/// <summary>
/// Creates a ChaCha RNG using the given seed and number of double rounds.
/// </summary>
/// <param name="seed">A seed containing the key and stream.</param>
/// <param name="doubleRounds">
/// 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>
/// <exception cref="ArgumentOutOfRangeException">
/// Thrown if <paramref name="doubleRounds"/> is equal to 0.
/// </exception>
public static ChaCha Create(Seed seed, UInt32 doubleRounds)
{
if (doubleRounds == 0)
{
throw new ArgumentOutOfRangeException(nameof(doubleRounds));
}
var key = seed.Key.Length != 0 ? seed.Key.Span : stackalloc UInt32[KeyLength];
#if X86_INTRINSICS
var core = ChaChaIntrinsics.Create(key, UInt64.MaxValue, seed.Stream, doubleRounds);
var blockBuffer = new BlockBuffer32 <ChaChaIntrinsics, UInt64>(core);
#else
var core = ChaChaSoftware.Create(key, UInt64.MaxValue, seed.Stream, doubleRounds);
var blockBuffer = new BlockBuffer32 <ChaChaSoftware, UInt64>(core);
#endif
return(new ChaCha(blockBuffer));
}
private CryptoServiceProvider(RNGCryptoServiceProvider rng)
{
_buffer = new BlockBuffer32 <BlockCore>(new BlockCore(rng));
_rng = rng;
}
private SystemCryptoRng(RandomNumberGenerator rng)
{
_buffer = new BlockBuffer32 <BlockCore>(new BlockCore(rng));
_rng = rng;
}
private ChaCha(BlockBuffer32 <ChaChaSoftware, UInt64> blockBuffer)
#endif
{
_blockBuffer = blockBuffer;
}
private ChaCha(BlockBuffer32 <ChaChaIntrinsics, UInt64> blockBuffer)
