#define ROUND_UP(X, STEP) (((X) + (STEP) - 1) / (STEP) * (STEP))
#define DIV_ROUND_UP(X, STEP) (((X) + (STEP) - 1) / (STEP))
+#define ROUND_DOWN(X, STEP) ((X) / (STEP) * (STEP))
void *memset (void *, int, size_t);
void *memcpy (void *, const void *, size_t);