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94 lines
3.6 KiB
94 lines
3.6 KiB
using System;
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using Org.BouncyCastle.Math.Raw;
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namespace Org.BouncyCastle.Utilities
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{
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public abstract class Integers
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{
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public const int NumBits = 32;
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public const int NumBytes = 4;
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private static readonly byte[] DeBruijnTZ = {
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0x1F, 0x00, 0x1B, 0x01, 0x1C, 0x0D, 0x17, 0x02, 0x1D, 0x15, 0x13, 0x0E, 0x18, 0x10, 0x03, 0x07,
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0x1E, 0x1A, 0x0C, 0x16, 0x14, 0x12, 0x0F, 0x06, 0x19, 0x0B, 0x11, 0x05, 0x0A, 0x04, 0x09, 0x08 };
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public static int NumberOfLeadingZeros(int i)
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{
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if (i <= 0)
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return (~i >> (31 - 5)) & (1 << 5);
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uint u = (uint)i;
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int n = 1;
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if (0 == (u >> 16)) { n += 16; u <<= 16; }
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if (0 == (u >> 24)) { n += 8; u <<= 8; }
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if (0 == (u >> 28)) { n += 4; u <<= 4; }
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if (0 == (u >> 30)) { n += 2; u <<= 2; }
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n -= (int)(u >> 31);
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return n;
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}
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public static int NumberOfTrailingZeros(int i)
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{
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int n = DeBruijnTZ[(uint)((i & -i) * 0x0EF96A62) >> 27];
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int m = (((i & 0xFFFF) | (int)((uint)i >> 16)) - 1) >> 31;
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return n - m;
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}
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public static int Reverse(int i)
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{
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return (int)Reverse((uint)i);
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}
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[CLSCompliantAttribute(false)]
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#pragma warning disable CS3021 // 由于程序集没有 CLSCompliant 特性，因此类型或成员不需要 CLSCompliant 特性
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public static uint Reverse(uint i)
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#pragma warning restore CS3021 // 由于程序集没有 CLSCompliant 特性，因此类型或成员不需要 CLSCompliant 特性
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{
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i = Bits.BitPermuteStepSimple(i, 0x55555555U, 1);
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i = Bits.BitPermuteStepSimple(i, 0x33333333U, 2);
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i = Bits.BitPermuteStepSimple(i, 0x0F0F0F0FU, 4);
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return ReverseBytes(i);
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}
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public static int ReverseBytes(int i)
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{
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return (int)ReverseBytes((uint)i);
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}
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[CLSCompliantAttribute(false)]
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#pragma warning disable CS3021 // 由于程序集没有 CLSCompliant 特性，因此类型或成员不需要 CLSCompliant 特性
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public static uint ReverseBytes(uint i)
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#pragma warning restore CS3021 // 由于程序集没有 CLSCompliant 特性，因此类型或成员不需要 CLSCompliant 特性
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{
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return RotateLeft(i & 0xFF00FF00U, 8) |
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RotateLeft(i & 0x00FF00FFU, 24);
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}
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public static int RotateLeft(int i, int distance)
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{
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return (i << distance) ^ (int)((uint)i >> -distance);
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}
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[CLSCompliantAttribute(false)]
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#pragma warning disable CS3021 // 由于程序集没有 CLSCompliant 特性，因此类型或成员不需要 CLSCompliant 特性
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public static uint RotateLeft(uint i, int distance)
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#pragma warning restore CS3021 // 由于程序集没有 CLSCompliant 特性，因此类型或成员不需要 CLSCompliant 特性
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{
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return (i << distance) ^ (i >> -distance);
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}
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public static int RotateRight(int i, int distance)
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{
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return (int)((uint)i >> distance) ^ (i << -distance);
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}
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[CLSCompliantAttribute(false)]
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#pragma warning disable CS3021 // 由于程序集没有 CLSCompliant 特性，因此类型或成员不需要 CLSCompliant 特性
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public static uint RotateRight(uint i, int distance)
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#pragma warning restore CS3021 // 由于程序集没有 CLSCompliant 特性，因此类型或成员不需要 CLSCompliant 特性
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{
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return (i >> distance) ^ (i << -distance);
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}
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}
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}
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