int sendInformationFrame(unsigned char * data, int length) {
//verificacions
if(data == NULL &&length <= 0)
return -1;
int C = (linkLayer.sequenceNumber << 6); //Comand is only sequence number on the 6 bit
int BCC1 = (A ^ C); //BCC1 xor adress and Command
int BCC2 = data[0]; //BCC2 xor data values
unsigned int lengthAfterStuffing;
int i;
unsigned char* frame = malloc(length*2+6);
unsigned char stuffed_data[(MAX_SIZE*2)];
unsigned char* tmpbuffer = malloc(length +1);
if(tmpbuffer == NULL || frame == NULL)
return ENOMEM; //memory error;
for(i = 1; i < length; i++) BCC2 = ((BCC2 ^ data[i]) ^ errorchar());
memcpy(tmpbuffer, data, length);
tmpbuffer[length] = BCC2;
lengthAfterStuffing = byte_stuffing(tmpbuffer, stuffed_data, length+1);
if(lengthAfterStuffing < length)
return -1; //error in stuffing
//Making Frame
frame[0] = FLAG ^errorchar();
frame[1] = A ^errorchar();
frame[2] = C^errorchar();
frame[3] = BCC1^errorchar();
memcpy(frame+4, stuffed_data, lengthAfterStuffing);
frame[4+lengthAfterStuffing] = FLAG^errorchar();
//End making frame
transmited++;
return (int) write(linkLayer.fd, frame, lengthAfterStuffing+5); // "+5" pois somamos 2FLAG,1BCC,1A,1C
}
int sendInformationFrame(unsigned char * data, int length) {
printf("[sendinf] START\n");
unsigned char stuffed_data[MAX_SIZE-6];
if(length > MAX_SIZE/2){
printf("That size is too big!");
return -1;
}
int C = linkLayer.sequenceNumber << 6;
int BCC1 = A ^ C;
int i;
//Se não funcionar, tentar usar um buffer auxiliar para onde vai
//a data antes de fazer estas operações
//De forma a calcular BBC2 simplesmente fazemos o calculo do XOR
//de cada byte de data com o proximo e desse resultado com o proximo.
//O cálculo de BBC2 é realizado antes do byte stuffing
int BCC2 = data[0];
for(i = 1; i < length; i++){
BCC2 = (BCC2 ^ data[i]);
}
unsigned int lengthAfterStuffing = byte_stuffing(data, stuffed_data, length);
linkLayer.frame[0] = FLAG;
linkLayer.frame[1] = A;
linkLayer.frame[2] = C;
linkLayer.frame[3] = BCC1;
memcpy(linkLayer.frame+4, stuffed_data, lengthAfterStuffing); //Ou linkLayer.frame+4
linkLayer.frame[3+lengthAfterStuffing] = BCC2;
linkLayer.frame[4+lengthAfterStuffing] = FLAG;
return (int) write(linkLayer.fd, linkLayer.frame, lengthAfterStuffing+6); // "+6" pois somamos 2FLAG,2BCC,1A,1C
printf("[sendinf] END\n");
}
