#include <stdio.h>
#include <inttypes.h>
#include <sys/io.h>
#include <signal.h>

#define BASE 0x378

int running = 1;

void signalHandler(int sig)
{
   running = 0;
}

int main(void)
{
   printf("Parallel Port Interface Test (Base: 0x%x)\n", BASE);

   signal(SIGINT, signalHandler);

   // Set permission bits of 4 ports starting from BASE
   int result = ioperm(BASE, 4, 1);

   // If setting permission failed, return
   if (result != 0)
   {
      printf("ERROR: Could not set permissions on ports");
      return result;
   }

   // This loop will keep running until ctrl-c is pressed
   while (running)
   {
      outb(0xFF, BASE);
      outb(0x00, BASE);
   }

   // Clear permission bits of 4 ports starting from BASE
   result = ioperm(BASE, 4, 0);

   if (result != 0)
   {
      printf("ERROR: Could not clear permissions on ports");
      return result;
   }

   return 0;
}

#include <stdio.h>
#include <sys/ioctl.h>
#include <linux/parport.h>
#include <linux/ppdev.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>

int running = 1;

void signalHandler(int sig)
{
   running = 0;
}

int main(void)
{
   int fd;
   int result;

   printf("Parallel Port Interface Test\n");

   // Set ctrl-c handler
   signal(SIGINT, signalHandler);

   // Open the parallel port for reading and writing
   fd = open("/dev/parport0", O_RDWR);

   if (fd == -1)
   {
      perror("Could not open parallel port");
      return 1;
   }

   // Try to claim port
   if (ioctl(fd, PPCLAIM, NULL))
   {
      perror("Could not claim parallel port");
      close(fd);
      return 1;
   }

   // Set the Mode
   int mode = IEEE1284_MODE_BYTE;
   if (ioctl(fd, PPSETMODE, &mode))
   {
      perror("Could not set mode");
      ioctl(fd, PPRELEASE);
      close(fd);
      return 1;
   }

   // Set data pins to output
   int dir = 0x00;
   if (ioctl(fd, PPDATADIR, &dir))
   {
      perror("Could not set parallel port direction");
      ioctl(fd, PPRELEASE);
      close(fd);
      return 1;
   }

   char dataH = 0xFF;
   char dataL = 0x00;

   // This loop will keep running until ctrl-c is pressed
   while(running)
   {
      // Output some data
      // Note that data is passed by a pointer
      ioctl(fd, PPWDATA, &dataH);
      ioctl(fd, PPWDATA, &dataL);
   }

   printf("Shutting down\n");

   // Release and close the parallel port
   ioctl(fd, PPRELEASE);
   close(fd);

   return 0;
}