private bool checkCycle()
{
var _logger = Log.ForContext <Share>();
if (Cycle.Length != CYCLE_LENGTH)
{
return(false);
}
var blakeHash = new HMACBlake2B(256);
byte[] keys = blakeHash.ComputeHash(Encoding.ASCII.GetBytes(BlockHash.ToHexString()));
UInt64 k0 = (UInt64)BitConverter.ToInt64(keys.Slice(0, 8), 0).LittleEndian();
UInt64 k1 = (UInt64)BitConverter.ToInt64(keys.Slice(8, 16), 0).LittleEndian();
UInt32 edgeMask = (UInt32)(1 << Job.EdgeBits) - 1;
UInt32[] uvs = new UInt32[2 * CYCLE_LENGTH];
UInt32 xor0 = 0;
UInt32 xor1 = 0;
for (var n = 0; n < CYCLE_LENGTH; n++)
{
if (Cycle[n] > edgeMask)
{
_logger.Error("POW_TOO_BIG");
return(false);
}
if (n > 0 && Cycle[n] <= Cycle[n - 1])
{
_logger.Error("POW_TOO_SMALL");
return(false);
}
xor0 ^= uvs[2 * n] = sipnode(k0, k1, edgeMask, Cycle[n], 0);
xor1 ^= uvs[2 * n + 1] = sipnode(k0, k1, edgeMask, Cycle[n], 1);
}
// matching endpoints imply zero xors
if ((xor0 | xor1) != 0)
{
var cycleStr = "";
foreach (var edge in Cycle)
{
cycleStr += edge.ToString("x") + ",";
}
cycleStr = cycleStr.Remove(cycleStr.Length - 1);
_logger.Debug("Block hash: {0}", BlockHash.ToHexString());
_logger.Debug("Cycle: {0}", cycleStr);
_logger.Error("POW_NON_MATCHING");
return(false);
}
int m = 0, i = 0, j;
do // follow cycle
{
for (int k = j = i; (k = (k + 2) % (2 * CYCLE_LENGTH)) != i;)
{
if (uvs[k] == uvs[i]) // find other edge endpoint identical to one at i
{
if (j != i) // already found one before
{
_logger.Error("POW_BRANCH");
return(false);
}
j = k;
}
}
if (j == i)
{
_logger.Error("POW_DEAD_END");
return(false);
}
i = j ^ 1;
m++;
} while (i != 0); // must cycle back to start or we would have found branch
if (m != CYCLE_LENGTH)
{
_logger.Error("POW_SHORT_CYCLE");
return(false);
}
return(true);
}