int llread(int fd,unsigned char* buffer) {
int num_chars_read = 0, aux_num_chars = 0;
int Type;
unsigned char aux[MAX_SIZE];
linkLayer.sequenceNumber = 0;
do {
Type= receiveframe(aux, &aux_num_chars);
if(Type == DATA_RECEIVED)
{
linkLayer.sequenceNumber = linkLayer.sequenceNumber ^ 1;
sendSupervisionFrame(linkLayer.fd, RR);
memcpy(buffer + num_chars_read, aux, aux_num_chars);
num_chars_read += aux_num_chars;
aux_num_chars = 0;
}
else if(Type == BAD_DATA_RECEIVED) {
rej_send_received++;
sendSupervisionFrame(linkLayer.fd, REJ);
}
else if(Type == DISC_RECEIVED) {
llclose(linkLayer.fd);
return num_chars_read;
}
} while(1);
return -1;
}
int llopen(int fd, int txrx) {
printf("[LLOPEN] START\n");
linkLayer.sequenceNumber = 0;
if(txrx == TRANSMITTER) {
int tmpvar;
(void) signal(SIGALRM, atende);
linkLayer.numTransmissions = 0;
linkLayer.timeout = MAXT;
printf("[llopen] Send SET\n");
sendSupervisionFrame(fd, SET);
alarm(linkLayer.timeout);
printf("[llopen] EXPETING UA\n");
tmpvar = receiveframe(NULL,NULL);
if( tmpvar != UA_RECEIVED ){
printf("[LLOPEN - TRANSMITTER] NOT UA\n");
return -1; //return error
}
else if(tmpvar == UA_RECEIVED) {
printf("[LLOPEN - TRANSMITTER] UA RECEIVED\n");
return fd; //retorn file ID
}
return -1;
}
else if (txrx == RECEIVER) {
printf("Waiting for SET\n");
if(receiveframe(NULL,NULL) == SET_RECEIVED) printf("SET_RECEIVED");
sendSupervisionFrame(fd,UA);
printf("UA sent\n");
return fd;
}
return 0;
}
int llopen(char* port, int txrx) {
int tmpvar;
linkLayer.fd = config(port);
linkLayer.State = txrx;
linkLayer.numTransmissions = 0;
linkLayer.timeout = MAXT;
linkLayer.frame = (unsigned char*) malloc((2*MAX_SIZE)+6);
linkLayer.alarm_char = SET;
linkLayer.alarm_inf = FALSE;
//printf("[RS-232] Port open - Starting");
if(txrx == TRANSMITTER) {
linkLayer.State = TRANSMITTER;
(void) signal(SIGALRM, Timeout);
sendSupervisionFrame(linkLayer.fd, SET);
alarm(linkLayer.timeout);
tmpvar = receiveframe(NULL,NULL);
if( tmpvar != UA_RECEIVED ) return -1; //return error
else if(tmpvar == UA_RECEIVED) {
(void) signal(SIGALRM, SIG_IGN);
return linkLayer.fd; //retorn file ID
}
return -1;
}
else if (txrx == RECEIVER) {
linkLayer.State = RECEIVER;
if(receiveframe(NULL,NULL) != SET_RECEIVED) {
return -1;
}
sendSupervisionFrame(linkLayer.fd,UA);
return linkLayer.fd;
}
return 1;
}
void atende() {
if(linkLayer.numTransmissions < MAXR){
printf("[DEBUG] Timeout %d waiting for UA, re-sending SET\n", linkLayer.numTransmissions);
sendSupervisionFrame(linkLayer.fd, SET);
alarm(linkLayer.timeout);
}else{
printf("[DEBUG] Receiver doesnt seem to like me, I give up :(\n");
//llclose();
}
linkLayer.numTransmissions++;
}
int llclose(int fd) {
int tmp;
(void) signal(SIGALRM, Timeout);
linkLayer.alarm_char = DISC;
if (linkLayer.State == TRANSMITTER) {
sendSupervisionFrame(fd, DISC);
alarm(linkLayer.timeout); //starting timout for DISC
tmp = receiveframe(NULL,NULL); //waiting for DISC
if (tmp == DISC_RECEIVED) {
(void) signal(SIGALRM, SIG_IGN); //closing Timeout if received
sendSupervisionFrame(fd, UA);
sleep(1);
close(fd);
return 1;
}
else{
return -1;
}
}
else if (linkLayer.State == RECEIVER) {
linkLayer.alarm_char = DISC;
sendSupervisionFrame(fd, DISC);
alarm(linkLayer.timeout); //starting timout for DISC
tmp = receiveframe(NULL,NULL);
if (tmp == UA_RECEIVED) {
(void) signal(SIGALRM, SIG_IGN); //closing Timeout if received
close(fd);
return 1;
}
else return -1;
}
else return -1;
}
void Timeout() {
if(linkLayer.numTransmissions < MAXR-1){
printf("[TIMEOUT] Timeout %d -> ", linkLayer.numTransmissions);
if(!linkLayer.alarm_inf){
printf("Sending Supervision Frame\n");
if(!sendSupervisionFrame(linkLayer.fd, linkLayer.alarm_char)) exit(-1);
}
else if(linkLayer.alarm_inf) {
printf("Sending Informacion Frame\n");
if(!sendInformationFrame(linkLayer.frame, linkLayer.frameLength)) exit(-1);
}
else exit(-1);
alarm(linkLayer.timeout);
}
else if (linkLayer.numTransmissions == MAXR-1) {
printf("[TIMEOUT] Port closing, didn't get any response\n");
close(linkLayer.fd);
exit(-1);
}
linkLayer.numTransmissions++;
timeout_time++; //for external variable
}
int receiveframe(unsigned char *data, int* length) {
int state = 0; //state machine state
int stop = FALSE; //control flag
int Rreturn; //for return
int Type; //type of frame received
int num_chars_read = 0; //number of chars read
unsigned char* charread = malloc(1); //char in serial port
unsigned char Aread, Cread; //adress and command
received++;
//State machine
while(stop == FALSE) {
Rreturn = read(linkLayer.fd, charread, 1); //keeps waiting for 1 char
if (Rreturn < 0) return -1; //nothing
switch(state) {
case 0:{ //State Start
if(*charread == FLAG) state = 1;
if(*charread == A) state =1;
break;
}
case 1:{ //Read Flag -> Expecting address
if(*charread == A) {
state = 2;
Aread = *charread;
} else if(*charread == FLAG) state = 1; //another flag
break;
}
case 2:{ //Read Address -> Expecting Command
Cread = *charread;
if(*charread == SET) {
Type = SET_RECEIVED;
state = 3;
}
else if(*charread == UA) {
Type = UA_RECEIVED;
state = 3;
}
else if(*charread == DISC) {
Type = DISC_RECEIVED;
state = 3;
}
else if(*charread == (RR | ((linkLayer.sequenceNumber) << 7))) {
Type = BAD_RR_RECEIVED;
state = 3;
}
else if(*charread == (RR | ((linkLayer.sequenceNumber^1) << 7))) { //BAD RR
Type = RR_RECEIVED;
state = 3;
}
else if(*charread == (REJ | (linkLayer.sequenceNumber << 7))) {
Type = BAD_REJ_RECEIVED;
state = 3;
}
else if(*charread == (REJ | ((linkLayer.sequenceNumber^1) << 7))) {
Type = REJ_RECEIVED;
state = 3;
}
//If I0 fails we must receive a REJ0 and send I0 again!
else if(*charread == ((linkLayer.sequenceNumber^1) << 6)) {
Type = BAD_DATA_RECEIVED;
state = 3;
}
else if(*charread == (linkLayer.sequenceNumber << 6)) {
Type = DATA_RECEIVED;
state = 3;
}
else if(*charread == FLAG) state = 1; //error
else state = 0; //error
break;
}
case 3:{ //Read Command -> Expecting BBC1
if(*charread == FLAG) state = 1;
else if(*charread != (Aread ^ Cread))
{
if(Type == DATA) {
sendSupervisionFrame(linkLayer.fd,REJ);
state = 2;
}
Type = BAD_BBC_RECEIVED;
}
else
{
if(Type == DATA_RECEIVED || Type == BAD_DATA_RECEIVED) state = 4;
else state = 6;
}
break;
}
case 4:{ //BCC1 correct -> Data expected
if (*charread == FLAG)
{
unsigned char BCC2exp = data[0];
int j;
for(j = 1;j < num_chars_read - 1; j++)
BCC2exp = (BCC2exp ^ data[j]);
if(data[num_chars_read -1] != BCC2exp) {
state = 1;
num_chars_read = 0;
Type = BAD_BBC_RECEIVED;
}
else //BCC2 Correct
{
*length = num_chars_read - 1;
free(charread);
return Type;
}
}
else if(*charread == ESC) state = 5; //deshuffel o proximo
else {
data[num_chars_read] = *charread;
num_chars_read++;
state = 4;
}
break;
}
case 5:{ //Destuffing
data[num_chars_read] = *charread ^ STFF;
num_chars_read++;
state = 4;
break;
}
case 6:{ //Flag
if(*charread == FLAG)
{ //flag
stop = TRUE;
state = 0;
}
else state = 0;
break;
}
}
}
free(charread);
return Type;
}
int receiveframe(char *data, int * length) {
printf("[receiveframe] START\n");
char* charread = malloc(1); //char in serial port
int state = 0; //state machine state
char Aread, Cread; //adress and command
int stop = FALSE; //control flag
int Rreturn; //for return
int Type; //type of frame received
int num_chars_read = 0; //number of chars read
//State machine
while(stop == FALSE) {
//printf("[receiveframe] State machine -> %d\n", state);
Rreturn = read(linkLayer.fd, charread, 1); //read 1 char
if (Rreturn == 1) printf("[Receiveframe] read -> %x (%d)\n", *charread, Rreturn);
if (Rreturn < 0) return -1; //nothing
switch(state) {
case 0:{ //State Start
printf("[receiveframe] START, char = %x\n", *charread);
if(*charread == FLAG) state = 1;
break;
}
case 1:{ //Flag -> expect address
if(*charread == A) {
printf("[receiveframe] ADRESS, char = %x\n", *charread);
state = 2;
Aread = *charread;
} else if(*charread == FLAG) state = 1; //another flag
break;
}
case 2:{ //Address -> Command (many commands possible)
printf("[receiveframe] COMMAND, char = %x ->", *charread);
Cread = *charread;
if(*charread == SET) {
printf("SET\n");
Type = SET_RECEIVED;
state = 3;
}
else if(*charread == UA) {
printf("UA\n");
Type = UA_RECEIVED;
state = 3;
}
else if(*charread == DISC) {
printf("DISC\n");
Type = DISC_RECEIVED;
state = 3;
}
else if(*charread == (RR | (linkLayer.sequenceNumber << 7))) {
printf("RR\n");
Type = RR_RECEIVED;
state = 3;
}
else if(*charread == (REJ | (linkLayer.sequenceNumber << 7))) {
printf("REJ\n");
Type = REJ_RECEIVED;
state = 3;
}
else if(*charread == (linkLayer.sequenceNumber << 6)) {
printf("DATA\n");
Type = DATA_RECEIVED;
state = 3;
}
else if(*charread == FLAG) state = 1;
else state = 0;
break;
}
case 3:{ //command -> BBC1
printf("[receiveframe] BCC, char = %x\n", *charread);
if(*charread == FLAG) state = 1;
else if(*charread != (Aread ^ Cread))
{
printf("[receiveframe] BCC INCORRECT\n");
state = 0; //bcc
}
else
{
printf("[receiveframe] BCC CORRECT\n");
if(Type == DATA_RECEIVED) state = 4;
else state = 6;
}
break;
}
case 4:{ //Data expected
printf("[receiveframe] DATA EXPECTED\n");
if (*charread == FLAG)
{
char BCC2exp = data[0];
int j;
for(j = 1;j < num_chars_read - 1; j++) BCC2exp = (BCC2exp ^ data[j]);
if(data[num_chars_read -1] != BCC2exp) {
sendSupervisionFrame(linkLayer.fd,REJ);
return -1;
}
else
{
*length = num_chars_read - 1;
sendSupervisionFrame(linkLayer.fd, RR);
linkLayer.sequenceNumber = linkLayer.sequenceNumber ^ 1;
}
stop = TRUE;
state = 0;
}
else if(*charread == ESC) state = 5; //deshuffel o proximo
else
{
data[num_chars_read] = *charread;
num_chars_read++;
state = 4;
}
break;
}
case 5:{ //Destuffing
data[num_chars_read] = *charread ^ STFF;
num_chars_read++;
state = 4;
break;
}
case 6:{ //Flag
if(*charread == FLAG)
{ //flag
stop = TRUE;
state = 0;
}
else state = 0;
break;
}
printf(",%d]", state);
}
}
printf("[receiveframe] STOP -> %d\n", Type);
free(charread);
return Type;
}
