113 lines
3.6 KiB
Java
113 lines
3.6 KiB
Java
package com.bytezone.diskbrowser.nib;
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import java.io.BufferedInputStream;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.IOException;
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import com.bytezone.diskbrowser.utilities.HexFormatter;
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import com.bytezone.diskbrowser.utilities.Utility;
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/*
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* from Gerard Putter's email:
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* Offsets in bytes
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* From To Meaning
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* 0000 0003 Length of disk image, from offset 8 to the end (big endian)
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* 0004 0007 Type indication; always 'D5NI'
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* 0008 0009 Number of tracks (typical value: $23, but can be different). Also big endian.
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* 000A 000B Track nummer * 4, starting with track # 0. Big endian.
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* 000C 000D Length of track, not counting this length-field. Big endian.
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* 000E 000E + length field - 1 Nibble-data of track, byte-for-byte.
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* After this, the pattern from offset 000A repeats for each track. Note that
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* "track number * 4" means that on a regular disk the tracks are numbered 0, 4, 8 etc.
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* Half-tracks are numbered 2, 6, etc. The stepper motor of the disk uses 4 phases to
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* travel from one track to the next, so quarter-tracks could also be stored with this
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* format (I have never heard of disk actually using quarter tracks, though).
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*/
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// Physical disk interleave:
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// Info from http://www.applelogic.org/TheAppleIIEGettingStarted.html
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// Block ..: 0 1 2 3 4 5 6 7 8 9 A B C D E F
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// Position: 0 8 1 9 2 A 3 B 4 C 5 D 6 E 7 F - Prodos (.PO disks)
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// Position: 0 7 E 6 D 5 C 4 B 3 A 2 9 1 8 F - Dos (.DO disks)
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public class V2dFile
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{
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// private static int[][] interleave =
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// { { 0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15 },
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// { 0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15 } };
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// private static final int DOS = 0;
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// private static final int PRODOS = 1;
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private static final int TRACK_LENGTH = 6304;
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private final Nibblizer nibbler;
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public final File file;
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final int tracks;
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final byte[] diskBuffer = new byte[4096 * 35];
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public V2dFile (File file)
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{
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this.file = file;
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int tracks = 0;
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nibbler = new Nibblizer ();
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try
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{
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byte[] header = new byte[10];
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BufferedInputStream in = new BufferedInputStream (new FileInputStream (file));
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in.read (header);
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int diskLength = Utility.getLongBigEndian (header, 0); // 4 bytes
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String id = HexFormatter.getString (header, 4, 4); // 4 bytes
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tracks = Utility.getShortBigEndian (header, 8); // 2 bytes
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assert diskLength + 8 == file.length ();
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assert "D5NI".equals (id);
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byte[] trackHeader = new byte[4];
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byte[] trackData = new byte[TRACK_LENGTH];
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for (int i = 0; i < tracks; i++)
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{
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in.read (trackHeader);
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int trackNumber = Utility.getShortBigEndian (trackHeader, 0);
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int trackLength = Utility.getShortBigEndian (trackHeader, 2); // 6304
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assert trackLength == TRACK_LENGTH;
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int dataRead = in.read (trackData);
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assert dataRead == TRACK_LENGTH;
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int fullTrackNo = trackNumber / 4;
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int halfTrackNo = trackNumber % 4;
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if (halfTrackNo == 0) // only process full tracks
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nibbler.processTrack (fullTrackNo, 16, trackData, diskBuffer);
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else
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System.out.printf ("%s skipping half track %02X / %02X%n", file.getName (),
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fullTrackNo, halfTrackNo);
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}
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in.close ();
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}
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catch (IOException e)
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{
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e.printStackTrace ();
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}
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this.tracks = tracks;
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}
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// ---------------------------------------------------------------------------------//
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// getDiskBuffer
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// ---------------------------------------------------------------------------------//
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public byte[] getDiskBuffer ()
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{
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return diskBuffer;
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}
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} |