#define MSEC_TO_NSEC(msec) ((msec) * 1000000)
#define USEC_TO_NSEC(usec) ((usec) * 1000)
extern void sleep_for(unsigned int sec, long nsec, bool wake_after_interrupt);
+extern bool is_directory(const char *path);
+extern bool is_file(const char *path);
#define _ROUND_UP(val, base) (((val) + (base) - 1) & ~(base - 1))
#define ROUND_UP(val, base) _ROUND_UP(val, (typeof(val))(base))