+//! Processor time used since invocation
+extern clock_t clock(void);
+
+//! Difference between two times in seconds
+extern double difftime(time_t time1, time_t time0);
+
+//! Convert a local time into the format returned by \a time
+//! \note Also updates tm_wday and tm_yday to the correct values
+extern time_t mktime(struct tm *timeptr);
+
+//! Get the current calendar time
+//! \note -1 is returned if the calendar time is not avaliable
+extern time_t time(time_t *t);
+
+//
+// Time conversions
+//
+//! Convert the time structure into a string of form 'Sun Sep 16 01:03:52 1973\n\0'
+extern char *asctime(const struct tm *timeptr);
+
+//! asctime(localtime(timer))
+extern char *ctime(const time_t *timer);
+
+//! Convert \a timter into UTC
+extern struct tm *gmtime(const time_t *timer);
+
+extern struct tm *localtime(const time_t *timer);
+
+extern size_t strftime(char*restrict s, size_t maxsize, const char*restrict format, const struct tm*restrict timeptr);
+
+#include <libposix_time.h>