fixed all exercices

ex03/include/mystd.h

@@ -0,0 +1,20 @@
+#ifndef MYSTDINT_H
+#define MYSTDINT_H
+
+#include <avr/io.h>
+
+typedef unsigned char uint8_t;
+typedef signed char	  int8_t;
+
+typedef uint8_t bool;
+
+#define true	(1)
+#define false	(0)
+
+#define BV(bit) (1 << bit)
+
+#ifndef NULL
+#define NULL	((void*)0)
+#endif
+
+#endif /* MYSTDINT_H */