private void LoadSector()
{
if (_pack == null)
{
return;
}
//
// Pull data off disk and pack it into our faked-up sector.
// Note that this data is packed in in REVERSE ORDER because that's
// how it gets written out and it's how the Alto expects it to be read back in.
//
DiskSector sector = _pack.GetSector(_cylinder, _head, _sector);
// Header (2 words data, 1 word cksum)
for (int i = HeaderOffset + 1, j = 1; i < HeaderOffset + 3; i++, j--)
{
// actual data to be loaded from disk / cksum calculated
_sectorData[i] = new DataCell(sector.ReadHeader(j), CellType.Data);
}
ushort checksum = CalculateChecksum(_sectorData, HeaderOffset + 1, 2);
_sectorData[HeaderOffset + 3].Data = checksum;
Log.Write(LogType.Verbose, LogComponent.DiskController, "Header checksum for C/H/S {0}/{1}/{2} is {3}", _cylinder, _head, _sector, Conversion.ToOctal(checksum));
// Label (8 words data, 1 word cksum)
for (int i = LabelOffset + 1, j = 7; i < LabelOffset + 9; i++, j--)
{
// actual data to be loaded from disk / cksum calculated
_sectorData[i] = new DataCell(sector.ReadLabel(j), CellType.Data);
}
checksum = CalculateChecksum(_sectorData, LabelOffset + 1, 8);
_sectorData[LabelOffset + 9].Data = checksum;
Log.Write(LogType.Verbose, LogComponent.DiskController, "Label checksum for C/H/S {0}/{1}/{2} is {3}", _cylinder, _head, _sector, Conversion.ToOctal(checksum));
// sector data (256 words data, 1 word cksum)
for (int i = DataOffset + 1, j = 255; i < DataOffset + 257; i++, j--)
{
// actual data to be loaded from disk / cksum calculated
_sectorData[i] = new DataCell(sector.ReadData(j), CellType.Data);
}
checksum = CalculateChecksum(_sectorData, DataOffset + 1, 256);
_sectorData[DataOffset + 257].Data = checksum;
Log.Write(LogType.Verbose, LogComponent.DiskController, "Data checksum for C/H/S {0}/{1}/{2} is {3}", _cylinder, _head, _sector, Conversion.ToOctal(checksum));
}
