#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <errno.h>

#define BAUDRATE B19200
#define MODEMDEVICE "/dev/cua0"
#define _POSIX_SOURCE 1 /* POSIX compliant source */
#define FALSE 0
#define TRUE 1

volatile int STOP=FALSE;

int fd;

main()
{
  int c, res,ret;
  struct termios oldtio,newtio;
  unsigned char buf[255];
    int i,count;
	long position,velocity,Oposition;

 fd = open(MODEMDEVICE, O_RDWR);
 if (fd <0) {perror(MODEMDEVICE); exit(-1); }

 tcgetattr(fd,&oldtio); /* save current port settings */

 /* bzero(newtio, sizeof(newtio)); */
 newtio.c_cflag = BAUDRATE | CS8 | CREAD;
 newtio.c_iflag = 0;
 newtio.c_oflag = 0;

 /* set input mode (non-canonical, no echo,...) */
 newtio.c_lflag = 0;

 newtio.c_cc[VTIME]    = 0;   /* inter-character timer unused */
 newtio.c_cc[VMIN]     = 1;   /* blocking read until 1 chars received */

 tcflush(fd, TCIFLUSH);
 tcsetattr(fd,TCSANOW,&newtio);

while(1) {
 ReadStatus();
 count = 0;
 do {
   ret = read(fd,&buf[count],6-count);
   count += ret;
  } while (count < 6);
  position = buf[1];
  position |= (buf[2] << 8);
  position |= (buf[3] << 16);
  position |= (buf[4] << 24);
  velocity = position - Oposition;
  printf("%ld %ld\n",position,velocity);
  Oposition = position;
}

 tcsetattr(fd,TCSANOW,&oldtio);
}



ReadStatus () {
    unsigned char a[40];
    int i = 0;
    int j;
    unsigned char sum = 0;
	int ret;

    a[i++] = 0xAA;
    a[i++] = 0x02;
    a[i++] = 0x13;
    a[i++] = 0x01;

	sum = 0;
    for(j=1;j<i;j++) sum += a[j];
    a[i] = sum & 0xFF;

    for(j=0;j<=i;j++) {
		ret = write(fd,&a[j],1);
		if(ret != 1) {
			printf("write returned %d errno = %d\n",ret,errno);
			perror("Write: ");
		}
	}
}