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using System;
namespace Org.BouncyCastle.Math.Raw
{
internal abstract class Interleave
{
private const ulong M32 = 0x55555555UL;
private const ulong M64 = 0x5555555555555555UL;
private const ulong M64R = 0xAAAAAAAAAAAAAAAAUL;
internal static uint Expand8to16(uint x)
{
x &= 0xFFU;
x = (x | (x << 4)) & 0x0F0FU;
x = (x | (x << 2)) & 0x3333U;
x = (x | (x << 1)) & 0x5555U;
return x;
}
internal static uint Expand16to32(uint x)
{
x &= 0xFFFFU;
x = (x | (x << 8)) & 0x00FF00FFU;
x = (x | (x << 4)) & 0x0F0F0F0FU;
x = (x | (x << 2)) & 0x33333333U;
x = (x | (x << 1)) & 0x55555555U;
return x;
}
internal static ulong Expand32to64(uint x)
{
// "shuffle" low half to even bits and high half to odd bits
x = Bits.BitPermuteStep(x, 0x0000FF00U, 8);
x = Bits.BitPermuteStep(x, 0x00F000F0U, 4);
x = Bits.BitPermuteStep(x, 0x0C0C0C0CU, 2);
x = Bits.BitPermuteStep(x, 0x22222222U, 1);
return ((x >> 1) & M32) << 32 | (x & M32);
}
internal static void Expand64To128(ulong x, ulong[] z, int zOff)
{
// "shuffle" low half to even bits and high half to odd bits
x = Bits.BitPermuteStep(x, 0x00000000FFFF0000UL, 16);
x = Bits.BitPermuteStep(x, 0x0000FF000000FF00UL, 8);
x = Bits.BitPermuteStep(x, 0x00F000F000F000F0UL, 4);
x = Bits.BitPermuteStep(x, 0x0C0C0C0C0C0C0C0CUL, 2);
x = Bits.BitPermuteStep(x, 0x2222222222222222UL, 1);
z[zOff ] = (x ) & M64;
z[zOff + 1] = (x >> 1) & M64;
}
internal static void Expand64To128(ulong[] zs, int zsOff, int zsLen)
{
int i = zsLen, zsPos = zsOff + zsLen << 1;
while (--i >= 0)
{
zsPos -= 2;
Expand64To128(zs[zsOff + i], zs, zsPos);
}
}
internal static void Expand64To128(ulong[] xs, int xsOff, int xsLen, ulong[] zs, int zsOff)
{
for (int i = 0; i < xsLen; ++i)
{
Expand64To128(xs[xsOff + i], zs, zsOff);
zsOff += 2;
}
}
internal static void Expand64To128Rev(ulong x, ulong[] z, int zOff)
{
// "shuffle" low half to even bits and high half to odd bits
x = Bits.BitPermuteStep(x, 0x00000000FFFF0000UL, 16);
x = Bits.BitPermuteStep(x, 0x0000FF000000FF00UL, 8);
x = Bits.BitPermuteStep(x, 0x00F000F000F000F0UL, 4);
x = Bits.BitPermuteStep(x, 0x0C0C0C0C0C0C0C0CUL, 2);
x = Bits.BitPermuteStep(x, 0x2222222222222222UL, 1);
z[zOff ] = (x ) & M64R;
z[zOff + 1] = (x << 1) & M64R;
}
internal static uint Shuffle(uint x)
{
// "shuffle" low half to even bits and high half to odd bits
x = Bits.BitPermuteStep(x, 0x0000FF00U, 8);
x = Bits.BitPermuteStep(x, 0x00F000F0U, 4);
x = Bits.BitPermuteStep(x, 0x0C0C0C0CU, 2);
x = Bits.BitPermuteStep(x, 0x22222222U, 1);
return x;
}
internal static ulong Shuffle(ulong x)
{
// "shuffle" low half to even bits and high half to odd bits
x = Bits.BitPermuteStep(x, 0x00000000FFFF0000UL, 16);
x = Bits.BitPermuteStep(x, 0x0000FF000000FF00UL, 8);
x = Bits.BitPermuteStep(x, 0x00F000F000F000F0UL, 4);
x = Bits.BitPermuteStep(x, 0x0C0C0C0C0C0C0C0CUL, 2);
x = Bits.BitPermuteStep(x, 0x2222222222222222UL, 1);
return x;
}
internal static uint Shuffle2(uint x)
{
// "shuffle" (twice) low half to even bits and high half to odd bits
x = Bits.BitPermuteStep(x, 0x00AA00AAU, 7);
x = Bits.BitPermuteStep(x, 0x0000CCCCU, 14);
x = Bits.BitPermuteStep(x, 0x00F000F0U, 4);
x = Bits.BitPermuteStep(x, 0x0000FF00U, 8);
return x;
}
internal static uint Unshuffle(uint x)
{
// "unshuffle" even bits to low half and odd bits to high half
x = Bits.BitPermuteStep(x, 0x22222222U, 1);
x = Bits.BitPermuteStep(x, 0x0C0C0C0CU, 2);
x = Bits.BitPermuteStep(x, 0x00F000F0U, 4);
x = Bits.BitPermuteStep(x, 0x0000FF00U, 8);
return x;
}
internal static ulong Unshuffle(ulong x)
{
// "unshuffle" even bits to low half and odd bits to high half
x = Bits.BitPermuteStep(x, 0x2222222222222222UL, 1);
x = Bits.BitPermuteStep(x, 0x0C0C0C0C0C0C0C0CUL, 2);
x = Bits.BitPermuteStep(x, 0x00F000F000F000F0UL, 4);
x = Bits.BitPermuteStep(x, 0x0000FF000000FF00UL, 8);
x = Bits.BitPermuteStep(x, 0x00000000FFFF0000UL, 16);
return x;
}
internal static uint Unshuffle2(uint x)
{
// "unshuffle" (twice) even bits to low half and odd bits to high half
x = Bits.BitPermuteStep(x, 0x0000FF00U, 8);
x = Bits.BitPermuteStep(x, 0x00F000F0U, 4);
x = Bits.BitPermuteStep(x, 0x0000CCCCU, 14);
x = Bits.BitPermuteStep(x, 0x00AA00AAU, 7);
return x;
}
}
}
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