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author
Douglas Crockford
committed
JSONzip
1 parent 327e9a5 commit 0cdef7d

14 files changed

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lines changed

‎zip/BitInputStream.java

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package org.json.zip;
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import java.io.IOException;
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import java.io.InputStream;
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/*
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Copyright (c) 2013 JSON.org
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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The Software shall be used for Good, not Evil.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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/**
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* This is a big endian bit reader. It reads its bits from an InputStream.
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*
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* @version 2013-04-18
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*
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*/
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public class BitInputStream implements BitReader {
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/**
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* 2^n - 1
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*/
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static final int[] mask = { 0, 1, 3, 7, 15, 31, 63, 127, 255 };
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/**
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* The number of bits remaining in the current byte.
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*/
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private int available = 0;
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/**
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* Up to a byte's worth of unread bits.
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*/
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private int unread = 0;
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/**
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* The source of the bits.
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*/
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private InputStream in;
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/**
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* The number of bits read so far. This is used in padding.
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*/
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private long nrBits = 0;
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/**
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* Make a BitReader from an InputStream. The BitReader will take bytes from
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* the InputStream and unpack them into bits.
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*
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* @param in
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* An InputStream.
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*/
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public BitInputStream(InputStream in) {
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this.in = in;
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}
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/**
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* Make a BitReader. The first byte is passed in explicitly, the remaining
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* bytes are obtained from the InputStream. This makes it possible to look
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* at the first byte of a stream before deciding that it should be read as
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* bits.
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*
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* @param in
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* An InputStream
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* @param firstByte
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* The first byte, which was probably read from in.
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*/
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public BitInputStream(InputStream in, int firstByte) {
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this.in = in;
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this.unread = firstByte;
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this.available = 8;
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}
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/**
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* Read one bit.
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*
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* @return true if it is a 1 bit.
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*/
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public boolean bit() throws IOException {
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return read(1) != 0;
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}
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/**
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* Get the number of bits that have been read from this BitInputStream.
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* This includes pad bits that have been skipped, but might not include
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* bytes that have been read from the underlying InputStream that have not
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* yet been delivered as bits.
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*
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* @return The number of bits read so far.
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*/
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public long nrBits() {
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return this.nrBits;
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}
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/**
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* Check that the rest of the block has been padded with zeroes.
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*
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* @param factor
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* The size of the block to pad. This will typically be 8, 16,
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* 32, 64, 128, 256, etc.
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* @return true if the block was zero padded, or false if the the padding
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* contains any one bits.
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* @throws IOException
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*/
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public boolean pad(int factor) throws IOException {
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int padding = factor - (int) (this.nrBits % factor);
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boolean result = true;
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for (int i = 0; i < padding; i += 1) {
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if (bit()) {
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result = false;
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}
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}
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return result;
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}
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/**
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* Read some bits.
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*
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* @param width
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* The number of bits to read. (0..32)
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* @throws IOException
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* @return the bits
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*/
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public int read(int width) throws IOException {
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if (width == 0) {
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return 0;
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}
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if (width < 0 || width > 32) {
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throw new IOException("Bad read width.");
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}
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int result = 0;
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while (width > 0) {
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if (this.available == 0) {
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this.unread = this.in.read();
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if (this.unread < 0) {
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throw new IOException("Attempt to read past end.");
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}
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this.available = 8;
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}
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int take = width;
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if (take > this.available) {
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take = this.available;
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}
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result |= ((this.unread >>> (this.available - take)) & mask[take])
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<< (width - take);
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this.nrBits += take;
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this.available -= take;
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width -= take;
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}
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return result;
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}
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}

‎zip/BitOutputStream.java

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package org.json.zip;
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import java.io.IOException;
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import java.io.OutputStream;
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/*
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Copyright (c) 2013 JSON.org
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13+
copies of the Software, and to permit persons to whom the Software is
14+
furnished to do so, subject to the following conditions:
15+
16+
The above copyright notice and this permission notice shall be included in all
17+
copies or substantial portions of the Software.
18+
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The Software shall be used for Good, not Evil.
20+
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
22+
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
23+
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
24+
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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/**
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* This is a big endian bit writer. It writes its bits to an OutputStream.
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*
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* @version 2013-04-18
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*
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*/
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public class BitOutputStream implements BitWriter {
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/**
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* The number of bits written.
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*/
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private long nrBits = 0;
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/**
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* The destination of the bits.
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*/
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private OutputStream out;
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/**
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* Holder of bits not yet written.
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*/
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private int unwritten;
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/**
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* The number of unused bits in this.unwritten.
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*/
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private int vacant = 8;
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/**
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* Use an OutputStream to produce a BitWriter. The BitWriter will send its
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* bits to the OutputStream as each byte is filled.
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*
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* @param out
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* An Output Stream
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*/
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public BitOutputStream(OutputStream out) {
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this.out = out;
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}
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/**
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* Returns the number of bits that have been written to this
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* bitOutputStream. This may include bits that have not yet been written
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* to the underlying outputStream.
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*/
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public long nrBits() {
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return this.nrBits;
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}
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/**
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* Write a 1 bit.
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*
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* @throws IOException
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*/
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public void one() throws IOException {
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write(1, 1);
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}
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/**
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* Pad the rest of the block with zeroes and flush. pad(8) flushes the last
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* unfinished byte. The underlying OutputStream will be flushed.
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*
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* @param factor
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* The size of the block to pad. This will typically be 8, 16,
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* 32, 64, 128, 256, etc.
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* @return this
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* @throws IOException
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*/
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public void pad(int factor) throws IOException {
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int padding = factor - (int) (nrBits % factor);
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int excess = padding & 7;
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if (excess > 0) {
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this.write(0, excess);
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padding -= excess;
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}
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while (padding > 0) {
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this.write(0, 8);
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padding -= 8;
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}
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this.out.flush();
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}
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/**
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* Write some bits. Up to 32 bits can be written at a time.
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*
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* @param bits
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* The bits to be written.
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* @param width
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* The number of bits to write. (0..32)
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* @throws IOException
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*/
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public void write(int bits, int width) throws IOException {
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if (bits == 0 && width == 0) {
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return;
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}
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if (width <= 0 || width > 32) {
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throw new IOException("Bad write width.");
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}
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while (width > 0) {
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int actual = width;
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if (actual > this.vacant) {
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actual = this.vacant;
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}
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this.unwritten |= ((bits >>> (width - actual)) &
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BitInputStream.mask[actual]) << (this.vacant - actual);
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width -= actual;
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nrBits += actual;
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this.vacant -= actual;
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if (this.vacant == 0) {
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this.out.write(this.unwritten);
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this.unwritten = 0;
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this.vacant = 8;
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}
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}
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}
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/**
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* Write a 0 bit.
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*
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* @throws IOException
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*/
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public void zero() throws IOException {
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write(0, 1);
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}
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}

‎zip/BitReader.java

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package org.json.zip;
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import java.io.IOException;
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public interface BitReader {
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/**
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* Read one bit.
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*
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* @return true if it is a 1 bit.
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*/
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public boolean bit() throws IOException;
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/**
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* Returns the number of bits that have been read from this bitreader.
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*
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* @return The number of bits read so far.
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*/
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public long nrBits();
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/**
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* Check that the rest of the block has been padded with zeroes.
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*
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* @param factor
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* The size in bits of the block to pad. This will typically be
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* 8, 16, 32, 64, 128, 256, etc.
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* @return true if the block was zero padded, or false if the the padding
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* contained any one bits.
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* @throws IOException
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*/
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public boolean pad(int factor) throws IOException;
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/**
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* Read some bits.
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*
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* @param width
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* The number of bits to read. (0..32)
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* @throws IOException
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* @return the bits
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*/
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public int read(int width) throws IOException;
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}

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