- offset = (monotonic[0] + monotonic[1]) >> 1;
- realtime = (uint64_t) rts.tv_sec * 1000000000ULL;
- realtime += rts.tv_nsec;
- offset = realtime - offset;
- return offset;
+ measure_delta = monotonic[1] - monotonic[0];
+ if (measure_delta > sample->measure_delta) {
+ /*
+ * Discard value if it took longer to read than the best
+ * sample so far.
+ */
+ return 0;
+ }
+ monotonic_avg = (monotonic[0] + monotonic[1]) >> 1;
+ realtime = (uint64_t) rts.tv_sec * tcf;
+ if (tcf == NSEC_PER_SEC) {
+ realtime += rts.tv_nsec;
+ } else {
+ realtime += (uint64_t) rts.tv_nsec * tcf / NSEC_PER_SEC;
+ }
+ offset = (int64_t) realtime - monotonic_avg;
+ sample->offset = max(offset, 0);
+ sample->measure_delta = measure_delta;
+ return 0;