#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>


static int
dev_init(int fd)
{
	struct termios t;
	t.c_iflag = IGNBRK | IGNPAR | INPCK;
	t.c_oflag = 0;
	t.c_cflag = B57600 | CLOCAL | CREAD | CS8 | PARENB;
	t.c_lflag = 0;
	memset(t.c_cc, _POSIX_VDISABLE, NCCS);
	t.c_cc[VMIN] = 0;
	t.c_cc[VTIME] = 0;
	if (tcsetattr(fd, TCSANOW, &t) == -1) {
		perror("tcsetattr");
		exit(2);
	}
	return 0;
}

static int
dev_open(const char *name)
{
	int fd = open(name, O_RDWR | O_NONBLOCK);
	if (fd == -1) {
		perror("open");
		exit(2);
	}
	return fd;
}

static ssize_t
dev_read(int fd, void *buf, size_t count)
{
	ssize_t ret = read(fd, buf, count);
	if (ret == -1) {
		perror("read");
		exit(2);
	}
	printf("%s: %d\n", __FUNCTION__, ret);
	return ret;
}

int
main(void)
{
	int fd = dev_open("/dev/ttyS0");
	dev_init(fd);

	fd_set rfds;
	FD_ZERO(&rfds);
	FD_SET(fd, &rfds);
	if (select(fd + 1, &rfds, NULL, NULL, NULL) == -1) {
		perror("select");
		exit(2);
	}

	char buf;
	dev_read(fd, &buf, 1);
	dev_read(fd, &buf, 1);

	return 0;
}