// code by SASANO Takayoshi, CC BY-SA

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <termios.h>
#include <fcntl.h>
#include <unistd.h>

static	int	char_length = 8;
static	int	stop_length = 1;
static	int	use_parity = 0;
static	int	odd_parity = 0;
static	int	use_rtscts = 0;
static	int	serial_bps = 38400;

#define	BUFSIZE	256

static	void	tx_test(int fd)
{
	uint8_t	i, m, n;
	uint8_t	buf[BUFSIZE + 1];

	buf[0] = 1;
	m = (1 << char_length) - 1;
		
	for (i = 0; ; i++) {
		n = i & m;
		if (n < 2) continue;

		memset(buf + 1, n, BUFSIZE);
		write(fd, buf, sizeof(buf));
		printf(".");
		fflush(stdout);
	}
}

static	void	rx_test(int fd)
{
	int	rxchar;
	uint8_t	buf;
	uint32_t	good, bad;

	rxchar = -1;
	good = bad = 0;

	while (1) {
		read(fd, &buf, sizeof(buf));
		if (buf == 1) {			/* reset, show prev result */
			if (rxchar >= 0) {
				if (good == BUFSIZE && bad == 0) {
					printf("o");
				} else {
					printf("x(%d/%d)", good, bad);
				}
				fflush(stdout);
				rxchar = -1;
			}
		} else if (rxchar < 0) {	/* 1st char */
			rxchar = buf;
			good = 1;
			bad = 0;
		} else {			/* 2nd and later */
			if (buf == rxchar) good++;
			else bad++;
		}
	}
}

static	void	parse_serialmode(char *p)
{
	int	i;

	for (i = 0; ; i++) {
		if (*p == '\0') break;

		switch (i) {
		case	0:	/* character length */
			if (*p >= '5' && *p <= '8') char_length = *p - '0';
			break;
		case	1:	/* parity bit */
			use_parity = (*p == 'E' || *p == 'e' ||
				      *p == 'O' || *p == 'o');
			odd_parity = (*p == 'O' || *p == 'o');
			break;
		case	2:	/* stop bits */
			if (*p >= '1' && *p <= '3') stop_length = *p - '0';
			break;
		case	3:	/* X flow control (not supported) */
			/* do nothing */
			break;
		case	4:	/* RTS/CTS flow control */
			use_rtscts = (*p == 'H' || *p == 'h');
			break;
		default:
			/* do nothing */
			break;
		}

		p++;
	}
}

static	int	get_baud(int baud)
{
	switch (baud) {
	case	50:	return B50;
	case	75:	return B75;
	case	110:	return B110;
	case	134:	return B134;
	case	150:	return B150;
	case	200:	return B200;
	case	300:	return B300;
	case	600:	return B600;
	case	1200:	return B1200;
	case	1800:	return B1800;
	case	2400:	return B2400;
	case	4800:	return B4800;
	case	9600:	return B9600;
	case	19200:	return B19200;
	case	38400:	return B38400;
#ifdef B7200
	case	7200:	return B7200;
#endif
#ifdef B14400
	case	14400:	return B14400;
#endif
#ifdef B28800
	case	28800:	return B28800;
#endif
#ifdef B57600
	case	57600:	return B57600;
#endif
#ifdef B76800
	case	76800:	return B76800;
#endif
#ifdef B115200
	case	115200:	return B115200;
#endif
#ifdef B230400
	case	230400:	return B230400;
#endif
#ifdef B460800
	case	460800:	return B460800;
#endif
#ifdef B500000
	case	500000:	return B500000;
#endif
#ifdef B576000
	case	576000:	return B576000;
#endif
#ifdef B921600
	case	921600:	return B921600;
#endif
#ifdef B1000000
	case	1000000:	return B1000000;
#endif
#ifdef B1152000
	case	1152000:	return B1152000;
#endif
#ifdef B2000000
	case	2000000:	return B2000000;
#endif
#ifdef B2500000
	case	2500000:	return B2500000;
#endif
#ifdef B3000000
	case	3000000:	return B3000000;
#endif
#ifdef B3500000
	case	3500000:	return B3500000;
#endif
#ifdef B4000000
	case	4000000:	return B4000000;
#endif
	default:	return -1;
	}
}

static	int	setup_serial(int fd)
{
	struct termios	t;
	static	int	cs[] = {CS5, CS6, CS7, CS8};
	int	baud;

	memset(&t, 0, sizeof(t));

	baud = get_baud(serial_bps);
	if (baud < 0) goto fail;
	cfsetospeed(&t, baud);
	cfsetispeed(&t, baud);

	t.c_cflag = CREAD | CLOCAL | cs[char_length - 5];;
	if (stop_length - 1) t.c_cflag |= CSTOPB;
	if (use_parity) t.c_cflag |= PARENB;
	if (odd_parity) t.c_cflag |= PARODD;
	if (use_rtscts) t.c_cflag |= CRTSCTS;

	t.c_iflag = INPCK;
	t.c_oflag = 0;
	t.c_lflag = 0;

	t.c_cc[VTIME] = 0;
	t.c_cc[VMIN] = 1;

	tcflush(fd, TCIFLUSH);
	if (tcsetattr(fd, TCSANOW, &t) < 0) goto fail;

	return 0;
fail:
	return -1;
}

int	main(int argc, char *argv[])
{
	int	fd;

	if (argc < 5) {
		printf("%s [device] [mode] [bps] [tx|rx]\n", argv[0]);
		goto fin0;
	}

	fd = open(argv[1], O_RDWR | O_NOCTTY);
	if (fd < 0) {
		printf("device open error\n");
		goto fin0;
	}

	parse_serialmode(argv[2]);
	serial_bps = atoi(argv[3]);
	if (setup_serial(fd) < 0) {
		printf("serial parameter error\n");
		goto fin1;
	}

	switch (argv[4][0]) {
	case	't':
		tx_test(fd);
		break;
	case	'r':
		rx_test(fd);
		break;
	default:
		printf("undefined test\n");
		break;
	}

fin1:
	close(fd);
fin0:
	return 0;
}