diff options
Diffstat (limited to 'Emby.Server.Implementations/Networking/IPNetwork/BigIntegerExt.cs')
| -rw-r--r-- | Emby.Server.Implementations/Networking/IPNetwork/BigIntegerExt.cs | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/Emby.Server.Implementations/Networking/IPNetwork/BigIntegerExt.cs b/Emby.Server.Implementations/Networking/IPNetwork/BigIntegerExt.cs new file mode 100644 index 000000000..afb202fa3 --- /dev/null +++ b/Emby.Server.Implementations/Networking/IPNetwork/BigIntegerExt.cs @@ -0,0 +1,168 @@ +using System.Collections.Generic; + +namespace System.Net +{ + using System; + using System.Numerics; + using System.Text; + + /// <summary> + /// Extension methods to convert <see cref="System.Numerics.BigInteger"/> + /// instances to hexadecimal, octal, and binary strings. + /// </summary> + public static class BigIntegerExtensions + { + /// <summary> + /// Converts a <see cref="BigInteger"/> to a binary string. + /// </summary> + /// <param name="bigint">A <see cref="BigInteger"/>.</param> + /// <returns> + /// A <see cref="System.String"/> containing a binary + /// representation of the supplied <see cref="BigInteger"/>. + /// </returns> + public static string ToBinaryString(this BigInteger bigint) + { + var bytes = bigint.ToByteArray(); + var idx = bytes.Length - 1; + + // Create a StringBuilder having appropriate capacity. + var base2 = new StringBuilder(bytes.Length * 8); + + // Convert first byte to binary. + var binary = Convert.ToString(bytes[idx], 2); + + // Ensure leading zero exists if value is positive. + if (binary[0] != '0' && bigint.Sign == 1) + { + base2.Append('0'); + } + + // Append binary string to StringBuilder. + base2.Append(binary); + + // Convert remaining bytes adding leading zeros. + for (idx--; idx >= 0; idx--) + { + base2.Append(Convert.ToString(bytes[idx], 2).PadLeft(8, '0')); + } + + return base2.ToString(); + } + + /// <summary> + /// Converts a <see cref="BigInteger"/> to a hexadecimal string. + /// </summary> + /// <param name="bigint">A <see cref="BigInteger"/>.</param> + /// <returns> + /// A <see cref="System.String"/> containing a hexadecimal + /// representation of the supplied <see cref="BigInteger"/>. + /// </returns> + public static string ToHexadecimalString(this BigInteger bigint) + { + return bigint.ToString("X"); + } + + /// <summary> + /// Converts a <see cref="BigInteger"/> to a octal string. + /// </summary> + /// <param name="bigint">A <see cref="BigInteger"/>.</param> + /// <returns> + /// A <see cref="System.String"/> containing an octal + /// representation of the supplied <see cref="BigInteger"/>. + /// </returns> + public static string ToOctalString(this BigInteger bigint) + { + var bytes = bigint.ToByteArray(); + var idx = bytes.Length - 1; + + // Create a StringBuilder having appropriate capacity. + var base8 = new StringBuilder(((bytes.Length / 3) + 1) * 8); + + // Calculate how many bytes are extra when byte array is split + // into three-byte (24-bit) chunks. + var extra = bytes.Length % 3; + + // If no bytes are extra, use three bytes for first chunk. + if (extra == 0) + { + extra = 3; + } + + // Convert first chunk (24-bits) to integer value. + int int24 = 0; + for (; extra != 0; extra--) + { + int24 <<= 8; + int24 += bytes[idx--]; + } + + // Convert 24-bit integer to octal without adding leading zeros. + var octal = Convert.ToString(int24, 8); + + // Ensure leading zero exists if value is positive. + if (octal[0] != '0') + { + if (bigint.Sign == 1) + { + base8.Append('0'); + } + } + + // Append first converted chunk to StringBuilder. + base8.Append(octal); + + // Convert remaining 24-bit chunks, adding leading zeros. + for (; idx >= 0; idx -= 3) + { + int24 = (bytes[idx] << 16) + (bytes[idx - 1] << 8) + bytes[idx - 2]; + base8.Append(Convert.ToString(int24, 8).PadLeft(8, '0')); + } + + return base8.ToString(); + } + + /// <summary> + /// + /// Reverse a Positive BigInteger ONLY + /// Bitwise ~ operator + /// + /// Input : FF FF FF FF + /// Width : 4 + /// Result : 00 00 00 00 + /// + /// + /// Input : 00 00 00 00 + /// Width : 4 + /// Result : FF FF FF FF + /// + /// Input : FF FF FF FF + /// Width : 8 + /// Result : FF FF FF FF 00 00 00 00 + /// + /// + /// Input : 00 00 00 00 + /// Width : 8 + /// Result : FF FF FF FF FF FF FF FF + /// + /// </summary> + /// <param name="input"></param> + /// <param name="width"></param> + /// <returns></returns> + public static BigInteger PositiveReverse(this BigInteger input, int width) + { + + var result = new List<byte>(); + var bytes = input.ToByteArray(); + var work = new byte[width]; + Array.Copy(bytes, 0, work, 0, bytes.Length - 1); // Length -1 : positive BigInteger + + for (int i = 0; i < work.Length; i++) + { + result.Add((byte)(~work[i])); + } + result.Add(0); // positive BigInteger + return new BigInteger(result.ToArray()); + + } + } +}
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