private byte[] Compress(ChecksummedByteCollection aInputs)
{
byte[] result = new byte[100];
uint seed = aInputs.Checksum;
Mersenne32 gen = new Mersenne32(seed);
int inputCount = aInputs.Count;
for (int i = 0; i < 100; i++)
{
byte[] source = aInputs.Get((int)(gen.NextUInt32() % inputCount));
result[i] = source[gen.NextUInt32() % source.Length];
}
return(result);
}
private ChecksummedByteCollection Hash(byte[] aBlockHeader, int aRound)
{
if ((aRound < 1) || (aRound > N))
{
throw new ArgumentOutOfRangeException(string.Format("Round '{0}' must be between 0 and N inclusive",
nameof(aRound)));
}
// NOTE: instance is destroyed by caller!
ChecksummedByteCollection roundOutputs = new ChecksummedByteCollection();
Mersenne32 gen = new Mersenne32(0);
byte[] roundInput;
uint seed;
if (aRound == 1)
{
seed = Checksum(aBlockHeader);
gen.Initialize(seed);
roundInput = aBlockHeader;
}
else
{
ChecksummedByteCollection parentOutputs;
if ((aRound == N) && (aBlockHeader.Length >= 4) && (NextNonce == GetNonce(aBlockHeader)) &&
Arrays.AreEqual(aBlockHeader, _cachedHeader))
{
// Parent (round N - 1) has already been calculated so re-use values. This saves 50% of calculations!
parentOutputs = _cachedOutput;
}
else
{
// Need to calculate parent output
parentOutputs = Hash(aBlockHeader, aRound - 1);
}
seed = parentOutputs.Checksum;
gen.Initialize(seed);
roundOutputs.AddRange(parentOutputs);
// Determine the neighbouring nonce
uint neighbourNonce = gen.NextUInt32();
byte[] neighbourNonceHeader = ChangeNonce(aBlockHeader, neighbourNonce);
ChecksummedByteCollection neighbourOutputs = Hash(neighbourNonceHeader, aRound - 1);
// Cache neighbour nonce n-1 calculation if on final round (neighbour will be next nonce)
if (aRound == N)
{
_cachedNonce = neighbourNonce;
_cachedHeader = neighbourNonceHeader;
_cachedOutput = neighbourOutputs.Clone();
}
roundOutputs.AddRange(neighbourOutputs);
roundInput = Compress(roundOutputs);
}
Func <byte[], byte[]> hashFunc = _hashAlg[gen.NextUInt32() % 18];
byte[] output = hashFunc(roundInput);
output = Expand(output, N - aRound);
roundOutputs.Add(output);
return(roundOutputs);
}
private byte[] Expand(byte[] aInput, int aExpansionFactor)
{
int inputSize = aInput.Length;
Mersenne32 gen = new Mersenne32(Checksum(aInput));
byte[] output = new byte[inputSize + (aExpansionFactor * M)];
// Copy the genesis blob
Array.Copy(aInput, 0, output, 0, inputSize);
int readEnd = inputSize - 1;
int copyLen = inputSize;
while (readEnd < (output.Length - 1))
{
if ((readEnd + 1 + copyLen) > output.Length)
{
copyLen = (output.Length) - (readEnd + 1);
}
switch (gen.NextUInt32() % 8)
{
case 0:
MemTransform1(ref output, 0, readEnd + 1, copyLen);
break;
case 1:
MemTransform2(ref output, 0, readEnd + 1, copyLen);
break;
case 2:
MemTransform3(ref output, 0, readEnd + 1, copyLen);
break;
case 3:
MemTransform4(ref output, 0, readEnd + 1, copyLen);
break;
case 4:
MemTransform5(ref output, 0, readEnd + 1, copyLen);
break;
case 5:
MemTransform6(ref output, 0, readEnd + 1, copyLen);
break;
case 6:
MemTransform7(ref output, 0, readEnd + 1, copyLen);
break;
case 7:
MemTransform8(ref output, 0, readEnd + 1, copyLen);
break;
default:
throw new ArgumentException("invalid argument");
}
readEnd += copyLen;
copyLen += copyLen;
}
return(output);
}
