Re:[lwip-devel] State of the latest efforts to port lwIP to 16-bitDSPs...

[Chris Jones]

Jean-Pierre,

I have been working with lwip for 2 months now to port it to the TI C55 DSP
which is a 16 bit DSP. I am using the DSP/BIOS kernel.

I started with version 0.7.1. This version already had some features which
attempted to address the problems with lack of byte addressing in DSPs, but
they didn't solve the entire porting problem.

The biggest problem I ran into was the reliance on byte pointers to access
data in the pbuf records. Also, the memory management code all relied on
byte accesses to memory.

I started my development by using the Win32 port and enabling
multithreading.
After getting the stack to work well with a SLIP connection to another PC, I
redefined the u8_t typedef to be 16 bits and started fixing issues.

The task was much bigger than I had expected. I created a few macros used to
pack bytes received on the serial interface into words and also extract them
again. I had to rework the memory manager to word with word sized quantities
instead of bytes. (Note: this had the added benefit of being able to
eliminate
memory alignment macros).

The changes I have had to make have been extensive, but the core logic of
the
stack code has not been modified.

I now have a version of the stack running of the DSK5510 development board
with
a SLIP network interface.


At this moment I am racing to get ready for a demo in 2 weeks. However, when
I get time in a few weeks, I am going to post the revised code on our
website
along with a description of all of the modifications I had to make.

My hope is that most or all of the changes can be incorporated into lwip and
bemaintained and improved on by the community. Otherwise, I will maintain
our
modified source and pull in updates and bug fixes as they come.

I think the lwip stack would really benefit from being DSP compatible.


Chris Jones
Engenium Technologies
www.engeniumtech.com



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[lwip-devel] State of the latest efforts to port lwIP to 16-bitDSPs...

----------------------------------------------------------------------------
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From:  Jean-Pierre Poulin
Subject:  [lwip-devel] State of the latest efforts to port lwIP to
16-bitDSPs...
Date:  Thu, 4 Mar 2004 09:44:47 -0800 (PST)

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Hi, I'm new to the list.


Poring over every message that contain the word 'DSP' on this list, I have
noticed that several
developers have attempted / are attempting a port of lwIP to 16-bit DSPs.

I would like to contribute to those efforts as I sure could use this stack
for
my next DSP
project, but it is unclear (from reading all those messages) what the best
possible point of entry
is to put my shoulder to the wheel.  (I would hate to redo work that has
already been done by
someone else)

What is the state of the most advanced / most stable port of lwIP to 16-bit
DSPs (such as TI's
C55xx family)?

If important development efforts are individually being made, may I suggest
we
create a new
mailing list to better synchronize and debug the port?

Many thanks!

   Jean-Pierre