/// <summary>
/// Creates a new instance of <see cref="ChaChaIntrinsics"/>.
/// </summary>
/// <param name="key">ChaCha20's key. Must have a length of 8.</param>
/// <param name="counter">ChaCha's 64-bit block counter.</param>
/// <param name="stream">ChaCha20's 64-bit stream id.</param>
/// <param name="doubleRoundCount">
/// The number of double rounds to perform. Half the total number of rounds,
/// ex. ChaCha20 has 10 double rounds and ChaCha8 has 4 double rounds.
/// </param>
public static ChaChaIntrinsics Create(ReadOnlySpan <UInt32> key, UInt64 counter, UInt64 stream, UInt32 doubleRoundCount)
{
Debug.Assert(key.Length == 8);
Debug.Assert(doubleRoundCount != 0);
if (Avx2.IsSupported)
{
return(new ChaChaIntrinsics(ChaChaAvx2.Create(key, counter, stream, doubleRoundCount)));
}
if (Sse2.IsSupported)
{
return(new ChaChaIntrinsics(ChaChaSse2.Create(key, counter, stream, doubleRoundCount)));
}
return(new ChaChaIntrinsics(ChaChaSoftware.Create(key, counter, stream, doubleRoundCount)));
}
private ChaChaIntrinsics(ChaChaAvx2 avx2)
{
_software = null !;
_sse2 = null !;
_avx2 = avx2;
}
private ChaChaIntrinsics(ChaChaSse2 sse2)
{
_software = null !;
_avx2 = null !;
_sse2 = sse2;
}
private ChaChaIntrinsics(ChaChaSoftware software)
{
_sse2 = null !;
_avx2 = null !;
_software = software;
}
