time-util: introduce usec_sub()

The dual_timestamp_from_realtime(), dual_timestamp_from_monotonic()
and dual_timestamp_from_boottime_or_monotonic() shares the same
code for comparison given ts with delta. Let's move it to the
separate inline function to prevent code duplication.

diff --git a/src/basic/time-util.c b/src/basic/time-util.c
index 28b20f41805379dd6661974f62c3cfe141805d80..047d2a66d042f03979de9c82dc9b694e360404fb 100644 (file)
--- a/src/basic/time-util.c
+++ b/src/basic/time-util.c
@@ -73,12 +73,7 @@ dual_timestamp* dual_timestamp_from_realtime(dual_timestamp *ts, usec_t u) {
         ts->realtime = u;
 
         delta = (int64_t) now(CLOCK_REALTIME) - (int64_t) u;
-        ts->monotonic = now(CLOCK_MONOTONIC);
-
-        if ((int64_t) ts->monotonic > delta)
-                ts->monotonic -= delta;
-        else
-                ts->monotonic = 0;
+        ts->monotonic = usec_sub(now(CLOCK_MONOTONIC), delta);
 
         return ts;
 }
@@ -95,12 +90,7 @@ dual_timestamp* dual_timestamp_from_monotonic(dual_timestamp *ts, usec_t u) {
 
         ts->monotonic = u;
         delta = (int64_t) now(CLOCK_MONOTONIC) - (int64_t) u;
-
-        ts->realtime = now(CLOCK_REALTIME);
-        if ((int64_t) ts->realtime > delta)
-                ts->realtime -= delta;
-        else
-                ts->realtime = 0;
+        ts->realtime = usec_sub(now(CLOCK_REALTIME), delta);
 
         return ts;
 }
@@ -115,16 +105,8 @@ dual_timestamp* dual_timestamp_from_boottime_or_monotonic(dual_timestamp *ts, us
 
         dual_timestamp_get(ts);
         delta = (int64_t) now(clock_boottime_or_monotonic()) - (int64_t) u;
-
-        if ((int64_t) ts->realtime > delta)
-                ts->realtime -= delta;
-        else
-                ts->realtime = 0;
-
-        if ((int64_t) ts->monotonic > delta)
-                ts->monotonic -= delta;
-        else
-                ts->monotonic = 0;
+        ts->realtime = usec_sub(ts->realtime, delta);
+        ts->monotonic = usec_sub(ts->monotonic, delta);
 
         return ts;
 }