Import BSDDB 4.7.25 (as of svn r89086)

os_windows/os_clock.c

@@ -0,0 +1,79 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2001,2008 Oracle.  All rights reserved.
+ *
+ * $Id: os_clock.c 63573 2008-05-23 21:43:21Z trent.nelson $
+ */
+
+#include "db_config.h"
+
+#include "db_int.h"
+
+/*
+ * __os_gettime --
+ *	Return the current time-of-day clock in seconds and nanoseconds.
+ */
+void
+__os_gettime(env, tp, monotonic)
+	ENV *env;
+	db_timespec *tp;
+	int monotonic;
+{
+	if (monotonic) {
+		/*
+		 * The elapsed time is stored as a DWORD value, so time wraps
+		 * around to zero if the system runs for 49.7 days.  Initialize
+		 * a base value with 50 days worth of seconds, and add 50 more
+		 * days every time the counter wraps.  That ensures we always
+		 * move forward.
+		 *
+		 * It's possible this code could race, but the danger is we
+		 * would increment base_seconds more than once per wrap and
+		 * eventually overflow, which is a pretty remote possibility.
+		 */
+#define	TIMER_WRAP_SECONDS	(50 * 24 * 60 * 60)
+		static DWORD last_ticks;
+		static time_t base_seconds;
+		DWORD ticks;
+
+		ticks = GetTickCount();
+		if (ticks < last_ticks)
+			base_seconds += TIMER_WRAP_SECONDS;
+		last_ticks = ticks;
+		tp->tv_sec = base_seconds + (u_int32_t)(ticks / 1000);
+		tp->tv_nsec = (u_int32_t)((ticks % 1000) * NS_PER_MS);
+	} else {
+#ifdef DB_WINCE
+		FILETIME ft;
+		LARGE_INTEGER large_int;
+		LONGLONG ns_since_epoch, utc1970;
+		SYSTEMTIME st;
+
+		(void)GetSystemTime(&st);
+		(void)SystemTimeToFileTime(&st, &ft);
+
+		/*
+		 * A FILETIME expresses time as 100 nanosecond chunks from
+		 * Jan 1, 1601; convert to a timespec where the time is
+		 * is expressed in seconds and nanoseconds from Jan 1, 1970.
+		 *
+		 * UTC_1970 is the number of 100-nano-second chunks from
+		 * 1601 to 1970.
+		 */
+#define	NS100_PER_SEC	(NS_PER_SEC / 100)
+#define	UTC_1970	(((LONGLONG)27111902 << 32) + (LONGLONG)3577643008)
+		memcpy(&large_int, &ft, sizeof(large_int));
+		utc1970 = UTC_1970;
+		ns_since_epoch = (large_int.QuadPart - utc1970);
+		tp->tv_sec = (time_t)(ns_since_epoch / NS100_PER_SEC);
+		tp->tv_nsec = (long)(ns_since_epoch % NS100_PER_SEC);
+#else
+		struct _timeb now;
+
+		_ftime(&now);
+		tp->tv_sec = now.time;
+		tp->tv_nsec = now.millitm * NS_PER_MS;
+#endif
+	}
+}