Arduino I/O with Linuxcnc

//arduinosend.ino
#include <SoftwareSerial.h>
#include "Wire.h"

void setup() 
{
    Serial.begin(9600);
    for(int x = 14; x < 50; x++)pinMode(x, INPUT);
}

void loop() 
{
int x, y, z;  
uint8_t  buff[5];

    buff[4] = '\0';
    z = 14;
    for(x = 0; x < 4; x++) // 4 packets 8 bits
        for(y = 0; y < 8 ; y++) bitWrite(buff[x], y, digitalRead(z++));
    Serial.write(buff, 4);
    delay(1000);    
}

//serialreceive.comp
component serialreceive              "Receiving 32 bits data from arduino";

pin out bit bit-##[32] = false       "Output bits";

option singleton yes;               
option userspace yes;

author "ArcEye arceye@mgware.co.uk";
license "GPL";
;;

#include <stdio.h>    /* Standard input/output definitions */
#include <stdlib.h> 
#include <stdint.h>   /* Standard types */
#include <string.h>   /* String function definitions */
#include <unistd.h>   /* UNIX standard function definitions */
#include <fcntl.h>    /* File control definitions */
#include <errno.h>    /* Error number definitions */
#include <termios.h>  /* POSIX terminal control definitions */
#include <sys/ioctl.h>

#define BAUDRATE B9600
#define DEVICE "/dev/ttyACM0"
#define _POSIX_SOURCE 1 /* POSIX compliant source */
#define bitRead(value, bit) (((value) >> (bit)) & 0x01)
#define bitSet(value, bit) ((value) |= (1UL << (bit)))
#define bitClear(value, bit) ((value) &= ~(1UL << (bit)))
#define bitWrite(value, bit, bitvalue) (bitvalue ? bitSet(value, bit) : bitClear(value, bit))

int serialport_init();
                             
struct termios toptions;;       // port setup

void user_mainloop(void)
{
int c, x, y, z;
char ch;
int fd = serialport_init();
  
    while (fd != -1) 
        {
        usleep(1000000);
        FOR_ALL_INSTS() 
            {
            z = 0;
            for(x = 0; x < 4; x++) // 4 packets 8 bits
                {
                read(fd,&ch,1); 
                for(y = 0; y < 8 ; y++) bit(z++) = bitRead(ch, y);
                }
            // test - to show that bits were written
            // comment out next 3 lines when using for real
            for(x = 0; x < 32; x++) 
                fprintf(stderr,"%d",bit(x));
            fprintf(stderr,"\n");
            }
        }
    close(fd);
    exit(0);
}


//######################################################################

int serialport_init()
{
int fd;
 
    fd = open(DEVICE, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1)  
        {
        perror("init_serialport: Unable to open port ");
        return -1;
        }
    if (tcgetattr(fd, &toptions) < 0) 
        {
        perror("init_serialport: Couldn't get term attributes");
        return -1;
        }
    speed_t brate = BAUDRATE; 
    cfsetispeed(&toptions, brate);
    cfsetospeed(&toptions, brate);
    // 8N1
    toptions.c_cflag &= ~PARENB;
    toptions.c_cflag &= ~CSTOPB;
    toptions.c_cflag &= ~CSIZE;
    toptions.c_cflag |= CS8;
    // no flow control
    toptions.c_cflag &= ~CRTSCTS;
    toptions.c_cflag |= CREAD | CLOCAL;  // turn on READ & ignore ctrl lines
    toptions.c_iflag &= ~(IXON | IXOFF | IXANY); // turn off s/w flow ctrl
    toptions.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); // make raw
    toptions.c_oflag &= ~OPOST; // make raw
    toptions.c_cc[VMIN]  = 0;
    toptions.c_cc[VTIME] = 20;
    if( tcsetattr(fd, TCSANOW, &toptions) < 0) 
        {
        perror("init_serialport: Couldn't set term attributes");
        return -1;
        }
    return fd;
}