Apple-2-Tools/dmolony-DiskBrowser
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use original buffer

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This commit is contained in:
Denis Molony 2016-08-17 19:42:28 +10:00
parent 816548386e
commit ee94f383ea
1 changed files with 22 additions and 31 deletions
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53
src/com/bytezone/diskbrowser/wizardry/Huffman.java
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@ -6,28 +6,19 @@ import com.bytezone.diskbrowser.applefile.AbstractFile;
public class Huffman extends AbstractFile public class Huffman extends AbstractFile
{ {
private final byte[] tree; private static final int LEFT = 256;
private final byte[] left; private static final int RIGHT = 512;
private final byte[] right;
private int bitNo; private int bitNo;
private int msgPtr; private int msgPtr;
private int currentByte; private int currentByte;
private byte[] message; private byte[] message;
private String treeContents; private String bufferContents;
public Huffman (String name, byte[] buffer) public Huffman (String name, byte[] buffer)
{ {
super (name, buffer); super (name, buffer);
tree = new byte[256];
left = new byte[256];
right = new byte[256];
System.arraycopy (buffer, 0, tree, 0, 256);
System.arraycopy (buffer, 256, left, 0, 256);
System.arraycopy (buffer, 512, right, 0, 256);
} }
public String getMessage (byte[] message) public String getMessage (byte[] message)
@ -47,7 +38,7 @@ public class Huffman extends AbstractFile
private byte getChar () private byte getChar ()
{ {
int treePtr = 0; // start at the root int treePtr = 0; // start at the root
while (true) while (true)
{ {
@ -57,20 +48,20 @@ public class Huffman extends AbstractFile
currentByte = message[msgPtr++] & 0xFF; currentByte = message[msgPtr++] & 0xFF;
} }
int currentBit = currentByte % 2; // get the next bit to process int currentBit = currentByte % 2; // get the next bit to process
currentByte /= 2; currentByte /= 2;
if (currentBit == 0) // take right path if (currentBit == 0) // take right path
{ {
if ((tree[treePtr] & 0x02) != 0) // if has right leaf... if ((buffer[treePtr] & 0x02) != 0) // if has right leaf...
return right[treePtr]; // return that character return buffer[treePtr + RIGHT]; // return that character
treePtr = right[treePtr] & 0xFF; // else go to right node treePtr = buffer[treePtr + RIGHT] & 0xFF; // else traverse right node
} }
else // take left path else // take left path
{ {
if ((tree[treePtr] & 0x01) != 0) // if has left leaf... if ((buffer[treePtr] & 0x01) != 0) // if has left leaf...
return left[treePtr]; // return that character return buffer[treePtr + LEFT]; // return that character
treePtr = left[treePtr] & 0xFF; // else go to left node treePtr = buffer[treePtr + LEFT] & 0xFF; // else traverse left node
} }
} }
} }
@ -78,26 +69,26 @@ public class Huffman extends AbstractFile
@Override @Override
public String getText () public String getText ()
{ {
if (treeContents == null) if (bufferContents == null)
{ {
StringBuilder text = new StringBuilder (); StringBuilder text = new StringBuilder ();
walk (0, "", text); walk (0, "", text);
treeContents = text.toString (); bufferContents = text.toString ();
} }
return treeContents; return bufferContents;
} }
private void walk (int treePtr, String path, StringBuilder text) private void walk (int treePtr, String path, StringBuilder text)
{ {
if ((tree[treePtr] & 0x01) == 0) if ((buffer[treePtr] & 0x01) == 0)
walk (left[treePtr] & 0xFF, path + "1", text); walk (buffer[treePtr + LEFT] & 0xFF, path + "1", text);
else else
print (path + "1", left[treePtr], text); print (path + "1", buffer[treePtr + LEFT], text);
if ((tree[treePtr] & 0x02) == 0) if ((buffer[treePtr] & 0x02) == 0)
walk (right[treePtr] & 0xFF, path + "0", text); walk (buffer[treePtr + RIGHT] & 0xFF, path + "0", text);
else else
print (path + "0", right[treePtr], text); print (path + "0", buffer[treePtr + RIGHT], text);
} }
private void print (String path, byte value, StringBuilder text) private void print (String path, byte value, StringBuilder text)