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using System.Diagnostics;
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
using System.Runtime.CompilerServices;
#endif
namespace Org.BouncyCastle.Math.Raw
{
internal static class Bits
{
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
[MethodImpl(MethodImplOptions.AggressiveInlining)]
#endif
internal static uint BitPermuteStep(uint x, uint m, int s)
{
Debug.Assert((m & (m << s)) == 0U);
Debug.Assert((m << s) >> s == m);
uint t = (x ^ (x >> s)) & m;
return t ^ (t << s) ^ x;
}
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
[MethodImpl(MethodImplOptions.AggressiveInlining)]
#endif
internal static ulong BitPermuteStep(ulong x, ulong m, int s)
{
Debug.Assert((m & (m << s)) == 0UL);
Debug.Assert((m << s) >> s == m);
ulong t = (x ^ (x >> s)) & m;
return t ^ (t << s) ^ x;
}
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
[MethodImpl(MethodImplOptions.AggressiveInlining)]
#endif
internal static void BitPermuteStep2(ref uint hi, ref uint lo, uint m, int s)
{
#if NETSTANDARD2_1_OR_GREATER || NETCOREAPP1_1_OR_GREATER
Debug.Assert(!Unsafe.AreSame(ref hi, ref lo) || (m & (m << s)) == 0U);
#endif
Debug.Assert((m << s) >> s == m);
uint t = ((lo >> s) ^ hi) & m;
lo ^= t << s;
hi ^= t;
}
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
[MethodImpl(MethodImplOptions.AggressiveInlining)]
#endif
internal static void BitPermuteStep2(ref ulong hi, ref ulong lo, ulong m, int s)
{
#if NETSTANDARD2_1_OR_GREATER || NETCOREAPP1_1_OR_GREATER
Debug.Assert(!Unsafe.AreSame(ref hi, ref lo) || (m & (m << s)) == 0UL);
#endif
Debug.Assert((m << s) >> s == m);
ulong t = ((lo >> s) ^ hi) & m;
lo ^= t << s;
hi ^= t;
}
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
[MethodImpl(MethodImplOptions.AggressiveInlining)]
#endif
internal static uint BitPermuteStepSimple(uint x, uint m, int s)
{
Debug.Assert((m << s) == ~m);
Debug.Assert((m & ~m) == 0U);
return ((x & m) << s) | ((x >> s) & m);
}
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
[MethodImpl(MethodImplOptions.AggressiveInlining)]
#endif
internal static ulong BitPermuteStepSimple(ulong x, ulong m, int s)
{
Debug.Assert((m << s) == ~m);
Debug.Assert((m & ~m) == 0UL);
return ((x & m) << s) | ((x >> s) & m);
}
}
}
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