#define rock_width 13
#define rock_height 13
static unsigned char rock_bits[] = {
   0x80, 0x01, 0x70, 0x02, 0x0c, 0x02, 0x04, 0x04, 0x02, 0x08, 0x01, 0x08,
   0x01, 0x10, 0x01, 0x10, 0x02, 0x10, 0x02, 0x10, 0x04, 0x08, 0xc8, 0x09,
   0x70, 0x07};
