| /* |
| * 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.archivers.zip; |
| |
| import java.io.DataInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.util.Arrays; |
| |
| /** |
| * Binary tree of positive values. |
| * |
| * @author Emmanuel Bourg |
| * @since 1.7 |
| */ |
| class BinaryTree { |
| |
| /** Value in the array indicating an undefined node */ |
| private static final int UNDEFINED = -1; |
| |
| /** Value in the array indicating a non leaf node */ |
| private static final int NODE = -2; |
| |
| /** |
| * The array representing the binary tree. The root is at index 0, |
| * the left children are at 2*i+1 and the right children at 2*i+2. |
| */ |
| private final int[] tree; |
| |
| public BinaryTree(int depth) { |
| tree = new int[(1 << (depth + 1)) - 1]; |
| Arrays.fill(tree, UNDEFINED); |
| } |
| |
| /** |
| * Adds a leaf to the tree. |
| * |
| * @param node the index of the node where the path is appended |
| * @param path the path to the leaf (bits are parsed from the right to the left) |
| * @param depth the number of nodes in the path |
| * @param value the value of the leaf (must be positive) |
| */ |
| public void addLeaf(int node, int path, int depth, int value) { |
| if (depth == 0) { |
| // end of the path reached, add the value to the current node |
| if (tree[node] == UNDEFINED) { |
| tree[node] = value; |
| } else { |
| throw new IllegalArgumentException("Tree value at index " + node + " has already been assigned (" + tree[node] + ")"); |
| } |
| } else { |
| // mark the current node as a non leaf node |
| tree[node] = NODE; |
| |
| // move down the path recursively |
| int nextChild = 2 * node + 1 + (path & 1); |
| addLeaf(nextChild, path >>> 1, depth - 1, value); |
| } |
| } |
| |
| /** |
| * Reads a value from the specified bit stream. |
| * |
| * @param stream |
| * @return the value decoded, or -1 if the end of the stream is reached |
| */ |
| public int read(BitStream stream) throws IOException { |
| int currentIndex = 0; |
| |
| while (true) { |
| int bit = stream.nextBit(); |
| if (bit == -1) { |
| return -1; |
| } |
| |
| int childIndex = 2 * currentIndex + 1 + bit; |
| int value = tree[childIndex]; |
| if (value == NODE) { |
| // consume the next bit |
| currentIndex = childIndex; |
| } else if (value != UNDEFINED) { |
| return value; |
| } else { |
| throw new IOException("The child " + bit + " of node at index " + currentIndex + " is not defined"); |
| } |
| } |
| } |
| |
| |
| /** |
| * Decodes the packed binary tree from the specified stream. |
| */ |
| static BinaryTree decode(InputStream in, final int totalNumberOfValues) throws IOException { |
| // the first byte contains the size of the structure minus one |
| int size = in.read() + 1; |
| if (size == 0) { |
| throw new IOException("Cannot read the size of the encoded tree, unexpected end of stream"); |
| } |
| |
| byte[] encodedTree = new byte[size]; |
| new DataInputStream(in).readFully(encodedTree); |
| |
| /** The maximum bit length for a value (16 or lower) */ |
| int maxLength = 0; |
| |
| int[] originalBitLengths = new int[totalNumberOfValues]; |
| int pos = 0; |
| for (byte b : encodedTree) { |
| // each byte encodes the number of values (upper 4 bits) for a bit length (lower 4 bits) |
| int numberOfValues = ((b & 0xF0) >> 4) + 1; |
| int bitLength = (b & 0x0F) + 1; |
| |
| for (int j = 0; j < numberOfValues; j++) { |
| originalBitLengths[pos++] = bitLength; |
| } |
| |
| maxLength = Math.max(maxLength, bitLength); |
| } |
| |
| // sort the array of bit lengths and memorize the permutation used to restore the order of the codes |
| int[] permutation = new int[originalBitLengths.length]; |
| for (int k = 0; k < permutation.length; k++) { |
| permutation[k] = k; |
| } |
| |
| int c = 0; |
| int[] sortedBitLengths = new int[originalBitLengths.length]; |
| for (int k = 0; k < originalBitLengths.length; k++) { |
| // iterate over the values |
| for (int l = 0; l < originalBitLengths.length; l++) { |
| // look for the value in the original array |
| if (originalBitLengths[l] == k) { |
| // put the value at the current position in the sorted array... |
| sortedBitLengths[c] = k; |
| |
| // ...and memorize the permutation |
| permutation[c] = l; |
| |
| c++; |
| } |
| } |
| } |
| |
| // decode the values of the tree |
| int code = 0; |
| int codeIncrement = 0; |
| int lastBitLength = 0; |
| |
| int[] codes = new int[totalNumberOfValues]; |
| |
| for (int i = totalNumberOfValues - 1; i >= 0; i--) { |
| code = code + codeIncrement; |
| if (sortedBitLengths[i] != lastBitLength) { |
| lastBitLength = sortedBitLengths[i]; |
| codeIncrement = 1 << (16 - lastBitLength); |
| } |
| codes[permutation[i]] = code; |
| } |
| |
| // build the tree |
| BinaryTree tree = new BinaryTree(maxLength); |
| |
| for (int k = 0; k < codes.length; k++) { |
| int bitLength = originalBitLengths[k]; |
| if (bitLength > 0) { |
| tree.addLeaf(0, Integer.reverse(codes[k] << 16), bitLength, k); |
| } |
| } |
| |
| return tree; |
| } |
| } |