* modules/gethrxtime: New file.

[gnulib.git] / lib / gethrxtime.c

diff --git a/lib/gethrxtime.c b/lib/gethrxtime.c
new file mode 100644 (file)
index 0000000..6f7bc09
--- /dev/null
+++ b/lib/gethrxtime.c
@@ -0,0 +1,80 @@
+/* gethrxtime -- get high resolution real time
+
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+/* Written by Paul Eggert.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "gethrxtime.h"
+
+#include <sys/types.h>
+#if TIME_WITH_SYS_TIME
+# include <sys/time.h>
+# include <time.h>
+#else
+# if HAVE_SYS_TIME_H
+#  include <sys/time.h>
+# else
+#  include <time.h>
+# endif
+#endif
+
+/* Get the time of a high-resolution clock, preferably one that is not
+   subject to resetting or drifting.  */
+
+xtime_t
+gethrxtime (void)
+{
+#if HAVE_NANOUPTIME
+  {
+    struct timespec ts;
+    nanouptime (&ts);
+    return xtime_make (ts.tv_sec, ts.tv_nsec);
+  }
+#else
+
+# if defined CLOCK_MONOTONIC && HAVE_CLOCK_GETTIME
+  {
+    struct timespec ts;
+    if (clock_gettime (CLOCK_MONOTONIC, &ts) == 0)
+      return xtime_make (ts.tv_sec, ts.tv_nsec);
+  }
+# endif
+
+#if HAVE_MICROUPTIME
+  {
+    struct timeval tv;
+    microuptime (&tv);
+    return xtime_make (tv.tv_sec, 1000 * tv.tv_usec);
+  }
+
+  /* No monotonically increasing clocks are available; fall back on a
+     clock that might jump backwards, since it's the best we can do.  */
+# elif HAVE_GETTIMEOFDAY && XTIME_PRECISION != 1
+  {
+    struct timeval tv;
+    gettimeofday (&tv, NULL);
+    return xtime_make (tv.tv_sec, 1000 * tv.tv_usec);
+  }
+# else
+  return xtime_make (time (NULL), 0);
+# endif
+#endif
+}