Question
Working with pointers to send Lan Data
Posted on April 16, 2013 at 08:39
Hi Guys,
I'm a bit confused with pointers.. I have a global variable named uint8_t DATAS [130] and I have a function that sends data through lan (note: Iam using stm32f4Discovery and DISC-BB board) my first data send OK... but on suceeding data the data doesnot change.. details: my setup is using a peer to peer connection laptop -> unit using stm32f4Discovery using Disc-BB expansion board (LAN, SD, LCD, RS232) for example.. (expected data:1234567890ASDFGHJKL:) RECIEVED DATA: 1234567890ASDFGHJKL: (expected data:ZXCVBNM) RECIEVED DATA: 1234567890ASDFGHJKL: (expected data:ZXCVBNM) RECIEVED DATA: 1234567890ASDFGHJKL: (expected data:ZXCVBNM) RECIEVED DATA: 1234567890ASDFGHJKL:void udp_echoclient_connect(void)
{
// struct udp_pcb *upcb;
struct pbuf *p;
struct ip_addr DestIPaddr;
err_t err;
if (Flag == 0) {
Flag = 1;
/* Create a new UDP control block */
upcb = udp_new();
} else {
//char *data1= '''';
for (int ctr=0;ctr<130;ctr++)
{
dataS[ctr] =(char)0;
}
for (int ctr=0;ctr<130;ctr++)
{
dataS[ctr]=(char)DATAS[ctr];
}
strcpy((char*)data,dataS);
p = pbuf_alloc(PBUF_TRANSPORT,strlen((char*)data), PBUF_POOL);
if (p != NULL) {
/* copy data to pbuf */
pbuf_take(p, (char*)data, strlen((char*)data));
/* send udp data */
udp_send(upcb, p);
/* free pbuf */
pbuf_free(p);
}
return ;
}
if (upcb!=NULL) {
/*assign destination IP address */
IP4_ADDR( &DestIPaddr, DEST_IP_ADDR0, DEST_IP_ADDR1, DEST_IP_ADDR2, DEST_IP_ADDR3 );
/* configure destination IP address and port */
err= udp_connect(upcb, &DestIPaddr, UDP_SERVER_PORT);
if (err == ERR_OK) {
/* Set a receive callback for the upcb */
udp_recv(upcb, udp_receive_callback, NULL);
//sprintf((char*)data, ''sending udp client message %d'', (int*)message_count);
//sprintf((char*)data, ''%d'', (int*)DATAS);
//strcpy(data,(char*)DATAS);
for (int ctr=0;ctr<130;ctr++)
{
dataS[ctr] =(char)0;
}
for (int ctr=0;ctr<130;ctr++)
{
dataS[ctr]=DATAS[ctr];
}
/* allocate pbuf from pool*/
strcpy((char*)data,dataS);
p = pbuf_alloc(PBUF_TRANSPORT,strlen((char*)data), PBUF_POOL);
strlen((char*)data);
if (p != NULL) {
/* copy data to pbuf */
pbuf_take(p, (char*)data, strlen((char*)data));
/* send udp data */
udp_send(upcb, p);
/* free pbuf */
pbuf_free(p);
} else {
#ifdef SERIAL_DEBUG
printf(''\n\r can not allocate pbuf '');
#endif
}
} else {
#ifdef SERIAL_DEBUG
printf(''\n\r can not connect udp pcb'');
#endif
}
} else {
#ifdef SERIAL_DEBUG
printf(''\n\r can not create udp pcb'');
#endif
}
}
err_t
pbuf_take(struct pbuf *buf, const void *dataptr, u16_t len)
{
struct pbuf *p;
u16_t buf_copy_len;
u16_t total_copy_len = len;
u16_t copied_total = 0;
LWIP_ERROR(''pbuf_take: invalid buf'', (buf != NULL), return 0;);
LWIP_ERROR(''pbuf_take: invalid dataptr'', (dataptr != NULL), return 0;);
if ((buf == NULL) || (dataptr == NULL) || (buf->tot_len <
len
)) {
return ERR_ARG;
}
/* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
for(
p
=
buf
; total_copy_len != 0;
p
= p->next) {
LWIP_ASSERT(''pbuf_take: invalid pbuf'', p != NULL);
buf_copy_len = total_copy_len;
if (buf_copy_len > p->len) {
/* this pbuf cannot hold all remaining data */
buf_copy_len = p->len;
}
/* copy the necessary parts of the buffer */
MEMCPY(p->payload, &((char*)dataptr)[copied_total], buf_copy_len);
total_copy_len -= buf_copy_len;
copied_total += buf_copy_len;
}
LWIP_ASSERT(''did not copy all data'', total_copy_len == 0 && copied_total == len);
return ERR_OK;
}