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fixing documentation errors / Edit Polynomial Formula of Crc16Algorithm.Ccitt #28

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Oct 9, 2023
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fixing documentation errors / Edit Polynomial Formula of Crc16Algorithm.Ccitt #28

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10 changes: 5 additions & 5 deletions NullFX.CRC/Crc16.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -112,7 +112,7 @@ internal static ushort ComputeChecksumInternal ( byte[] bytes, int start, int le
/// A CRC 16 CCITT Utility using a reversed x^16 + x^12 + x^8 + 1 polynomial (0x8408) with an initial CRC value of 0
/// </summary>
internal static class Crc16CcittKermitImpl {
// pre-computed table using reversed x^16 + x^15 + x^2 + 1 poly / 0x8408
// pre-computed table using reversed x^16 + x^12 + x^8 + 1 poly / 0x8408
static ushort[] table = { 0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF, 0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7, 0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E, 0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876, 0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD, 0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5, 0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C, 0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974, 0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB, 0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3, 0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A, 0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72, 0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9, 0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1, 0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738, 0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70, 0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7, 0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF, 0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036, 0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E, 0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5, 0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD, 0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134, 0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C, 0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3, 0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB, 0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232, 0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A, 0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1, 0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9, 0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330, 0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78 };
private const ushort InitialValue = ushort.MinValue;
/// <summary>
Expand Down Expand Up @@ -148,7 +148,7 @@ internal static ushort ComputeChecksumInternal ( byte[] bytes, int start, int le
}

/// <summary>
/// A CRC 16 CCITT Utility using x^16 + x^15 + x^2 + 1 polynomial with an initial CRC value of 0
/// A CRC 16 CCITT Utility using x^16 + x^12 + x^5 + 1 polynomial with an initial CRC value of 0
/// </summary>
internal static class Crc16CcittInitialZeroImpl {
private const ushort LocalInitialValue = ushort.MinValue;
Expand All @@ -174,7 +174,7 @@ public static ushort ComputeChecksumInternal ( byte[] bytes, int start, int leng
}

/// <summary>
/// A CRC 16 CCITT Utility using x^16 + x^15 + x^2 + 1 polynomial with an initial CRC value of 0xFFFF
/// A CRC 16 CCITT Utility using x^16 + x^12 + x^5 + 1 polynomial with an initial CRC value of 0xFFFF
/// </summary>
internal static class Crc16CcittInitial0XFfffImpl {
private const ushort LocalInitialValue = ushort.MaxValue;
Expand All @@ -200,7 +200,7 @@ public static ushort ComputeChecksumInternal ( byte[] bytes, int start, int leng
}

/// <summary>
/// A CRC 16 CCITT Utility using x^16 + x^15 + x^2 + 1 polynomial with an initial CRC value of 0x1D0F
/// A CRC 16 CCITT Utility using x^16 + x^12 + x^5 + 1 polynomial with an initial CRC value of 0x1D0F
/// </summary>
internal static class Crc16CcittInitial0X1D0FImpl {
private const ushort LocalInitialValue = 0x1D0F;
Expand All @@ -226,7 +226,7 @@ public static ushort ComputeChecksumInternal ( byte[] bytes, int start, int leng
}
// Base CRC 16 CCITT implementation
internal static class Crc16CcittBaseImpl {
// pre-computed table using x^16 + x^15 + x^2 + 1 polynomial / 0x1021
// pre-computed table using x^16 + x^12 + x^5 + 1 polynomial / 0x1021
internal static ushort[] Table { get; private set; } = { 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7, 0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF, 0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6, 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE, 0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485, 0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D, 0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4, 0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC, 0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823, 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B, 0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12, 0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A, 0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41, 0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49, 0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70, 0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78, 0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F, 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067, 0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E, 0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256, 0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D, 0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C, 0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634, 0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB, 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3, 0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A, 0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92, 0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9, 0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1, 0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8, 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0 };
// base compute checksum code
internal static ushort ComputeChecksumInternal ( ushort initialValue, params byte[] bytes ) {
Expand Down
8 changes: 4 additions & 4 deletions NullFX.CRC/Crc16Algorithm.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,19 +34,19 @@ public enum Crc16Algorithm {
/// </summary>
Standard,
/// <summary>
/// A CRC 16 CCITT Utility using x^16 + x^15 + x^2 + 1 polynomial with an initial CRC value of 0 (used in XMODEM, Bluetooth PACTOR, SD, DigRF and other communication)
/// A CRC 16 CCITT Utility using x^16 + x^12 + x^5 + 1 polynomial with an initial CRC value of 0 (used in XMODEM, Bluetooth PACTOR, SD, DigRF and other communication)
/// </summary>
Ccitt,
/// <summary>
/// Performs CRC 16 CCITT using a reversed x^16 + x^15 + x^2 + 1 polynomial with an initial CRC value of 0
/// Performs CRC 16 CCITT using a reversed x^16 + x^12 + x^8 + 1 polynomial with an initial CRC value of 0
/// </summary>
CcittKermit,
/// <summary>
/// Performs CRC 16 CCITT using x^16 + x^15 + x^2 + 1 polynomial with an initial CRC value of 0xffff
/// Performs CRC 16 CCITT using x^16 + x^12 + x^5 + 1 polynomial with an initial CRC value of 0xffff
/// </summary>
CcittInitialValue0xFFFF,
/// <summary>
/// Performs CRC 16 CCITT using x^16 + x^15 + x^2 + 1 polynomial with an initial CRC value of 0x1D0F
/// Performs CRC 16 CCITT using x^16 + x^12 + x^5 + 1 polynomial with an initial CRC value of 0x1D0F
/// </summary>
CcittInitialValue0x1D0F,
/// <summary>
Expand Down
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