private ExtentBlock LoadExtentBlock(ExtentIndex idxEntry)
{
uint blockSize = _context.SuperBlock.BlockSize;
_context.RawStream.Position = idxEntry.LeafPhysicalBlock * blockSize;
byte[] buffer = Utilities.ReadFully(_context.RawStream, (int)blockSize);
ExtentBlock subBlock = Utilities.ToStruct <ExtentBlock>(buffer, 0);
return(subBlock);
}
private Extent FindExtent(ExtentBlock node, uint logicalBlock)
{
if (node.Index != null)
{
ExtentIndex idxEntry = null;
if (node.Index.Length == 0)
{
return(null);
}
else if (node.Index[0].FirstLogicalBlock >= logicalBlock)
{
idxEntry = node.Index[0];
}
else
{
for (int i = 0; i < node.Index.Length; ++i)
{
if (node.Index[i].FirstLogicalBlock > logicalBlock)
{
idxEntry = node.Index[i - 1];
break;
}
}
}
if (idxEntry == null)
{
idxEntry = node.Index[node.Index.Length - 1];
}
ExtentBlock subBlock = LoadExtentBlock(idxEntry);
return(FindExtent(subBlock, logicalBlock));
}
else if (node.Extents != null)
{
Extent entry = null;
if (node.Extents.Length == 0)
{
return(null);
}
else if (node.Extents[0].FirstLogicalBlock >= logicalBlock)
{
return(node.Extents[0]);
}
else
{
for (int i = 0; i < node.Extents.Length; ++i)
{
if (node.Extents[i].FirstLogicalBlock > logicalBlock)
{
entry = node.Extents[i - 1];
break;
}
}
}
if (entry == null)
{
entry = node.Extents[node.Extents.Length - 1];
}
return(entry);
}
else
{
return(null);
}
}