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Document rtptime.

This commit is contained in:
Juliusz Chroboczek 2021-04-30 12:57:03 +02:00
parent 6c752b58bc
commit cd1ac8a8c9

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@ -1,40 +1,51 @@
// Package rtptime manipulates RTP and NTP time
package rtptime
import (
"time"
)
// epoch is the origin of NTP time
var epoch = time.Now()
// FromDuration converts a time.Duration into units of 1/hz.
func FromDuration(d time.Duration, hz uint32) uint64 {
return uint64(d) * uint64(hz) / uint64(time.Second)
}
// ToDuration converts units of 1/hz into a time.Duration.
func ToDuration(tm uint64, hz uint32) time.Duration {
return time.Duration(tm * uint64(time.Second) / uint64(hz))
}
// Now returns the current time in units of 1/hz from an arbitrary origin.
func Now(hz uint32) uint64 {
return FromDuration(time.Since(epoch), hz)
}
// Microseconds is like Now, but uses microseconds.
func Microseconds() uint64 {
return Now(1000000)
}
// JiffiesPerSec is the LCM of 48000, 96000 and 65536
// JiffiesPerSec is the number of jiffies in a second. This is the LCM of
// 48000, 96000 and 65536.
const JiffiesPerSec = 24576000
// Jiffies returns the current time in jiffies.
func Jiffies() uint64 {
return Now(JiffiesPerSec)
}
// TimeToJiffies converts a time.Time into jiffies.
func TimeToJiffies(tm time.Time) uint64 {
return FromDuration(tm.Sub(epoch), JiffiesPerSec)
}
// The origin of NTP time.
var ntpEpoch = time.Date(1900, 1, 1, 0, 0, 0, 0, time.UTC)
// NTPToTime converts an NTP time into a time.Time.
func NTPToTime(ntp uint64) time.Time {
sec := uint32(ntp >> 32)
frac := uint32(ntp & 0xFFFFFFFF)
@ -44,6 +55,7 @@ func NTPToTime(ntp uint64) time.Time {
)
}
// TimeToNTP converts a time.Time into an NTP time.
func TimeToNTP(tm time.Time) uint64 {
d := tm.Sub(ntpEpoch)
sec := uint32(d / time.Second)