Quick check compressability

#include <stdio.h>

#define INC 1024*1024*1024

int main(int argc, char **argv)
{
  char c;
  char cp = '\0';

  FILE *fp = fopen(argv[1], "r");

  do {
    c = fgetc(fp);
    printf("%c", c == cp ? 's' : 'D');
    fflush(stdout);
    cp = c;
  } while (!fseek(fp, INC, SEEK_CUR));

  putchar('\n');

  fclose(fp);

  return 0;
}