#define wall_width 16
#define wall_height 16
static char wall_bits[] = {
   0x00, 0x00, 0xfe, 0x7f, 0xea, 0x57, 0xfe, 0x7f, 0xea, 0x57, 0xfe, 0x7f,
   0x3e, 0x7d, 0xfe, 0x7d, 0xbe, 0x7f, 0xbe, 0x7c, 0xfe, 0x7f, 0xea, 0x57,
   0xfe, 0x7f, 0xea, 0x57, 0xfe, 0x7f, 0x00, 0x00};