[lwip-users] RAW Api to receive large image data

[nkumar]

Hello,

I am newbie to lwip stack. After looking at a typical echo server example, I
am trying to implement a raw-api based server on arm-based board. I expect
to receive large (~4Mb) image data to server. I notice it works fine with
smaller data (~4k) however, it gets stuck on large data. While receiving I
keep track of data-received-so-far and keep appending the new data using
memcpy on pbuf->payload with pbuf->len size. I have been experimenting with
memory settings in lwipopts.h but no luck. My data is in format: 
+--------------------------+------------------+
| img size (4-byte field) |   image data ... |    <--- (image data = ~ 4Mb)
+--------------------------+------------------+

Here's my code:
const int MAX_BUFF_SIZE = 4096000;
typedef struct _data_info {
   u8_t   datat[MAX_BUFF_SIZE];
   u32_t expectedBytes;
   u32_t bytesRxd;
   bool   readyRead;
} DataInfo;

err_t rxd_callback(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t
err)
{
   DataInfo *info = (DataInfo *)arg; 
   if (!p) {
          tcp_close(tpcb);
          tcp_recv(tpcb, NULL);
         return ERR_OK;
  }

 /* Begin of data */
 if ( (info->expectedBytes == 0) && (p->len > 0))
 {
      info->bytesRxd = 0;
      info->readyRead = false;
      info->expectedBytes = *((u32_t*)p->payload) + 4;  //reading img size    
 }
 
  if (info->expectedBytes > 0)
 {
     memcpy(&info->data[info->bytesRxd], p->payload, p->len);  
    info->bytesRxd += p->len;
    info->expectedBytes -= p->len;

    if (info->expectedBytes == 0)
   {
       info->readyRead = true; // Ready to process data.    
   }
 
 }
   tcp_recved(tpcp, p->len);
   pbuf_free(p);
   
   return ERR_OK;
 }

My PBUF_POOL_BUFSIZE to 1700 & PBUF_POOL_SIZE is 516 in lwipopts.h. My
hardware has 1G of RAM available. This client - server completely
synchronous, i.e. client will not send any data until server is done
processing current data.
 
Please help.

nkumar



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