Re: [lwip-users] LwIP port on Blackfin, some questions and 1.3.0

[S. Ali Tokmen]

Hello, Stéphane

Analog Devices has normally been using lwIP 1.2.0 as of VisualDSP 5.0; I'm 
pretty sure about it since in our product we've been using some features 
that didn't exist in the old (0.6.something) release. If you think you're 
not linking with the correct lwIP version, please double check the .lib's 
name and the include paths of your VisualDSP project.

The major version change (VisualDSP 4.5 to VisualDSP 5.0) is actually not 
due to functional changes but to architectural ones: VisualDSP 5.0 has been 
rearchitectured and recompiled with Visual Studio 2005 SP1 (I guess 
VisualDSP 4.5 was with Visual Studio 6 SP6), but most functionalities stay 
the same and some major bugs (in their System Services API library for 
example) have disappeared. They've also upgraded to lwIP 1.2.0 and fixed 
bugs in their Ethernet driver.

To upgrade the lwIP library used by Analog Devices, you may try the 
following:

    1. Do a checkout of version 1.2.0
    2. Copy and paste on to that checkout the lwIP source code from 
VisualDSP 5's "src" folder.
    3. Your versionning tool (I use Tortoise in Windows) should then show 
you that there are some differences. Now do an "update" on your checkout.

As for your real-time audio project, how does it work? Are you using VDK or 
the lwIP core with your semaphore code? If you're having problems with 
dropped audio frames, are you sure you're using DMA the correct way? If 
you're having lags, are you sure you have the right buffer sizes?

If you're doing the whole job with VDK, you must know that the lwIP 
performance (mostly when opening connections) is extremely dependent on VDK 
settings. For better performance, you should also enable all optimizations, 
mostly "whole program optimization" (compiling then takes twice more time, 
but the result is 20-30% faster!).

I cannot give you details about what has been happening in AD's world for 
the past month since I've changed job, and now will be working on Enterprise 
Service Bus systems (which has nothing to do with embedded computing or 
lwIP). Perhaps there has been some important changes that I'm not aware of.

Cheers

S. Ali Tokmen
http://ali.tokmen.com

GSM (fr): +33 66 43 00 555 [Bouygues Telecom]
GSM (tr): +90 555 266 52 73 [Avea]

My AIM, ICQ, MSN Messenger, and Yahoo IM
contact details are on http://contact.ali.tokmen.com/


----- Original Message ----- 
From: "Stéphane Lesage" <address@hidden>
To: <address@hidden>
Sent: Saturday, November 24, 2007 5:24 PM
Subject: [lwip-users] LwIP port on Blackfin, some questions and 1.3.0



Hi,

I'm using LwIP on Blackfin for my VoIP project,
and I've been reading the mailing lists for a few months.

First of all, it's great to see this project is very active,
developers are reactive,
and new features I will need in the future have been added :-)

1. We can't say so about the Blackfin/VDK port from Analog Devices :-(
I've been very disapointed with the new release of Visual DSP 5.0.
S. Ali Tokmen said they ported 1.2.0, but a diff with VDSP 4.5 latest update
shows it's still the same old version...
Or am I wrong ?

Several months ago I tried to compile the CVS head,
but didn't go further, considering all the modifications the guys from A.D
made.
(alignment problems ?)

Did someone succeed to compile ?

2. I think I will investigate on the BF536/7 driver,
because we have problems with real-time audio interrupts,
and I'm not convinced by the performance of the implementation.
(double-layer for the sys_arch, ADI driver model)

Is there someone interested in the development of a new port ?
Maybe someone already did it ?

3. The old version I'm currently using is stable with the socket API.
But I needed of lot of basic features which were not implemented
(MSG_PEEK, receive time-out)
Unfortunately, the corresponding macros are defined,
letting the user think they are implemented !!!

Can you please be careful about that in the next release ?
-> comment the #define with something like // Currently not implemented

4. I have a big problem for handling TCP connection loss.
When I unplug my device, or shut-down the peer,
no error is reported and I can't know the connection is lost.

Is this bug corrected ?

(I currently must send data and time-out, and I feel like doing TCP's job !)

5. About 1.3.0 required features:
-> backlog for listening sockets.
I think this is a very basic feature,
and I actually accidentally learned it was not implemented in this list !

-> more documentation about lwip_select(), and implementation of exceptset
How is a TCP connection close reported ?
How is a TCP connection accept reported ?
Why is a new connection on a listening socket reported by readset ?
What will be signalled on exceptset ?

Best regards.

-- 
Stéphane Lesage
ATEIS International



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