#define guard_width 16
#define guard_height 16
static char guard_bits[] = {
 0xc0,0x00,0x66,0x00,0x36,0x00,0x1f,0x18,0xcf,0x0c,0xcf,0x06,0xef,0x03,0xe6,
 0x99,0xe6,0xd9,0xe0,0x7d,0xc0,0x3c,0xc0,0x3c,0x00,0x3c,0x00,0x18,0x00,0x18,
 0x00,0x00};