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Implement NTP time.

This commit is contained in:
Juliusz Chroboczek 2020-05-02 18:41:18 +02:00
parent 303d15539c
commit 8fb8f7b7d5
2 changed files with 60 additions and 0 deletions

View file

@ -10,6 +10,10 @@ func fromDuration(d time.Duration, hz uint32) uint64 {
return uint64(d) * uint64(hz) / uint64(time.Second) return uint64(d) * uint64(hz) / uint64(time.Second)
} }
func toDuration(tm uint64, hz uint32) time.Duration {
return time.Duration(tm * uint64(time.Second) / uint64(hz))
}
func Now(hz uint32) uint64 { func Now(hz uint32) uint64 {
return fromDuration(time.Since(epoch), hz) return fromDuration(time.Since(epoch), hz)
} }
@ -17,3 +21,21 @@ func Now(hz uint32) uint64 {
func Microseconds() uint64 { func Microseconds() uint64 {
return Now(1000000) return Now(1000000)
} }
var ntpEpoch = time.Date(1900, 1, 1, 0, 0, 0, 0, time.UTC)
func NTPToTime(ntp uint64) time.Time {
sec := uint32(ntp >> 32)
frac := uint32(ntp & 0xFFFFFFFF)
return ntpEpoch.Add(
time.Duration(sec) * time.Second +
((time.Duration(frac) * time.Second) >> 32),
)
}
func TimeToNTP(tm time.Time) uint64 {
d := tm.Sub(ntpEpoch)
sec := uint32(d / time.Second)
frac := uint32(d % time.Second)
return (uint64(sec) << 32) + (uint64(frac) << 32) / uint64(time.Second)
}

View file

@ -5,6 +5,18 @@ import (
"time" "time"
) )
func TestDuration(t *testing.T) {
a := fromDuration(time.Second, 48000)
if a != 48000 {
t.Errorf("Expected 48000, got %v", a)
}
b := toDuration(48000, 48000)
if b != time.Second {
t.Errorf("Expected %v, got %v", time.Second, b)
}
}
func differs(a, b, delta uint64) bool { func differs(a, b, delta uint64) bool {
if a < b { if a < b {
a, b = b, a a, b = b, a
@ -27,3 +39,29 @@ func TestMono(t *testing.T) {
t.Errorf("Expected %v, got %v", 4000, d) t.Errorf("Expected %v, got %v", 4000, d)
} }
} }
func TestNTP(t *testing.T) {
now := time.Now()
ntp := TimeToNTP(now)
now2 := NTPToTime(ntp)
ntp2 := TimeToNTP(now2)
diff1 := now2.Sub(now)
if diff1 < 0 {
diff1 = -diff1
}
if diff1 > time.Nanosecond {
t.Errorf("Expected %v, got %v (diff=%v)",
now, now2, diff1)
}
diff2 := int64(ntp2 - ntp)
if diff2 < 0 {
diff2 = -diff2
}
if diff2 > (1 << 8) {
t.Errorf("Expected %v, got %v (diff=%v)",
ntp, ntp2, float64(diff2) / float64(1<<32))
}
}