RE: [lwip-users] LWIP Stack [using TCP] buffer limit

[Bill Auerbach]

> -----Original Message-----
> From: address@hidden
> [mailto:address@hidden On
> Behalf Of Jonathan Larmour
> Sent: Tuesday, August 26, 2008 11:36 AM
> To: Mailing list for lwIP users
> Subject: Re: [lwip-users] LWIP Stack [using TCP] buffer limit
> 
> Muhamed Fauzi Bin Abbas wrote:
> > Hello,
> >
> > I have managed to get LWIP working on an RTOS called T-Kernel. I have
> > also added a simple http server on it. However, I recently realised
> that
> > I can only access files that have a max file size of 63K. Anything
> > bigger then 63K would return only part of the file. So if I tried to
> > retrieve file ranging from 64K and above, I would only get about 30K
> of
> > data, but if I tried to retrieve a 63K or smaller file, I can get it
> > completely.
> >
> > I suspect I might be due to a buffer limit, but I do not know where
> to
> > look at. I have tried to read and re-read the lwip documents and past
> > mailing list, but can't pin-point where the limit might be set (too
> many
> > option which I do not understand). Can anyone please point me out to
> a
> > right direction so that I may be able to resolve this problem. Thank
> > you.
> 
> Which API are you using? And which version of lwIP? With the raw API,
> lwIP
> can only write up to 64k at a time. With other APIs it should work, but
> maybe hasn't been well tested.

With the raw API, you should use the tcp_sent callback and call tcp_write
from it - see the httpserver_raw demo. I have sent a 750k file with the
method shown in this example.

Bill