diff --git a/include/common/ticks.h b/include/common/ticks.h
new file mode 100644
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--- /dev/null
+++ b/include/common/ticks.h
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+/*
+  include/common/ticks.h
+  Functions and macros for manipulation of expiration timers
+
+  Copyright (C) 2000-2008 Willy Tarreau - w@1wt.eu
+  
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation, version 2.1
+  exclusively.
+
+  This library 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+/*
+ * Using a mix of milliseconds and timeval for internal timers is expensive and
+ * overkill, because we don't need such a precision to compute timeouts.
+ * So we're converting them to "ticks". Right now, one tick equals one
+ * millisecond, but that might change in the future. Ticks are stored as 32bit
+ * values, and sorted in four 30bit-wide rotating arrays, which means that any
+ * timer may be 2^30 ms in the future, or 12.4 days. The ticks are designed to
+ * wrap after they pass 2^32. That means that we cannot directly compare them,
+ * but we can check the sign of their difference.
+ *
+ * We must both support absolute dates (well in fact, dates relative to now+/-
+ * 12 days), and intervals (for timeouts). Both types need an "eternity" magic
+ * value. For optimal code generation, we'll use zero as the magic value
+ * indicating that an expiration timer or a timeout is not set. We have to
+ * check that we don't return this value when adding timeouts to <now>. If a
+ * computation returns 0, we must increase it to 1 (which will push the timeout
+ * 1 ms further).
+ */
+
+#ifndef _COMMON_TICKS_H
+#define _COMMON_TICKS_H
+
+#include <common/config.h>
+#include <common/standard.h>
+
+#define TICK_ETERNITY   0
+
+/* right now, ticks are milliseconds. Both negative ms and negative ticks
+ * indicate eternity.
+ */
+#define MS_TO_TICKS(ms) (ms)
+#define TICKS_TO_MS(tk) (tk)
+
+/* return 1 if tick is set, otherwise 0 */
+static inline int tick_isset(int expire)
+{
+	return expire != 0;
+}
+
+/* Add <timeout> to <now>, and return the resulting expiration date.
+ * <timeout> will not be checked for null values.
+ */
+static inline int tick_add(int now, int timeout)
+{
+	now += timeout;
+	if (unlikely(!now))
+		now++;    /* unfortunate value */
+	return now;
+}
+
+/* add <timeout> to <now> if it is set, otherwise set it to eternity.
+ * Return the resulting expiration date.
+ */
+static inline int tick_add_ifset(int now, int timeout)
+{
+	if (!timeout)
+		return TICK_ETERNITY;
+	return tick_add(now, timeout);
+}
+
+/* return 1 if timer <timer> is expired at date <now>, otherwise zero */
+static inline int tick_is_expired(int timer, int now)
+{
+	if (!tick_isset(timer))
+		return 0;
+	return (timer - now) <= 0;
+}
+
+/* return the first one of the two timers, both of which may be infinite */
+static inline int tick_first(int t1, int t2)
+{
+	if (!tick_isset(t1))
+		return t2;
+	if (!tick_isset(t2))
+		return t1;
+	if ((t1 - t2) <= 0)
+		return t1;
+	else
+		return t2;
+}
+
+/* return the number of ticks remaining from <now> to <exp>, or zero if expired */
+static inline int tick_remain(int now, int exp)
+{
+	if (tick_is_expired(exp, now))
+		return 0;
+	return exp - now;
+}
+
+#endif /* _COMMON_TICKS_H */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */