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// Copyright 2018 The GoPacket Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree.
package gopacket
import (
"fmt"
"math"
"time"
)
// TimestampResolution represents the resolution of timestamps in Base^Exponent.
type TimestampResolution struct {
Base, Exponent int
}
func (t TimestampResolution) String() string {
return fmt.Sprintf("%d^%d", t.Base, t.Exponent)
}
// ToDuration returns the smallest representable time difference as a time.Duration
func (t TimestampResolution) ToDuration() time.Duration {
if t.Base == 0 {
return 0
}
if t.Exponent == 0 {
return time.Second
}
switch t.Base {
case 10:
return time.Duration(math.Pow10(t.Exponent + 9))
case 2:
if t.Exponent < 0 {
return time.Second >> uint(-t.Exponent)
}
return time.Second << uint(t.Exponent)
default:
// this might loose precision
return time.Duration(float64(time.Second) * math.Pow(float64(t.Base), float64(t.Exponent)))
}
}
// TimestampResolutionInvalid represents an invalid timestamp resolution
var TimestampResolutionInvalid = TimestampResolution{}
// TimestampResolutionMillisecond is a resolution of 10^-3s
var TimestampResolutionMillisecond = TimestampResolution{10, -3}
// TimestampResolutionMicrosecond is a resolution of 10^-6s
var TimestampResolutionMicrosecond = TimestampResolution{10, -6}
// TimestampResolutionNanosecond is a resolution of 10^-9s
var TimestampResolutionNanosecond = TimestampResolution{10, -9}
// TimestampResolutionNTP is the resolution of NTP timestamps which is 2^-32 ≈ 233 picoseconds
var TimestampResolutionNTP = TimestampResolution{2, -32}
// TimestampResolutionCaptureInfo is the resolution used in CaptureInfo, which his currently nanosecond
var TimestampResolutionCaptureInfo = TimestampResolutionNanosecond
// PacketSourceResolution is an interface for packet data sources that
// support reporting the timestamp resolution of the aqcuired timestamps.
// Returned timestamps will always have NanosecondTimestampResolution due
// to the use of time.Time, but scaling might have occured if acquired
// timestamps have a different resolution.
type PacketSourceResolution interface {
// Resolution returns the timestamp resolution of acquired timestamps before scaling to NanosecondTimestampResolution.
Resolution() TimestampResolution
}
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