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Re: [lwip-users] Partial read on receive callback
From: |
Simon Goldschmidt |
Subject: |
Re: [lwip-users] Partial read on receive callback |
Date: |
Fri, 13 May 2011 11:54:28 +0200 |
Kieran Mansley <address@hidden> wrote:
> You don't need to copy it, as this is the
> point of tcp_recved() - it allows you to keep hold of the data until
> you've finished with them, even if that's not straight away during the
> callback. Once you've processed and finished with the data, call
> tcp_recved() and the stack will be allowed to reuse those buffers.
Actually, tcp_recved() only updates the TCP window, it does not free data: Once
a pbuf has been passed to a recv-callback, it is up to the application to free
it (unless returning != ERR_OK, but that's another issue).
So you are free to keep the pbufs pass to your callback on your own list (you
can even chain them, as long as tot_len fits into an u16_t), call tcp_recved()
for the window to be updated and return ERR_OK to tell the stack that you took
over the pbuf.
Delaying tcp_recved() might really not be the best idea, as it might prevent
the remote side from sending more data. However, that depends on your
application and the window size.
Then, it's up to you if you want to copy the data into a buffer or parse the
linked list of pbufs every time you received a new pbuf. This mainly depends on
RAM and speed: copying takes some time and RAM, but always scanning a linked
list of pbufs may be slow, too.
Simon
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- [lwip-users] Partial read on receive callback, Enrico Murador - Research & Development - CET, 2011/05/13
- Re: [lwip-users] Partial read on receive callback, Kieran Mansley, 2011/05/13
- Re: [lwip-users] Partial read on receive callback, Enrico Murador - Research & Development - CET, 2011/05/13
- Re: [lwip-users] Partial read on receive callback, Kieran Mansley, 2011/05/13
- Re: [lwip-users] Partial read on receive callback, Tomas Hruby, 2011/05/13
- Re: [lwip-users] Partial read on receive callback, Bill Auerbach, 2011/05/13
- Re: [lwip-users] Partial read on receive callback, Simon Goldschmidt, 2011/05/13
- Re: [lwip-users] Partial read on receive callback, Bill Auerbach, 2011/05/13
- Re: [lwip-users] Partial read on receive callback, Enrico Murador - Research & Development - CET, 2011/05/16
Re: [lwip-users] Partial read on receive callback,
Simon Goldschmidt <=