer .

I'm sorry. Seems I did not understand what you were saying about your own api 
layer ;-)
You'd have to point out (I think it's clear for you, but maybe not for 
beginners), that
in this case, you mustn't use the files in the api directory!

> 
> ----- Original Message -----
> From: "Frédéric BERNON" <address@hidden>
> To: "Mailing list for lwIP users" <address@hidden>
> Sent: Wednesday, May 23, 2007 1:56 PM
> Subject: RE : [lwip-users] Example port for a beginner
> 
> 
> >That's not exactly true...
> I suppose that Mumtaz talk to a "full" api layer, even 
> without api_msg.c &
> tcpip.c, so, I think in this case, it''s right
> 
> >If you want to know more about timeouts:
> It's a good explain, I think it will be good to copy/paste it in
> sys_arch.txt and sys.c...
> 
> ====================================
> Frédéric BERNON
> HYMATOM SA
> Chef de projet informatique
> Microsoft Certified Professional
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> P Avant d'imprimer, penser à l'environnement
> 
> 
> 
> -----Message d'origine-----
> De : address@hidden
> [mailto:address@hidden
> rg] De la part
> de Goldschmidt Simon
> Envoyé : mercredi 23 mai 2007 10:47
> À : Mailing list for lwIP users
> Objet : RE: [lwip-users] Example port for a beginner
> 
> 
> > 4    Yes sys_timeouts  is pretty confusing but if you implement your
> own api layer then you can ignore it all together
> 
> That's not exactly true: if NO_SYS=0, you
> a) have to supply a function in sys_arch.c (if NO_SYS=0) that 
> returns a
> pointer to a list of timeouts that is unique for the current thread
> B) have to make sure the value returned by sys_arch_mbox_wait() (and
> sys_arch_sem_wait()) is correct (the number of miliseconds 
> waited for a
> message)!
> 
> If you want to know more about timeouts: it is a linked list including
> function pointers and values of miliseconds to wait before calling the
> function. When waiting for a message in an mbox, the time waited is
> substracted from the first timeout, and if that time is 0, the timeout
> function is called and the first item is popped off the list. 
> This mechanism
> only works if NO_SYS=0 since otherwise, you don't have 
> mboxes. But if you
> have mboxes, you kind of get the timeout functionality for free. The
> downside of this approach is that the timing is pretty 
> inaccurate. If you
> have many messages in the mbox and you will not have to wait 
> on any message,
> sys_arch_mbox_wait() will always return 0 since it didn't 
> have to wait for
> the message. That way timeouts will not be called. Another 
> bad example are
> some ports that always return 1 when waiting for a message and 0 if a
> message was available right away. That of course leads to 
> totally inaccurate
> timeouts.
> 
> 
> Simon
> 
> 
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