public Task UpdateParity(bool force, UpdateParityStatus status, CancellationToken token)
{
return(Task.Run(() => updateParityAsyncInternal(force, status, token), token));
}
private void updateParityAsyncInternal(bool force, UpdateParityStatus status, CancellationToken token)
{
if (!force && !DataModified && ParityWritten)
{
return;
}
int dataClustersPerTrack = Configuration.Geometry.DataClustersPerTrack;
int parityClustersPerTrack = Configuration.Geometry.ParityClustersPerTrack;
int bytesPerCluster = Configuration.Geometry.BytesPerCluster;
using (var p = new Parity(dataClustersPerTrack, parityClustersPerTrack, bytesPerCluster / 2)) {
int codewordExponent = dataClustersPerTrack + parityClustersPerTrack - 1;
byte[] emptyCluster = null;
int clustersComplete = -1;
foreach (var absoluteClusterNumber in DataClusters)
{
ClusterState state = _fileSystem.GetClusterState(absoluteClusterNumber);
if (!state.IsSystem())
{
if ((state & ClusterState.Unwritten) != 0)
{
if (emptyCluster == null)
{
EmptyCluster c = new EmptyCluster(absoluteClusterNumber);
_fileSystem.ClusterIO.Save(c);
emptyCluster = new byte[bytesPerCluster];
c.Save(emptyCluster, 0);
}
p.Calculate(emptyCluster, 0, codewordExponent);
state &= ~ClusterState.Unwritten;
_fileSystem.SetClusterState(absoluteClusterNumber, state);
}
else
{
Cluster c = new Cluster(absoluteClusterNumber, bytesPerCluster);
_fileSystem.ClusterIO.Load(c);
byte[] bytes = new byte[bytesPerCluster];
c.Save(bytes, 0);
p.Calculate(bytes, 0, codewordExponent);
}
}
clustersComplete++;
status.Cluster = clustersComplete;
codewordExponent--;
if (token.IsCancellationRequested)
{
return;
}
}
for (int i = 0; i < parityClustersPerTrack; i++)
{
ParityCluster c = new ParityCluster(_fileSystem.BlockSize, _trackNumber, i);
byte[] bytes = new byte[bytesPerCluster];
p.GetParity(bytes, 0, parityClustersPerTrack - 1 - i);
c.Data.Set(0, bytes);
_fileSystem.ClusterIO.Save(c);
_fileSystem.SetClusterState(c.ClusterAddress, ClusterState.Parity);
clustersComplete++;
status.Cluster = clustersComplete;
if (token.IsCancellationRequested)
{
return;
}
}
}
// Update states after the parity is modified in case there is an error
foreach (var i in DataClusters)
{
ClusterState state = _fileSystem.GetClusterState(i) & (~ClusterState.Modified);
_fileSystem.SetClusterState(i, state);
}
_fileSystem.Flush();
}
