// Copyright 2001-2005, FreeHEP.
package org.freehep.util.io;
import java.io.IOException;
import java.io.InputStream;
/**
* The RunLengthStream decodes Run Length encoding. The exact definition of Run
* Length encoding can be found in the PostScript Language Reference (3rd ed.)
* chapter 3.13.3.
*
* IMPORTANT: inherits from InputStream rather than FilterInputStream so that
* the correct read(byte[], int, int) method is used.
*
* @author Mark Donszelmann
* @version $Id: RunLengthInputStream.java,v 1.3 2008-05-04 12:21:33 murkle Exp
* $
*/
public class RunLengthInputStream extends InputStream implements RunLength {
private int[] buffer = new int[LENGTH];
private int index;
private int count;
private InputStream in;
/**
* Create a Run Length input stream
*
* @param input
* stream to read from
*/
public RunLengthInputStream(InputStream input) {
super();
in = input;
index = 0;
count = 0;
}
@Override
public int read() throws IOException {
if ((index >= count) || (index > 128)) {
if (!fillBuffer()) {
return -1;
}
}
int b = buffer[index];
index++;
return b & 0x00FF;
}
private boolean fillBuffer() throws IOException {
count = in.read();
if (end(count)) {
return false;
}
if (count < 128) {
// buffered
count++;
for (int i = 0; i < count; i++) {
buffer[i] = in.read();
if (end(buffer[i])) {
return false;
}
}
} else {
// counted
count = 257 - count;
int b = in.read();
if (end(b)) {
return false;
}
for (int i = 0; i < count; i++) {
buffer[i] = b;
}
}
index = 0;
return true;
}
private static boolean end(int b) {
if ((b < 0) || (b == EOD)) {
return true;
}
return false;
}
}