Hi Simon, Once the data is sent and the acknowledgement is received; I think, LWIP is supposed to increment the tcp_sndbuf( ) value so that the next set of data can be sent right ? Should I do something in the http_sent callback to make room for next set of data ?
Thanks Anand On Wed, Aug 31, 2016 at 6:42 PM, goldsimon <goldsi...@gmx.de> wrote: > Calling tcp_output() sends the data, but that doesn't mean the buffer is > free afterwards: it stays allocated until the remote host acknowledges it. > At this point, lwip calls your 'sent' callback. > > Simon > > Gesendet mit AquaMail für Android > http://www.aqua-mail.com > > Am 31. August 2016 12:22:08 nachm. schrieb anand arjunan < > anand.ar...@gmail.com>: > >> 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 >
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