/// <summary>
/// Returns an empty directory entry, suitable for writing to a newly created disk or sanitizing a directory track.
/// </summary>
/// <returns></returns>
public static DragonDosDirectoryEntry GetEmptyEntry()
{
var entry = new DragonDosDirectoryEntry();
entry.Flags = DirectoryFlags.Invalid | DirectoryFlags.EndOfDirectory;
return(entry);
}
/// <summary>
/// Sets the directory entry at a given index.
/// </summary>
/// <param name="index"></param>
/// <param name="entry"></param>
private void SetDirectoryEntry(int index, DragonDosDirectoryEntry entry)
{
int sector = index / DirectoryEntryCount + DirectoryEntryOffset;
int offset = index % DirectoryEntryCount * DirectoryEntrySize;
entry.Encode(directoryTrack[sector], offset);
}
/// <summary>
/// Create a set of directory entries for a file.
/// </summary>
/// <param name="filename">Filename</param>
/// <param name="extents">Ordered list of extents containing the file payload data.</param>
/// <param name="dirInx">Orderes list of directory entry indexes to use.</param>
/// <returns>Orderes list of directory entries</returns>
private DragonDosDirectoryEntry[] CreateDirectoryEntries(string filename, DragonDosDirectoryEntry.Extent[] extents, int[] dirInx, int lastSectorSize)
{
var dirEntries = new DragonDosDirectoryEntry[dirInx.Length];
int maxExtents;
int extentOffset = 0;
for (int i = 0; i < dirInx.Length; i++)
{
var dir = new DragonDosDirectoryEntry()
{
Flags = 0
};
if (i == 0)
{
dir.Filename = filename;
dir.IsExtensionEntry = false;
maxExtents = 4;
}
else
{
dir.IsExtensionEntry = true;
maxExtents = 7;
}
if (i == dirInx.Length - 1)
{
dir.LastSectorSize = lastSectorSize;
}
else
{
dir.NextEntry = dirInx[i + 1];
}
dir.Extents = new DragonDosDirectoryEntry.Extent[Math.Min(maxExtents, extents.Length - extentOffset)];
Array.Copy(extents, extentOffset, dir.Extents, 0, dir.Extents.Length);
extentOffset += dir.Extents.Length;
dirEntries[i] = dir;
}
return(dirEntries);
}
/// <summary>
/// Initialize an empty DragonDos filesystem on a disk.
/// </summary>
/// <param name="disk">Disk to initialize filesystem on.</param>
/// <returns>DragonDos filesystem.</returns>
/// <exception cref="DiskNotWriteableException">The disk does not support write operations.</exception>
/// <exception cref="UnsupportedGeometryException">The disk geometry is not supported by DragonDos.</exception>
public static DragonDos Initialize(IDisk disk)
{
if (disk == null)
{
throw new ArgumentNullException("disk");
}
if (!disk.IsWriteable)
{
throw new DiskNotWriteableException();
}
if (disk.Tracks != 40 && disk.Tracks != 80)
{
throw new UnsupportedGeometryException(String.Format("DragonDos only supports 40 or 80 tracks while this disk has {0} tracks", disk.Tracks));
}
if (disk.Heads != 1 && disk.Heads != 2)
{
throw new UnsupportedGeometryException(String.Format("DragonDos only supports single or double sided disks while this disk has {0} sides", disk.Heads));
}
/* Write blank data to all sectors. */
var sectorData = new byte[SectorSize];
for (int t = 0; t < disk.Tracks; t++)
{
for (int h = 0; h < disk.Heads; h++)
{
for (int s = 1; s < SectorsPerHead; s++)
{
disk.WriteSector(h, t, s, sectorData);
}
}
}
/* Write empty directory entries to the directory track. */
var emptyDirEntry = DragonDosDirectoryEntry.GetEmptyEntry();
var emptyEncodedEntry = new byte[DirectoryEntrySize];
emptyDirEntry.Encode(emptyEncodedEntry, 0);
for (int i = 0; i < DirectoryEntryCount; i++)
{
Array.Copy(emptyEncodedEntry, 0, sectorData, i * DirectoryEntrySize, DirectoryEntrySize);
}
for (int s = DirectoryEntryOffset + 1; s <= SectorsPerHead; s++)
{
disk.WriteSector(0, DirectoryTrackPrimary, s, sectorData);
disk.WriteSector(0, DirectoryTrackBackup, s, sectorData);
}
/* Write the sector allocation map. */
var allocationmap = new byte[2][];
allocationmap[0] = new byte[SectorSize];
allocationmap[1] = new byte[SectorSize];
int sectors = SectorsPerHead * disk.Heads;
allocationmap[0][252] = (byte)disk.Tracks; // encode disk geometry
allocationmap[0][253] = (byte)sectors;
allocationmap[0][254] = (byte)(~disk.Tracks & 0xff);
allocationmap[0][255] = (byte)(~sectors & 0xff);
for (var i = 0; i < disk.Tracks * disk.Heads * SectorsPerHead; i++) // mark all sectors as unallocated
{
SetSectorAllocated(i, false, allocationmap);
}
int lsnPrimaryDirectory = DirectoryTrackPrimary * disk.Heads * SectorsPerHead; // mark directory track as allocated
int lsnBackupDirectory = DirectoryTrackBackup * disk.Heads * SectorsPerHead;
for (var i = 0; i < SectorsPerHead; i++)
{
SetSectorAllocated(lsnPrimaryDirectory++, true, allocationmap);
SetSectorAllocated(lsnBackupDirectory++, true, allocationmap);
}
for (var i = 0; i < 2; i++)
{
disk.WriteSector(0, DirectoryTrackPrimary, i + 1, allocationmap[i]);
disk.WriteSector(0, DirectoryTrackBackup, i + 1, allocationmap[i]);
}
return(new DragonDos(disk, true));
}