mirror of
https://github.com/icsharpcode/ILSpy.git
synced 2026-10-12 11:09:54 +00:00
Siegfried Pammer
07d5a01d2b
Backfills the standard MIT X11 header on hand-written files that never got one, attributing each to its first-commit author and year from git history. Code vendored from dotnet/runtime and Humanizr/Humanizer gets its origin's license lines and a provenance note instead. Generated files (Resources.Designer.cs, the version-info template), tool-managed suppression files, and BAML test-case fixtures intentionally stay header-less. Assisted-by: Claude:claude-fable-5:Claude Code
63 lines
1.8 KiB
C#
63 lines
1.8 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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//
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// Vendored from dotnet/runtime: the System.Numerics.BitOperations members used by this
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// project, as a polyfill for target frameworks that lack the type.
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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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#if !NET8_0_OR_GREATER
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namespace System.Numerics
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{
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internal static class BitOperations
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{
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static uint RotateLeft(uint value, int offset)
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=> (value << offset) | (value >> (32 - offset));
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private static ReadOnlySpan<byte> TrailingZeroCountDeBruijn => new byte[32]
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{
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00, 01, 28, 02, 29, 14, 24, 03,
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30, 22, 20, 15, 25, 17, 04, 08,
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31, 27, 13, 23, 21, 19, 16, 07,
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26, 12, 18, 06, 11, 05, 10, 09
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};
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public static int TrailingZeroCount(uint value)
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{
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// Unguarded fallback contract is 0->0, BSF contract is 0->undefined
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if (value == 0)
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{
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return 32;
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}
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unchecked
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{
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// uint.MaxValue >> 27 is always in range [0 - 31] so we use Unsafe.AddByteOffset to avoid bounds check
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return Unsafe.AddByteOffset(
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// Using deBruijn sequence, k=2, n=5 (2^5=32) : 0b_0000_0111_0111_1100_1011_0101_0011_0001u
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ref MemoryMarshal.GetReference(TrailingZeroCountDeBruijn),
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// uint|long -> IntPtr cast on 32-bit platforms does expensive overflow checks not needed here
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(IntPtr)(int)(((value & (uint)-(int)value) * 0x077CB531u) >> 27)); // Multi-cast mitigates redundant conv.u8
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}
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}
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public static int TrailingZeroCount(ulong value)
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{
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unchecked
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{
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uint lo = (uint)value;
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if (lo == 0)
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{
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return 32 + TrailingZeroCount((uint)(value >> 32));
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}
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return TrailingZeroCount(lo);
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}
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}
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}
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}
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#endif
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