#define bdiag_width 16
#define bdiag_height 16
-static char bdiag_bits[] = {
+static unsigned char bdiag_bits[] = {
0x80, 0x80, 0x40, 0x40, 0x20, 0x20, 0x10, 0x10, 0x08, 0x08, 0x04, 0x04,
0x02, 0x02, 0x01, 0x01, 0x80, 0x80, 0x40, 0x40, 0x20, 0x20, 0x10, 0x10,
0x08, 0x08, 0x04, 0x04, 0x02, 0x02, 0x01, 0x01};