From: Christian Grothoff <christian@grothoff.org>
Date: Mon, 3 May 2010 20:39:50 +0000 (+0000)
Subject: time subtract
X-Git-Tag: initial-import-from-subversion-38251~21907
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=e098493e473fcdc4824e9ab05518ffe1460af1e6;p=oweals%2Fgnunet.git

time subtract
---

diff --git a/src/include/gnunet_time_lib.h b/src/include/gnunet_time_lib.h
index b9c2d92f0..aa4e8d5db 100644
--- a/src/include/gnunet_time_lib.h
+++ b/src/include/gnunet_time_lib.h
@@ -314,6 +314,22 @@ struct GNUNET_TIME_Absolute GNUNET_TIME_absolute_add (struct
                                                       GNUNET_TIME_Relative
                                                       duration);
 
+
+/**
+ * Subtract a given relative duration from the
+ * given start time.
+ *
+ * @param start some absolute time
+ * @param duration some relative time to subtract
+ * @return ZERO if start <= duration, or FOREVER if start time is FOREVER; start-duration otherwise
+ */
+struct GNUNET_TIME_Absolute GNUNET_TIME_absolute_subtract (struct
+							   GNUNET_TIME_Absolute
+							   start,
+							   struct
+							   GNUNET_TIME_Relative
+							   duration);
+
 /**
  * Multiply relative time by a given factor.
  *
diff --git a/src/util/time.c b/src/util/time.c
index 6eccf4d9a..3d53e0af2 100644
--- a/src/util/time.c
+++ b/src/util/time.c
@@ -270,6 +270,33 @@ GNUNET_TIME_absolute_add (struct GNUNET_TIME_Absolute start,
   return ret;
 }
 
+
+/**
+ * Subtract a given relative duration from the
+ * given start time.
+ *
+ * @param start some absolute time
+ * @param duration some relative time to subtract
+ * @return ZERO if start <= duration, or FOREVER if start time is FOREVER; start-duration otherwise
+ */
+struct GNUNET_TIME_Absolute 
+GNUNET_TIME_absolute_subtract (struct
+			       GNUNET_TIME_Absolute
+			       start,
+			       struct
+			       GNUNET_TIME_Relative
+			       duration)
+{
+  struct GNUNET_TIME_Absolute ret;
+  if (start.value <= duration.value)
+    return GNUNET_TIME_UNIT_ZERO_ABS;
+  if (start.value == GNUNET_TIME_UNIT_FOREVER_ABS.value)
+    return GNUNET_TIME_UNIT_FOREVER_ABS;
+  ret.value = start.value - duration.value;
+  return ret;
+}
+
+
 /**
  * Multiply relative time by a given factor.
  *