Loopback test

Question

Hello, I was running through the loopback tcp example program with the W5500 evaluation board .And i got some doubts . Can anyone please explain whats happening on this particular portion, switch(getSn_SR(sn)) { case SOCK_ESTABLISHED : if(getSn_IR(sn) & Sn_IR_CON) { #ifdef LOOPBACK_DEBUG getSn_DIPR(sn, destip); destport = getSn_DPORT(sn); printf("%d:Connected - %d.%d.%d.%d : %d ",sn, destip[0], destip[1], destip[2], destip[3], destport); #endif setSn_IR(sn,Sn_IR_CON); } if((size = getSn_RX_RSR(sn)) > 0) { if(size > DATA_BUF_SIZE) size = DATA_BUF_SIZE; ret = recv(sn, buf, size); if(ret <= 0) return ret; sentsize = 0; while(size != sentsize) { ret = send(sn,buf+sentsize,size-sentsize); if(ret < 0) { close(sn); return ret; } sentsize += ret; // Don’t care SOCKERR_BUSY, because it is zero. } } break;

becky · Answer

soorajsuresh80: if(getSn_IR(sn) & Sn_IR_CON) { #ifdef LOOPBACK_DEBUG getSn_DIPR(sn, destip); destport = getSn_DPORT(sn); printf("%d:Connected - %d.%d.%d.%d : %d ",sn, destip[0], destip[1], destip[2], destip[3], destport); #endif setSn_IR(sn,Sn_IR_CON); } When a connect interrupt occurs (connect interrupt occurs immediately after tcp connection via handshaking), check the connected target. soorajsuresh80: if((size = getSn_RX_RSR(sn)) > 0) { if(size > DATA_BUF_SIZE) size = DATA_BUF_SIZE; ret = recv(sn, buf, size); if(ret <= 0) return ret; sentsize = 0; while(size != sentsize) { ret = send(sn,buf+sentsize,size-sentsize); if(ret < 0) { close(sn); return ret; } sentsize += ret; // Don’t care SOCKERR_BUSY, because it is zero. } } When data is received it is sent again.

becky · Answer

Check the size of received data through getSn_RX_RSR and receive the data through recv () function.

soorajsuresh80 · Answer

HELLO Becky! Thanks for the help. The loopback test is working fine for me now. I wonder if you could help me with something , I want to change the loopback data for some reason, basically to ensure control over the data transfer, If so where should i edit in the code?

becky · Answer

soorajsuresh80: ret = recv(sn, buf, size); soorajsuresh80: ret = send(sn,buf+sentsize,size-sentsize); The received data is stored to “buf” and send the data stored “buf”. So you can modify data via “buf”.