github.com/gopacket/gopacket@v1.1.0/time.go (about)

     1  // Copyright 2018 The GoPacket Authors. All rights reserved.
     2  //
     3  // Use of this source code is governed by a BSD-style license
     4  // that can be found in the LICENSE file in the root of the source
     5  // tree.
     6  
     7  package gopacket
     8  
     9  import (
    10  	"fmt"
    11  	"math"
    12  	"time"
    13  )
    14  
    15  // TimestampResolution represents the resolution of timestamps in Base^Exponent.
    16  type TimestampResolution struct {
    17  	Base, Exponent int
    18  }
    19  
    20  func (t TimestampResolution) String() string {
    21  	return fmt.Sprintf("%d^%d", t.Base, t.Exponent)
    22  }
    23  
    24  // ToDuration returns the smallest representable time difference as a time.Duration
    25  func (t TimestampResolution) ToDuration() time.Duration {
    26  	if t.Base == 0 {
    27  		return 0
    28  	}
    29  	if t.Exponent == 0 {
    30  		return time.Second
    31  	}
    32  	switch t.Base {
    33  	case 10:
    34  		return time.Duration(math.Pow10(t.Exponent + 9))
    35  	case 2:
    36  		if t.Exponent < 0 {
    37  			return time.Second >> uint(-t.Exponent)
    38  		}
    39  		return time.Second << uint(t.Exponent)
    40  	default:
    41  		// this might loose precision
    42  		return time.Duration(float64(time.Second) * math.Pow(float64(t.Base), float64(t.Exponent)))
    43  	}
    44  }
    45  
    46  // TimestampResolutionInvalid represents an invalid timestamp resolution
    47  var TimestampResolutionInvalid = TimestampResolution{}
    48  
    49  // TimestampResolutionMillisecond is a resolution of 10^-3s
    50  var TimestampResolutionMillisecond = TimestampResolution{10, -3}
    51  
    52  // TimestampResolutionMicrosecond is a resolution of 10^-6s
    53  var TimestampResolutionMicrosecond = TimestampResolution{10, -6}
    54  
    55  // TimestampResolutionNanosecond is a resolution of 10^-9s
    56  var TimestampResolutionNanosecond = TimestampResolution{10, -9}
    57  
    58  // TimestampResolutionNTP is the resolution of NTP timestamps which is 2^-32 ≈ 233 picoseconds
    59  var TimestampResolutionNTP = TimestampResolution{2, -32}
    60  
    61  // TimestampResolutionCaptureInfo is the resolution used in CaptureInfo, which his currently nanosecond
    62  var TimestampResolutionCaptureInfo = TimestampResolutionNanosecond
    63  
    64  // PacketSourceResolution is an interface for packet data sources that
    65  // support reporting the timestamp resolution of the aqcuired timestamps.
    66  // Returned timestamps will always have NanosecondTimestampResolution due
    67  // to the use of time.Time, but scaling might have occured if acquired
    68  // timestamps have a different resolution.
    69  type PacketSourceResolution interface {
    70  	// Resolution returns the timestamp resolution of acquired timestamps before scaling to NanosecondTimestampResolution.
    71  	Resolution() TimestampResolution
    72  }