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using System;
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
using System.Buffers.Binary;
#endif
#if NETCOREAPP3_0_OR_GREATER
using System.Numerics;
using System.Runtime.Intrinsics.X86;
#endif
using Org.BouncyCastle.Math.Raw;
namespace Org.BouncyCastle.Utilities
{
public static class Longs
{
public const int NumBits = 64;
public const int NumBytes = 8;
#if !NETCOREAPP3_0_OR_GREATER
private static readonly byte[] DeBruijnTZ = {
0x3F, 0x00, 0x01, 0x34, 0x02, 0x06, 0x35, 0x1A, 0x03, 0x25, 0x28, 0x07, 0x21, 0x36, 0x2F, 0x1B,
0x3D, 0x04, 0x26, 0x2D, 0x2B, 0x29, 0x15, 0x08, 0x17, 0x22, 0x3A, 0x37, 0x30, 0x11, 0x1C, 0x0A,
0x3E, 0x33, 0x05, 0x19, 0x24, 0x27, 0x20, 0x2E, 0x3C, 0x2C, 0x2A, 0x14, 0x16, 0x39, 0x10, 0x09,
0x32, 0x18, 0x23, 0x1F, 0x3B, 0x13, 0x38, 0x0F, 0x31, 0x1E, 0x12, 0x0E, 0x1D, 0x0D, 0x0C, 0x0B };
#endif
public static long HighestOneBit(long i)
{
return (long)HighestOneBit((ulong)i);
}
[CLSCompliant(false)]
public static ulong HighestOneBit(ulong i)
{
i |= i >> 1;
i |= i >> 2;
i |= i >> 4;
i |= i >> 8;
i |= i >> 16;
i |= i >> 32;
return i - (i >> 1);
}
public static long LowestOneBit(long i)
{
return i & -i;
}
[CLSCompliant(false)]
public static ulong LowestOneBit(ulong i)
{
return (ulong)LowestOneBit((long)i);
}
public static int NumberOfLeadingZeros(long i)
{
#if NETCOREAPP3_0_OR_GREATER
return BitOperations.LeadingZeroCount((ulong)i);
#else
int x = (int)(i >> 32), n = 0;
if (x == 0)
{
n = 32;
x = (int)i;
}
return n + Integers.NumberOfLeadingZeros(x);
#endif
}
public static int NumberOfTrailingZeros(long i)
{
#if NETCOREAPP3_0_OR_GREATER
return BitOperations.TrailingZeroCount((ulong)i);
#else
int n = DeBruijnTZ[(uint)((ulong)((i & -i) * 0x045FBAC7992A70DAL) >> 58)];
long m = (((i & 0xFFFFFFFFL) | (long)((ulong)i >> 32)) - 1L) >> 63;
return n - (int)m;
#endif
}
public static long Reverse(long i)
{
return (long)Reverse((ulong)i);
}
[CLSCompliant(false)]
public static ulong Reverse(ulong i)
{
i = Bits.BitPermuteStepSimple(i, 0x5555555555555555UL, 1);
i = Bits.BitPermuteStepSimple(i, 0x3333333333333333UL, 2);
i = Bits.BitPermuteStepSimple(i, 0x0F0F0F0F0F0F0F0FUL, 4);
return ReverseBytes(i);
}
public static long ReverseBytes(long i)
{
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
return BinaryPrimitives.ReverseEndianness(i);
#else
return (long)ReverseBytes((ulong)i);
#endif
}
[CLSCompliant(false)]
public static ulong ReverseBytes(ulong i)
{
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
return BinaryPrimitives.ReverseEndianness(i);
#else
return RotateLeft(i & 0xFF000000FF000000UL, 8) |
RotateLeft(i & 0x00FF000000FF0000UL, 24) |
RotateLeft(i & 0x0000FF000000FF00UL, 40) |
RotateLeft(i & 0x000000FF000000FFUL, 56);
#endif
}
public static long RotateLeft(long i, int distance)
{
#if NETCOREAPP3_0_OR_GREATER
return (long)BitOperations.RotateLeft((ulong)i, distance);
#else
return (i << distance) | (long)((ulong)i >> -distance);
#endif
}
[CLSCompliant(false)]
public static ulong RotateLeft(ulong i, int distance)
{
#if NETCOREAPP3_0_OR_GREATER
return BitOperations.RotateLeft(i, distance);
#else
return (i << distance) | (i >> -distance);
#endif
}
public static long RotateRight(long i, int distance)
{
#if NETCOREAPP3_0_OR_GREATER
return (long)BitOperations.RotateRight((ulong)i, distance);
#else
return (long)((ulong)i >> distance) | (i << -distance);
#endif
}
[CLSCompliant(false)]
public static ulong RotateRight(ulong i, int distance)
{
#if NETCOREAPP3_0_OR_GREATER
return BitOperations.RotateRight(i, distance);
#else
return (i >> distance) | (i << -distance);
#endif
}
}
}
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