96 lines
4 KiB
C#
96 lines
4 KiB
C#
/*************************************************************************
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* ModernUO *
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* Copyright 2019-2023 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: HashUtility.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System;
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using System.Numerics;
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using System.Runtime.CompilerServices;
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using Standart.Hash.xxHash;
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namespace Server;
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/// <summary>
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/// Represents supported non-cryptographic fast hash algorithms.
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/// </summary>
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public enum FastHashAlgorithm
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{
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None, // Used for collisions where full-data is serialized instead
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XxHash3_64, // xxHash3 64bit
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XxHash_32, // xxHash 32bit
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}
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public static class HashUtility
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{
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// *************** DO NOT CHANGE THIS NUMBER ****************
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// * Computed hashes might be serialized against this seed! *
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// **********************************************************
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private const ulong xxHash3Seed = 9609125370673258709ul; // Randomly generated 64-bit prime number
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private const uint xxHash1Seed = 665738807u; // Randomly generated 32-bit prime number
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static ulong ComputeHash64(string? data, FastHashAlgorithm algorithm = FastHashAlgorithm.XxHash3_64) =>
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algorithm switch
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{
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FastHashAlgorithm.XxHash3_64 => ComputeXXHash3_64(data),
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_ => throw new NotSupportedException($"Hash {algorithm} is not supported.")
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};
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static ulong ComputeXXHash3_64(string? data) => data == null ? 0 : xxHash3.ComputeHash(data, xxHash3Seed);
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static uint ComputeHash32(string? data, FastHashAlgorithm algorithm = FastHashAlgorithm.XxHash_32) =>
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algorithm switch
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{
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FastHashAlgorithm.XxHash_32 => ComputeXXHash_32(data),
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_ => throw new NotSupportedException($"Hash {algorithm} is not supported.")
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};
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static uint ComputeXXHash_32(string? data) => data == null ? 0 : xxHash32.ComputeHash(data, xxHash1Seed);
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public static unsafe int GetNetFrameworkHashCode(this string? str)
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{
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if (str == null)
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{
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return 0;
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}
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fixed (char* src = &str.GetPinnableReference())
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{
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uint hash1 = (5381 << 16) + 5381;
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uint hash2 = hash1;
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uint* ptr = (uint*)src;
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int length = str.Length;
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while (length > 2)
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{
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length -= 4;
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// Where length is 4n-1 (e.g. 3,7,11,15,19) this additionally consumes the null terminator
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hash1 = (BitOperations.RotateLeft(hash1, 5) + hash1) ^ ptr[0];
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hash2 = (BitOperations.RotateLeft(hash2, 5) + hash2) ^ ptr[1];
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ptr += 2;
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}
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if (length > 0)
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{
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// Where length is 4n-3 (e.g. 1,5,9,13,17) this additionally consumes the null terminator
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hash2 = (BitOperations.RotateLeft(hash2, 5) + hash2) ^ ptr[0];
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}
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return (int)(hash1 + hash2 * 1566083941);
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}
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}
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}
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