Author: damjan
Date: Tue Oct 28 04:01:00 2014
New Revision: 1634775
URL: http://svn.apache.org/r1634775
Log:
Optimize the LZW implementation,
support reading bit patterns that are either big or little endian,
and make LZWInputStream public.
Added:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/LZWInputStream.java
(with props)
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/package.html
(with props)
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/utils/BitInputStream.java
(with props)
Removed:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/z/_internal_/
Modified:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/archivers/zip/UnshrinkingInputStream.java
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/z/ZCompressorInputStream.java
Modified:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/archivers/zip/UnshrinkingInputStream.java
URL:
http://svn.apache.org/viewvc/commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/archivers/zip/UnshrinkingInputStream.java?rev=1634775&r1=1634774&r2=1634775&view=diff
==============================================================================
---
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/archivers/zip/UnshrinkingInputStream.java
(original)
+++
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/archivers/zip/UnshrinkingInputStream.java
Tue Oct 28 04:01:00 2014
@@ -20,21 +20,22 @@ package org.apache.commons.compress.arch
import java.io.IOException;
import java.io.InputStream;
+import java.nio.ByteOrder;
-import
org.apache.commons.compress.compressors.z._internal_.InternalLZWInputStream;
+import org.apache.commons.compress.compressors.lzw.LZWInputStream;
/**
* Input stream that decompresses ZIP method 1 (unshrinking). A variation of
the LZW algorithm, with some twists.
* @NotThreadSafe
* @since 1.7
*/
-class UnshrinkingInputStream extends InternalLZWInputStream {
+class UnshrinkingInputStream extends LZWInputStream {
private static final int MAX_CODE_SIZE = 13;
private static final int MAX_TABLE_SIZE = 1 << MAX_CODE_SIZE;
private final boolean[] isUsed;
public UnshrinkingInputStream(InputStream inputStream) throws IOException {
- super(inputStream);
+ super(inputStream, ByteOrder.LITTLE_ENDIAN);
setClearCode(codeSize);
initializeTables(MAX_CODE_SIZE);
isUsed = new boolean[prefixes.length];
Added:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/LZWInputStream.java
URL:
http://svn.apache.org/viewvc/commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/LZWInputStream.java?rev=1634775&view=auto
==============================================================================
---
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/LZWInputStream.java
(added)
+++
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/LZWInputStream.java
Tue Oct 28 04:01:00 2014
@@ -0,0 +1,178 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.compress.compressors.lzw;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteOrder;
+
+import org.apache.commons.compress.compressors.CompressorInputStream;
+import org.apache.commons.compress.utils.BitInputStream;
+
+/**
+ * <p>Generic LZW implementation. It is used internally for
+ * the Z decompressor and the Unshrinking Zip file compression method,
+ * but may be useful for third-party projects in implementing their own LZW
variations.</p>
+ *
+ * @NotThreadSafe
+ * @since 1.10
+ */
+public abstract class LZWInputStream extends CompressorInputStream {
+ private final byte[] oneByte = new byte[1];
+
+ protected final BitInputStream in;
+ protected int clearCode = -1;
+ protected int codeSize = 9;
+ protected byte previousCodeFirstChar;
+ protected int previousCode = -1;
+ protected int tableSize = 0;
+ protected int[] prefixes;
+ protected byte[] characters;
+ private byte[] outputStack;
+ private int outputStackLocation;
+
+ protected LZWInputStream(final InputStream inputStream, final ByteOrder
byteOrder) {
+ this.in = new BitInputStream(inputStream, byteOrder);
+ }
+
+ @Override
+ public void close() throws IOException {
+ in.close();
+ }
+
+ @Override
+ public int read() throws IOException {
+ int ret = read(oneByte);
+ if (ret < 0) {
+ return ret;
+ }
+ return 0xff & oneByte[0];
+ }
+
+ @Override
+ public int read(byte[] b, int off, int len) throws IOException {
+ int bytesRead = readFromStack(b, off, len);
+ while (len - bytesRead > 0) {
+ int result = decompressNextSymbol();
+ if (result < 0) {
+ if (bytesRead > 0) {
+ count(bytesRead);
+ return bytesRead;
+ }
+ return result;
+ }
+ bytesRead += readFromStack(b, off + bytesRead, len - bytesRead);
+ }
+ count(bytesRead);
+ return bytesRead;
+ }
+
+ /**
+ * Read the next code and expand it.
+ */
+ protected abstract int decompressNextSymbol() throws IOException;
+
+ /**
+ * Add a new entry to the dictionary.
+ */
+ protected abstract int addEntry(int previousCode, byte character)
+ throws IOException;
+
+ /**
+ * Sets the clear code based on the code size.
+ */
+ protected void setClearCode(int codeSize) {
+ clearCode = (1 << (codeSize - 1));
+ }
+
+ /**
+ * Initializes the arrays based on the maximum code size.
+ */
+ protected void initializeTables(int maxCodeSize) {
+ final int maxTableSize = 1 << maxCodeSize;
+ prefixes = new int[maxTableSize];
+ characters = new byte[maxTableSize];
+ outputStack = new byte[maxTableSize];
+ outputStackLocation = maxTableSize;
+ final int max = 1 << 8;
+ for (int i = 0; i < max; i++) {
+ prefixes[i] = -1;
+ characters[i] = (byte) i;
+ }
+ }
+
+ /**
+ * Reads the next code from the stream.
+ */
+ protected int readNextCode() throws IOException {
+ return in.readBits(codeSize);
+ }
+
+ /**
+ * Adds a new entry if the maximum table size hasn't been exceeded
+ * and returns the new index.
+ */
+ protected int addEntry(int previousCode, byte character, int maxTableSize)
{
+ if (tableSize < maxTableSize) {
+ prefixes[tableSize] = previousCode;
+ characters[tableSize] = character;
+ return tableSize++;
+ }
+ return -1;
+ }
+
+ /**
+ * Add entry for repeat of previousCode we haven't added, yet.
+ */
+ protected int addRepeatOfPreviousCode() throws IOException {
+ if (previousCode == -1) {
+ // can't have a repeat for the very first code
+ throw new IOException("The first code can't be a reference to its
preceding code");
+ }
+ return addEntry(previousCode, previousCodeFirstChar);
+ }
+
+ /**
+ * Expands the entry with index code to the output stack and may
+ * create a new entry
+ */
+ protected int expandCodeToOutputStack(int code, boolean
addedUnfinishedEntry)
+ throws IOException {
+ for (int entry = code; entry >= 0; entry = prefixes[entry]) {
+ outputStack[--outputStackLocation] = characters[entry];
+ }
+ if (previousCode != -1 && !addedUnfinishedEntry) {
+ addEntry(previousCode, outputStack[outputStackLocation]);
+ }
+ previousCode = code;
+ previousCodeFirstChar = outputStack[outputStackLocation];
+ return outputStackLocation;
+ }
+
+ private int readFromStack(byte[] b, int off, int len) {
+ int remainingInStack = outputStack.length - outputStackLocation;
+ if (remainingInStack > 0) {
+ int maxLength = Math.min(remainingInStack, len);
+ System.arraycopy(outputStack, outputStackLocation, b, off,
maxLength);
+ outputStackLocation += maxLength;
+ return maxLength;
+ }
+ return 0;
+ }
+}
Propchange:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/LZWInputStream.java
------------------------------------------------------------------------------
svn:eol-style = native
Added:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/package.html
URL:
http://svn.apache.org/viewvc/commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/package.html?rev=1634775&view=auto
==============================================================================
---
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/package.html
(added)
+++
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/package.html
Tue Oct 28 04:01:00 2014
@@ -0,0 +1,23 @@
+<html>
+<!--
+
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+-->
+ <body>
+ <p>Generic LZW implementation.</p>
+ </body>
+</html>
Propchange:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/lzw/package.html
------------------------------------------------------------------------------
svn:eol-style = native
Modified:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/z/ZCompressorInputStream.java
URL:
http://svn.apache.org/viewvc/commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/z/ZCompressorInputStream.java?rev=1634775&r1=1634774&r2=1634775&view=diff
==============================================================================
---
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/z/ZCompressorInputStream.java
(original)
+++
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/compressors/z/ZCompressorInputStream.java
Tue Oct 28 04:01:00 2014
@@ -20,14 +20,16 @@ package org.apache.commons.compress.comp
import java.io.IOException;
import java.io.InputStream;
-import
org.apache.commons.compress.compressors.z._internal_.InternalLZWInputStream;
+import java.nio.ByteOrder;
+
+import org.apache.commons.compress.compressors.lzw.LZWInputStream;
/**
* Input stream that decompresses .Z files.
* @NotThreadSafe
* @since 1.7
*/
-public class ZCompressorInputStream extends InternalLZWInputStream {
+public class ZCompressorInputStream extends LZWInputStream {
private static final int MAGIC_1 = 0x1f;
private static final int MAGIC_2 = 0x9d;
private static final int BLOCK_MODE_MASK = 0x80;
@@ -37,10 +39,10 @@ public class ZCompressorInputStream exte
private long totalCodesRead = 0;
public ZCompressorInputStream(InputStream inputStream) throws IOException {
- super(inputStream);
- int firstByte = in.read();
- int secondByte = in.read();
- int thirdByte = in.read();
+ super(inputStream, ByteOrder.LITTLE_ENDIAN);
+ int firstByte = in.readBits(8);
+ int secondByte = in.readBits(8);
+ int thirdByte = in.readBits(8);
if (firstByte != MAGIC_1 || secondByte != MAGIC_2 || thirdByte < 0) {
throw new IOException("Input is not in .Z format");
}
@@ -87,8 +89,7 @@ public class ZCompressorInputStream exte
for (long i = 0; i < codeReadsToThrowAway; i++) {
readNextCode();
}
- bitsCached = 0;
- bitsCachedSize = 0;
+ in.clearBitCache();
}
/**
Added:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/utils/BitInputStream.java
URL:
http://svn.apache.org/viewvc/commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/utils/BitInputStream.java?rev=1634775&view=auto
==============================================================================
---
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/utils/BitInputStream.java
(added)
+++
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/utils/BitInputStream.java
Tue Oct 28 04:01:00 2014
@@ -0,0 +1,83 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.compress.utils;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteOrder;
+
+/**
+ * Reads bits from an InputStream.
+ * @since 1.10
+ * @NotThreadSafe
+ */
+public class BitInputStream implements Closeable {
+ private final InputStream in;
+ private final ByteOrder byteOrder;
+ private int bitsCached = 0;
+ private int bitsCachedSize = 0;
+
+ /**
+ * Constructor taking an InputStream and its bit arrangement.
+ * @param in the InputStream
+ * @param byteOrder the bit arrangement across byte boundaries,
+ * either BIG_ENDIAN (aaaaabbb bb000000) or LITTLE_ENDIAN (bbbaaaaa
000000bb)
+ */
+ public BitInputStream(final InputStream in, final ByteOrder byteOrder) {
+ this.in = in;
+ this.byteOrder = byteOrder;
+ }
+
+ public void close() throws IOException {
+ in.close();
+ }
+
+ public void clearBitCache() {
+ bitsCached = 0;
+ bitsCachedSize = 0;
+ }
+
+ public int readBits(final int count) throws IOException {
+ while (bitsCachedSize < count) {
+ final int nextByte = in.read();
+ if (nextByte < 0) {
+ return nextByte;
+ }
+ if (byteOrder == ByteOrder.LITTLE_ENDIAN) {
+ bitsCached |= (nextByte << bitsCachedSize);
+ } else {
+ bitsCached <<= 8;
+ bitsCached |= nextByte;
+ }
+ bitsCachedSize += 8;
+ }
+
+ final int mask = (1 << count) - 1;
+ final int bitsOut;
+ if (byteOrder == ByteOrder.LITTLE_ENDIAN) {
+ bitsOut = (bitsCached & mask);
+ bitsCached >>>= count;
+ } else {
+ bitsOut = (bitsCached >> (bitsCachedSize - count)) & mask;
+ }
+ bitsCachedSize -= count;
+ return bitsOut;
+ }
+}
Propchange:
commons/proper/compress/trunk/src/main/java/org/apache/commons/compress/utils/BitInputStream.java
------------------------------------------------------------------------------
svn:eol-style = native
