76 lines
3.5 KiB
C#
76 lines
3.5 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System.Runtime.CompilerServices;
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namespace CommunityToolkit.HighPerformance;
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/// <summary>
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/// Helpers for working with the <see cref="bool"/> type.
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/// </summary>
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public static class BoolExtensions
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{
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/// <summary>
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/// Converts the given <see cref="bool"/> value into a <see cref="byte"/>.
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/// </summary>
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/// <param name="flag">The input value to convert.</param>
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/// <returns>1 if <paramref name="flag"/> is <see langword="true"/>, 0 otherwise.</returns>
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/// <remarks>This method does not contain branching instructions.</remarks>
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static unsafe byte ToByte(this bool flag)
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{
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// Whenever we need to take the address of an argument, we make a local copy first.
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// This will be removed by the JIT anyway, but it can help produce better codegen and
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// remove unwanted stack spills if the caller is using constant arguments. This is
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// because taking the address of an argument can interfere with some of the flow
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// analysis executed by the JIT, which can in some cases block constant propagation.
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bool copy = flag;
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return *(byte*)©
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}
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/// <summary>
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/// Converts the given <see cref="bool"/> value to an <see cref="int"/> mask with
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/// all bits representing the value of the input flag (either 0xFFFFFFFF or 0x00000000).
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/// </summary>
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/// <param name="flag">The input value to convert.</param>
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/// <returns>0xFFFFFFFF if <paramref name="flag"/> is <see langword="true"/>, 0x00000000 otherwise.</returns>
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/// <remarks>
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/// This method does not contain branching instructions, and it is only guaranteed to work with
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/// <see cref="bool"/> values being either 0 or 1. Operations producing a <see cref="bool"/> result,
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/// such as numerical comparisons, always result in a valid value. If the <see cref="bool"/> value is
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/// produced by fields with a custom <see cref="System.Runtime.InteropServices.FieldOffsetAttribute"/>,
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/// or by using <see cref="Unsafe.As{T}"/> or other unsafe APIs to directly manipulate the underlying
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/// data though, it is responsibility of the caller to ensure the validity of the provided value.
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/// </remarks>
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static unsafe int ToBitwiseMask32(this bool flag)
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{
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bool copy = flag;
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byte rangeFlag = *(byte*)©
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int negativeFlag = rangeFlag - 1;
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int mask = ~negativeFlag;
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return mask;
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}
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/// <summary>
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/// Converts the given <see cref="bool"/> value to a <see cref="long"/> mask with
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/// all bits representing the value of the input flag (either all 1s or 0s).
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/// </summary>
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/// <param name="flag">The input value to convert.</param>
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/// <returns>All 1s if <paramref name="flag"/> is <see langword="true"/>, all 0s otherwise.</returns>
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/// <remarks>This method does not contain branching instructions. See additional note in <see cref="ToBitwiseMask32"/>.</remarks>
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static unsafe long ToBitwiseMask64(this bool flag)
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{
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bool copy = flag;
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byte rangeFlag = *(byte*)©
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long negativeFlag = (long)rangeFlag - 1;
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long mask = ~negativeFlag;
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return mask;
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}
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}
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