69 lines
2.6 KiB
C#
69 lines
2.6 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;
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using System.Runtime.CompilerServices;
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using System.Runtime.InteropServices;
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namespace CommunityToolkit.Diagnostics;
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/// <summary>
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/// Helpers for working with value types.
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/// </summary>
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public static class ValueTypeExtensions
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{
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/// <summary>
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/// Gets the table of hex characters (doesn't allocate, maps to .text section, see <see href="https://github.com/dotnet/roslyn/pull/24621"/>).
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/// </summary>
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private static ReadOnlySpan<byte> HexCharactersTable => new[]
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{
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(byte)'0', (byte)'1', (byte)'2', (byte)'3',
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(byte)'4', (byte)'5', (byte)'6', (byte)'7',
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(byte)'8', (byte)'9', (byte)'A', (byte)'B',
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(byte)'C', (byte)'D', (byte)'E', (byte)'F'
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};
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/// <summary>
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/// Returns a hexadecimal <see cref="string"/> representation of a given <typeparamref name="T"/> value, left-padded and ordered as big-endian.
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/// </summary>
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/// <typeparam name="T">The input type to format to <see cref="string"/>.</typeparam>
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/// <param name="value">The input value to format to <see cref="string"/>.</param>
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/// <returns>
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/// The hexadecimal representation of <paramref name="value"/> (with the '0x' prefix), left-padded to byte boundaries and ordered as big-endian.
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/// </returns>
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/// <remarks>
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/// As a byte (8 bits) is represented by two hexadecimal digits (each representing a group of 4 bytes), each <see cref="string"/>
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/// representation will always contain an even number of digits. For instance:
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/// <code>
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/// Console.WriteLine(1.ToHexString()); // "0x01"
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/// Console.WriteLine(((byte)255).ToHexString()); // "0xFF"
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/// Console.WriteLine((-1).ToHexString()); // "0xFFFFFFFF"
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/// </code>
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/// </remarks>
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public static unsafe string ToHexString<T>(this T value)
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where T : unmanaged
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{
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int sizeOfT = Unsafe.SizeOf<T>();
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int bufferSize = (2 * sizeOfT) + 2;
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char* p = stackalloc char[bufferSize];
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p[0] = '0';
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p[1] = 'x';
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ref byte rh = ref MemoryMarshal.GetReference(HexCharactersTable);
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for (int i = 0, j = bufferSize - 2; i < sizeOfT; i++, j -= 2)
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{
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byte b = ((byte*)&value)[i];
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int low = b & 0x0F;
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int high = (b & 0xF0) >> 4;
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p[j + 1] = (char)Unsafe.Add(ref rh, low);
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p[j] = (char)Unsafe.Add(ref rh, high);
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}
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return new(p, 0, bufferSize);
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}
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}
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