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using System;
using Org.BouncyCastle.Math.Raw;
namespace Org.BouncyCastle.Utilities
{
public abstract class Integers
{
public const int NumBits = 32;
public const int NumBytes = 4;
private static readonly byte[] DeBruijnTZ = {
0x00, 0x01, 0x02, 0x18, 0x03, 0x13, 0x06, 0x19, 0x16, 0x04, 0x14, 0x0A,
0x10, 0x07, 0x0C, 0x1A, 0x1F, 0x17, 0x12, 0x05, 0x15, 0x09, 0x0F, 0x0B,
0x1E, 0x11, 0x08, 0x0E, 0x1D, 0x0D, 0x1C, 0x1B };
public static int NumberOfLeadingZeros(int i)
{
if (i <= 0)
return (~i >> (31 - 5)) & (1 << 5);
uint u = (uint)i;
int n = 1;
if (0 == (u >> 16)) { n += 16; u <<= 16; }
if (0 == (u >> 24)) { n += 8; u <<= 8; }
if (0 == (u >> 28)) { n += 4; u <<= 4; }
if (0 == (u >> 30)) { n += 2; u <<= 2; }
n -= (int)(u >> 31);
return n;
}
public static int NumberOfTrailingZeros(int i)
{
return DeBruijnTZ[(uint)((i & -i) * 0x04D7651F) >> 27];
}
public static int Reverse(int i)
{
i = (int)Bits.BitPermuteStepSimple((uint)i, 0x55555555U, 1);
i = (int)Bits.BitPermuteStepSimple((uint)i, 0x33333333U, 2);
i = (int)Bits.BitPermuteStepSimple((uint)i, 0x0F0F0F0FU, 4);
return ReverseBytes(i);
}
public static int ReverseBytes(int i)
{
return RotateLeft((int)((uint)i & 0xFF00FF00U), 8) |
RotateLeft((int)((uint)i & 0x00FF00FFU), 24);
}
public static int RotateLeft(int i, int distance)
{
return (i << distance) ^ (int)((uint)i >> -distance);
}
[CLSCompliantAttribute(false)]
public static uint RotateLeft(uint i, int distance)
{
return (i << distance) ^ (i >> -distance);
}
public static int RotateRight(int i, int distance)
{
return (int)((uint)i >> distance) ^ (i << -distance);
}
[CLSCompliantAttribute(false)]
public static uint RotateRight(uint i, int distance)
{
return (i >> distance) ^ (i << -distance);
}
}
}
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