/// <summary>
/// Create a new, empty track with the specified format, sector size and sector count.
/// </summary>
/// <param name="format"></param>
/// <param name="cylinder"></param>
/// <param name="head"></param>
/// <param name="sectorCount"></param>
/// <param name="sectorSize"></param>
public Track(Format format, int cylinder, int head, int sectorCount, int sectorSize)
{
_format = format;
_cylinder = cylinder;
_head = head;
_sectorCount = sectorCount;
_sectorSize = sectorSize;
_sectors = new FloppySector[_sectorCount];
for (int i = 0; i < _sectorCount; i++)
{
_sectors[i] = new FloppySector(_sectorSize, _format);
}
}
/// <summary>
/// Create a new track loaded from the given stream. The stream is expected to be positioned
/// at the beginning of an IMD sector definition.
/// </summary>
/// <param name="s"></param>
public Track(Stream s)
{
bool bCylMap = false;
bool bHeadMap = false;
_format = (Format)s.ReadByte();
_cylinder = s.ReadByte();
_head = s.ReadByte();
_sectorCount = s.ReadByte();
int sectorSizeIndex = s.ReadByte();
// Basic sanity check of values
if (_format > Format.MFM250 ||
_cylinder > 77 ||
(_head & 0x3f) > 1 ||
sectorSizeIndex > _sectorSizes.Length - 1)
{
throw new InvalidOperationException("Invalid header data for track.");
}
_sectorSize = _sectorSizes[sectorSizeIndex];
bCylMap = (_head & 0x80) != 0;
bHeadMap = (_head & 0x40) != 0;
// Head is just the first bit.
_head = (byte)(_head & 0x1);
//
// Read sector numbering
//
_sectorOrdering = new List <int>(_sectorCount);
for (int i = 0; i < _sectorCount; i++)
{
_sectorOrdering.Add(s.ReadByte());
}
//
// At this time, cyl and head maps are not supported.
// It's not expected any Star disk would use such a format.
//
if (bCylMap | bHeadMap)
{
throw new NotImplementedException("IMD Cylinder and Head maps not supported.");
}
//
// Read the sector data in.
//
_sectors = new FloppySector[_sectorCount];
for (int i = 0; i < _sectorCount; i++)
{
SectorRecordType type = (SectorRecordType)s.ReadByte();
byte compressedData;
switch (type)
{
case SectorRecordType.Unavailable:
// Nothing, sectors left null.
break;
case SectorRecordType.Normal:
case SectorRecordType.NormalDeleted:
case SectorRecordType.NormalError:
case SectorRecordType.DeletedError:
_sectors[_sectorOrdering[i] - 1] = new FloppySector(_sectorSize, _format, s);
break;
case SectorRecordType.Compressed:
case SectorRecordType.CompressedDeleted:
case SectorRecordType.CompressedError:
case SectorRecordType.CompressedDeletedError:
compressedData = (byte)s.ReadByte();
// Fill sector with compressed data
_sectors[_sectorOrdering[i] - 1] = new FloppySector(_sectorSize, _format, compressedData);
break;
default:
throw new InvalidOperationException(String.Format("Unexpected IMD sector data type {0}", type));
}
}
}
