static EVENT_HANDLER(transmit)
{
WLAN_FRAME frame;
int link = 1;
// POPULATE A NEW FRAME
do {
frame.header.dest = CNET_rand() % NNODES;
} while(frame.header.dest == nodeinfo.nodenumber);
frame.header.src = nodeinfo.nodenumber;
frame.header.prevpos = positions[nodeinfo.nodenumber]; // me!
sprintf(frame.payload, "hello from %d", nodeinfo.nodenumber);
frame.header.length = strlen(frame.payload) + 1; // send nul-byte too
// TRANSMIT THE FRAME
size_t len = sizeof(WLAN_HEADER) + frame.header.length;
CHECK(CNET_write_physical_reliable(link, &frame, &len));
++stats[0];
if(verbose) {
fprintf(stdout, "\n%s: transmitting '%s' to %d\n",
nodeinfo.nodename, frame.payload, frame.header.dest);
}
// SCHEDULE OUR NEXT TRANSMISSION
CNET_start_timer(EV_TIMER1, TX_NEXT, 0);
}
static void transmit_frame(MSG *msg, FRAMEKIND kind, size_t length, int seqno)
{
FRAME f;
int link = 1;
f.kind = kind;
f.seq = seqno;
f.checksum = 0;
f.len = length;
switch (kind) {
case ACK :
CHECK(CNET_set_wlancolour(link, "blue"));
break;
case DATA: {
CnetTime timeout;
CHECK(CNET_set_wlancolour(link, "red"));
memcpy(&f.msg, (char *)msg, length);
timeout = (FRAME_SIZE(f)*(CnetTime)8000000 / linkinfo[link].bandwidth +
linkinfo[link].propagationdelay);
timeout = 300000;
lasttimer = CNET_start_timer(EV_TIMER1, 3 * timeout, 0);
break;
}
}
length = FRAME_SIZE(f);
f.checksum = CNET_ccitt((unsigned char *)&f, length);
CHECK(CNET_write_physical_reliable(link, (char *)&f, &length));
}
static EVENT_HANDLER(talking)
{
if(am_walking() == false) {
size_t len = sizeof(int);
fprintf(stdout,"%d: transmitting\n", nodeinfo.nodenumber);
CHECK(
CNET_write_physical_reliable(1, (char *)&nodeinfo.nodenumber, &len));
}
CNET_start_timer(EV_TALKING, TALK_FREQUENCY, data);
}
/****************************************************************************
Write length bytes of the packet to the data link layer on a link.
****************************************************************************/
int down_to_datalink(int link, char *packet, int length)
{
if (!linkinfo[link].linkup) { return 0; }
#ifndef LOSSIE
CHECK(CNET_write_physical_reliable(link, (char *)packet, &length));
#else
CHECK(CNET_write_physical(link, (char *)packet, &length));
#endif
return(0);
}
/**
* @brief transmit a frame
*
* @param kind
* @param dst
* @param msg
* @param rxsignal
*/
void
transmit(KIND kind, int dst, char *msg, double rxsignal)
{
FRAME frame = initFrame(kind, dst, msg);
size_t length = sizeof(FRAME);
int link = 1;
frame.rxsignal = rxsignal;
CHECK(CNET_write_physical_reliable(link, (FRAME *)&frame, &length));
printf("transmitting a %s frame to ap %d\n", msg, dst);
}
static void send_reliable(CnetEvent ev, CnetTimer timer, CnetData data)
{
char frame[256];
int length;
sprintf(frame, "message %d is %s", ++count, fruit[random()%NFRUITS]);
length = strlen(frame) + 1;
printf("sending %d bytes, checksum=%6d\n\n",
length, checksum_internet((unsigned short *)frame,length));
CHECK(CNET_write_physical_reliable(1, frame, &length));
}
static EVENT_HANDLER(receive)
{
WLAN_FRAME frame;
size_t len;
int link;
// READ THE ARRIVING FRAME FROM OUR PHYSICAL LINK
len = sizeof(frame);
CHECK(CNET_read_physical(&link, &frame, &len));
if(verbose) {
double rx_signal;
CHECK(CNET_wlan_arrival(link, &rx_signal, NULL));
fprintf(stdout, "\t%5s: received '%s' @%.3fdBm\n",
nodeinfo.nodename, frame.payload, rx_signal);
}
// IS THIS FRAME FOR ME?
if(frame.header.dest == nodeinfo.nodenumber) {
++stats[1];
if(verbose)
fprintf(stdout, "\t\tfor me!\n");
}
// NO; RETRANSMIT FRAME IF WE'RE CLOSER TO THE DESTINATION THAN THE PREV NODE
else {
CnetPosition dest = positions[frame.header.dest];
double prev = distance(frame.header.prevpos, dest);
double now = distance(positions[nodeinfo.nodenumber],dest);
if(now < prev) { // closer?
frame.header.prevpos = positions[nodeinfo.nodenumber]; // me!
len = sizeof(WLAN_HEADER) + frame.header.length;
CHECK(CNET_write_physical_reliable(link, &frame, &len));
if(verbose)
fprintf(stdout, "\t\tretransmitting\n");
}
}
}
