/*
* #%L
* Fork of JAI Image I/O Tools.
* %%
* Copyright (C) 2008 - 2014 Open Microscopy Environment:
* - Board of Regents of the University of Wisconsin-Madison
* - Glencoe Software, Inc.
* - University of Dundee
* %%
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation are
* those of the authors and should not be interpreted as representing official
* policies, either expressed or implied, of any organization.
* #L%
*/
/*
* $RCSfile: BitToByteOutput.java,v $
* $Revision: 1.1 $
* $Date: 2005/02/11 05:02:07 $
* $State: Exp $
*
* Class: BitToByteOutput
*
* Description: Adapter to perform bit based output on a byte
* based one.
*
*
*
* COPYRIGHT:
*
* This software module was originally developed by Raphaël Grosbois and
* Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
* Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
* Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
* Centre France S.A) in the course of development of the JPEG2000
* standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
* software module is an implementation of a part of the JPEG 2000
* Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
* Systems AB and Canon Research Centre France S.A (collectively JJ2000
* Partners) agree not to assert against ISO/IEC and users of the JPEG
* 2000 Standard (Users) any of their rights under the copyright, not
* including other intellectual property rights, for this software module
* with respect to the usage by ISO/IEC and Users of this software module
* or modifications thereof for use in hardware or software products
* claiming conformance to the JPEG 2000 Standard. Those intending to use
* this software module in hardware or software products are advised that
* their use may infringe existing patents. The original developers of
* this software module, JJ2000 Partners and ISO/IEC assume no liability
* for use of this software module or modifications thereof. No license
* or right to this software module is granted for non JPEG 2000 Standard
* conforming products. JJ2000 Partners have full right to use this
* software module for his/her own purpose, assign or donate this
* software module to any third party and to inhibit third parties from
* using this software module for non JPEG 2000 Standard conforming
* products. This copyright notice must be included in all copies or
* derivative works of this software module.
*
* Copyright (c) 1999/2000 JJ2000 Partners.
* */
package jj2000.j2k.entropy.encoder;
import jj2000.j2k.io.*;
/**
* This class provides an adapter to perform bit based output on byte based
* output objects that inherit from a 'ByteOutputBuffer' class. This class
* implements the bit stuffing policy needed for the 'selective arithmetic
* coding bypass' mode of the entropy coder. This class also delays the output
* of a trailing 0xFF, since they are synthetized be the decoder.
* */
class BitToByteOutput {
/** Whether or not predictable termination is requested. This value is
* important when the last byte before termination is an 0xFF */
private boolean isPredTerm = false;
/** The alternating sequence of 0's and 1's used for byte padding */
static final int PAD_SEQ = 0x2A;
/** Flag that indicates if an FF has been delayed */
boolean delFF = false;
/** The byte based output */
ByteOutputBuffer out;
/** The bit buffer */
int bbuf;
/** The position of the next bit to put in the bit buffer. When it is 7
* the bit buffer 'bbuf' is empty. The value should always be between 7
* and 0 (i.e. if it gets to -1, the bit buffer should be immediately
* written to the byte output). */
int bpos = 7;
/** The number of written bytes (excluding the bit buffer) */
int nb = 0;
/**
* Instantiates a new 'BitToByteOutput' object that uses 'out' as the
* underlying byte based output.
*
* @param out The underlying byte based output
* */
BitToByteOutput(ByteOutputBuffer out) {
this.out = out;
}
/**
* Writes to the bit stream the symbols contained in the 'symbuf'
* buffer. The least significant bit of each element in 'symbuf'is
* written.
*
* @param symbuf The symbols to write
*
* @param nsym The number of symbols in symbuf
* */
final void writeBits(int[] symbuf, int nsym) {
int i;
int bbuf,bpos;
bbuf = this.bbuf;
bpos = this.bpos;
// Write symbol by symbol to bit buffer
for (i=0; i<nsym; i++) {
bbuf |= (symbuf[i]&0x01)<<(bpos--);
if (bpos<0) { // Bit buffer is full, write it
if (bbuf != 0xFF) { // No bit-stuffing needed
if (delFF) { // Output delayed 0xFF if any
out.write(0xFF);
delFF = false;
nb++;
}
out.write(bbuf);
nb++;
bpos = 7;
}
else { // We need to do bit stuffing on next byte
delFF = true;
bpos = 6; // One less bit in next byte
}
bbuf = 0;
}
}
this.bbuf = bbuf;
this.bpos = bpos;
}
/**
* Write a bit to the output. The least significant bit of 'bit' is
* written to the output.
*
* @param bit
* */
final void writeBit(int bit) {
bbuf |= (bit&0x01)<<(bpos--);
if (bpos<0) {
if (bbuf != 0xFF) { // No bit-stuffing needed
if (delFF) { // Output delayed 0xFF if any
out.write(0xFF);
delFF = false;
nb++;
}
// Output the bit buffer
out.write(bbuf);
nb++;
bpos = 7;
}
else { // We need to do bit stuffing on next byte
delFF = true;
bpos = 6; // One less bit in next byte
}
bbuf = 0;
}
}
/**
* Writes the contents of the bit buffer and byte aligns the output by
* filling bits with an alternating sequence of 0's and 1's.
* */
void flush() {
if (delFF) { // There was a bit stuffing
if (bpos != 6) { // Bit buffer is not empty
// Output delayed 0xFF
out.write(0xFF);
delFF = false;
nb++;
// Pad to byte boundary with an alternating sequence of 0's
// and 1's.
bbuf |= (PAD_SEQ >>> (6-bpos));
// Output the bit buffer
out.write(bbuf);
nb++;
bpos = 7;
bbuf = 0;
}else if(isPredTerm) {
out.write(0xFF);
nb++;
out.write(0x2A);
nb++;
bpos = 7;
bbuf = 0;
delFF = false;
}
}
else { // There was no bit stuffing
if (bpos != 7) { // Bit buffer is not empty
// Pad to byte boundary with an alternating sequence of 0's and
// 1's.
bbuf |= (PAD_SEQ >>> (6-bpos));
// Output the bit buffer (bbuf can not be 0xFF)
out.write(bbuf);
nb++;
bpos = 7;
bbuf = 0;
}
}
}
/**
* Terminates the bit stream by calling 'flush()' and then 'reset()'.
* */
public int terminate() {
flush();
int savedNb = nb;
reset();
return savedNb;
}
/**
* Resets the bit buffer to empty, without writing anything to the
* underlying byte output, and resets the byte count. The underlying byte
* output is NOT reset.
* */
void reset() {
delFF = false;
bpos = 7;
bbuf = 0;
nb = 0;
}
/**
* Returns the length, in bytes, of the output bit stream as written by
* this object. If the output bit stream does not have an integer number
* of bytes in length then it is rounded to the next integer.
*
* @return The length, in bytes, of the output bit stream.
* */
int length() {
if (delFF) {
// If bit buffer is empty we just need 'nb' bytes. If not we need
// the delayed FF and the padded bit buffer.
return nb + 2;
}
else {
// If the bit buffer is empty, we just need 'nb' bytes. If not, we
// add length of the padded bit buffer
return nb + ((bpos==7) ? 0 : 1);
}
}
/**
* Set the flag according to whether or not the predictable termination is
* requested.
*
* @param isPredTerm Whether or not predictable termination is requested.
* */
void setPredTerm(boolean isPredTerm) {
this.isPredTerm = isPredTerm;
}
}