RadioTapFields.cs

/*
This file is part of PacketDotNet.

This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/

using System;
using System.IO;
using PacketDotNet.Utils.Converters;

namespace PacketDotNet.Ieee80211;

/// <summary>
/// The presence of this field indicates that the frame was received or transmitted using the VHT PHY (Wi-Fi 5 / ieee802.11ac).
/// </summary>
public class VeryHighThroughputRadioTapField : RadioTapField
{
    /// <summary>
    /// Indicates the precense of data in this field
    /// </summary>
    public RadioTapVhtKnown Known { get; set; }

    /// <summary>
    /// VHT Flags
    /// </summary>
    public RadioTapVhtFlags Flags { get; set; }

    /// <summary>
    /// Indicates the bandwidth and side channel for a frame capture with VHT
    /// </summary>
    public RadioTapVhtBandwidth Bandwidth { get; set; }

    /// <summary>
    /// Indicates MCS and NSS for user 1
    /// </summary>
    public RadioTapVhtMcsNss McsNss1 { get; set; }

    /// <summary>
    /// Indicates MCS and NSS for user 2
    /// </summary>
    public RadioTapVhtMcsNss McsNss2 { get; set; }

    /// <summary>
    /// Indicates MCS and NSS for user 3
    /// </summary>
    public RadioTapVhtMcsNss McsNss3 { get; set; }

    /// <summary>
    /// Indicates MCS and NSS for user 4
    /// </summary>
    public RadioTapVhtMcsNss McsNss4 { get; set; }

    /// <summary>
    /// The coding for a user is only valid if the NSS (in the mcs_nss field) for that user is nonzero.
    /// Encodes the FEC for up to four users
    /// </summary>
    public RadioTapVhtCoding Coding { get; set; }

    /// <summary>
    /// Group ID
    /// The Group ID can be used to differentiate between SU PPDUs (group ID is 0 or 63) and MU PPDUs (group ID is 1 through 62).
    /// </summary>
    public byte GroupId { get; set; }

    /// <summary>
    /// Partial AID
    /// Only applicable to SU PPDUs.
    /// </summary>
    public ushort PartialAid { get; set; }

    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public VeryHighThroughputRadioTapField(BinaryReader br)
    {
        Known = (RadioTapVhtKnown)br.ReadUInt16();
        Flags = (RadioTapVhtFlags)br.ReadByte();
        Bandwidth = (RadioTapVhtBandwidth)br.ReadByte();
        McsNss1 = (RadioTapVhtMcsNss)br.ReadByte();
        McsNss2 = (RadioTapVhtMcsNss)br.ReadByte();
        McsNss3 = (RadioTapVhtMcsNss)br.ReadByte();
        McsNss4 = (RadioTapVhtMcsNss)br.ReadByte();
        Coding = (RadioTapVhtCoding)br.ReadByte();
        GroupId = br.ReadByte();
        PartialAid = br.ReadUInt16();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="VeryHighThroughputRadioTapField" /> class.
    /// </summary>
    public VeryHighThroughputRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="VeryHighThroughputRadioTapField" /> class.
    /// </summary>
    public VeryHighThroughputRadioTapField(
        RadioTapVhtKnown known, 
        RadioTapVhtFlags flags, 
        RadioTapVhtBandwidth bandwidth,
        RadioTapVhtMcsNss mcsNss1,
        RadioTapVhtMcsNss mcsNss2,
        RadioTapVhtMcsNss mcsNss3,
        RadioTapVhtMcsNss mcsNss4,
        RadioTapVhtCoding coding,
        byte groupId,
        ushort partialAid)
    {
        Known = known;
        Flags = flags;
        Bandwidth = bandwidth;
        McsNss1 = mcsNss1;
        McsNss2 = mcsNss2;
        McsNss3 = mcsNss3;
        McsNss4 = mcsNss4;
        Coding = coding;
        GroupId = groupId;
        PartialAid = partialAid;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.VeryHighThroughput;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 12;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => 2;


    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        EndianBitConverter.Little.CopyBytes((ushort)Known, dest, offset);
        EndianBitConverter.Little.CopyBytes((byte)Flags, dest, offset + 2);
        EndianBitConverter.Little.CopyBytes((byte)Bandwidth, dest, offset + 3);
        EndianBitConverter.Little.CopyBytes((byte)McsNss1, dest, offset + 4);
        EndianBitConverter.Little.CopyBytes((byte)McsNss2, dest, offset + 5);
        EndianBitConverter.Little.CopyBytes((byte)McsNss3, dest, offset + 6);
        EndianBitConverter.Little.CopyBytes((byte)McsNss4, dest, offset + 7);
        EndianBitConverter.Little.CopyBytes((byte)Coding, dest, offset + 8);
        EndianBitConverter.Little.CopyBytes(GroupId, dest, offset + 9);
        EndianBitConverter.Little.CopyBytes(PartialAid, dest, offset + 10);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"Known {Known}, Flags {Flags}, Bandwidth {Bandwidth}, McsNss1 {McsNss1}, McsNss2 {McsNss2}, McsNss3 {McsNss3}, McsNss4 {McsNss4}, Coding {Coding}, GroupId {GroupId}, PartialAid {PartialAid}";
    }
}

/// <summary>
/// The presence of this field indicates that the frame was received or transmitted using the HE PHY (Wi-Fi 6 / ieee802.11ax).
/// </summary>
public class HighEfficiencyRadioTapField : RadioTapField
{
    /// <summary>
    /// Indicates the presence of known fields as well as the HE PPDU format
    /// </summary>
    public RadioTapHighEfficiencyData1 Data1 { get; set; }

    /// <summary>
    /// Indicates the presence of known fields as well as the PRI/SEC 80MHz field
    /// </summary>
    public RadioTapHighEfficiencyData2 Data2 { get; set; }

    /// <summary>
    /// Indicates the presence of additional known fields as well as the value of pri/sec 80MHz
    /// </summary>
    public RadioTapHighEfficiencyData3 Data3 { get; set; }

    /// <summary>
    /// Data depends on the PPDU Format (See Data.HePpduFormat)
    /// </summary>
    public ushort Data4 { get; set; }

    /// <summary>
    /// Data fields where the availability depends on the known flags from Data1/Data2
    /// </summary>
    public RadioTapHighEfficiencyData5 Data5 { get; set; }

    /// <summary>
    /// Data fields where the availability depends on the known flags from Data1/Data2
    /// </summary>
    public RadioTapHighEfficiencyData6 Data6 { get; set; }

    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public HighEfficiencyRadioTapField(BinaryReader br)
    {
        Data1 = (RadioTapHighEfficiencyData1)br.ReadUInt16();
        Data2 = (RadioTapHighEfficiencyData2)br.ReadUInt16();
        Data3 = (RadioTapHighEfficiencyData3)br.ReadUInt16();
        Data4 = br.ReadUInt16();
        Data5 = (RadioTapHighEfficiencyData5)br.ReadUInt16();
        Data6 = (RadioTapHighEfficiencyData6)br.ReadUInt16();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="HighEfficiencyRadioTapField" /> class.
    /// </summary>
    public HighEfficiencyRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="HighEfficiencyRadioTapField" /> class.
    /// </summary>
    public HighEfficiencyRadioTapField(RadioTapHighEfficiencyData1 data1, RadioTapHighEfficiencyData2 data2, RadioTapHighEfficiencyData3 data3, ushort data4, RadioTapHighEfficiencyData5 data5, RadioTapHighEfficiencyData6 data6)
    {
        Data1 = data1;
        Data2 = data2;
        Data3 = data3;
        Data4 = data4;
        Data5 = data5;
        Data6 = data6;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.HighEfficiency;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 12;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => 2;

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        EndianBitConverter.Little.CopyBytes((ushort)Data1, dest, offset);
        EndianBitConverter.Little.CopyBytes((ushort)Data2, dest, offset + 2);
        EndianBitConverter.Little.CopyBytes((ushort)Data3, dest, offset + 4);
        EndianBitConverter.Little.CopyBytes(Data4, dest, offset + 6);
        EndianBitConverter.Little.CopyBytes((ushort)Data5, dest, offset + 8);
        EndianBitConverter.Little.CopyBytes((ushort)Data6, dest, offset + 10);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"Data1 {Data1}, Data2 {Data2}, Data3 {Data3}, Data4 {Data4}, Data5 {Data5}, Data6 {Data6}";
    }
}

public class McsRadioTapField : RadioTapField
{
    /// <summary>
    /// Indicates which information is known
    /// </summary>
    public RadioTapMcsKnown Known { get; set; }

    /// <summary>
    /// Indicates which information is known
    /// </summary>
    public RadioTapMcsFlags Flags { get; set; }

    /// <summary>
    /// Modulation and Coding Scheme
    /// Determines the modulation type and coding rate.
    /// </summary>
    public byte Mcs { get; set; }

    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public McsRadioTapField(BinaryReader br)
    {
        Known = (RadioTapMcsKnown)br.ReadByte();
        Flags = (RadioTapMcsFlags)br.ReadByte();
        Mcs = br.ReadByte();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="McsRadioTapField" /> class.
    /// </summary>
    public McsRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="McsRadioTapField" /> class.
    /// <param name="known">Known information</param>
    /// <param name="flags">MCS Flags</param>
    /// <param name="mcs">Known information</param>
    /// </summary>
    public McsRadioTapField(RadioTapMcsKnown known, RadioTapMcsFlags flags, byte mcs)
    {
        Known = known;
        Flags = flags;
        Mcs = mcs;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.Mcs;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 3;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => 1;

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        EndianBitConverter.Little.CopyBytes((byte)Known, dest, offset);
        EndianBitConverter.Little.CopyBytes((byte)Flags, dest, offset + 1);
        EndianBitConverter.Little.CopyBytes((byte)Mcs, dest, offset + 2);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"Known {Known}, Flags {Flags}, Mcs {Mcs}";
    }
}

/// <summary>
/// Channel field
/// </summary>
public class ChannelRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public ChannelRadioTapField(BinaryReader br)
    {
        FrequencyMHz = br.ReadUInt16();
        Channel = ChannelFromFrequencyMHz(FrequencyMHz);
        Flags = (RadioTapChannelFlags) br.ReadUInt16();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="ChannelRadioTapField" /> class.
    /// </summary>
    public ChannelRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="ChannelRadioTapField" /> class.
    /// </summary>
    /// <param name="frequencyMhz">Tx/Rx Frequency in MHz.</param>
    /// <param name="flags">Flags.</param>
    public ChannelRadioTapField(ushort frequencyMhz, RadioTapChannelFlags flags)
    {
        FrequencyMHz = frequencyMhz;
        Channel = ChannelFromFrequencyMHz(FrequencyMHz);
        Flags = flags;
    }

    /// <summary>
    /// Channel number derived from frequency
    /// </summary>
    public int Channel { get; set; }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.Channel;

    /// <summary>
    /// Gets the channel flags.
    /// </summary>
    public RadioTapChannelFlags Flags { get; }

    /// <summary>
    /// Frequency in MHz
    /// </summary>
    public ushort FrequencyMHz { get; set; }

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 4;

    /// <summary>
    /// Note that the alignment of the channel field is two bytes as it is comprised of two 2 byte fields
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => 2;

    /// <summary>
    /// Convert a frequency to a channel
    /// </summary>
    /// <remarks>
    /// There is some overlap between the 802.11b/g channel numbers and the 802.11a channel numbers. This means that while a particular frequncy will only
    /// ever map to single channel number the same channel number may be returned for more than one frequency. At present this affects channel numbers 8 and 12.
    /// </remarks>
    /// <param name="frequencyMHz">
    /// A <see cref="int" />
    /// </param>
    /// <returns>
    /// A <see cref="int" />
    /// </returns>
    public static int ChannelFromFrequencyMHz(int frequencyMHz)
    {
        switch (frequencyMHz)
        {
            //802.11 bg channel numbers
            case 2412:
            {
                return 1;
            }
            case 2417:
            {
                return 2;
            }
            case 2422:
            {
                return 3;
            }
            case 2427:
            {
                return 4;
            }
            case 2432:
            {
                return 5;
            }
            case 2437:
            {
                return 6;
            }
            case 2442:
            {
                return 7;
            }
            case 2447:
            {
                return 8;
            }
            case 2452:
            {
                return 9;
            }
            case 2457:
            {
                return 10;
            }
            case 2462:
            {
                return 11;
            }
            case 2467:
            {
                return 12;
            }
            case 2472:
            {
                return 13;
            }
            case 2484:
            {
                return 14;
            }
            //802.11 a channel numbers
            case 4920:
            {
                return 240;
            }
            case 4940:
            {
                return 244;
            }
            case 4960:
            {
                return 248;
            }
            case 4980:
            {
                return 252;
            }
            case 5040:
            {
                return 8;
            }
            case 5060:
            {
                return 12;
            }
            case 5080:
            {
                return 16;
            }
            case 5170:
            {
                return 34;
            }
            case 5180:
            {
                return 36;
            }
            case 5190:
            {
                return 38;
            }
            case 5200:
            {
                return 40;
            }
            case 5210:
            {
                return 42;
            }
            case 5220:
            {
                return 44;
            }
            case 5230:
            {
                return 46;
            }
            case 5240:
            {
                return 48;
            }
            case 5260:
            {
                return 52;
            }
            case 5280:
            {
                return 56;
            }
            case 5300:
            {
                return 60;
            }
            case 5320:
            {
                return 64;
            }
            case 5500:
            {
                return 100;
            }
            case 5520:
            {
                return 104;
            }
            case 5540:
            {
                return 108;
            }
            case 5560:
            {
                return 112;
            }
            case 5580:
            {
                return 116;
            }
            case 5600:
            {
                return 120;
            }
            case 5620:
            {
                return 124;
            }
            case 5640:
            {
                return 128;
            }
            case 5660:
            {
                return 132;
            }
            case 5680:
            {
                return 136;
            }
            case 5700:
            {
                return 140;
            }
            case 5745:
            {
                return 149;
            }
            case 5765:
            {
                return 153;
            }
            case 5785:
            {
                return 157;
            }
            case 5805:
            {
                return 161;
            }
            case 5825:
            {
                return 165;
            }
            default:
            {
                return 0;
            }
        }
    }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        EndianBitConverter.Little.CopyBytes(FrequencyMHz, dest, offset);
        EndianBitConverter.Little.CopyBytes((ushort) Flags, dest, offset + 2);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"FrequencyMHz {FrequencyMHz}, Channel {Channel}, Flags {Flags}";
    }
}

/// <summary>
/// Fhss radio tap field
/// </summary>
public class FhssRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public FhssRadioTapField(BinaryReader br)
    {
        var u16 = br.ReadUInt16();

        ChannelHoppingSet = (byte) (u16 & 0xff);
        Pattern = (byte) ((u16 >> 8) & 0xff);
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="FhssRadioTapField" /> class.
    /// </summary>
    public FhssRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="FhssRadioTapField" /> class.
    /// </summary>
    /// <param name='channelHoppingSet'>
    /// Channel hopping set.
    /// </param>
    /// <param name='pattern'>
    /// Channel hopping pattern.
    /// </param>
    public FhssRadioTapField(byte channelHoppingSet, byte pattern)
    {
        ChannelHoppingSet = channelHoppingSet;
        Pattern = pattern;
    }

    /// <summary>
    /// Hop set
    /// </summary>
    public byte ChannelHoppingSet { get; set; }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.Fhss;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 2;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Hop pattern
    /// </summary>
    public byte Pattern { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = ChannelHoppingSet;
        dest[offset + 1] = Pattern;
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"ChannelHoppingSet {ChannelHoppingSet}, Pattern {Pattern}";
    }
}

/// <summary>
/// Radio tap flags
/// </summary>
public class FlagsRadioTapField : RadioTapField
{
    /// <summary>
    /// Flags set
    /// </summary>
    public RadioTapFlags Flags;

    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public FlagsRadioTapField(BinaryReader br)
    {
        var u8 = br.ReadByte();
        Flags = (RadioTapFlags) u8;
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="FlagsRadioTapField" /> class.
    /// </summary>
    public FlagsRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="FlagsRadioTapField" /> class.
    /// </summary>
    /// <param name='flags'>
    /// Flags.
    /// </param>
    public FlagsRadioTapField(RadioTapFlags flags)
    {
        Flags = flags;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.Flags;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 1;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = (byte) Flags;
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"Flags {Flags}";
    }
}

/// <summary>
/// Rate field
/// </summary>
public class RateRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public RateRadioTapField(BinaryReader br)
    {
        var u8 = br.ReadByte();
        RateMbps = 0.5 * (u8 & 0x7f);
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="RateRadioTapField" /> class.
    /// </summary>
    public RateRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="RateRadioTapField" /> class.
    /// </summary>
    /// <param name='rateMbps'>
    /// Rate mbps.
    /// </param>
    public RateRadioTapField(double rateMbps)
    {
        RateMbps = rateMbps;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.Rate;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 1;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Rate in Mbps
    /// </summary>
    public double RateMbps { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = (byte) (RateMbps / 0.5);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"RateMbps {RateMbps}";
    }
}

/// <summary>
/// Db antenna signal
/// </summary>
public class DbAntennaSignalRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public DbAntennaSignalRadioTapField(BinaryReader br)
    {
        SignalStrengthdB = br.ReadByte();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbAntennaSignalRadioTapField" /> class.
    /// </summary>
    public DbAntennaSignalRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbAntennaSignalRadioTapField" /> class.
    /// </summary>
    /// <param name='signalStrengthdB'>
    /// Signal strength in dB
    /// </param>
    public DbAntennaSignalRadioTapField(byte signalStrengthdB)
    {
        SignalStrengthdB = signalStrengthdB;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.DbAntennaSignal;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 1;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Signal strength in dB
    /// </summary>
    public byte SignalStrengthdB { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = SignalStrengthdB;
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"SignalStrengthdB {SignalStrengthdB}";
    }
}

/// <summary>
/// Antenna noise in dB
/// </summary>
public class DbAntennaNoiseRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public DbAntennaNoiseRadioTapField(BinaryReader br)
    {
        AntennaNoisedB = br.ReadByte();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbAntennaNoiseRadioTapField" /> class.
    /// </summary>
    public DbAntennaNoiseRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbAntennaNoiseRadioTapField" /> class.
    /// </summary>
    /// <param name='antennaNoisedB'>
    /// Antenna signal noise in dB.
    /// </param>
    public DbAntennaNoiseRadioTapField(byte antennaNoisedB)
    {
        AntennaNoisedB = antennaNoisedB;
    }

    /// <summary>
    /// Antenna noise in dB
    /// </summary>
    public byte AntennaNoisedB { get; set; }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.DbAntennaNoise;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 1;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = AntennaNoisedB;
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"AntennaNoisedB {AntennaNoisedB}";
    }
}

/// <summary>
/// Antenna field
/// </summary>
public class AntennaRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public AntennaRadioTapField(BinaryReader br)
    {
        Antenna = br.ReadByte();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="AntennaRadioTapField" /> class.
    /// </summary>
    public AntennaRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="AntennaRadioTapField" /> class.
    /// </summary>
    /// <param name='antenna'>
    /// Antenna index of the Rx/Tx antenna for this packet. The first antenna is antenna 0.
    /// </param>
    public AntennaRadioTapField(byte antenna)
    {
        Antenna = antenna;
    }

    /// <summary>
    /// Antenna number
    /// </summary>
    public byte Antenna { get; set; }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.Antenna;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 1;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = Antenna;
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"Antenna {Antenna}";
    }
}

/// <summary>
/// Antenna signal in dBm
/// </summary>
public class DbmAntennaSignalRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public DbmAntennaSignalRadioTapField(BinaryReader br)
    {
        AntennaSignalDbm = br.ReadSByte();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbmAntennaSignalRadioTapField" /> class.
    /// </summary>
    public DbmAntennaSignalRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbmAntennaSignalRadioTapField" /> class.
    /// </summary>
    /// <param name='antennaSignalDbm'>
    /// Antenna signal power in dB.
    /// </param>
    public DbmAntennaSignalRadioTapField(sbyte antennaSignalDbm)
    {
        AntennaSignalDbm = antennaSignalDbm;
    }

    /// <summary>
    /// Antenna signal in dBm
    /// </summary>
    public sbyte AntennaSignalDbm { get; set; }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.DbmAntennaSignal;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 1;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = (byte) AntennaSignalDbm;
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"AntennaSignalDbm {AntennaSignalDbm}";
    }
}

/// <summary>
/// Antenna noise in dBm
/// </summary>
public class DbmAntennaNoiseRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public DbmAntennaNoiseRadioTapField(BinaryReader br)
    {
        AntennaNoisedBm = br.ReadSByte();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbmAntennaNoiseRadioTapField" /> class.
    /// </summary>
    public DbmAntennaNoiseRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbmAntennaNoiseRadioTapField" /> class.
    /// </summary>
    /// <param name='antennaNoisedBm'>
    /// Antenna noise in dBm.
    /// </param>
    public DbmAntennaNoiseRadioTapField(sbyte antennaNoisedBm)
    {
        AntennaNoisedBm = antennaNoisedBm;
    }

    /// <summary>
    /// Antenna noise in dBm
    /// </summary>
    public sbyte AntennaNoisedBm { get; set; }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.DbmAntennaNoise;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 1;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = (byte) AntennaNoisedBm;
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"AntennaNoisedBm {AntennaNoisedBm}";
    }
}

/// <summary>
/// Lock quality
/// </summary>
public class LockQualityRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public LockQualityRadioTapField(BinaryReader br)
    {
        SignalQuality = br.ReadUInt16();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="LockQualityRadioTapField" /> class.
    /// </summary>
    public LockQualityRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="LockQualityRadioTapField" /> class.
    /// </summary>
    /// <param name='signalQuality'>
    /// Signal quality.
    /// </param>
    public LockQualityRadioTapField(ushort signalQuality)
    {
        SignalQuality = signalQuality;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.LockQuality;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 2;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Signal quality
    /// </summary>
    public ushort SignalQuality { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        EndianBitConverter.Little.CopyBytes(SignalQuality, dest, offset);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"SignalQuality {SignalQuality}";
    }
}

/// <summary>
/// Tsft radio tap field
/// </summary>
public class TsftRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public TsftRadioTapField(BinaryReader br)
    {
        TimestampUsec = br.ReadUInt64();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="TsftRadioTapField" /> class.
    /// </summary>
    public TsftRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="TsftRadioTapField" /> class.
    /// </summary>
    /// <param name='timestampUsec'>
    /// Value in microseconds of the Time Synchronization Function timer
    /// </param>
    public TsftRadioTapField(ulong timestampUsec)
    {
        TimestampUsec = timestampUsec;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.Tsft;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 8;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Timestamp in microseconds
    /// </summary>
    public ulong TimestampUsec { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        EndianBitConverter.Little.CopyBytes(TimestampUsec, dest, offset);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"TimestampUsec {TimestampUsec}";
    }
}

/// <summary>
/// Contains properties about the received from.
/// </summary>
public class RxFlagsRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public RxFlagsRadioTapField(BinaryReader br)
    {
        var flags = br.ReadUInt16();
        PlcpCrcCheckFailed = (flags & 0x2) == 0x2;
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="RxFlagsRadioTapField" /> class.
    /// </summary>
    public RxFlagsRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="RxFlagsRadioTapField" /> class.
    /// </summary>
    /// <param name='plcpCrcCheckFailed'>
    /// PLCP CRC check failed.
    /// </param>
    public RxFlagsRadioTapField(bool plcpCrcCheckFailed)
    {
        PlcpCrcCheckFailed = plcpCrcCheckFailed;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.RxFlags;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 2;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Gets or sets a value indicating whether the frame failed the PLCP CRC check.
    /// </summary>
    /// <value>
    /// <c>true</c> if the PLCP CRC check failed; otherwise, <c>false</c>.
    /// </value>
    public bool PlcpCrcCheckFailed { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        var flags = (ushort) (PlcpCrcCheckFailed ? 0x2 : 0x0);
        EndianBitConverter.Little.CopyBytes(flags, dest, offset);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"PlcpCrcCheckFailed {PlcpCrcCheckFailed}";
    }
}

/// <summary>
/// Transmit power expressed as unitless distance from max
/// power set at factory calibration.  0 is max power.
/// Monotonically nondecreasing with lower power levels.
/// </summary>
public class TxAttenuationRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public TxAttenuationRadioTapField(BinaryReader br)
    {
        TxPower = -br.ReadUInt16();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="TxAttenuationRadioTapField" /> class.
    /// </summary>
    public TxAttenuationRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="TxAttenuationRadioTapField" /> class.
    /// </summary>
    /// <param name='txPower'>
    /// Transmit power expressed as unitless distance from max power set at factory calibration. 0 is max power.
    /// </param>
    public TxAttenuationRadioTapField(int txPower)
    {
        TxPower = txPower;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.TxAttenuation;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 2;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Transmit power
    /// </summary>
    public int TxPower { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        var absValue = (ushort) Math.Abs(TxPower);
        EndianBitConverter.Little.CopyBytes(absValue, dest, offset);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"TxPower {TxPower}";
    }
}

/// <summary>
/// Transmit power expressed as decibel distance from max power
/// set at factory calibration.  0 is max power.  Monotonically
/// nondecreasing with lower power levels.
/// </summary>
public class DbTxAttenuationRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public DbTxAttenuationRadioTapField(BinaryReader br)
    {
        TxPowerdB = -br.ReadUInt16();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbTxAttenuationRadioTapField" /> class.
    /// </summary>
    public DbTxAttenuationRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbTxAttenuationRadioTapField" /> class.
    /// </summary>
    /// <param name='txPowerdB'>
    /// Transmit power expressed as decibel distance from max power set at factory calibration. 0 is max power.
    /// </param>
    public DbTxAttenuationRadioTapField(int txPowerdB)
    {
        TxPowerdB = txPowerdB;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.DbTxAttenuation;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 2;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Transmit power
    /// </summary>
    public int TxPowerdB { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        var absValue = (ushort) Math.Abs(TxPowerdB);
        EndianBitConverter.Little.CopyBytes(absValue, dest, offset);
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"TxPowerdB {TxPowerdB}";
    }
}

/// <summary>
/// Transmit power expressed as dBm (decibels from a 1 milliwatt
/// reference). This is the absolute power level measured at
/// the antenna port.
/// </summary>
public class DbmTxPowerRadioTapField : RadioTapField
{
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    public DbmTxPowerRadioTapField(BinaryReader br)
    {
        TxPowerdBm = br.ReadSByte();
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbmTxPowerRadioTapField" /> class.
    /// </summary>
    public DbmTxPowerRadioTapField()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="DbmTxPowerRadioTapField" /> class.
    /// </summary>
    /// <param name='txPowerdBm'>
    /// Transmit power expressed as dBm (decibels from a 1 milliwatt reference).
    /// </param>
    public DbmTxPowerRadioTapField(sbyte txPowerdBm)
    {
        TxPowerdBm = txPowerdBm;
    }

    /// <summary>Type of the field</summary>
    public override RadioTapType FieldType => RadioTapType.DbmTxPower;

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public override ushort Length => 1;

    /// <summary>
    /// Gets the alignment.
    /// </summary>
    /// <value>The alignment.</value>
    public override ushort Alignment => Length;

    /// <summary>
    /// Tx power in dBm
    /// </summary>
    public sbyte TxPowerdBm { get; set; }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public override void CopyTo(byte[] dest, int offset)
    {
        dest[offset] = (byte) TxPowerdBm;
    }

    /// <summary>
    /// ToString() override
    /// </summary>
    /// <returns>
    /// A <see cref="string" />
    /// </returns>
    public override string ToString()
    {
        return $"TxPowerdBm {TxPowerdBm}";
    }
}

/// <summary>
/// Abstract class for all radio tap fields
/// </summary>
public abstract class RadioTapField
{
    /// <summary>Type of the field</summary>
    public abstract RadioTapType FieldType { get; }

    /// <summary>
    /// Gets the length of the field data.
    /// </summary>
    /// <value>
    /// The length.
    /// </value>
    public abstract ushort Length { get; }

    /// <summary>
    /// Gets the alignment length for this field.
    /// </summary>
    /// <value>The alignment.</value>
    public abstract ushort Alignment { get; }

    /// <summary>
    /// Based on the radiotap bitfield determine the fieldAlignment
    /// </summary>
    /// <returns><c>true</c>, if field was found, <c>false</c> otherwise.</returns>
    /// <param name="bitIndex">Bit index.</param>
    /// <param name="fieldAlignment">Field length.</param>
    public static bool FieldAlignment(int bitIndex, out ushort fieldAlignment)
    {
        // leverage the existing Parse() routine with a dummy buffer to decode a
        // RadioTapField instance so we can retrieve its length
        var emptyBuffer = new byte[32];
        var memoryStream = new MemoryStream(emptyBuffer);
        var binaryReader = new BinaryReader(memoryStream);

        var field = Parse(bitIndex, binaryReader);
        if (field != null)
        {
            fieldAlignment = field.Alignment;
            return true;
        }

        fieldAlignment = 0;
        return false;
    }

    /// <summary>
    /// Parse a radio tap field, indicated by bitIndex, from a given BinaryReader
    /// </summary>
    /// <param name="bitIndex">
    /// A <see cref="int" />
    /// </param>
    /// <param name="br">
    /// A <see cref="BinaryReader" />
    /// </param>
    /// <returns>
    /// A <see cref="RadioTapField" />
    /// </returns>
    public static RadioTapField Parse(int bitIndex, BinaryReader br)
    {
        var type = (RadioTapType) bitIndex;
        switch (type)
        {
            case RadioTapType.Flags:
            {
                return new FlagsRadioTapField(br);
            }
            case RadioTapType.Rate:
            {
                return new RateRadioTapField(br);
            }
            case RadioTapType.DbAntennaSignal:
            {
                return new DbAntennaSignalRadioTapField(br);
            }
            case RadioTapType.DbAntennaNoise:
            {
                return new DbAntennaNoiseRadioTapField(br);
            }
            case RadioTapType.Antenna:
            {
                return new AntennaRadioTapField(br);
            }
            case RadioTapType.DbmAntennaSignal:
            {
                return new DbmAntennaSignalRadioTapField(br);
            }
            case RadioTapType.DbmAntennaNoise:
            {
                return new DbmAntennaNoiseRadioTapField(br);
            }
            case RadioTapType.Channel:
            {
                return new ChannelRadioTapField(br);
            }
            case RadioTapType.Fhss:
            {
                return new FhssRadioTapField(br);
            }
            case RadioTapType.LockQuality:
            {
                return new LockQualityRadioTapField(br);
            }
            case RadioTapType.TxAttenuation:
            {
                return new TxAttenuationRadioTapField(br);
            }
            case RadioTapType.DbTxAttenuation:
            {
                return new DbTxAttenuationRadioTapField(br);
            }
            case RadioTapType.DbmTxPower:
            {
                return new DbmTxPowerRadioTapField(br);
            }
            case RadioTapType.Tsft:
            {
                return new TsftRadioTapField(br);
            }
            case RadioTapType.RxFlags:
            {
                return new RxFlagsRadioTapField(br);
            }
            case RadioTapType.Mcs:
            {
                return new McsRadioTapField(br);
            }
            case RadioTapType.HighEfficiency:
            {
                return new HighEfficiencyRadioTapField(br);
            }
            case RadioTapType.VeryHighThroughput:
            {
                return new VeryHighThroughputRadioTapField(br);
            }
            default:
            {
                //the RadioTap fields are extendable so there may be some we dont know about
                return null;
            }
        }
    }

    /// <summary>
    /// Copies the field data to the destination buffer at the specified offset.
    /// </summary>
    public abstract void CopyTo(byte[] dest, int offset);
}