273 lines
9.4 KiB
C#
273 lines
9.4 KiB
C#
///
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/// Copyright (c) 2013-2021 Sensus Metering Systems
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///
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using System;
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using System.Collections.Generic;
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namespace Common
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{
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public static class Telegram
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{
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const UInt16 crcSeed = 0xFFFF; // Initial crc value
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const UInt16 crcGP = 0xA001; // Generating polynomial
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/// <summary>
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/// For standard CRC16 (remainder of division)
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/// to start a new crc, set CRC16 = SEED
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/// then for each byte call UpdateCRC(byte, &CRC16);
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/// CRC16 will contain the result
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/// (if you calculate all of the incoming data
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/// INCLUDING the crc, the result should be 0x0000
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/// and if you are sending the crc be sure to
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/// send the bytes in the correct order)
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/// <summary>
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static void UpdateCRC(byte b, ref UInt16 crc)
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{
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crc ^= (UInt16)b;
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for (int i = 0; i < 8; i++)
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{
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bool carry = (crc & 0x0001) != 0;
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crc >>= 1;
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if (carry) crc ^= crcGP;
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}
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}
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/// <summary>
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/// Calculates the CRC from a data telegram (an array of bytes).
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/// A complete telegram including two bytes reserved for the CRC
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="data">Data telegram</param>
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/// <returns>Calculated CRC</returns>
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public static UInt16 CalculateTelegramCRC(byte[] data, int enforcedLen = 0)
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{
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int len = (enforcedLen != 0) ? Math.Min(enforcedLen, data.Length) : data.Length;
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UInt16 crc = crcSeed;
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for (int i = 0; i < len - 2; i++) UpdateCRC(data[i], ref crc);
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return crc;
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}
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/// <summary>
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/// Calculates the CRC from a data telegram (an array of bytes).
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/// A complete telegram including two bytes reserved for the CRC
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="data">Data telegram</param>
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/// <returns>Calculated CRC</returns>
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public static UInt16 CalculateTelegramCRC(int offset, byte[] data, int enforcedLen = 0)
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{
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int len = (enforcedLen != 0) ? Math.Min(enforcedLen, data.Length - offset) : data.Length - offset;
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UInt16 crc = crcSeed;
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for (int i = 0; i < len - 2; i++) UpdateCRC(data[offset + i], ref crc);
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return crc;
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}
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/// <summary>
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/// This function modifies the last 2 bytes in the message buffer
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/// by the CRC calculated from the remaining first (Lenght - 2) bytes.
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/// A complete telegram including two bytes reserved for the CRC
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="data">Data telegram</param>
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public static void UpdateTelegramCRC(byte[] data)
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{
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int len = data.Length;
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if (len < 2) return;
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UInt16 crc = CalculateTelegramCRC(data);
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data[len - 2] = (byte)(crc & 0xFF);
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data[len - 1] = (byte)(crc >> 8);
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}
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/// <summary>
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/// This function compares the last 2 bytes in the message buffer
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/// with the CRC calculated from the remaining first (Lenght - 2) bytes.
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/// A complete telegram including two bytes reserved for the CRC
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="data">Data telegram</param>
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/// <returns>true if the CRC in the telegram is correct</returns>
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public static bool VerifyTelegramCRC(byte[] data, int enforcedLen = 0)
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{
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if (data == null || data.Length == 0 || enforcedLen > data.Length) return false;
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int len = (enforcedLen != 0) ? enforcedLen : data.Length;
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if (len < 2) return false;
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UInt16 crc = CalculateTelegramCRC(data, len);
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return (data[len - 2] == (byte)(crc & 0xFF)) && (data[len - 1] == (byte)(crc >> 8));
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}
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/// <summary>
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/// This function compares the last 2 bytes in the message buffer
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/// with the CRC calculated from the remaining first (Lenght - 2) bytes.
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/// A complete telegram including two bytes reserved for the CRC
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="data">Data telegram</param>
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/// <returns>true if the CRC in the telegram is correct</returns>
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public static bool VerifyTelegramCRC(int offset, byte[] data, int enforcedLen = 0)
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{
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if (data == null || data.Length == 0 || enforcedLen > data.Length - offset) return false;
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int len = (enforcedLen != 0) ? enforcedLen : data.Length - offset;
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if (len < 2) return false;
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UInt16 crc = CalculateTelegramCRC(offset, data, len);
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return (data[offset + len - 2] == (byte)(crc & 0xFF)) && (data[offset + len - 1] == (byte)(crc >> 8));
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}
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/// <summary>
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/// Calculates the checksum from a data telegram (an array of bytes).
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/// A complete telegram including one byte reserved for the checksum
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="data">Data telegram</param>
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/// <returns>Calculated checksum</returns>
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public static byte CalculateTelegramChecksum(byte[] data)
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{
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byte checksum = 0;
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for (int i = 0; i < data.Length - 1; i++) checksum = (byte)(checksum ^ data[i]);
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return checksum;
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}
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/// <summary>
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/// Calculates the checksum from a data telegram (an array of bytes).
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/// A complete telegram including one bytes reserved for the checksum
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="hartPreambLen">Length of HART telegram preamble (FF bytes)</param>
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/// <param name="data">Data telegram</param>
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/// <returns>Calculated checksum</returns>
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public static byte CalculateTelegramChecksum(int hartPreambLen, byte[] data)
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{
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byte checksum = 0;
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for (int i = hartPreambLen; i < data.Length - 1; i++) checksum = (byte)(checksum ^ data[i]);
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return checksum;
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}
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/// <summary>
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/// This function modifies the last byte in the message buffer
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/// by the checksum calculated from the remaining first (Lenght - 1) bytes.
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/// A complete telegram including one bytes reserved for the checksum
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="data">Data telegram</param>
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public static void UpdateTelegramChecksum(byte[] data)
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{
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int len = data.Length;
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if (len < 1) return;
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data[len - 1] = CalculateTelegramChecksum(data);
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}
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/// <summary>
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/// This function modifies the last byte in the message buffer
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/// by the checksum calculated from the preceeding (Lenght - hartPreambLen - 1) bytes.
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/// First hartPreambLen bytes in the telegram are skipped.
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/// A complete telegram including preamble and one bytes reserved for the checksum
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/// after data bytes must be supplied as an argument.
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/// </summary>
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/// <param name="hartPreambLen">Length of HART telegram preamble (FF bytes)</param>
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/// <param name="data">Data telegram</param>
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public static void UpdateTelegramChecksum(int hartPreambLen, byte[] data)
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{
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if (data.Length - hartPreambLen < 1) return;
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data[data.Length - 1] = CalculateTelegramChecksum(hartPreambLen, data);
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}
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/// <summary>
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/// This function compares the last byte in the message buffer
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/// with the checksum calculated from the remaining first (Lenght - 1) bytes.
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/// A complete telegram including two bytes reserved for the checksum
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="data">Data telegram</param>
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/// <returns>true if the checksum in the telegram is correct</returns>
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public static bool VerifyTelegramChecksum(byte[] data)
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{
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int len = data.Length;
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if (len < 1) return false;
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return (data[len - 1] == CalculateTelegramChecksum(data));
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}
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/// <summary>
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/// This function compares the last byte in the message buffer
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/// with the checksum calculated from the remaining first (Lenght - 1) bytes.
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/// A complete telegram including two bytes reserved for the checksum
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/// must be supplied as an argument.
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/// </summary>
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/// <param name="hartPreambLen">Length of HART telegram preamble (FF bytes)</param>
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/// <param name="data">Data telegram</param>
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/// <returns>true if the checksum in the telegram is correct</returns>
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public static bool VerifyTelegramChecksum(int hartPreambLen, byte[] data)
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{
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if (data.Length - hartPreambLen < 1) return false;
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return (data[data.Length - 1] == CalculateTelegramChecksum(hartPreambLen, data));
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}
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public static string LogTelegram(string intro, byte[] data, int from = 0, int len = -1)
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{
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System.Text.StringBuilder sb = new System.Text.StringBuilder(256);
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int length = (len >= 0) ? len : (data.Length - from);
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sb.Append(intro);
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sb.Append(length.ToString());
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sb.Append(" bytes:");
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for (int i = from; i < from + length; i++)
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{
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byte b = data[i];
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sb.Append(" ");
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sb.Append(((int)b).ToString("X2"));
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}
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return sb.ToString();
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}
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public static string LogTelegram(string intro, IList<byte> data, int from = 0, int len = -1)
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{
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System.Text.StringBuilder sb = new System.Text.StringBuilder(256);
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int length = (len >= 0) ? len : (data.Count - from);
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sb.Append(intro);
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sb.Append(length.ToString());
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sb.Append(" bytes:");
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for (int i = from; i < from + length; i++)
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{
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byte b = data[i];
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sb.Append(" ");
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sb.Append(((int)b).ToString("X2"));
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}
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return sb.ToString();
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}
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public static string LogTelegram(string intro, string data)
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{
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System.Text.StringBuilder sb = new System.Text.StringBuilder(80);
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sb.Append(intro);
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sb.Append(data.Length.ToString());
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sb.Append(" bytes:");
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foreach (var d in data)
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{
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sb.Append(" ");
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sb.Append(((int)d).ToString("X2"));
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}
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return sb.ToString();
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}
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}
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}
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