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Denis Molony 2016-11-30 11:37:10 +11:00
parent 681b33df4f
commit d6418f82cf
1 changed files with 41 additions and 79 deletions
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120
src/com/bytezone/diskbrowser/disk/Nibblizer.java
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@ -22,6 +22,7 @@ public class Nibblizer
private static byte[] readTranslateTable = new byte[106];
// this array is just here for testing - it matches the example in Beneath Apple Prodos
private static byte[] xor =
{ (byte) 0x00, (byte) 0x00, (byte) 0x03, (byte) 0x00, (byte) 0xFA, (byte) 0x55,
(byte) 0x53, (byte) 0x45, (byte) 0x52, (byte) 0x53, (byte) 0x2E, (byte) 0x44,
@ -84,15 +85,19 @@ public class Nibblizer
}
}
private final byte[] decode1 = new byte[343];
private final byte[] decode2 = new byte[342];
private final byte[] encode1 = new byte[342];
private final byte[] encode2 = new byte[343];
public Nibblizer ()
{
if (false)
{
byte[] buffer = encode6and2 (xor);
byte[] buffer2 = decode6and2 (buffer, 0);
byte[] testBuffer = decode6and2 (encode6and2 (xor), 0);
for (int i = 0; i < 256; i++)
if (xor[i] != buffer2[i])
if (xor[i] != testBuffer[i])
System.out.println ("bollocks");
return;
@ -118,43 +123,29 @@ public class Nibblizer
byte[] decode6and2 (byte[] buffer, int offset)
{
// System.out.println ("\n\n343 byte disk buffer:\n");
// System.out.println (HexFormatter.format (buffer, offset, 343));
byte[] temp = new byte[343];
for (int i = 0; i < temp.length; i++)
for (int i = 0; i < decode1.length; i++)
{
int val = (buffer[offset++] & 0xFF) - 150;
byte trans = readTranslateTable[val];
assert trans != 0;
temp[i] = (byte) ((trans - 1) << 2);
decode1[i] = (byte) ((trans - 1) << 2);
}
// System.out.println ("\nTranslated 343 byte buffer:\n");
// System.out.println (HexFormatter.format (temp));
byte[] temp2 = new byte[342];
byte chk = 0;
for (int i = 342; i > 0; i--)
{
temp2[i - 1] = (byte) (temp[i] ^ chk);
chk = temp2[i - 1];
decode2[i - 1] = (byte) (decode1[i] ^ chk);
chk = decode2[i - 1];
}
// System.out.println ("\nChecksummed 342 byte buffer:\n");
// System.out.println (HexFormatter.format (temp2));
// System.out.printf ("%nChecksum: %02X%n", chk ^ temp2[0]);
byte[] decodedBuffer = new byte[256];
for (int i = 0; i < 256; i++)
decodedBuffer[i] = temp2[i + 86];
decodedBuffer[i] = decode2[i + 86];
for (int i = 0; i < 84; i++)
{
int val = temp2[i] & 0xFF;
int val = decode2[i] & 0xFF;
int b1 = reverse ((val & 0x0C) >> 2);
int b2 = reverse ((val & 0x30) >> 4);
int b3 = reverse ((val & 0xC0) >> 6);
@ -166,7 +157,7 @@ public class Nibblizer
for (int i = 84; i < 86; i++)
{
int val = temp2[i] & 0xFF;
int val = decode2[i] & 0xFF;
int b1 = reverse ((val & 0x0C) >> 2);
int b2 = reverse ((val & 0x30) >> 4);
@ -174,75 +165,49 @@ public class Nibblizer
decodedBuffer[i + 86] |= b2;
}
// System.out.println ("\nOriginal 256 byte buffer:\n");
// System.out.println (HexFormatter.format (decodedBuffer));
return decodedBuffer;
}
byte[] encode6and2 (byte[] buffer)
{
// System.out.println ("Original 256 byte buffer:\n");
// System.out.println (HexFormatter.format (buffer));
byte[] temp1 = new byte[342];
byte[] temp2 = new byte[343];
byte[] temp3 = new byte[343];
byte[] encodedBuffer = new byte[343];
for (int i = 0; i < 256; i++)
temp1[i + 86] = buffer[i];
encode1[i + 86] = buffer[i];
for (int i = 0; i < 84; i++)
{
int b1 = reverse (buffer[i] & 0x03) << 2;
int b2 = reverse (buffer[i + 86] & 0x03) << 4;
int b3 = reverse (buffer[i + 172] & 0x03) << 6;
temp1[i] = (byte) (b1 | b2 | b3);
encode1[i] = (byte) (b1 | b2 | b3);
}
for (int i = 84; i < 86; i++)
{
int b1 = reverse (buffer[i] & 0x03) << 2;
int b2 = reverse (buffer[i + 86] & 0x03) << 4;
temp1[i] = (byte) (b1 | b2);
encode1[i] = (byte) (b1 | b2);
}
// System.out.println ("\nNew 342 byte buffer:\n");
// System.out.println (HexFormatter.format (temp1));
// if (false)
// {
// temp2[0] = temp1[0];
// temp2[342] = temp1[341];
// for (int i = 1; i < 342; i++)
// temp2[i] = (byte) (temp1[i] ^ temp1[i - 1]);
// }
// else
byte chk = 0;
for (int i = 0; i < 342; i++)
{
byte chk = 0;
for (int i = 0; i < 342; i++)
{
temp2[i] = (byte) (chk ^ temp1[i]);
chk = temp1[i];
}
temp2[342] = chk;
encode2[i] = (byte) (chk ^ encode1[i]);
chk = encode1[i];
}
// System.out.println ("\nChecksummed 343 byte buffer:\n");
// System.out.println (HexFormatter.format (temp2));
encode2[342] = chk;
for (int i = 0; i < 343; i++)
temp3[i] = writeTranslateTable[(temp2[i] & 0xFC) / 4];
encodedBuffer[i] = writeTranslateTable[(encode2[i] & 0xFC) / 4];
// System.out.println ("\n\n\nTranslated 343 byte buffer:\n");
// System.out.println (HexFormatter.format (temp3));
return temp3;
return encodedBuffer;
}
// reverse 2 bits - 0 <= b <= 3
private static int reverse (int b)
// reverse 2 bits - 0 <= bits <= 3
private static int reverse (int bits)
{
return b == 1 ? 2 : b == 2 ? 1 : b;
return bits == 1 ? 2 : bits == 2 ? 1 : bits;
}
private boolean matchBytes (byte[] buffer, int offset, byte[] valueBuffer)
@ -275,15 +240,16 @@ public class Nibblizer
System.out.printf ("%02X ", buffer[offset++]);
++count;
}
// System.out.println ();
return count;
}
abstract class Field
{
boolean valid;
byte[] buffer;
int offset;
protected boolean valid;
protected byte[] buffer;
protected int offset;
protected int length;
public Field (byte[] buffer, int offset)
{
@ -296,7 +262,11 @@ public class Nibblizer
return valid;
}
public abstract int size ();
public int size ()
{
assert length > 0;
return length;
}
}
class AddressField extends Field
@ -321,12 +291,8 @@ public class Nibblizer
listBytes (buffer, offset, 14);
System.out.println ();
}
}
@Override
public int size ()
{
return 14;
length = 14;
}
}
@ -352,12 +318,8 @@ public class Nibblizer
listBytes (buffer, offset, 3);
System.out.println ();
}
}
@Override
public int size ()
{
return 349;
length = 349;
}
}
}