+#ifdef _SC_CLK_TCK
+#define GNU_HZ sysconf(_SC_CLK_TCK)
+#else
+#ifdef HZ
+#define GNU_HZ HZ
+#else
+#ifdef CLOCKS_PER_SEC
+#define GNU_HZ CLOCKS_PER_SEC
+#endif
+#endif
+#endif
+
+/*
+
+@deftypefn Replacement long get_run_time (void)
+
+Returns the time used so far, in microseconds. If possible, this is
+the time used by this process, else it is the elapsed time since the
+process started.
+
+@end deftypefn
+
+*/
+