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/*
* LZDecoder
*
* Authors: Lasse Collin <lasse.collin@tukaani.org>
* Igor Pavlov <http://7-zip.org/>
*
* This file has been put into the public domain.
* You can do whatever you want with this file.
*/
package org.tukaani.xz.lz;
import java.io.DataInputStream;
import java.io.IOException;
import org.tukaani.xz.ArrayCache;
import org.tukaani.xz.CorruptedInputException;
public final class LZDecoder {
private final byte[] buf;
private final int bufSize; // To avoid buf.length with an array-cached buf.
private int start = 0;
private int pos = 0;
private int full = 0;
private int limit = 0;
private int pendingLen = 0;
private int pendingDist = 0;
public LZDecoder(int dictSize, byte[] presetDict, ArrayCache arrayCache) {
bufSize = dictSize;
buf = arrayCache.getByteArray(bufSize, false);
if (presetDict != null) {
pos = Math.min(presetDict.length, dictSize);
full = pos;
start = pos;
System.arraycopy(presetDict, presetDict.length - pos, buf, 0, pos);
}
}
public void putArraysToCache(ArrayCache arrayCache) {
arrayCache.putArray(buf);
}
public void reset() {
start = 0;
pos = 0;
full = 0;
limit = 0;
buf[bufSize - 1] = 0x00;
}
public void setLimit(int outMax) {
if (bufSize - pos <= outMax)
limit = bufSize;
else
limit = pos + outMax;
}
public boolean hasSpace() {
return pos < limit;
}
public boolean hasPending() {
return pendingLen > 0;
}
public int getPos() {
return pos;
}
public int getByte(int dist) {
int offset = pos - dist - 1;
if (dist >= pos)
offset += bufSize;
return buf[offset] & 0xFF;
}
public void putByte(byte b) {
buf[pos++] = b;
if (full < pos)
full = pos;
}
public void repeat(int dist, int len) throws IOException {
if (dist < 0 || dist >= full)
throw new CorruptedInputException();
int left = Math.min(limit - pos, len);
pendingLen = len - left;
pendingDist = dist;
int back = pos - dist - 1;
if (dist >= pos)
back += bufSize;
do {
buf[pos++] = buf[back++];
if (back == bufSize)
back = 0;
} while (--left > 0);
if (full < pos)
full = pos;
}
public void repeatPending() throws IOException {
if (pendingLen > 0)
repeat(pendingDist, pendingLen);
}
public void copyUncompressed(DataInputStream inData, int len)
throws IOException {
int copySize = Math.min(bufSize - pos, len);
inData.readFully(buf, pos, copySize);
pos += copySize;
if (full < pos)
full = pos;
}
public int flush(byte[] out, int outOff) {
int copySize = pos - start;
if (pos == bufSize)
pos = 0;
System.arraycopy(buf, start, out, outOff, copySize);
start = pos;
return copySize;
}
}
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