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