+#if HAVE_CLOCK_GETTIME
+# define GetClockTime(t) clock_gettime(CLOCK_REALTIME, t)
+# define TimeType struct timespec
+# define TimeScale 1000000000L /* 1e9 */
+# define ElapsedSeconds(b,e) \
+ (double) (((e)->tv_sec - (b)->tv_sec) \
+ + ((e)->tv_nsec - (b)->tv_nsec) / TimeScale)
+#elif HAVE_GETTIMEOFDAY
+# define GetClockTime(t) gettimeofday(t, 0)
+# define TimeType struct timeval
+# define TimeScale 1000000L /* 1e6 */
+# define ElapsedSeconds(b,e) \
+ (double) (((e)->tv_sec - (b)->tv_sec) \
+ + ((e)->tv_usec - (b)->tv_usec) / TimeScale)
+#else
+# define TimeType time_t
+# define GetClockTime(t) time((time_t*)0)
+# define ElapsedSeconds(b,e) (double)((e) - (b))
+#endif
+