protected override Result WriteImpl(long offset, ReadOnlySpan <byte> source)
{
var iterator = new AllocationTableIterator(Fat, InitialBlock);
long inPos = offset;
int outPos = 0;
int remaining = source.Length;
while (remaining > 0)
{
int blockNum = (int)(inPos / BlockSize);
iterator.Seek(blockNum);
int segmentPos = (int)(inPos - (long)iterator.VirtualBlock * BlockSize);
long physicalOffset = iterator.PhysicalBlock * BlockSize + segmentPos;
int remainingInSegment = iterator.CurrentSegmentSize * BlockSize - segmentPos;
int bytesToWrite = Math.Min(remaining, remainingInSegment);
Result rc = BaseStorage.Write(physicalOffset, source.Slice(outPos, bytesToWrite));
if (rc.IsFailure())
{
return(rc);
}
outPos += bytesToWrite;
inPos += bytesToWrite;
remaining -= bytesToWrite;
}
return(Result.Success);
}
public static IEnumerable <(int block, int length)> DumpChain(this AllocationTable table, int startBlock)
{
var iterator = new AllocationTableIterator(table, startBlock);
do
{
yield return(iterator.PhysicalBlock, iterator.CurrentSegmentSize);
} while (iterator.MoveNext());
}
protected override Result DoRead(long offset, Span <byte> destination)
{
var iterator = new AllocationTableIterator(Fat, InitialBlock);
long inPos = offset;
int outPos = 0;
int remaining = destination.Length;
while (remaining > 0)
{
int blockNum = (int)(inPos / BlockSize);
if (!iterator.Seek(blockNum))
{
return(ResultFs.InvalidAllocationTableOffset.Log());
}
int segmentPos = (int)(inPos - (long)iterator.VirtualBlock * BlockSize);
long physicalOffset = iterator.PhysicalBlock * BlockSize + segmentPos;
int remainingInSegment = iterator.CurrentSegmentSize * BlockSize - segmentPos;
int bytesToRead = Math.Min(remaining, remainingInSegment);
Result rc = BaseStorage.Read(physicalOffset, destination.Slice(outPos, bytesToRead));
if (rc.IsFailure())
{
return(rc);
}
outPos += bytesToRead;
inPos += bytesToRead;
remaining -= bytesToRead;
}
return(Result.Success);
}
