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