This saves a few bytes of static storage and less instructions are
executed when looking for the best offset.
Signed-off-by: Georg Sauthoff <m...@gms.tf>
---
sysoff.c | 55 +++++++++++++++++++++++++++----------------------------
1 file changed, 27 insertions(+), 28 deletions(-)
diff --git a/sysoff.c b/sysoff.c
index 05d2ed6..ec77a0d 100644
--- a/sysoff.c
+++ b/sysoff.c
@@ -34,12 +34,6 @@ static int64_t pctns(struct ptp_clock_time *t)
return t->sec * NS_PER_SEC + t->nsec;
}
-static struct {
- int64_t interval;
- int64_t offset;
- uint64_t timestamp;
-} samples[PTP_MAX_SAMPLES];
-
static int sysoff_precise(int fd, int64_t *result, uint64_t *ts)
{
#ifdef PTP_SYS_OFFSET_PRECISE
@@ -57,28 +51,28 @@ static int sysoff_precise(int fd, int64_t *result, uint64_t
*ts)
#endif
}
-static void insertion_sort(int length, int64_t interval, int64_t offset,
uint64_t ts)
-{
- int i = length - 1;
- while (i >= 0) {
- if (samples[i].interval < interval)
- break;
- samples[i+1] = samples[i];
- i--;
- }
- samples[i+1].interval = interval;
- samples[i+1].offset = offset;
- samples[i+1].timestamp = ts;
-}
-
static int64_t sysoff_estimate(struct ptp_clock_time *pct, int extended,
int n_samples, uint64_t *ts, int64_t *delay)
{
int64_t t1, t2, tp;
- int64_t interval, offset;
- int i;
+ int64_t interval, timestamp, offset;
+ int64_t shortest_interval, best_timestamp, best_offset;
+ int i = 0;
+
+ if (extended) {
+ t1 = pctns(&pct[3*i]);
+ tp = pctns(&pct[3*i+1]);
+ t2 = pctns(&pct[3*i+2]);
+ } else {
+ t1 = pctns(&pct[2*i]);
+ tp = pctns(&pct[2*i+1]);
+ t2 = pctns(&pct[2*i+2]);
+ }
+ shortest_interval = t2 - t1;
+ best_timestamp = (t2 + t1) / 2;
+ best_offset = best_timestamp - tp;
- for (i = 0; i < n_samples; i++) {
+ for (i = 1; i < n_samples; i++) {
if (extended) {
t1 = pctns(&pct[3*i]);
tp = pctns(&pct[3*i+1]);
@@ -89,12 +83,17 @@ static int64_t sysoff_estimate(struct ptp_clock_time *pct,
int extended,
t2 = pctns(&pct[2*i+2]);
}
interval = t2 - t1;
- offset = (t2 + t1) / 2 - tp;
- insertion_sort(i, interval, offset, (t2 + t1) / 2);
+ timestamp = (t2 + t1) / 2;
+ offset = timestamp - tp;
+ if (interval < shortest_interval) {
+ shortest_interval = interval;
+ best_timestamp = timestamp;
+ best_offset = offset;
+ }
}
- *ts = samples[0].timestamp;
- *delay = samples[0].interval;
- return samples[0].offset;
+ *ts = best_timestamp;
+ *delay = shortest_interval;
+ return best_offset;
}
static int sysoff_extended(int fd, int n_samples,
--
2.25.4
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