svn propset svn:eol-style native
git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1738435 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Javen O'Neal
parent
d7981342e0
commit
8898db6b2e
@ -1,273 +1,273 @@
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/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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||||
The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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||||
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
|
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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||||
limitations under the License.
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==================================================================== */
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package org.apache.poi.util;
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import java.io.IOException;
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import java.io.InputStream;
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/**
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* Wrapper of InputStream which provides Run Length Encoding (RLE)
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* decompression on the fly. Uses MS-OVBA decompression algorithm. See
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* http://download.microsoft.com/download/2/4/8/24862317-78F0-4C4B-B355-C7B2C1D997DB/[MS-OVBA].pdf
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*/
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public class RLEDecompressingInputStream extends InputStream {
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/**
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* Bitmasks for performance
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*/
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private static final int[] POWER2 = new int[] { 0x0001, // 0
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0x0002, // 1
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0x0004, // 2
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0x0008, // 3
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0x0010, // 4
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0x0020, // 5
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0x0040, // 6
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0x0080, // 7
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0x0100, // 8
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0x0200, // 9
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0x0400, // 10
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0x0800, // 11
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0x1000, // 12
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0x2000, // 13
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0x4000, // 14
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0x8000 // 15
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};
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/** the wrapped inputstream */
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private InputStream in;
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/** a byte buffer with size 4096 for storing a single chunk */
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private byte[] buf;
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/** the current position in the byte buffer for reading */
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private int pos;
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/** the number of bytes in the byte buffer */
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private int len;
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/**
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* Creates a new wrapper RLE Decompression InputStream.
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*
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* @param in
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* @throws IOException
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*/
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public RLEDecompressingInputStream(InputStream in) throws IOException {
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this.in = in;
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buf = new byte[4096];
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pos = 0;
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int header = in.read();
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if (header != 0x01) {
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throw new IllegalArgumentException(String.format("Header byte 0x01 expected, received 0x%02X", header & 0xFF));
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}
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len = readChunk();
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}
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@Override
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public int read() throws IOException {
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if (len == -1) {
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return -1;
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}
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if (pos >= len) {
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if ((len = readChunk()) == -1) {
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return -1;
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}
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}
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return buf[pos++];
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}
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@Override
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public int read(byte[] b) throws IOException {
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return read(b, 0, b.length);
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}
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@Override
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public int read(byte[] b, int off, int l) throws IOException {
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if (len == -1) {
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return -1;
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}
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int offset = off;
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int length = l;
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while (length > 0) {
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if (pos >= len) {
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if ((len = readChunk()) == -1) {
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return offset > off ? offset - off : -1;
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}
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}
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int c = Math.min(length, len - pos);
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System.arraycopy(buf, pos, b, offset, c);
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pos += c;
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length -= c;
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offset += c;
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}
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return l;
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}
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@Override
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public long skip(long n) throws IOException {
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long length = n;
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while (length > 0) {
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if (pos >= len) {
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if ((len = readChunk()) == -1) {
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return -1;
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}
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}
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int c = (int) Math.min(n, len - pos);
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pos += c;
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length -= c;
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}
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return n;
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}
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@Override
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public int available() {
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return (len > 0 ? len - pos : 0);
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}
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@Override
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public void close() throws IOException {
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in.close();
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}
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/**
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* Reads a single chunk from the underlying inputstream.
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*
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* @return
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* @throws IOException
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*/
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private int readChunk() throws IOException {
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pos = 0;
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int w = readShort(in);
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if (w == -1) {
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return -1;
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}
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int chunkSize = (w & 0x0FFF) + 1; // plus 3 bytes minus 2 for the length
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if ((w & 0x7000) != 0x3000) {
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throw new IllegalArgumentException(String.format("Chunksize header A should be 0x3000, received 0x%04X", w & 0xE000));
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}
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boolean rawChunk = (w & 0x8000) == 0;
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if (rawChunk) {
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if (in.read(buf, 0, chunkSize) < chunkSize) {
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throw new IllegalStateException(String.format("Not enough bytes read, expected %d", chunkSize));
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}
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return chunkSize;
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} else {
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int inOffset = 0;
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int outOffset = 0;
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while (inOffset < chunkSize) {
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int tokenFlags = in.read();
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inOffset++;
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if (tokenFlags == -1) {
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break;
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}
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for (int n = 0; n < 8; n++) {
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if (inOffset >= chunkSize) {
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break;
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}
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if ((tokenFlags & POWER2[n]) == 0) {
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// literal
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final int b = in.read();
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if (b == -1) {
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return -1;
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}
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buf[outOffset++] = (byte) b;
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inOffset++;
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} else {
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// compressed token
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int token = readShort(in);
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if (token == -1) {
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return -1;
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}
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inOffset += 2;
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int copyLenBits = getCopyLenBits(outOffset - 1);
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int copyOffset = (token >> (copyLenBits)) + 1;
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int copyLen = (token & (POWER2[copyLenBits] - 1)) + 3;
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int startPos = outOffset - copyOffset;
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int endPos = startPos + copyLen;
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for (int i = startPos; i < endPos; i++) {
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buf[outOffset++] = buf[i];
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}
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}
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}
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}
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return outOffset;
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}
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}
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/**
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* Helper method to determine how many bits in the CopyToken are used for the CopyLength.
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*
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* @param offset
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* @return
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*/
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static int getCopyLenBits(int offset) {
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for (int n = 11; n >= 4; n--) {
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if ((offset & POWER2[n]) != 0) {
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return 15 - n;
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}
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}
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return 12;
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}
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/**
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* Convenience method for read a 2-bytes short in little endian encoding.
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*
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* @return
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* @throws IOException
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*/
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public int readShort() throws IOException {
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return readShort(this);
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}
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/**
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* Convenience method for read a 4-bytes int in little endian encoding.
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*
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* @return
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* @throws IOException
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*/
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public int readInt() throws IOException {
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return readInt(this);
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}
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private int readShort(InputStream stream) throws IOException {
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int b0, b1;
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if ((b0 = stream.read()) == -1) {
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return -1;
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}
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if ((b1 = stream.read()) == -1) {
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return -1;
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}
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return (b0 & 0xFF) | ((b1 & 0xFF) << 8);
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}
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private int readInt(InputStream stream) throws IOException {
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int b0, b1, b2, b3;
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if ((b0 = stream.read()) == -1) {
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return -1;
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}
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if ((b1 = stream.read()) == -1) {
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return -1;
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}
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if ((b2 = stream.read()) == -1) {
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return -1;
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}
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if ((b3 = stream.read()) == -1) {
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return -1;
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}
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return (b0 & 0xFF) | ((b1 & 0xFF) << 8) | ((b2 & 0xFF) << 16) | ((b3 & 0xFF) << 24);
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}
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}
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/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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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
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||||
|
||||
Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
|
||||
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
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See the License for the specific language governing permissions and
|
||||
limitations under the License.
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||||
==================================================================== */
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package org.apache.poi.util;
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import java.io.IOException;
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import java.io.InputStream;
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/**
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* Wrapper of InputStream which provides Run Length Encoding (RLE)
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* decompression on the fly. Uses MS-OVBA decompression algorithm. See
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* http://download.microsoft.com/download/2/4/8/24862317-78F0-4C4B-B355-C7B2C1D997DB/[MS-OVBA].pdf
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*/
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public class RLEDecompressingInputStream extends InputStream {
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|
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/**
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* Bitmasks for performance
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*/
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private static final int[] POWER2 = new int[] { 0x0001, // 0
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0x0002, // 1
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0x0004, // 2
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0x0008, // 3
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0x0010, // 4
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0x0020, // 5
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0x0040, // 6
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0x0080, // 7
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0x0100, // 8
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0x0200, // 9
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0x0400, // 10
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0x0800, // 11
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0x1000, // 12
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0x2000, // 13
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0x4000, // 14
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0x8000 // 15
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};
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/** the wrapped inputstream */
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private InputStream in;
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|
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/** a byte buffer with size 4096 for storing a single chunk */
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private byte[] buf;
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|
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/** the current position in the byte buffer for reading */
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private int pos;
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/** the number of bytes in the byte buffer */
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private int len;
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|
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/**
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* Creates a new wrapper RLE Decompression InputStream.
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*
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* @param in
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* @throws IOException
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*/
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public RLEDecompressingInputStream(InputStream in) throws IOException {
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this.in = in;
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buf = new byte[4096];
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pos = 0;
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int header = in.read();
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if (header != 0x01) {
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throw new IllegalArgumentException(String.format("Header byte 0x01 expected, received 0x%02X", header & 0xFF));
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}
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len = readChunk();
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}
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@Override
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public int read() throws IOException {
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if (len == -1) {
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return -1;
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}
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if (pos >= len) {
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if ((len = readChunk()) == -1) {
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return -1;
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}
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}
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return buf[pos++];
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}
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@Override
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public int read(byte[] b) throws IOException {
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return read(b, 0, b.length);
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}
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@Override
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public int read(byte[] b, int off, int l) throws IOException {
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if (len == -1) {
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return -1;
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}
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int offset = off;
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int length = l;
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while (length > 0) {
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if (pos >= len) {
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if ((len = readChunk()) == -1) {
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return offset > off ? offset - off : -1;
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}
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}
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int c = Math.min(length, len - pos);
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System.arraycopy(buf, pos, b, offset, c);
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pos += c;
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length -= c;
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offset += c;
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}
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return l;
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}
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@Override
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public long skip(long n) throws IOException {
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long length = n;
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while (length > 0) {
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if (pos >= len) {
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if ((len = readChunk()) == -1) {
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return -1;
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}
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}
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int c = (int) Math.min(n, len - pos);
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pos += c;
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length -= c;
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}
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return n;
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}
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@Override
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public int available() {
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return (len > 0 ? len - pos : 0);
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}
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@Override
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public void close() throws IOException {
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in.close();
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}
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||||
|
||||
/**
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* Reads a single chunk from the underlying inputstream.
|
||||
*
|
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* @return
|
||||
* @throws IOException
|
||||
*/
|
||||
private int readChunk() throws IOException {
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pos = 0;
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int w = readShort(in);
|
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if (w == -1) {
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return -1;
|
||||
}
|
||||
int chunkSize = (w & 0x0FFF) + 1; // plus 3 bytes minus 2 for the length
|
||||
if ((w & 0x7000) != 0x3000) {
|
||||
throw new IllegalArgumentException(String.format("Chunksize header A should be 0x3000, received 0x%04X", w & 0xE000));
|
||||
}
|
||||
boolean rawChunk = (w & 0x8000) == 0;
|
||||
if (rawChunk) {
|
||||
if (in.read(buf, 0, chunkSize) < chunkSize) {
|
||||
throw new IllegalStateException(String.format("Not enough bytes read, expected %d", chunkSize));
|
||||
}
|
||||
return chunkSize;
|
||||
} else {
|
||||
int inOffset = 0;
|
||||
int outOffset = 0;
|
||||
while (inOffset < chunkSize) {
|
||||
int tokenFlags = in.read();
|
||||
inOffset++;
|
||||
if (tokenFlags == -1) {
|
||||
break;
|
||||
}
|
||||
for (int n = 0; n < 8; n++) {
|
||||
if (inOffset >= chunkSize) {
|
||||
break;
|
||||
}
|
||||
if ((tokenFlags & POWER2[n]) == 0) {
|
||||
// literal
|
||||
final int b = in.read();
|
||||
if (b == -1) {
|
||||
return -1;
|
||||
}
|
||||
buf[outOffset++] = (byte) b;
|
||||
inOffset++;
|
||||
} else {
|
||||
// compressed token
|
||||
int token = readShort(in);
|
||||
if (token == -1) {
|
||||
return -1;
|
||||
}
|
||||
inOffset += 2;
|
||||
int copyLenBits = getCopyLenBits(outOffset - 1);
|
||||
int copyOffset = (token >> (copyLenBits)) + 1;
|
||||
int copyLen = (token & (POWER2[copyLenBits] - 1)) + 3;
|
||||
int startPos = outOffset - copyOffset;
|
||||
int endPos = startPos + copyLen;
|
||||
for (int i = startPos; i < endPos; i++) {
|
||||
buf[outOffset++] = buf[i];
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
return outOffset;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Helper method to determine how many bits in the CopyToken are used for the CopyLength.
|
||||
*
|
||||
* @param offset
|
||||
* @return
|
||||
*/
|
||||
static int getCopyLenBits(int offset) {
|
||||
for (int n = 11; n >= 4; n--) {
|
||||
if ((offset & POWER2[n]) != 0) {
|
||||
return 15 - n;
|
||||
}
|
||||
}
|
||||
return 12;
|
||||
}
|
||||
|
||||
/**
|
||||
* Convenience method for read a 2-bytes short in little endian encoding.
|
||||
*
|
||||
* @return
|
||||
* @throws IOException
|
||||
*/
|
||||
public int readShort() throws IOException {
|
||||
return readShort(this);
|
||||
}
|
||||
|
||||
/**
|
||||
* Convenience method for read a 4-bytes int in little endian encoding.
|
||||
*
|
||||
* @return
|
||||
* @throws IOException
|
||||
*/
|
||||
public int readInt() throws IOException {
|
||||
return readInt(this);
|
||||
}
|
||||
|
||||
private int readShort(InputStream stream) throws IOException {
|
||||
int b0, b1;
|
||||
if ((b0 = stream.read()) == -1) {
|
||||
return -1;
|
||||
}
|
||||
if ((b1 = stream.read()) == -1) {
|
||||
return -1;
|
||||
}
|
||||
return (b0 & 0xFF) | ((b1 & 0xFF) << 8);
|
||||
}
|
||||
|
||||
private int readInt(InputStream stream) throws IOException {
|
||||
int b0, b1, b2, b3;
|
||||
if ((b0 = stream.read()) == -1) {
|
||||
return -1;
|
||||
}
|
||||
if ((b1 = stream.read()) == -1) {
|
||||
return -1;
|
||||
}
|
||||
if ((b2 = stream.read()) == -1) {
|
||||
return -1;
|
||||
}
|
||||
if ((b3 = stream.read()) == -1) {
|
||||
return -1;
|
||||
}
|
||||
return (b0 & 0xFF) | ((b1 & 0xFF) << 8) | ((b2 & 0xFF) << 16) | ((b3 & 0xFF) << 24);
|
||||
}
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user