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

#define	SERIAL	"/dev/ttyS0"
#define	OK	0
#define	ERROR	(-1)

static int	fd = -1;
static char	*device = NULL;

int	serial_init(char *);
int	serial_finish(void);
int	serial_out(int);

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

	if ( argc != 2 ) {
		fprintf(stderr, "usage: %s string\n", argv[0] );
		exit (1);
	}
	for ( p = argv[1]; *p != '\0'; p++ ) {
		serial_init(SERIAL);
		serial_out( *p );
		serial_finish();
		if ( *p < ' ' ) {
			usleep( 1000 );
		}
	}
	return (0);
}

int	serial_init(char *dev)
{
	struct termios termio;

	if ( fd >= 0 ) {
		return (OK);
	}
	if ( device != NULL) {
		device = (char *)malloc( strlen(dev) + 1 );
		strcpy( device, dev );
	}
	if ( (fd = open(device, O_WRONLY)) < 0 ) {
		perror("open()");
		return (ERROR);
	}
	bzero(&termio, sizeof(termio));
	termio.c_cflag = B9600 | CS8 | CLOCAL;
	termio.c_iflag = IGNPAR;
	tcflush(fd, TCIFLUSH);
	if ( tcsetattr(fd, TCSANOW, &termio) < 0 ) {
		perror("tcsetattr()");
		return (ERROR);
	}

	return (OK);
}

int	serial_finish()
{
	if ( fd < 0 ) {
		return (ERROR);
	}
	if ( close(fd) < 0 ) {
		perror("close()");
		return (ERROR);
	}
	fd = -1;
	return (OK);
}

int	serial_out(int i)
{
	char	c;

	c = i;

	if ( write( fd, &c, sizeof(char)) != sizeof(char) ) {
		perror("write()");
		return (ERROR);
	}
	return (OK);
}
/*	EOF	**************************************************************/