#define rock_width 13
#define rock_height 13
static char rock_bits[] = {
   0x00, 0x00, 0x70, 0x00, 0xfc, 0x01, 0x34, 0x07, 0x3a, 0x08, 0x0f, 0x08,
   0x01, 0x10, 0x03, 0x10, 0x42, 0x10, 0x02, 0x11, 0x04, 0x08, 0x08, 0x06,
   0xf0, 0x01};
