+#else
+
+static double currentSystemTime()
+{
+ FILETIME ft;
+ GetCurrentFT(&ft);
+
+ // As per Windows documentation for FILETIME, copy the resulting FILETIME structure to a
+ // ULARGE_INTEGER structure using memcpy (using memcpy instead of direct assignment can
+ // prevent alignment faults on 64-bit Windows).
+
+ ULARGE_INTEGER t;
+ memcpy(&t, &ft, sizeof(t));
+
+ // Windows file times are in 100s of nanoseconds.
+ // To convert to seconds, we have to divide by 10,000,000, which is more quickly
+ // done by multiplying by 0.0000001.
+
+ // Between January 1, 1601 and January 1, 1970, there were 369 complete years,
+ // of which 89 were leap years (1700, 1800, and 1900 were not leap years).
+ // That is a total of 134774 days, which is 11644473600 seconds.
+
+ return t.QuadPart * 0.0000001 - 11644473600.0;
+}
+
+double currentTime()
+{
+ static bool init = false;
+ static double lastTime;
+ static DWORD lastTickCount;
+ if (!init) {
+ lastTime = currentSystemTime();
+ lastTickCount = GetTickCount();
+ init = true;
+ return lastTime;
+ }
+
+ DWORD tickCountNow = GetTickCount();
+ DWORD elapsed = tickCountNow - lastTickCount;
+ double timeNow = lastTime + (double)elapsed / 1000.;
+ if (elapsed >= 0x7FFFFFFF) {
+ lastTime = timeNow;
+ lastTickCount = tickCountNow;
+ }
+ return timeNow;
+}
+
+#endif // USE(QUERY_PERFORMANCE_COUNTER)
+