forked from BilalY/Rasagar
275 lines
10 KiB
C#
275 lines
10 KiB
C#
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// This file was copied and modified from
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// https://github.com/xoofx/smash/blob/v0.3.0/src/Smash/xxHash.cs
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// Copyright (c) 2017, Alexandre Mutel
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification
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// , are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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/*
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* xxHash - Fast Hash algorithm
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* Copyright (C) 2012-2016, Yann Collet
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*
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* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* You can contact the author at :
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* - xxHash homepage: http://www.xxhash.com
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* - xxHash source repository : https://github.com/Cyan4973/xxHash
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*/
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using System;
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using System.Runtime.CompilerServices;
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// ReSharper disable InconsistentNaming
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using U64 = System.UInt64;
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using U32 = System.UInt32;
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namespace PvpXray
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{
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/// <summary>
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/// The xxHash method. Use <see cref="Create64"/>.
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/// </summary>
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static class xxHash
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{
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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public static Hash64 Create64(ulong seed)
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{
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return new Hash64(seed);
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}
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/// <summary>
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/// xxHash for computing a 64bit hash.
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/// </summary>
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public struct Hash64
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{
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const U64 PRIME64_1 = 11400714785074694791UL;
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const U64 PRIME64_2 = 14029467366897019727UL;
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const U64 PRIME64_3 = 1609587929392839161UL;
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const U64 PRIME64_4 = 9650029242287828579UL;
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// BUG: Prime #5 is unused. It is SUPPOSED to be used for inputs that are not a multiple
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// of 32 bytes. Which explains why this xxHash implementation is broken for such inputs.
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const U64 PRIME64_5 = 2870177450012600261UL;
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U64 _v1;
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U64 _v2;
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U64 _v3;
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U64 _v4;
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ulong _writeCount;
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ulong _length;
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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internal Hash64(ulong seed)
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{
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// NOTE: Duplicated with Reset method, keep in sync!
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_v1 = seed + PRIME64_1 + PRIME64_2;
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_v2 = seed + PRIME64_2;
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_v3 = seed + 0;
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_v4 = seed - PRIME64_1;
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_writeCount = 0;
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_length = 0;
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}
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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void Write(ulong input)
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{
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WriteInternal(input);
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_length += 8;
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}
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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void Write(byte input)
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{
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WriteInternal(input * PRIME64_1);
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_length += 1;
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}
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unsafe void Write(IntPtr buffer, ulong length)
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{
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if (buffer == IntPtr.Zero) throw new ArgumentNullException(nameof(buffer));
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var pBuffer = (byte*)(void*)buffer;
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const ulong FetchSize = sizeof(ulong) * 4;
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while (length >= FetchSize)
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{
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var pulong = (ulong*)pBuffer;
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Write(pulong[0]);
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Write(pulong[1]);
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Write(pulong[2]);
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Write(pulong[3]);
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pBuffer += FetchSize;
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length -= FetchSize;
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}
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while (length >= 8)
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{
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Write(*(ulong*)pBuffer);
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pBuffer += 8;
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length -= 8;
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}
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while (length > 0)
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{
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Write(*(byte*)pBuffer);
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pBuffer += 1;
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length -= 1;
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}
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}
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public unsafe void Write(byte[] buffer, int offset, int count)
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{
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if (buffer == null) throw new ArgumentNullException(nameof(buffer));
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if (offset < 0)
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throw new ArgumentOutOfRangeException(nameof(offset), "offset cannot be < 0");
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if (count < 0)
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throw new ArgumentOutOfRangeException(nameof(count), "count cannot be < 0");
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if (buffer.Length - offset < count)
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throw new ArgumentException("Invalid offset + count > length");
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if (count == 0)
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{
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return;
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}
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fixed (void* pByte = &buffer[offset])
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{
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Write(new IntPtr(pByte), (ulong)count);
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}
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}
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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public ulong Compute()
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{
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// This part is slightly different from xxHash to use a generic algorithm
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// depending on the number of writes
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// Might not give the exact same result as we are feeding all states v1,v2,v3,v4
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// while xxHash calculates the hash differently for input buffer < 64/32/8/4 bytes
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var h64 = XXH_rotl64(_v1, 1);
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if (_writeCount >= 2)
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{
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h64 += XXH_rotl64(_v2, 7);
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if (_writeCount >= 3)
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{
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h64 += XXH_rotl64(_v3, 12);
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if (_writeCount >= 4)
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{
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h64 += XXH_rotl64(_v4, 18);
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}
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}
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}
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h64 = XXH64_mergeRound(h64, _v1);
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if (_writeCount >= 2)
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{
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h64 = XXH64_mergeRound(h64, _v2);
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if (_writeCount >= 3)
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{
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h64 = XXH64_mergeRound(h64, _v3);
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if (_writeCount >= 4)
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{
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h64 = XXH64_mergeRound(h64, _v4);
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}
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}
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}
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h64 += _length;
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h64 ^= h64 >> 33;
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h64 *= PRIME64_2;
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h64 ^= h64 >> 29;
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h64 *= PRIME64_3;
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h64 ^= h64 >> 32;
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return h64;
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}
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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void WriteInternal(ulong input)
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{
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switch (_writeCount & 3)
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{
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case 0:
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_v1 = XXH64_round(_v1, input);
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break;
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case 1:
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_v2 = XXH64_round(_v2, input);
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break;
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case 2:
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_v3 = XXH64_round(_v3, input);
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break;
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case 3:
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_v4 = XXH64_round(_v4, input);
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break;
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}
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_writeCount++;
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}
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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static U64 XXH_rotl64(U64 x, int r)
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{
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return (x << r) | (x >> (64 - r));
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}
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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static U64 XXH64_round(U64 acc, U64 input)
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{
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acc += input * PRIME64_2;
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acc = XXH_rotl64(acc, 31);
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acc *= PRIME64_1;
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return acc;
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}
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[MethodImpl((MethodImplOptions)0x100)] // Aggressive inlining for all .NETs
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static U64 XXH64_mergeRound(U64 acc, U64 val)
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{
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val = XXH64_round(0, val);
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acc ^= val;
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acc = acc * PRIME64_1 + PRIME64_4;
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return acc;
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}
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}
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}
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}
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