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110 lines
2.6 KiB
C#
110 lines
2.6 KiB
C#
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using System.Runtime.CompilerServices;
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namespace ARMeilleure.Common
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{
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static class BitUtils
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{
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private const int DeBrujinSequence = 0x77cb531;
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private static int[] DeBrujinLbsLut;
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static BitUtils()
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{
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DeBrujinLbsLut = new int[32];
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for (int index = 0; index < DeBrujinLbsLut.Length; index++)
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{
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uint lutIndex = (uint)(DeBrujinSequence * (1 << index)) >> 27;
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DeBrujinLbsLut[lutIndex] = index;
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}
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static int LowestBitSet(int value)
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{
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if (value == 0)
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{
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return -1;
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}
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int lsb = value & -value;
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return DeBrujinLbsLut[(uint)(DeBrujinSequence * lsb) >> 27];
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}
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public static int HighestBitSet(int value)
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{
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if (value == 0)
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{
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return -1;
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}
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for (int bit = 31; bit >= 0; bit--)
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{
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if (((value >> bit) & 1) != 0)
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{
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return bit;
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}
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}
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return -1;
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}
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private static readonly sbyte[] HbsNibbleLut = { -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3 };
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public static int HighestBitSetNibble(int value) => HbsNibbleLut[value & 0b1111];
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public static long Replicate(long bits, int size)
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{
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long output = 0;
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for (int bit = 0; bit < 64; bit += size)
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{
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output |= bits << bit;
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}
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return output;
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}
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public static int CountBits(int value)
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{
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int count = 0;
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while (value != 0)
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{
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value &= ~(value & -value);
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count++;
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}
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return count;
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}
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public static long FillWithOnes(int bits)
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{
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return bits == 64 ? -1L : (1L << bits) - 1;
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}
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public static int RotateRight(int bits, int shift, int size)
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{
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return (int)RotateRight((uint)bits, shift, size);
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}
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public static uint RotateRight(uint bits, int shift, int size)
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{
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return (bits >> shift) | (bits << (size - shift));
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}
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public static long RotateRight(long bits, int shift, int size)
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{
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return (long)RotateRight((ulong)bits, shift, size);
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}
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public static ulong RotateRight(ulong bits, int shift, int size)
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{
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return (bits >> shift) | (bits << (size - shift));
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}
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}
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}
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