85 lines
2.6 KiB
C#
85 lines
2.6 KiB
C#
using System.Text;
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// MIT License
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//
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// Copyright (c) 2017 Jitbit, 2022 TakoTako contributors
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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namespace TakoTako.Common;
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public class MurmurHash2
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{
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public static uint Hash(string data)
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{
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return Hash(Encoding.UTF8.GetBytes(data));
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}
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public static uint Hash(byte[] data)
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{
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return Hash(data, 0xc58f1a7a);
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}
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private const uint m = 0x5bd1e995;
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private const int r = 24;
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public static uint Hash(byte[] data, uint seed)
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{
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var length = data.Length;
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if (length == 0)
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return 0;
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var h = seed ^ (uint)length;
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var currentIndex = 0;
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while (length >= 4)
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{
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var k = (uint)(data[currentIndex++] | (data[currentIndex++] << 8) | (data[currentIndex++] << 16) |
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(data[currentIndex++] << 24));
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k *= m;
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k ^= k >> r;
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k *= m;
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h *= m;
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h ^= k;
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length -= 4;
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}
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switch (length)
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{
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case 3:
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h ^= (ushort)(data[currentIndex++] | (data[currentIndex++] << 8));
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h ^= (uint)(data[currentIndex] << 16);
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h *= m;
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break;
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case 2:
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h ^= (ushort)(data[currentIndex++] | (data[currentIndex] << 8));
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h *= m;
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break;
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case 1:
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h ^= data[currentIndex];
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h *= m;
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break;
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}
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h ^= h >> 13;
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h *= m;
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h ^= h >> 15;
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return h;
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}
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} |