int llwrite(int control, char * buf, int seqNum) {
switch(control) {
case 0:
return send_rr(control,buf);
break;
case 1:
return send_rr(control,buf);
break;
case 2:
return prepare_inf(buf, seqNum);
break;
}
return -1;
}
int rec_data(int fd, unsigned char * buffer) {
unsigned char addr = 0;
unsigned char ctrl = 0;
unsigned int dataCount = 0;
unsigned char stuffed_buffer[MAX_SIZE];
int i = START_FLAG;
STOP = FALSE;
while (STOP == FALSE) {
unsigned char c = 0;
//printf("start while \n");
if (read(fd, &c, 1)) {
//printf("received a: %x\n",c);
switch (i) {
case START_FLAG:
//printf("start\n");
if (c == FLAG)
i = ADDR;
break;
case ADDR:
//printf("adr\n");
if (c == ADDR_TRANS) {
addr = c;
i = CTRL;
} else if (c != FLAG) {
i = START_FLAG;
}
break;
case CTRL:
//printf("ctrl\n");
if (c == NEXT_CTRL_INDEX(linklayer.sequenceNumber) || c == CTRL_DISC) {
ctrl = c;
i = BCC1;
} else if (c == FLAG) {
i = ADDR;
} else {
i = FLAG;
}
break;
case BCC1:
//printf("bcc1\n");
;
int headerErrorProb = rand() % 100;
if (headerErrorProb < linklayer.her) {
i = START_FLAG;
} else {
if (c == (addr ^ ctrl)) {
i = DATA;
} else if (c == FLAG) {
i = ADDR;
} else {
i = START_FLAG;
}
}
break;
case DATA:
//printf("data\n");
if (c != FLAG) {
stuffed_buffer[dataCount] = c;
//printf("stuffed: %x\n",stuffed_buffer[dataCount]);
dataCount++;
} else {
//printf("else\n");
if (ctrl == CTRL_DISC) {
printf("send disc\n");
if (send_disc(fd, RECEIVER))
return -1;
printf("rec ua\n");
if (rec_ua(fd, RECEIVER))
return -1;
linklayer.openLink = 0;
return DISCONECTED;
} else {
//printf("else data lenght\n");
unsigned int dataLength = 0;
//printf("data count: %d",dataCount);
if ((dataLength = byteDestuffing(stuffed_buffer, dataCount, buffer)) == -1)
return -1;
unsigned char bcc2_received = buffer[dataLength - 1];
//printf("bcc2 received: %x\n", bcc2_received);
unsigned char bcc2 = 0;
//printf("bcc2\n");
generate_bcc2(buffer, dataLength - 1, &bcc2);
//printf("bcc generated: %x\n",bcc2);
int frameErrorProb = rand() % 100;
if (frameErrorProb < linklayer.fer) {
printf("send rej\n");
send_rej(fd);
i = START_FLAG;
dataCount = 0;
} else {
//printf("else bcc2\n");
if (bcc2 == bcc2_received) {
printf("same bcc2\n");
if (ctrl != NEXT_CTRL_INDEX(linklayer.sequenceNumber)) {
printf("send rr1\n");
send_rr(fd);
i = START_FLAG;
dataCount = 0;
} else {
printf("send rr 2\n");
linklayer.sequenceNumber = NEXT_INDEX(linklayer.sequenceNumber);
send_rr(fd);
return (dataLength - 1);
}
} else {
printf("not the same bcc2\n");
if (ctrl != NEXT_CTRL_INDEX(linklayer.sequenceNumber))
send_rr(fd);
else
send_rej(fd);
i = START_FLAG;
dataCount = 0;
}
}
}
}
break;
}
}
}
printf("return\n");
return 0;
}
