VirtuaNet Code

int readPPM(const char *filename, 
	    unsigned char **data, 
	    unsigned int *width, 
	    unsigned int *height) {
  *data =0;
  char header[256];
  int nbyte;

  FILE *fp = fopen(filename, "rb");
  if (!fp)return 0;
  header[2]=0;
  fscanf(fp,"%c%c%c",&header[0],&header[1],&header[3]);
  
  assert (!strncmp(header, "P6", strlen("P6")));
  int err;
  do {
     err=fscanf(fp,"#%*[^#\n]\n");
  }while (err!=0&&err!=EOF);
  fscanf (fp, "%d %d %d\n", width, height, &nbyte);
  assert (nbyte == 255);
  //assert (*width > 0 && *width <= 2048);
  //assert (*height > 0 && *height <= 2048);

  *data = (unsigned char *) malloc (*width * *height * 3);
  assert (*data);
  fread(*data, *width * *height, 3, fp);
  fclose(fp);

  return 1;
}

int diff(char * f1,char * f2) {
  FILE * f=fopen(f1,"rb");
  FILE * fp=fopen(f2,"rb");
  if ((!f)||!fp) {
     return 1;
  }
  int chr;
  while (!feof(f)) {
     chr=fgetc(fp);
     int diff = chr-fgetc(f);
     diff = diff<0?-diff:diff;
     if (diff>5) {
        printf ("diff of %d\n",diff);
        fclose(f);
        fclose(fp);
        return 1;  
     }
    
  }
  if ((!feof(f))||(!feof(fp)))
     return 1;
  fclose(f);
  fclose(fp);
  return 0;
}

int writePPM(const char *filename, 
	     const unsigned char *data, 
	     unsigned int width, 
	     unsigned int height) {

  FILE *fp = fopen(filename, "wb");
  assert (fp);
   
  fprintf(fp, "%s\n%d %d %d\n", "P6", width, height, 255);
  fwrite(data, width*height, 3, fp);
  fclose(fp);

  return 0;
}