mirror of https://github.com/jech/galene.git
72 lines
1.8 KiB
Go
72 lines
1.8 KiB
Go
// Package rtptime manipulates RTP and NTP time
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package rtptime
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import (
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"time"
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)
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// epoch is the origin of NTP time
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var epoch = time.Now()
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// FromDuration converts a time.Duration into units of 1/hz.
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func FromDuration(d time.Duration, hz uint32) int64 {
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return int64(d) * int64(hz) / int64(time.Second)
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}
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// ToDuration converts units of 1/hz into a time.Duration.
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func ToDuration(tm int64, hz uint32) time.Duration {
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return time.Duration(tm * int64(time.Second) / int64(hz))
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}
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func sat(a int64) uint64 {
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if a < 0 {
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return 0
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}
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return uint64(a)
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}
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// Now returns the current time in units of 1/hz from an arbitrary origin.
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func Now(hz uint32) uint64 {
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return sat(FromDuration(time.Since(epoch), hz))
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}
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// Microseconds is like Now, but uses microseconds.
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func Microseconds() uint64 {
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return Now(1000000)
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}
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// JiffiesPerSec is the number of jiffies in a second. This is the LCM of
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// 48000, 96000 and 65536.
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const JiffiesPerSec = 24576000
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// Jiffies returns the current time in jiffies.
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func Jiffies() uint64 {
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return Now(JiffiesPerSec)
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}
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// TimeToJiffies converts a time.Time into jiffies.
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func TimeToJiffies(tm time.Time) uint64 {
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return sat(FromDuration(tm.Sub(epoch), JiffiesPerSec))
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}
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// The origin of NTP time.
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var ntpEpoch = time.Date(1900, 1, 1, 0, 0, 0, 0, time.UTC)
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// NTPToTime converts an NTP time into a time.Time.
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func NTPToTime(ntp uint64) time.Time {
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sec := uint32(ntp >> 32)
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frac := uint32(ntp & 0xFFFFFFFF)
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return ntpEpoch.Add(
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time.Duration(sec)*time.Second +
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((time.Duration(frac) * time.Second) >> 32),
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)
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}
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// TimeToNTP converts a time.Time into an NTP time.
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func TimeToNTP(tm time.Time) uint64 {
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d := tm.Sub(ntpEpoch)
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sec := uint32(d / time.Second)
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frac := uint32(d % time.Second)
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return (uint64(sec) << 32) + (uint64(frac)<<32)/uint64(time.Second)
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}
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