public void UpdateParity(bool force = false)
{
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;
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);
Console.WriteLine($"Saving empty cluster {absoluteClusterNumber}");
_fileSystem.ClusterIO.Save(c);
emptyCluster = new byte[bytesPerCluster];
c.Save(emptyCluster, 0);
}
p.Calculate(emptyCluster, 0, codewordExponent);
state &= ~ClusterState.Unwritten;
_fileSystem.SetClusterState(absoluteClusterNumber, state);
}
else
{
Cluster c = new Cluster(absoluteClusterNumber, bytesPerCluster);
Console.WriteLine($"Loading cluster {absoluteClusterNumber}");
_fileSystem.ClusterIO.Load(c);
byte[] bytes = new byte[bytesPerCluster];
c.Save(bytes, 0);
p.Calculate(bytes, 0, codewordExponent);
}
}
codewordExponent--;
}
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);
Console.WriteLine($"Saving Parity Cluster {c.ClusterAddress}");
_fileSystem.ClusterIO.Save(c);
_fileSystem.SetClusterState(c.ClusterAddress, ClusterState.Parity);
}
}
// 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);
}
}
public void ReedsolomonRepairTest()
{
int nData = 100;
int nParity = 25;
int nMessages = 1000;
int nErrors = 20;
Random r = new Random(1234);
byte[][] data = new byte[nData][];
byte[][] original = new byte[nData][];
for (int i = 0; i < nData; i++)
{
data[i] = new byte[nMessages];
original[i] = new byte[nMessages];
r.NextBytes(data[i]);
for (int j = 0; j < nMessages; j++)
{
original[i][j] = data[i][j];
}
}
byte[][] parity = new byte[nParity][];
for (int i = 0; i < nParity; i++)
{
parity[i] = new byte[nMessages * sizeof(ushort)];
}
using (Parity p = new Parity(nData, nParity, nMessages / 2)) {
for (int i = 0; i < nData; i++)
{
p.Calculate(data[i], 0, nData + nParity - 1 - i);
}
for (int i = 0; i < nParity; i++)
{
p.GetParity(parity[i], 0, nParity - 1 - i);
}
}
List <int> choices = Enumerable.Range(0, nData + nParity).ToList();
List <int> errorExponents = new List <int>();
for (int i = 0; i < nErrors; i++)
{
int l = r.Next(choices.Count);
errorExponents.Add(choices[l]);
choices.RemoveAt(l);
}
foreach (var errorExponent in errorExponents)
{
byte[] d = errorExponent < nParity ? parity[nParity - 1 - errorExponent] : data[nData + nParity - 1 - errorExponent];
r.NextBytes(d);
}
using (Syndrome s = new Syndrome(nData, nParity, nMessages / 2)) {
for (int i = 0; i < nData; i++)
{
s.AddCodewordSlice(data[i], 0, nData + nParity - 1 - i);
}
for (int i = 0; i < nParity; i++)
{
s.AddCodewordSlice(parity[i], 0, nParity - 1 - i);
}
using (Repair repair = new Repair(s, nData + nParity, errorExponents)) {
int index = 0;
foreach (var errorExponent in errorExponents)
{
byte[] d = errorExponent < nParity ? parity[nParity - 1 - errorExponent] : data[nData + nParity - 1 - errorExponent];
repair.Correction(index, d, 0);
index++;
}
}
}
for (int i = 0; i < nData; i++)
{
Assert.IsTrue(data[i].SequenceEqual(original[i]));
}
}
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();
}