| | | 1 | | // Copyright © 2021-present Hibi_10000 |
| | | 2 | | // |
| | | 3 | | // This file is part of HashCalculator program. |
| | | 4 | | // |
| | | 5 | | // This program is free software: you can redistribute it and/or modify |
| | | 6 | | // it under the terms of the GNU General Public License as published by |
| | | 7 | | // the Free Software Foundation, either version 3 of the License, or |
| | | 8 | | // (at your option) any later version. |
| | | 9 | | // |
| | | 10 | | // This program is distributed in the hope that it will be useful, |
| | | 11 | | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| | | 12 | | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| | | 13 | | // GNU General Public License for more details. |
| | | 14 | | // |
| | | 15 | | // You should have received a copy of the GNU General Public License |
| | | 16 | | // along with this program. If not, see <http://www.gnu.org/licenses/>. |
| | | 17 | | |
| | | 18 | | using System; |
| | | 19 | | using System.Buffers.Binary; |
| | | 20 | | using System.IO.Hashing; |
| | | 21 | | |
| | | 22 | | namespace Hash.Core; |
| | | 23 | | |
| | | 24 | | public class CRC8_CCITT () : CRC(sizeof(byte), 0x07, 0x00, false); |
| | | 25 | | public class CRC16_CCITT() : CRC(sizeof(ushort), 0x1021, 0x0000, true); |
| | | 26 | | public class CRC16_IBM () : CRC(sizeof(ushort), 0x8005, 0x0000, true); |
| | | 27 | | public class CRC32 () : CRC(sizeof(uint), 0x04C11DB7, 0xffffffff, true); |
| | | 28 | | public class CRC32C () : CRC(sizeof(uint), 0x1EDC6F41, 0xffffffff, true); |
| | 1 | 29 | | public class CRC64_ECMA () : CRC(sizeof(ulong), 0x42F0E1EBA9EA3693, 0x0000000000000000, false); |
| | | 30 | | public class CRC64_ISO () : CRC(sizeof(ulong), 0x000000000000001B, 0xffffffffffffffff, true); |
| | | 31 | | public class CRC64_XZ () : CRC(sizeof(ulong), 0x42F0E1EBA9EA3693, 0xffffffffffffffff, true); |
| | | 32 | | |
| | | 33 | | public class CRC : NonCryptographicHashAlgorithm |
| | | 34 | | { |
| | | 35 | | private ulong _hash; |
| | | 36 | | private readonly ulong[] _table; |
| | | 37 | | private readonly ulong _seed; |
| | | 38 | | private readonly bool _refOut; |
| | | 39 | | private readonly ulong _xorOut; |
| | | 40 | | private readonly int _size; |
| | | 41 | | |
| | | 42 | | protected internal CRC(int size, ulong poly, ulong init, bool refInOut) : base(size) |
| | | 43 | | { |
| | | 44 | | _table = InitializeTable(size, poly, refInOut); |
| | | 45 | | _seed = init; |
| | | 46 | | _refOut = refInOut; |
| | | 47 | | _xorOut = init; |
| | | 48 | | _size = size; |
| | | 49 | | _hash = _seed; |
| | | 50 | | } |
| | | 51 | | |
| | | 52 | | public override void Append(ReadOnlySpan<byte> source) |
| | | 53 | | { |
| | | 54 | | _hash = CalculateHash(_size, _table, _hash, _refOut, source); |
| | | 55 | | } |
| | | 56 | | |
| | | 57 | | public override void Reset() |
| | | 58 | | { |
| | | 59 | | _hash = _seed; |
| | | 60 | | } |
| | | 61 | | |
| | | 62 | | private static ulong[] InitializeTable(int size, ulong poly, bool refIn) |
| | | 63 | | { |
| | | 64 | | ulong[] table = new ulong[256]; //byte.MaxValue + 1 |
| | | 65 | | if (refIn) |
| | | 66 | | { |
| | | 67 | | for (int i = 0; i < 256; i++) |
| | | 68 | | { |
| | | 69 | | ulong entry = (ulong)i; |
| | | 70 | | for (int j = 0; j < 8; j++) |
| | | 71 | | { |
| | | 72 | | if ((entry & 1) != 0) |
| | | 73 | | entry = (entry >> 1) ^ ReverseBits(poly, size * 8); |
| | | 74 | | else |
| | | 75 | | entry >>= 1; |
| | | 76 | | } |
| | | 77 | | table[i] = size == sizeof(byte) ? (byte)entry : entry; |
| | | 78 | | } |
| | | 79 | | } |
| | | 80 | | else |
| | | 81 | | { |
| | | 82 | | for (int i = 0; i < 256; i++) |
| | | 83 | | { |
| | | 84 | | ulong entry = size == sizeof(byte) ? (ulong)i : (ulong)i << 56; |
| | | 85 | | for (int j = 0; j < 8; j++) |
| | | 86 | | { |
| | | 87 | | if ((entry & ReverseBits(1, size * 8)) != 0) |
| | | 88 | | entry = (entry << 1) ^ poly; |
| | | 89 | | else |
| | | 90 | | entry <<= 1; |
| | | 91 | | } |
| | | 92 | | table[i] = size == sizeof(byte) ? (byte)entry : entry; |
| | | 93 | | } |
| | | 94 | | } |
| | | 95 | | return table; |
| | | 96 | | } |
| | | 97 | | |
| | | 98 | | private static ulong ReverseBits(ulong source, int size) |
| | | 99 | | { |
| | | 100 | | ulong reverse = 0; |
| | | 101 | | for (int i = 0; i < size; i++) |
| | | 102 | | { |
| | | 103 | | reverse = (reverse << 1) | ((source >> i) & 1); |
| | | 104 | | } |
| | | 105 | | return reverse; |
| | | 106 | | } |
| | | 107 | | |
| | | 108 | | private static ulong CalculateHash(int size, ulong[] table, ulong seed, bool refOut, ReadOnlySpan<byte> buffer) |
| | | 109 | | { |
| | | 110 | | ulong crc = seed; |
| | | 111 | | if (refOut) |
| | | 112 | | { |
| | | 113 | | foreach (byte bufferEntry in buffer) |
| | | 114 | | { |
| | | 115 | | crc = (crc >> 8) ^ table[(byte)(bufferEntry ^ crc)]; |
| | | 116 | | } |
| | | 117 | | } |
| | | 118 | | else |
| | | 119 | | { |
| | | 120 | | foreach (byte bufferEntry in buffer) |
| | | 121 | | { |
| | | 122 | | crc = (crc << 8) ^ table[(byte)(bufferEntry ^ (size == sizeof(byte) ? crc : crc >> 56))]; |
| | | 123 | | } |
| | | 124 | | } |
| | | 125 | | return crc; |
| | | 126 | | } |
| | | 127 | | |
| | | 128 | | protected override void GetCurrentHashCore(Span<byte> destination) |
| | | 129 | | { |
| | | 130 | | ulong hash = _hash ^ _xorOut; |
| | | 131 | | switch (_size) |
| | | 132 | | { |
| | | 133 | | case sizeof(byte ): //1 8 |
| | | 134 | | destination[0] = (byte)hash; |
| | | 135 | | break; |
| | | 136 | | case sizeof(ushort): //2 16 |
| | | 137 | | BinaryPrimitives.WriteUInt16BigEndian(destination, (ushort)hash); |
| | | 138 | | break; |
| | | 139 | | case sizeof(uint ): //4 32 |
| | | 140 | | BinaryPrimitives.WriteUInt32BigEndian(destination, (uint) hash); |
| | | 141 | | break; |
| | | 142 | | case sizeof(ulong ): //8 64 |
| | | 143 | | BinaryPrimitives.WriteUInt64BigEndian(destination, hash); |
| | | 144 | | break; |
| | | 145 | | } |
| | | 146 | | } |
| | | 147 | | } |