add GNUNET_TIME_absolute_round_down() function

2 files changed, 26 insertions, 0 deletions

diff --git a/src/include/gnunet_time_lib.h b/src/include/gnunet_time_lib.h
index 55af62b72..d59eb984d 100644
--- a/src/include/gnunet_time_lib.h
+++ b/src/include/gnunet_time_lib.h
@@ -482,6 +482,18 @@ GNUNET_TIME_absolute_max (struct GNUNET_TIME_Absolute t1,
 
 
 /**
+ * Round down absolute time @a at to multiple of @a rt.
+ *
+ * @param at absolute time to round
+ * @param rt multiple to round to (non-zero)
+ * @return rounded time
+ */
+struct GNUNET_TIME_Absolute
+GNUNET_TIME_absolute_round_down (struct GNUNET_TIME_Absolute at,
+                                 struct GNUNET_TIME_Relative rt);
+
+
+/**
  * Return the maximum of two timestamps.
  *
  * @param t1 first timestamp
diff --git a/src/util/time.c b/src/util/time.c
index aeec2b3f9..cf072aebf 100644
--- a/src/util/time.c
+++ b/src/util/time.c
@@ -386,6 +386,20 @@ GNUNET_TIME_timestamp_min (struct GNUNET_TIME_Timestamp t1,
 }
 
 
+struct GNUNET_TIME_Absolute
+GNUNET_TIME_absolute_round_down (struct GNUNET_TIME_Absolute at,
+                                 struct GNUNET_TIME_Relative rt)
+{
+  struct GNUNET_TIME_Absolute ret;
+
+  GNUNET_assert (! GNUNET_TIME_relative_is_zero (rt));
+  ret.abs_value_us
+    = at.abs_value_us
+    - at.abs_value_us % rt.rel_value_us;
+  return ret;
+}
+
+
 struct GNUNET_TIME_Relative
 GNUNET_TIME_absolute_get_remaining (struct GNUNET_TIME_Absolute future)
 {