Starterware lwIP-Port: why is IP address byte order changed?

qxc

Hi,

the lwIP-port that comes with Starterware contains following statement in lwiplib.c / lwIPInit() - a piece of code TI is responsible for:

if(lwipIf->ipMode == IPADDR_USE_STATIC)
{
   ip_addr.addr = htonl(lwipIf->ipAddr);
   net_mask.addr = htonl(lwipIf->netMask);
   gw_addr.addr = htonl(lwipIf->gwAddr);
}

This leads to the strange situation that all IP's that are parsed with

ipaddr_aton(c, &myIP);

need an additional conversion with

myIP.addr=ntohl(myIP.addr)

This is done only to change back the byteorder later on initialisation.

So...what is the diea behind this? Why is it done this way?

over 9 years ago

0 qxc over 9 years ago

Genius 5820 points

So still no answer from TI? Since this strange code is part of TI's implementation I can't ask anybody from lwIP team for that - and TI should know why they have done it this way!?

0 Ramesh Dandamudi over 9 years ago in reply to qxc

TI__Intellectual 1480 points

The difference is the format in which the application provides and LwIP expects. This part of the implementation can be customised .

Regards,

Ramesh D

0 qxc over 9 years ago in reply to Ramesh Dandamudi

Genius 5820 points

This doesn't really explains why it has to be byte-swapped just to get swapped back:

ipaddr_aton(c, &myIP);

already returns a byteorder which is correct for lwIP. So why does lwiplib.c / lwIPInit() swap the byteorder? This makes it necessary for application the do a byteswap too - which in my opinion is not necessary because the byteorder was already correct!

0 qxc over 9 years ago in reply to qxc

Genius 5820 points

Any feedback from TI?

0 qxc over 9 years ago in reply to Ramesh Dandamudi

Genius 5820 points

Since this is still not answered anbd since only TI can answer it I'll push this thread once more...

0 Ramesh Dandamudi over 9 years ago in reply to qxc

TI__Intellectual 1480 points

Enduser has freedom to modify the implementation as per his requirement. There will not be any changes to the existing implementation in the release. It is recommended that correct format to be provided to LwIP.

Regards,

Ramesh D

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Starterware lwIP-Port: why is IP address byte order changed?