// --- options to control terminal output --- c_oflag
if(terminal_options->c_oflag & OLCUC)	printf("\tmap lowercase characters to uppercase on output\n");
if(terminal_options->c_oflag & ONLCR)	printf("\tmap NL to CR+NL on output.\n");
if(terminal_options->c_oflag & OCRNL)	printf("\tmap CR to NL on output.\n");
if(terminal_options->c_oflag & OPOST)	printf("\tEnable implementation-defined output processing.\n");
if(terminal_options->c_oflag & ONOCR)	printf("\tDon't output CR at column 0.\n");
if(terminal_options->c_oflag & ONLRET)	printf("\tDon't output CR.\n");
if(terminal_options->c_oflag & OFILL)	printf("\tSend fill characters for a delay, rather than using a timed\n");
if(terminal_options->c_oflag & OFDEL)	printf("\tFill character is ASCII DEL (0177).  If unset, fill character\n");
if(terminal_options->c_oflag & NLDLY)	printf("\tNL delay mask.  Values are NL0 and NL1.  [requires\n");
if(terminal_options->c_oflag & CRDLY)	printf("\tCR return delay mask.  Values are CR0, CR1, CR2, or CR3.\n");
if(terminal_options->c_oflag & TABDLY)	printf("\tHorizontal tab delay mask.  Values are TAB0, TAB1, TAB2, TAB3\n");
if(terminal_options->c_oflag & BSDLY)	printf("\tBackspace delay mask.  Values are BS0 or BS1.  (Has never been\n");
if(terminal_options->c_oflag & VTDLY)	printf("\tVertical tab delay mask.  Values are VT0 or VT1.\n");
if(terminal_options->c_oflag & FFDLY)	printf("\tForm feed delay mask.  Values are FF0 or FF1.  [requires\n");


// --- options to control terminal hardware --- c_cflag
if(terminal_options->c_cflag & CLOCAL)	printf("\tignore modem control lines.\n");
if(terminal_options->c_cflag & CREAD)	printf("\tenable read\n");
if(terminal_options->c_cflag & CSIZE)	printf("\tcharacter size mask.  Values are CS5, CS6, CS7, or CS8.\n");
if(terminal_options->c_cflag & CSTOPB)	printf("\tSet two stop bits, rather than one.\n");
if(terminal_options->c_cflag & PARENB)	printf("\tenable parity generation on output and parity checking for\n");
if(terminal_options->c_cflag & CRTSCTS)	printf("\tEnable RTS/CTS (hardware) flow control\n");

if(terminal_options->c_cflag & CBAUD)	printf("\tBaud speed mask (4+1 bits).  [requires\n");
if(terminal_options->c_cflag & CBAUDEX)	printf("\tExtra baud speed mask (1 bit)\n");
if(terminal_options->c_cflag & PARODD)	printf("\tIf set, then parity for input and output is odd; otherwise\n");
if(terminal_options->c_cflag & HUPCL)	printf("\tlower modem control lines after last process closes the device\n");
if(terminal_options->c_cflag & CIBAUD)	printf("\tMask for input speeds.  The values for the\n");
if(terminal_options->c_cflag & CMSPAR)	printf("\tUse 'stick' (mark/space) parity (supported on\n");


// --- options to control terminal user interface --- c_lflag
if(terminal_options->c_lflag & ISIG)	printf("\tWhen any of the characters INTR, QUIT, SUSP, or DSUSP are\n");
if(terminal_options->c_lflag & ECHO)	printf("\tEcho input characters.\n");
if(terminal_options->c_lflag & ICANON)	printf("\tcanonical mode enabled\n");
if(terminal_options->c_lflag & ECHOCTL)	printf("\tECHOCTL\n");
if(terminal_options->c_lflag & ECHOPRT)	printf("\tECHOPRT\n");
if(terminal_options->c_lflag & NOFLSH)	printf("\tDisable flushing the input and output queues when generating\n");
if(terminal_options->c_lflag & TOSTOP)	printf("\tSend the SIGTTOU signal to the process group of a background\n");
if(terminal_options->c_lflag & IEXTEN)	printf("\tEnable implementation-defined input processing.  This flag, as\n");
if(terminal_options->c_lflag & ECHOE)	printf("\tIf ICANON is also set, the ERASE character erases the\n");
if(terminal_options->c_lflag & ECHOK)	printf("\tIf ICANON is also set, the KILL character erases the current\n");
if(terminal_options->c_lflag & ECHONL)	printf("\tIf ICANON is also set, echo the NL character even if ECHO is\n");
if(terminal_options->c_lflag & ECHOKE)	printf("\tIf ICANON is also set, KILL is echoed by\n");
printf("--------------------------------------------------------------\n");

gettimeofday(&end_time, NULL);

elapsed_time	= (end_time.tv_usec / 1000.0 + end_time.tv_sec * 1000)
				- (start_time->tv_usec / 1000.0 + start_time->tv_sec * 1000);

return elapsed_time;

n = write(fd, g_code, strlen(g_code));

if(n < 0)
{
	printf("Error writing: %s\n", strerror(errno));
}

printf("Write : %2d bytes "ANSI_COLOR_YELLOW"%s"ANSI_COLOR_RESET,
	strlen(g_code), g_code);
return n;

memset(response, '\0', G_CODE_LINE_LENGTH);

gettimeofday(&start_time, NULL);
n = read(fd, response, G_CODE_LINE_LENGTH);

if(n < 0)
{
	printf("Error reading: %s\n", strerror(errno));
}
else
if(strlen(response) == 0)
{
	printf("Read : %s zero length\n", response);
	n = 0;
}
else
{
	milliseconds = compute_task_milli_seconds(&start_time);
	printf("Read  : %2d bytes "ANSI_COLOR_GREEN"%s"ANSI_COLOR_RESET,
		strlen(response), response);
	if(milliseconds > 100.0)
		printf(ANSI_COLOR_RED"\t%6.2lf seconds\n"ANSI_COLOR_RESET,
			milliseconds / 1000.0);
}

return n;

fd = open(serial_port, O_RDWR | O_NOCTTY);
sleep(3); // wait for connection
memset(&terminal_options, 0, sizeof(struct termios));

printf("Connecting to Arduino via %s\n", serial_port);

if(tcgetattr(fd, &terminal_options) != 0)
{
	printf("error from tcgetattr: %s\n", strerror(errno));
	ok = FALSE;
	return ok;
}

show_terminal_options(&terminal_options);

// set Baud rates
cfsetospeed(&terminal_options, (speed_t)B115200);
cfsetispeed(&terminal_options, (speed_t)B115200);

// --- options to control terminal input
terminal_options.c_iflag	|= IGNCR;		// ignore CR on input
terminal_options.c_iflag	&= ~ICRNL;		// translate CR to NL on input
terminal_options.c_iflag	&= ~INLCR;		// translate NL to CR on input

// --- options to control terminal output
terminal_options.c_oflag	|= OLCUC;		// map lowercase to uppercase on output

// --- options to control terminal hardware
terminal_options.c_cflag	&= ~PARENB;		// no parity
terminal_options.c_cflag	&= ~CSTOPB;		// one stop bit
terminal_options.c_cflag	&= ~CSIZE;		// character size mask
terminal_options.c_cflag	|= CS8;			// make 8N1
terminal_options.c_cflag	&= ~CRTSCTS;	// no flow control
terminal_options.c_cflag	|= CREAD;		// turn on read
terminal_options.c_cflag	|= CLOCAL;		// ignore modem ctrl lines

// --- options to control terminal user interface
terminal_options.c_lflag	|= ICANON;		// enable canonical mode

show_terminal_options(&terminal_options);

// flush port, then apply attributes
tcflush(fd, TCIFLUSH);
if(tcsetattr(fd, TCSANOW, &terminal_options) != 0)
{
	printf("error from tcsetattr %s\n", strerror(errno));
	ok = FALSE;
	return ok;
}

write_arduino(Ctrl_X_Reset_Grbl);
sleep(3); // wait for reset

Grbl_is_connected = TRUE;
ok = TRUE;
return ok;