/*
 * hex2bin - simple hex to bin filter
 * address@hidden - under GPL version 2
 */
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <string.h>

static int hex2bin (void)
{
  char     hex[3];
  int      d = 0;
  unsigned char c;
  int      stdin_fd = fileno(stdin);
  int      n_read;

  while ((n_read = read(stdin_fd, hex, sizeof(hex)-1)) > 0)
  {
    if (n_read == 1)
    {
      if (hex[0] != '\n')
      {
        fprintf (stderr, "input parse error, odd digits in hex file\n");
        return (1);
      }
      return (1);
    }
    hex[2] = '\0';
    sscanf (hex, "%x", &d);
    c = (unsigned char) d;
    printf ("%c", c);
  }
  return (0);
}

static int bin2hex (void)
{
  int      stdin_fd = fileno(stdin);
  int      n_read;
  unsigned char c;

#ifdef _WIN32
  setmode (fileno(stdin), O_BINARY);
  setmode (fileno(stdout), O_BINARY);
#endif

  while ((n_read = read(stdin_fd, &c, 1)) > 0)
        printf ("%.2x", c);
  return (0);
}

int main (int argc, char **argv)
{
  if (argc >= 2 && strstr(argv[1], "-r"))
     return bin2hex();
  return hex2bin();
}