Package org.applecommander.device.nibble

Class NibbleScanner

java.lang.Object

org.applecommander.device.nibble.NibbleScanner

public class NibbleScanner
extends Object

Scan a nibble disk and try to identify the formatting. Note that this is really only good for protected DOS disks. Also note that the DOS catalog track has likely been moved, so the DOS filesystem needs to also support it.

This appears to be a rather successful algorithm:

1. Locate address prolog bytes by simply looking for the track number and a sensible sector using 4invalid input: '&'4 encoding.
2. From that prolog (per track), start from end of address prolog and scan for sync bytes.
3. Try reading based on the sector count (16 vs 13).

Constructor Summary

Constructors

Constructor	Description
NibbleScanner()

Method Summary

Modifier and Type	Method	Description
static Map<Integer,Set<Integer>>	findAddressPrologs(int track, DataBuffer trackData)	Look for likely address prologs on disk.
static int	findDataProlog(int addressProlog, DataBuffer trackData, NibbleDiskCodec nibbleDiskCodec)	Scan from an address prolog, look for sync bytes, and then assume next 3 are data prolog.
static Optional<DiskMarker[]>	identify(NibbleTrackReaderWriter trackReaderWriter)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

NibbleScanner

public NibbleScanner()

Method Details

identify

public static Optional<DiskMarker[]> identify(NibbleTrackReaderWriter trackReaderWriter)

findAddressPrologs

public static Map<Integer,Set<Integer>> findAddressPrologs(int track,
 DataBuffer trackData)

Look for likely address prologs on disk. Returns raw results in case there is more than one possibility and to identify likely sectors per track.

Generate strategy is to look for byte sequence P1 P2 P3 VX VY TX TY SX SY CX CY E1 E2 E3 where 1,2,3 = prolog/epilog bytes, X,Y = 4+4 encoded data, and V,T,S,C identify volume, track, sector, and checksum.

findDataProlog

public static int findDataProlog(int addressProlog,
 DataBuffer trackData,
 NibbleDiskCodec nibbleDiskCodec)

Scan from an address prolog, look for sync bytes, and then assume next 3 are data prolog. Note that this makes a bunch of assumptions!