25 lines
987 B
C#
25 lines
987 B
C#
// Copyright (c) .NET Foundation. All rights reserved.
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// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
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namespace Microsoft.AspNet.Server.Kestrel.Extensions
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{
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public static class LongExtensions
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{
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public static int BitCount(this long value)
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{
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// see https://github.com/dotnet/corefx/blob/master/src/System.Reflection.Metadata/src/System/Reflection/Internal/Utilities/BitArithmetic.cs
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const ulong Mask01010101 = 0x5555555555555555UL;
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const ulong Mask00110011 = 0x3333333333333333UL;
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const ulong Mask00001111 = 0x0F0F0F0F0F0F0F0FUL;
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const ulong Mask00000001 = 0x0101010101010101UL;
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var v = (ulong)value;
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v = v - ((v >> 1) & Mask01010101);
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v = (v & Mask00110011) + ((v >> 2) & Mask00110011);
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return (int)(unchecked(((v + (v >> 4)) & Mask00001111) * Mask00000001) >> 56);
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}
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}
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}
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