RE : [lwip-users] Sending UDP

[Frédéric BERNON]

I suppose that udp_send call pbuf_header, this last call change newBuf->payload value, but don't restore it (I don't know if this is an expected behavior).

 

Check that by a display of newBuf->payload before and after udp_send. It should change by -(8(udp_hdr)+14(eth_hdr)).

 

 

====================================
Frédéric BERNON
HYMATOM SA
Chef de projet informatique
Microsoft Certified Professional
Tél. : +33 (0)4-67-87-61-10
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====================================

P Avant d'imprimer, penser à l'environnement

 

-----Message d'origine-----
De : address@hidden [mailto:address@hidden De la part de Julian Gardner [RSD]
Envoyé : mardi 11 septembre 2007 15:37
À : address@hidden
Objet : [lwip-users] Sending UDP

I am sending data via UDP, but for every block of data i send which is 1324 bytes i do the following

  while( bytesToSend)
  {
    newBuf = pbuf_alloc( PBUF_TRANSPORT, 1324, PBUF_RAM);
    memcpy( newBuf->payload, currentBufferPointer, 1324);
    udp_send( outUdp, newBuf);
    pbuf_free( newBuf);
    currentBufferPointer += 1324;
    bytesToSend -= 1324;
  }

if i do the allocate outside of the send loop and the delete after sending all , my code fails!

  newBuf = pbuf_alloc( PBUF_TRANSPORT, 1324, PBUF_RAM);
  while( bytesToSend)
  {
    memcpy( newBuf->payload, currentBufferPointer, 1324);
    udp_send( outUdp, newBuf);
    currentBufferPointer += 1324;
    bytesToSend -= 1324;
  }
  pbuf_free( newBuf);

Also i have to copy the data from its original place to the newBuf->payload every time

What is the best way, pbuf_chain to do the same but just point the newBuf->payload at the data without copying it!!

eg
  newBuf = pbuf_alloc( PBUF_TRANSPORT, 1324, PBUF_RAM);
  while( bytesToSend)
  {
    newBuf->payload = currentBufferPointer;
    udp_send( outUdp, newBuf);
    currentBufferPointer += 1324;
    bytesToSend -= 1324;
  }
  pbuf_free( newBuf);

joolz

Frédéric BERNON.vcf
Description: Frédéric BERNON.vcf