67 lines
2.6 KiB
Java
67 lines
2.6 KiB
Java
package com.bytezone.diskbrowser.nib;
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// -----------------------------------------------------------------------------------//
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class ByteTranslator5and3 implements ByteTranslator
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// -----------------------------------------------------------------------------------//
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{
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// 32 valid bytes that can be stored on a disk (plus 0xAA and 0xD5)
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private static byte[] writeTranslateTable5and3 =
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{ (byte) 0xAB, (byte) 0xAD, (byte) 0xAE, (byte) 0xAF, (byte) 0xB5, (byte) 0xB6,
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(byte) 0xB7, (byte) 0xBA, (byte) 0xBB, (byte) 0xBD, (byte) 0xBE, (byte) 0xBF,
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(byte) 0xD6, (byte) 0xD7, (byte) 0xDA, (byte) 0xDB, //
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(byte) 0xDD, (byte) 0xDE, (byte) 0xDF, (byte) 0xEA, (byte) 0xEB, (byte) 0xED,
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(byte) 0xEE, (byte) 0xEF, (byte) 0xF5, (byte) 0xF6, (byte) 0xF7, (byte) 0xFA,
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(byte) 0xFB, (byte) 0xFD, (byte) 0xFE, (byte) 0xFF };
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private static final int SKIP = 0xAB;
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private static byte[] readTranslateTable5and3 = new byte[256 - SKIP];
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private static boolean debug = false;
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static
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{
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for (int i = 0; i < writeTranslateTable5and3.length; i++)
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{
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int j = (writeTranslateTable5and3[i] & 0xFF) - SKIP; // skip first 171 blanks
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readTranslateTable5and3[j] = (byte) (i + 1); // offset by 1 to avoid zero
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if (debug)
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System.out.printf ("%02X %02X %02X%n", i, writeTranslateTable5and3[i], j);
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}
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if (debug)
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for (int j = 0; j < readTranslateTable5and3.length; j++)
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{
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int target = readTranslateTable5and3[j] - 1;
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if (target >= 0)
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{
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int value = writeTranslateTable5and3[target] & 0xFF;
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System.out.printf ("%02X -> %02X%n", j, value);
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}
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else
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System.out.printf ("%02X%n", j);
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}
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}
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// ---------------------------------------------------------------------------------//
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@Override
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public byte encode (byte b)
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// ---------------------------------------------------------------------------------//
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{
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System.out.println ("encode() not written");
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return 0;
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}
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// ---------------------------------------------------------------------------------//
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@Override
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public byte decode (byte b) throws DiskNibbleException
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// ---------------------------------------------------------------------------------//
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{
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int val = (b & 0xFF) - SKIP; // 0 - 84
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if (val < 0 || val > 84)
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throw new DiskNibbleException ("5&3 val: " + val);
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byte trans = (byte) (readTranslateTable5and3[val] - 1); // 0 - 31 (5 bits)
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if (trans < 0 || trans > 31)
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throw new DiskNibbleException ("5&3 trans: " + trans);
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return trans;
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}
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}
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