/*
* Copyright (c) 2011 Matthew Francis
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.itadaki.bzip2;
import java.io.IOException;
import java.io.OutputStream;
/**
* <p>
* An OutputStream wrapper that allows the writing of single bit booleans, unary
* numbers, bit strings of arbitrary length (up to 24 bits), and bit aligned
* 32-bit integers. A single byte at a time is written to the wrapped stream
* when sufficient bits have been accumulated
*/
public class BZip2BitOutputStream {
/**
* The stream to which bits are written
*/
private final OutputStream outputStream;
/**
* A buffer of bits waiting to be written to the output stream
*/
private int bitBuffer;
/**
* The number of bits currently buffered in {@link #bitBuffer}
*/
private int bitCount;
/**
* The number of bits that have been written to the wrapped OutputStream
*/
private long bitsWritten;
/**
* Writes a single bit to the wrapped output stream
*
* @param value
* The bit to write
* @throws IOException
* if an error occurs writing to the stream
*/
public void writeBoolean(final boolean value) throws IOException {
int bitCount = this.bitCount + 1;
int bitBuffer = this.bitBuffer | ((value ? 1 : 0) << (32 - bitCount));
if (bitCount == 8) {
this.outputStream.write(bitBuffer >>> 24);
bitBuffer = 0;
bitCount = 0;
bitsWritten += 8;
}
this.bitBuffer = bitBuffer;
this.bitCount = bitCount;
}
/**
* Writes a zero-terminated unary number to the wrapped output stream
*
* @param value
* The number to write (must be non-negative)
* @throws IOException
* if an error occurs writing to the stream
*/
public void writeUnary(int value) throws IOException {
while (value-- > 0) {
writeBoolean(true);
}
writeBoolean(false);
}
/**
* Writes up to 24 bits to the wrapped output stream
*
* @param count
* The number of bits to write (maximum 24)
* @param value
* The bits to write
* @throws IOException
* if an error occurs writing to the stream
*/
public void writeBits(final int count, final int value) throws IOException {
int bitCount = this.bitCount;
int bitBuffer = this.bitBuffer | ((value << (32 - count)) >>> bitCount);
bitCount += count;
while (bitCount >= 8) {
this.outputStream.write(bitBuffer >>> 24);
bitBuffer <<= 8;
bitCount -= 8;
bitsWritten += 8;
}
this.bitBuffer = bitBuffer;
this.bitCount = bitCount;
}
/**
* Writes an integer as 32 bits of output
*
* @param value
* The integer to write
* @throws IOException
* if an error occurs writing to the stream
*/
public void writeInteger(final int value) throws IOException {
writeBits(16, (value >>> 16) & 0xffff);
writeBits(16, value & 0xffff);
}
/**
* Writes any remaining bits to the output stream, zero padding to a whole
* byte as required
*
* @throws IOException
* if an error occurs writing to the stream
*/
public void flush() throws IOException {
if (this.bitCount > 0) {
writeBits(8 - this.bitCount, 0);
}
this.bitCount = 0;
}
/**
* @param outputStream
* The OutputStream to wrap
*/
public BZip2BitOutputStream(final OutputStream outputStream) {
this.outputStream = outputStream;
}
/**
* @return The total bit count. Number of bits written to the OutputStream +
* Number of bits in the buffer.
*/
public long totalBitCount() {
return bitsWritten + bitCount;
}
}