void main1(int argc, char** argv) {
srand(time(0));
//init
protocol_init(argc, argv);
//arguments
windowSize = 22;
retimer = 3300;//retransmit timer
acktimer = 600;
bufferSize = windowSize / 2;//buffer size
//init datalink layer
senderLeft = 0;//left edge of sender
senderRight = 0;//right edge of sender, which has data unfilled
receiverLeft = 0;//left edge of receiver
//receiverRight = bufferSize - 1;//right edge of receiver
isPhysicalLayerReady = -1;
lastAck = windowSize - 1;
//init buffer
sender = (buffer*)malloc(sizeof(buffer)* bufferSize);
receiver = (buffer*)malloc(sizeof(buffer)* bufferSize);
for (int i = 0; i < bufferSize; i++) {
sender[i].frameArrived = false;
receiver[i].frameArrived = false;
sender[i].hasSent = false;
receiver[i].hasSent = false;
}
//init interfcace
enable_network_layer();
bool isNetworkEnabled = true;
//init event args
int eventArgs = -1;
int eventKind = -1;
//allocate temp space
unsigned char temp[MAX_PACKET_SIZE + 11];
//main loop
while (true) {
static int frameLength;
eventKind = wait_for_event(&eventArgs);//get event
switch (eventKind) {
case PHYSICAL_LAYER_READY:
isPhysicalLayerReady = 1;
break;
case NETWORK_LAYER_READY:
//if buffer nearly full
if (((senderRight > senderLeft) && (senderRight - senderLeft == bufferSize - 1)) || (senderRight < senderLeft) && (windowSize - senderLeft + senderRight == bufferSize - 1)) {
disable_network_layer();
isNetworkEnabled = false;
}
//store frame in buffer
sender[senderRight % bufferSize].length = get_packet(sender[senderRight % bufferSize].data);
//slide window
senderRight = (senderRight + 1) % windowSize;
break;
case FRAME_RECEIVED:
//init temperory variables
frameLength = recv_frame(temp, MAX_PACKET_SIZE + 7);
if (frameLength > MAX_PACKET_SIZE + 7)
;//frame is too large, discard it
else {
//check crc
if (crc32(temp, frameLength) != 0) {//crc faild
if (isInBuffer(senderLeft, senderRight, temp[0] == FRAME_DATA ? temp[2] : temp[1], false)) {
//send nak
temp[0] = FRAME_NAK;//if the 2nd byte is error, it may sends false nak, but it doesn't matter
mySendFrame(temp, 2);
}
}
else {
if (temp[0] == FRAME_ACK) {//if it's an ack frame
if (isInBuffer(senderLeft, senderRight, temp[1], false)) {
if (isInBuffer(lastAck, senderRight, temp[1], false))
lastAck = temp[1];
//else do noting
break;
}
}
else if (temp[0] == FRAME_NAK) {//if it's a nak frame
if (isInBuffer(senderLeft, senderRight, temp[1], false)) {
//retranmit
temp[0] = 1;
memcpy(temp + 3, sender[temp[1] % bufferSize].data, sender[temp[1] % bufferSize].length * sizeof(unsigned char));
mySendFrame(temp, sender[temp[1] % bufferSize].length + 3);
break;
}
}
else if (temp[0] == FRAME_DATA) {//if it's a data frame
if (isInBuffer(lastAck, senderRight, temp[2], false))
lastAck = temp[2];
if (isInBuffer(receiverLeft, (receiverLeft + bufferSize) % windowSize, temp[1], true)){
if (!receiver[temp[1] % bufferSize].frameArrived) {
receiver[temp[1] % bufferSize].frameArrived = true;
receiver[temp[1] % bufferSize].length = frameLength - 7;
for (int i = 0; i < frameLength - 7; i++) {
receiver[temp[1] % bufferSize].data[i] = temp[3 + i];
}
}
}
}
}
}
break;
case DATA_TIMEOUT:
//just retransmit the frame
if (isInBuffer(lastAck, senderRight, eventArgs, false) && isInBuffer(senderLeft, senderRight, eventArgs, false)) {
if (sender[eventArgs % bufferSize].hasSent) {//if it has been sent
if (eventArgs == senderLeft || rand() % 10 > 10) {
//build the frame
temp[0] = FRAME_DATA;
temp[1] = eventArgs;
memcpy((void*)(temp + 3), sender[eventArgs % bufferSize].data, sender[eventArgs % bufferSize].length * sizeof(unsigned char));
//transmit
mySendFrame(temp, sender[eventArgs % bufferSize].length + 3);
}
else
start_timer(eventArgs, retimer * (rand() % 10 / 10.0 + 1));
}
}
break;
case ACK_TIMEOUT:
//just send an ack
temp[0] = FRAME_ACK;
mySendFrame(temp, 2);
break;
}
//sliding the sender window
//send
{
int i = senderLeft;
while (isInBuffer(senderLeft, senderRight, i, false)) {
if (sender[i % bufferSize].hasSent == false){
if (isPhysicalLayerReady == 1 || isPhysicalLayerReady == -1 || phl_sq_len() < 1000) {
//build the frame
temp[0] = FRAME_DATA;
temp[1] = i % windowSize;
memcpy((void*)(temp + 3), sender[i % bufferSize].data, sender[i % bufferSize].length * sizeof(unsigned char));
//transmit
mySendFrame(temp, sender[i % bufferSize].length + 3);
sender[i % bufferSize].hasSent = true;
isPhysicalLayerReady = 0;
}
break;
}
i = (i + 1) % windowSize;
}
}
//slide
while (isInBuffer(senderLeft, senderRight, lastAck, false)) {//·â×°º¯Êý
sender[senderLeft % bufferSize].hasSent = false;
stop_timer(senderLeft);
senderLeft = (senderLeft + 1) % windowSize;
}
//enable network layer
if (!(((senderRight > senderLeft) && (senderRight - senderLeft == bufferSize)) || (senderRight < senderLeft) && (windowSize - senderLeft + senderRight == bufferSize)) && !isNetworkEnabled) {
enable_network_layer();
isNetworkEnabled = true;
}
//sliding the receiver window
{
int i = 0;
for (i = 0; i < bufferSize; i++) {
if (receiver[(receiverLeft + i) % bufferSize].frameArrived) {
put_packet(receiver[(receiverLeft + i) % bufferSize].data, receiver[(receiverLeft + i) % bufferSize].length);
receiver[(receiverLeft + i) % bufferSize].frameArrived = false;
}
else break;
}
receiverLeft = (receiverLeft + i) % windowSize;
}
}
}
void protocol6(void)
{
seq_nr ack_expected; /* lower edge of sender's window */
seq_nr next_frame_to_send; /* upper edge of sender's window + 1 */
seq_nr frame_expected; /* lower edge of receiver's window */
seq_nr too_far; /* upper edge of receiver's window + 1 */
int i; /* index into buffer pool */
frame r; /* scratch variable */
packet out_buf[NR_BUFS]; /* buffers for the outbound stream */
packet in_buf[NR_BUFS]; /* buffers for the inbound stream */
boolean arrived[NR_BUFS]; /* inbound bit map */
seq_nr nbuffered; /* how many output buffers currently used */
event_type event;
enable_network_layer(); /* initialize */
ack_expected = 0; /* next ack expected on the inbound stream */
next_frame_to_send = 0; /* number of next outgoing frame */
frame_expected = 0; /* frame number expected */
too_far = NR_BUFS; /* receiver's upper window + 1 */
nbuffered = 0; /* initially no packets are buffered */
for (i = 0; i < NR_BUFS; i++) arrived[i] = false;
while (true) {
wait_for_event(&event); /* five possibilities: see event_type above */
switch(event) {
case network_layer_ready: /* accept, save, and transmit a new frame */
nbuffered = nbuffered + 1; /* expand the window */
from_network_layer(&out_buf[next_frame_to_send % NR_BUFS]); /* fetch new packet */
send_frame(data, next_frame_to_send, frame_expected, out_buf); /* transmit the frame */
inc(next_frame_to_send); /* advance upper window edge */
break;
case frame_arrival: /* a data or control frame has arrived */
from_physical_layer(&r); /* fetch incoming frame from physical layer */
if (r.kind == data) {
/* An undamaged frame has arrived. */
if ((r.seq != frame_expected) && no_nak)
send_frame(nak, 0, frame_expected, out_buf); else start_ack_timer();
if (between(frame_expected, r.seq, too_far) && (arrived[r.seq%NR_BUFS] == false)) {
/* Frames may be accepted in any order. */
arrived[r.seq % NR_BUFS] = true; /* mark buffer as full */
in_buf[r.seq % NR_BUFS] = r.info; /* insert data into buffer */
while (arrived[frame_expected % NR_BUFS]) {
/* Pass frames and advance window. */
to_network_layer(&in_buf[frame_expected % NR_BUFS]);
no_nak = true;
arrived[frame_expected % NR_BUFS] = false;
inc(frame_expected); /* advance lower edge of receiver's window */
inc(too_far); /* advance upper edge of receiver's window */
start_ack_timer(); /* to see if (a separate ack is needed */
}
}
}
if((r.kind==nak) && between(ack_expected,(r.ack+1)%(MAX_SEQ+1),next_frame_to_send))
send_frame(data, (r.ack+1) % (MAX_SEQ + 1), frame_expected, out_buf);
while (between(ack_expected, r.ack, next_frame_to_send)) {
nbuffered = nbuffered - 1; /* handle piggybacked ack */
stop_timer(ack_expected % NR_BUFS); /* frame arrived intact */
inc(ack_expected); /* advance lower edge of sender's window */
}
break;
case cksum_err: if (no_nak) send_frame(nak, 0, frame_expected, out_buf); break; /* damaged frame */
case timeout: send_frame(data, get_timedout_seqnr(), frame_expected, out_buf); break; /* we timed out */
case ack_timeout: send_frame(ack,0,frame_expected, out_buf); /* ack timer expired; send ack */
}
if (nbuffered < NR_BUFS) enable_network_layer(); else disable_network_layer();
}
}
int main(int argc, char ** argv)
{
int event, arg;
struct FRAME r;
int len = 0;
int i;
protocol_init(argc, argv);
lprintf("Designed by JackalDire\n");
disable_network_layer();
for (;;) {
event = wait_for_event(&arg);
switch (event) {
case NETWORK_LAYER_READY:
get_packet(buffer[next_frame_to_send]); // fetch new packet from physical layer
nbuffered++;
send_data_frame();
inc(&next_frame_to_send);
break;
case PHYSICAL_LAYER_READY:
phl_ready = 1;
break;
case FRAME_RECEIVED:
len = recv_frame((unsigned char *)&r, sizeof r);
if (len < 5 || crc32((unsigned char *)&r, len) != 0) {
/* discard the error packet with wrong crc checksum */
/* TODO : add NAK to accelerate resending */
dbg_event("**** receiver error, bad CRC checksum, packet discarded.\n");
break;
}
if (r.kind == FRAME_DATA) {
dbg_frame("Recv DATA %d %d, ID %d\n", r.seq, r.ack, *(short *)r.data);
if (r.seq == frame_expected) {
/* transmit the receive packet to network layer */
put_packet(r.data, PKT_LEN); // 7 = 3B other fields + 4B crc code
inc(&frame_expected);
start_ack_timer(ACK_TIMER);
}
}
/* ACK n means packets earlier than n were received correctly,
* so make packet ack_expeced ~ r.ack acknowledged */
while (between(ack_expected, r.ack, next_frame_to_send)) {
--nbuffered;
stop_timer(ack_expected);
inc(&ack_expected);
}
break;
case DATA_TIMEOUT:
dbg_event("---- DATA %d timeout\n", arg);
next_frame_to_send = ack_expected;
/* retransmit all packets in the buffer when timeout */
for (i = 1; i <= nbuffered; ++i) {
send_data_frame();
inc(&next_frame_to_send);
}
break;
case ACK_TIMEOUT:
/* send a separate ACK frame if there is no outstream for a specific time */
dbg_event("---- ACK %d timeout\n", arg);
send_ack_frame();
}
/* disable networklayer when outstrem buffer if full */
if (nbuffered < MAX_SEQ && phl_ready)
enable_network_layer();
else
disable_network_layer();
}
}
