80 lines
1.8 KiB
C#
80 lines
1.8 KiB
C#
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/*
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* Copyright 2023 Eduard Kargin <kargin.eduard@gmail.com>
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System.Runtime.CompilerServices;
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namespace Ragon.Protocol
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{
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public static class DeBruijn
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{
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private static readonly int[] _lookup = new int[32]
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{
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0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30,
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8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31
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};
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public static int Log2(uint value)
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{
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value |= value >> 1;
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value |= value >> 2;
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value |= value >> 4;
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value |= value >> 8;
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value |= value >> 16;
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return _lookup[(value * 0x07C4ACDDU) >> 27];
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}
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}
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public static class Bits
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{
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static int[] _lookup = new int[256];
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static Bits()
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{
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_lookup[0] = 0;
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for (int i = 0; i < 256; i++)
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_lookup[i] = (i & 1) + _lookup[i / 2];
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}
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[MethodImpl(256)]
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public static int Compute(int value)
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{
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var count = 0;
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do
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{
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value >>= 8;
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count += 8;
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} while (value > 0);
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return count;
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}
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[MethodImpl(256)]
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public static int FindBitPosition(byte data)
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{
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int shiftCount = 0;
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while (data > 0)
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{
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data >>= 1;
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shiftCount++;
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}
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return shiftCount;
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}
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}
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}
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