Check out tcp_sent() callback, it is called after data was successfully sent to remote station.
http://www.nongnu.org/lwip/2_0_0/group__tcp__raw.html# ga1596332b93bb6249179f3b89f24bd808 Ciao Dirk -- Dirk Ziegelmeier * d...@ziegelmeier.net * http://www.ziegelmeier.net On Wed, Aug 31, 2016 at 11:17 AM, anand arjunan <anand.ar...@gmail.com> wrote: > Hi, > > I am using LWIP (Raw TCP mode) (in FreeRTOS) for handling http page > requests, construct the web page and send the page to the client. I have > set the TCP_SND_BUF as 8*TCP_MSS where TCP_MSS is 1460. There will be only > one client / browser connecting to the system at a time. > > In the receive call back function, I constructed the entire web page and > used the tcp_write () (with TCP_WRITE_FLAG_COPY ) to send the data to LWIP > buffer. Due to memory limitations, I have to reuse a buffer size of 2.5 K > to construct the page before writing it to LWIP using tcp_write () as the > actual page size to be sent to client is more than 14 K. I was thinking > that as and when I call tcp_output () the data would be > sent instantaneously to the client. But, I got to know that tcp_Output() > does not work in the callback function and LWIP will start sending the > packets automatically once the control is out of the callback function. > > Due to this limitation I slightly modified the design. I have made the > actual LWIP receive callback to just set another (second) callback function > so that the actual LWIP callback would return immediately (so that > tcp_output( ) can work). The second callback would actually construct the > page and would be invoked by http_poll function or some other timer. > > Even this does not work. It still accumulates the data worth of of 8*1460 > bytes fully and sends only that much to the client. Once the buffer is > full, tcp_sndbuf(pcb) returns zero and I cannot write anymore to it. I > thought this would return non zero value as I am calling tcp_output ( ) > outside the LWIP calling function using a timer function. > > I tried disabling the nagle's algorithm using tcp_nagle_disbale( ) before > transmitting the packets. That did not help either. > > I want the data to be sent to the client (without accumulating) as and > when I call tcp_output( ) because of the limitation that I can construct > only 2.5 K bytes of page at a time and reuse it to construct the next > section of the page. > > Please help. Any help / pointers would be appreciated. > > Thanks > LWIP_Starter > > _______________________________________________ > lwip-users mailing list > lwip-users@nongnu.org > https://lists.nongnu.org/mailman/listinfo/lwip-users >
_______________________________________________ lwip-users mailing list lwip-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/lwip-users
