readCmd

int read_com_buffer(const int toReadBytes, char *serInBuf, const int stream_status){

    unsigned int idx=0; //index of the serInBuf
    char b1,b2; //receive 2 bytes in one swipe of this procedure
    fd_set rfds;    // File pointer set for select
    struct timeval serInWait;   // Time to wait for serial input
    int stream=stream_status; //receiving 1st (START_STREAM), or following bytes (CONT_STREAM)
    int selRetVal;  // Return value of select

    //inits
    serInWait.tv_sec = SERIAL_TIMEOUT_SEC;
    serInWait.tv_usec = SERIAL_TIMEOUT_USEC;
    FD_ZERO(&rfds);
    FD_SET(fd, &rfds);
    DEBUG_SERIAL(printf("SERIAL: will read bytes %d\n",toReadBytes));

    //main fn
    for(idx=0;idx<toReadBytes;idx++) {
        if (stream==CONT_STREAM){//add (or not) a timeout on the select()
            selRetVal = select(fd+1, &rfds, NULL, NULL, &serInWait);
        } else if (stream==START_STREAM) { //waiting for 1st byte
            selRetVal = select(fd+1, &rfds, NULL, NULL, NULL);
            pthread_mutex_lock(&serial_lock_mutex);
            stream=CONT_STREAM;
        }

        if (selRetVal==0){
            return SERIAL_TIMEOUT;
        } else if (selRetVal>0){
            read(fd,&b1,1);
            if((b1 == '#') || (b1 == '\n')) { // Skip comment lines
                while( b1 != '\n')
                    read(fd,&b1,1);
            } else if (b1==' '){    //Skip spaces
            } else if (b1 == EOF) {
                return ERROR;   // Nothing else to read
            } else { //go on to read 2nd byte
                selRetVal = select(fd+1, &rfds, NULL, NULL, &serInWait);

                if (selRetVal==0){
                    return SERIAL_TIMEOUT;
                } else if (selRetVal>0){
                    read(fd,&b2,1);

                    //convert asciiHex to Hex
                    if (asciiToHex(&b1)==ERROR) return ERROR;
                    if (asciiToHex(&b2)==ERROR) return ERROR;

                    //merge bytes b1 & b2
                    b1 = b1 << 4;
                    b1 = b1 | b2;

                    serInBuf[idx] = b1;
                }
            }
        }
    }//end for [idx] loop
    return 0;
}